Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices
Identifieur interne : 002C46 ( Pmc/Corpus ); précédent : 002C45; suivant : 002C47Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices
Auteurs : Ninita Lindfors ; Henrik Lund ; Hans Johansson ; Annika EkestubbeSource :
- European Journal of Radiology Open [ 2352-0477 ] ; 2017.
Abstract
Patient head position can affect the image quality in CBCT-examinations. CNR values can be used to evaluate image quality. Inherent factors influence effective dose variations between CBCT-devices.
Url:
DOI: 10.1016/j.ejro.2017.10.001
PubMed: 29159206
PubMed Central: 5675893
Links to Exploration step
PMC:5675893Le document en format XML
<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices</title><author><name sortKey="Lindfors, Ninita" sort="Lindfors, Ninita" uniqKey="Lindfors N" first="Ninita" last="Lindfors">Ninita Lindfors</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation><affiliation><nlm:aff id="aff0010">Institute for Postgraduate Dental Education, Jönköping, Sweden</nlm:aff></affiliation></author><author><name sortKey="Lund, Henrik" sort="Lund, Henrik" uniqKey="Lund H" first="Henrik" last="Lund">Henrik Lund</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation></author><author><name sortKey="Johansson, Hans" sort="Johansson, Hans" uniqKey="Johansson H" first="Hans" last="Johansson">Hans Johansson</name><affiliation><nlm:aff id="aff0015">Department of Medical Physics/Department of Oncology, Ryhov County Hospital, Jönköping, Sweden</nlm:aff></affiliation></author><author><name sortKey="Ekestubbe, Annika" sort="Ekestubbe, Annika" uniqKey="Ekestubbe A" first="Annika" last="Ekestubbe">Annika Ekestubbe</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">29159206</idno><idno type="pmc">5675893</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5675893</idno><idno type="RBID">PMC:5675893</idno><idno type="doi">10.1016/j.ejro.2017.10.001</idno><date when="2017">2017</date><idno type="wicri:Area/Pmc/Corpus">002C46</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">002C46</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices</title><author><name sortKey="Lindfors, Ninita" sort="Lindfors, Ninita" uniqKey="Lindfors N" first="Ninita" last="Lindfors">Ninita Lindfors</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation><affiliation><nlm:aff id="aff0010">Institute for Postgraduate Dental Education, Jönköping, Sweden</nlm:aff></affiliation></author><author><name sortKey="Lund, Henrik" sort="Lund, Henrik" uniqKey="Lund H" first="Henrik" last="Lund">Henrik Lund</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation></author><author><name sortKey="Johansson, Hans" sort="Johansson, Hans" uniqKey="Johansson H" first="Hans" last="Johansson">Hans Johansson</name><affiliation><nlm:aff id="aff0015">Department of Medical Physics/Department of Oncology, Ryhov County Hospital, Jönköping, Sweden</nlm:aff></affiliation></author><author><name sortKey="Ekestubbe, Annika" sort="Ekestubbe, Annika" uniqKey="Ekestubbe A" first="Annika" last="Ekestubbe">Annika Ekestubbe</name><affiliation><nlm:aff id="aff0005">Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</nlm:aff></affiliation></author></analytic><series><title level="j">European Journal of Radiology Open</title><idno type="eISSN">2352-0477</idno><imprint><date when="2017">2017</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><title>Highlights</title><p><list list-type="simple"><list-item id="lsti0005"><label>•</label><p>Patient head position can affect the image quality in CBCT-examinations.</p></list-item><list-item id="lsti0010"><label>•</label><p>CNR values can be used to evaluate image quality.</p></list-item><list-item id="lsti0015"><label>•</label><p>Inherent factors influence effective dose variations between CBCT-devices.</p></list-item></list></p></div></front><back><div1 type="bibliography"><listBibl><biblStruct><analytic><author><name sortKey="Mozzo, P" uniqKey="Mozzo P">P. Mozzo</name></author><author><name sortKey="Procacci, C" uniqKey="Procacci C">C. Procacci</name></author><author><name sortKey="Tacconi, A" uniqKey="Tacconi A">A. Tacconi</name></author><author><name sortKey="Martini, P T" uniqKey="Martini P">P.T. Martini</name></author><author><name sortKey="Andreis, I A" uniqKey="Andreis I">I.A. Andreis</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Davies, A" uniqKey="Davies A">A. Davies</name></author><author><name sortKey="Patel, S" uniqKey="Patel S">S. Patel</name></author><author><name sortKey="Foschi, F" uniqKey="Foschi F">F. Foschi</name></author><author><name sortKey="Andiappan, M" uniqKey="Andiappan M">M. Andiappan</name></author><author><name sortKey="Mitchell, P J" uniqKey="Mitchell P">P.J. Mitchell</name></author><author><name sortKey="Mannocci, F" uniqKey="Mannocci F">F. Mannocci</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kapila, S D" uniqKey="Kapila S">S.D. Kapila</name></author><author><name sortKey="Nervina, J M" uniqKey="Nervina J">J.M. Nervina</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chan, H L" uniqKey="Chan H">H.L. Chan</name></author><author><name sortKey="Misch, K" uniqKey="Misch K">K. Misch</name></author><author><name sortKey="Wang, H L" uniqKey="Wang H">H.L. Wang</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bahadure, R N" uniqKey="Bahadure R">R.N. Bahadure</name></author><author><name sortKey="Thosar, N" uniqKey="Thosar N">N. Thosar</name></author><author><name sortKey="Khubchandani, M" uniqKey="Khubchandani M">M. Khubchandani</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Goodarzi Pour, D" uniqKey="Goodarzi Pour D">D. Goodarzi Pour</name></author><author><name sortKey="Romoozi, E" uniqKey="Romoozi E">E. Romoozi</name></author><author><name sortKey="Soleimani Shayesteh, Y" uniqKey="Soleimani Shayesteh Y">Y. Soleimani Shayesteh</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Nemtoi, A" uniqKey="Nemtoi A">A. Nemtoi</name></author><author><name sortKey="Czink, C" uniqKey="Czink C">C. Czink</name></author><author><name sortKey="Haba, D" uniqKey="Haba D">D. Haba</name></author><author><name sortKey="Gahleitner, A" uniqKey="Gahleitner A">A. Gahleitner</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Pauwels, R" uniqKey="Pauwels R">R. Pauwels</name></author><author><name sortKey="Araki, K" uniqKey="Araki K">K. Araki</name></author><author><name sortKey="Siewerdsen, J H" uniqKey="Siewerdsen J">J.H. Siewerdsen</name></author><author><name sortKey="Thongvigitmanee, S S" uniqKey="Thongvigitmanee S">S.S. Thongvigitmanee</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Suomalainen, A" uniqKey="Suomalainen A">A. Suomalainen</name></author><author><name sortKey="Kiljunen, T" uniqKey="Kiljunen T">T. Kiljunen</name></author><author><name sortKey="Kaser, Y" uniqKey="Kaser Y">Y. Kaser</name></author><author><name sortKey="Peltola, J" uniqKey="Peltola J">J. Peltola</name></author><author><name sortKey="Kortesniemi, M" uniqKey="Kortesniemi M">M. Kortesniemi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bornstein, M M" uniqKey="Bornstein M">M.M. Bornstein</name></author><author><name sortKey="Scarfe, W C" uniqKey="Scarfe W">W.C. Scarfe</name></author><author><name sortKey="Vaughn, V M" uniqKey="Vaughn V">V.M. Vaughn</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R. Jacobs</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Horner, K" uniqKey="Horner K">K. Horner</name></author><author><name sortKey="O Malley, L" uniqKey="O Malley L">L. O'Malley</name></author><author><name sortKey="Taylor, K" uniqKey="Taylor K">K. Taylor</name></author><author><name sortKey="Glenny, A M" uniqKey="Glenny A">A.M. Glenny</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Pauwels, R" uniqKey="Pauwels R">R. Pauwels</name></author><author><name sortKey="Silkosessak, O" uniqKey="Silkosessak O">O. Silkosessak</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R. Jacobs</name></author><author><name sortKey="Bogaerts, R" uniqKey="Bogaerts R">R. Bogaerts</name></author><author><name sortKey="Bosmans, H" uniqKey="Bosmans H">H. Bosmans</name></author><author><name sortKey="Panmekiate, S" uniqKey="Panmekiate S">S. Panmekiate</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bechara, B" uniqKey="Bechara B">B. Bechara</name></author><author><name sortKey="Mcmahan, C A" uniqKey="Mcmahan C">C.A. McMahan</name></author><author><name sortKey="Moore, W S" uniqKey="Moore W">W.S. Moore</name></author><author><name sortKey="Noujeim, M" uniqKey="Noujeim M">M. Noujeim</name></author><author><name sortKey="Geha, H" uniqKey="Geha H">H. Geha</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bechara, B" uniqKey="Bechara B">B. Bechara</name></author><author><name sortKey="Mcmahan, C A" uniqKey="Mcmahan C">C.A. McMahan</name></author><author><name sortKey="Moore, W S" uniqKey="Moore W">W.S. Moore</name></author><author><name sortKey="Noujeim, M" uniqKey="Noujeim M">M. Noujeim</name></author><author><name sortKey="Geha, H" uniqKey="Geha H">H. Geha</name></author><author><name sortKey="Teixeira, F B" uniqKey="Teixeira F">F.B. Teixeira</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Pauwels, R" uniqKey="Pauwels R">R. Pauwels</name></author><author><name sortKey="Stamatakis, H" uniqKey="Stamatakis H">H. Stamatakis</name></author><author><name sortKey="Manousaridis, G" uniqKey="Manousaridis G">G. Manousaridis</name></author><author><name sortKey="Walker, A" uniqKey="Walker A">A. Walker</name></author><author><name sortKey="Michielsen, K" uniqKey="Michielsen K">K. Michielsen</name></author><author><name sortKey="Bosmans, H" uniqKey="Bosmans H">H. Bosmans</name></author><author><name sortKey="Bogaerts, R" uniqKey="Bogaerts R">R. Bogaerts</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R. Jacobs</name></author><author><name sortKey="Horner, K" uniqKey="Horner K">K. Horner</name></author><author><name sortKey="Tsiklakis, K" uniqKey="Tsiklakis K">K. Tsiklakis</name></author><author><name sortKey="Consortium, S P" uniqKey="Consortium S">S.P. Consortium</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kalender, W A" uniqKey="Kalender W">W.A. Kalender</name></author><author><name sortKey="Deak, P" uniqKey="Deak P">P. Deak</name></author><author><name sortKey="Kellermeier, M" uniqKey="Kellermeier M">M. Kellermeier</name></author><author><name sortKey="Van Straten, M" uniqKey="Van Straten M">M. van Straten</name></author><author><name sortKey="Vollmar, S V" uniqKey="Vollmar S">S.V. Vollmar</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Choi, J W" uniqKey="Choi J">J.W. Choi</name></author><author><name sortKey="Lee, S S" uniqKey="Lee S">S.S. Lee</name></author><author><name sortKey="Choi, S C" uniqKey="Choi S">S.C. Choi</name></author><author><name sortKey="Heo, M S" uniqKey="Heo M">M.S. Heo</name></author><author><name sortKey="Huh, K H" uniqKey="Huh K">K.H. Huh</name></author><author><name sortKey="Yi, W J" uniqKey="Yi W">W.J. Yi</name></author><author><name sortKey="Kang, S R" uniqKey="Kang S">S.R. Kang</name></author><author><name sortKey="Han, D H" uniqKey="Han D">D.H. Han</name></author><author><name sortKey="Kim, E K" uniqKey="Kim E">E.K. Kim</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="J Morita Mfg Corp" uniqKey="J Morita Mfg Corp">J. Morita Mfg. Corp</name></author></analytic></biblStruct><biblStruct></biblStruct><biblStruct><analytic><author><name sortKey="Koivisto, J" uniqKey="Koivisto J">J. Koivisto</name></author><author><name sortKey="Kiljunen, T" uniqKey="Kiljunen T">T. Kiljunen</name></author><author><name sortKey="Tapiovaara, M" uniqKey="Tapiovaara M">M. Tapiovaara</name></author><author><name sortKey="Wolff, J" uniqKey="Wolff J">J. Wolff</name></author><author><name sortKey="Kortesniemi, M" uniqKey="Kortesniemi M">M. Kortesniemi</name></author></analytic></biblStruct><biblStruct></biblStruct><biblStruct><analytic><author><name sortKey="Bryant, J A" uniqKey="Bryant J">J.A. Bryant</name></author><author><name sortKey="Drage, N A" uniqKey="Drage N">N.A. Drage</name></author><author><name sortKey="Richmond, S" uniqKey="Richmond S">S. Richmond</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Koivisto, J" uniqKey="Koivisto J">J. Koivisto</name></author><author><name sortKey="Wolff, J" uniqKey="Wolff J">J. Wolff</name></author><author><name sortKey="Jarnstedt, J" uniqKey="Jarnstedt J">J. Jarnstedt</name></author><author><name sortKey="Dastidar, P" uniqKey="Dastidar P">P. Dastidar</name></author><author><name sortKey="Kortesniemi, M" uniqKey="Kortesniemi M">M. Kortesniemi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Katsumata, A" uniqKey="Katsumata A">A. Katsumata</name></author><author><name sortKey="Hirukawa, A" uniqKey="Hirukawa A">A. Hirukawa</name></author><author><name sortKey="Okumura, S" uniqKey="Okumura S">S. Okumura</name></author><author><name sortKey="Naitoh, M" uniqKey="Naitoh M">M. Naitoh</name></author><author><name sortKey="Fujishita, M" uniqKey="Fujishita M">M. Fujishita</name></author><author><name sortKey="Ariji, E" uniqKey="Ariji E">E. Ariji</name></author><author><name sortKey="Langlais, R P" uniqKey="Langlais R">R.P. Langlais</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ganguly, R" uniqKey="Ganguly R">R. Ganguly</name></author><author><name sortKey="Ramesh, A" uniqKey="Ramesh A">A. Ramesh</name></author><author><name sortKey="Pagni, S" uniqKey="Pagni S">S. Pagni</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Spin Neto, R" uniqKey="Spin Neto R">R. Spin-Neto</name></author><author><name sortKey="Gotfredsen, E" uniqKey="Gotfredsen E">E. Gotfredsen</name></author><author><name sortKey="Wenzel, A" uniqKey="Wenzel A">A. Wenzel</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Schulze, R" uniqKey="Schulze R">R. Schulze</name></author><author><name sortKey="Heil, U" uniqKey="Heil U">U. Heil</name></author><author><name sortKey="Gross, D" uniqKey="Gross D">D. Gross</name></author><author><name sortKey="Bruellmann, D D" uniqKey="Bruellmann D">D.D. Bruellmann</name></author><author><name sortKey="Dranischnikow, E" uniqKey="Dranischnikow E">E. Dranischnikow</name></author><author><name sortKey="Schwanecke, U" uniqKey="Schwanecke U">U. Schwanecke</name></author><author><name sortKey="Schoemer, E" uniqKey="Schoemer E">E. Schoemer</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Spin Neto, R" uniqKey="Spin Neto R">R. Spin-Neto</name></author><author><name sortKey="Wenzel, A" uniqKey="Wenzel A">A. Wenzel</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Al Okshi, A" uniqKey="Al Okshi A">A. Al-Okshi</name></author><author><name sortKey="Lindh, C" uniqKey="Lindh C">C. Lindh</name></author><author><name sortKey="Sale, H" uniqKey="Sale H">H. Sale</name></author><author><name sortKey="Gunnarsson, M" uniqKey="Gunnarsson M">M. Gunnarsson</name></author><author><name sortKey="Rohlin, M" uniqKey="Rohlin M">M. Rohlin</name></author></analytic></biblStruct></listBibl></div1></back></TEI><pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">Eur J Radiol Open</journal-id><journal-id journal-id-type="iso-abbrev">Eur J Radiol Open</journal-id><journal-title-group><journal-title>European Journal of Radiology Open</journal-title></journal-title-group><issn pub-type="epub">2352-0477</issn><publisher><publisher-name>Elsevier</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">29159206</article-id><article-id pub-id-type="pmc">5675893</article-id><article-id pub-id-type="publisher-id">S2352-0477(17)30034-5</article-id><article-id pub-id-type="doi">10.1016/j.ejro.2017.10.001</article-id><article-categories><subj-group subj-group-type="heading"><subject>Article</subject></subj-group></article-categories><title-group><article-title>Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices</article-title></title-group><contrib-group><contrib contrib-type="author"><name><surname>Lindfors</surname><given-names>Ninita</given-names></name><email>ninita.lindfors@rjl.se</email><xref rid="aff0005" ref-type="aff">a</xref><xref rid="aff0010" ref-type="aff">b</xref><xref rid="cor0005" ref-type="corresp">⁎</xref></contrib><contrib contrib-type="author"><name><surname>Lund</surname><given-names>Henrik</given-names></name><xref rid="aff0005" ref-type="aff">a</xref></contrib><contrib contrib-type="author"><name><surname>Johansson</surname><given-names>Hans</given-names></name><xref rid="aff0015" ref-type="aff">c</xref></contrib><contrib contrib-type="author"><name><surname>Ekestubbe</surname><given-names>Annika</given-names></name><xref rid="aff0005" ref-type="aff">a</xref></contrib></contrib-group><aff id="aff0005"><label>a</label>Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden</aff><aff id="aff0010"><label>b</label>Institute for Postgraduate Dental Education, Jönköping, Sweden</aff><aff id="aff0015"><label>c</label>Department of Medical Physics/Department of Oncology, Ryhov County Hospital, Jönköping, Sweden</aff><author-notes><corresp id="cor0005"><label>⁎</label>Corresponding author at: Department of Dentomaxillofacial Radiology, Institute for Postgraduate Dental Education, P.O. Box 1030, SE-551 11 Jönköping, Sweden.Institute for Postgraduate Dental EducationJönköpingSweden <email>ninita.lindfors@rjl.se</email></corresp></author-notes><pub-date pub-type="pmc-release"><day>01</day><month>11</month><year>2017</year></pub-date><pmc-comment> PMC Release delay is 0 months and 0 days and was based on .</pmc-comment>
<pub-date pub-type="collection"><year>2017</year></pub-date><pub-date pub-type="epub"><day>01</day><month>11</month><year>2017</year></pub-date><volume>4</volume><fpage>132</fpage><lpage>137</lpage><history><date date-type="received"><day>10</day><month>7</month><year>2017</year></date><date date-type="accepted"><day>20</day><month>10</month><year>2017</year></date></history><permissions><copyright-statement>© 2017 The Author(s)</copyright-statement><copyright-year>2017</copyright-year><license license-type="CC BY-NC-ND" xlink:href="http://creativecommons.org/licenses/by-nc-nd/4.0/"><license-p>This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).</license-p></license></permissions><abstract abstract-type="author-highlights" id="abs0005"><title>Highlights</title><p><list list-type="simple"><list-item id="lsti0005"><label>•</label><p>Patient head position can affect the image quality in CBCT-examinations.</p></list-item><list-item id="lsti0010"><label>•</label><p>CNR values can be used to evaluate image quality.</p></list-item><list-item id="lsti0015"><label>•</label><p>Inherent factors influence effective dose variations between CBCT-devices.</p></list-item></list></p></abstract><abstract id="abs0010"><sec><title>Objectives</title><p>The aim of this <italic>in vitro</italic> study was to evaluate how a deviation from the horizontal plane, affects the image quality in two different CBCT-devices.</p></sec><sec><title>Methods</title><p>A phantom head SK150 (RANDO, The Phantom Laboratory, Salem, NY, USA) was examined in two CBCT-units: Accuitomo 80 and Veraviewepocs 3D R100 (J. Morita Mfg. Corp. Kyoto, Japan). The phantom head was placed with the hard palate parallel to the horizontal plane and tilted 20 ° backwards. Exposures were performed with different field of views (FOVs), voxel sizes, slice thicknesses and exposure settings. Effective dose was calculated using PCXMC 2.0 (STUK, Helsinki, Finland). Image quality was assessed using contrast-to-noise-ratio (CNR). Region of interest (ROI) was set at three different levels of the mandibular bone and soft tissue, uni- and bilaterally in small and large FOVs, respectively. CNR values were calculated by CT-value and standard deviation for each ROI. Factor analysis was used to analyze the material.</p></sec><sec><title>Results</title><p>Tilting the phantom head backwards rendered significantly higher mean CNR values regardless of FOV. The effective dose was lower in small than in large FOVs and varied to a larger extent between CBCT-devices in large FOVs.</p></sec><sec><title>Conclusions</title><p>Head position can affect the image quality. Tilting the head backward improved image quality in the mandibular region. However, if influenced by other variables <italic>e.g.</italic> motion artifacts in a clinical situation, remains to be further investigated.</p></sec><sec><title>Advances in knowledge</title><p>Image quality assessed using CNR values to investigate the influence of different patient positions and FOVs.</p></sec></abstract><kwd-group id="kwd0005"><title>Keywords</title><kwd>Image quality</kwd><kwd>CBCT</kwd><kwd>Radiation dose</kwd><kwd>Patient position</kwd><kwd>FOV</kwd></kwd-group></article-meta></front><body><sec id="sec0005"><label>1</label><title>Introduction</title><p>Cone beam computed tomography (CBCT) is an imaging modality that since its introduction into the field of diagnostic radiology in the late 1990s <xref rid="bib0005" ref-type="bibr">[1]</xref> has gained a widespread use in various disciplines: endodontics <xref rid="bib0010" ref-type="bibr">[2]</xref>, orthodontics <xref rid="bib0015" ref-type="bibr">[3]</xref>, implantology <xref rid="bib0020" ref-type="bibr">[4]</xref>, pediatric dentistry <xref rid="bib0025" ref-type="bibr">[5]</xref> and periodontology <xref rid="bib0030" ref-type="bibr">[6]</xref>. Due to its relatively high availability, low cost and small footprint the technique is often used to enhance the diagnostic capability of different pathological conditions in the dento-maxillofacial area, as well as an aid in digital treatment planning.</p><p>The number of CBCT devices has increased substantially since the introduction, and today there are a large number of CBCT devices from different manufacturers on the market <xref rid="bib0035" ref-type="bibr">[7]</xref>. However, even if the term CBCT often is addressed as a generic name for the technique, the devices may vary in several aspects such as patient positioning (sitting or lying down, standing up), X-ray spectrum (voltage peak, filtration), X-ray exposure (mA-value, number of projections, rotation angle), volume of the exposed field and voxel size <xref rid="bib0040" ref-type="bibr">[8]</xref>. Further, a majority of the devices today is equipped with different imaging protocols and thus, varying voxel sizes and acquisition/exposure time to adapt the image resolution to the specific diagnostic task and the cooperation of the patient. Due to these differences between CBCT devices the radiation dose to the patient reveals a large variation, 27–674 μSv <xref rid="bib0045" ref-type="bibr">[9]</xref> depending on region of interest (ROI) and different exposure settings used <xref rid="bib0050" ref-type="bibr">[10]</xref>.</p><p>There are several publications including guideline statements on the use of CBCT in the head and neck region <xref rid="bib0055" ref-type="bibr">[11]</xref>. However, there is still a lack of specific instructions of how to optimize the radiographic examination on basis of the individual patient and region of interest. This may be due to the large number of different CBCT devices with their inherent differences.</p><p>A possibility to overcome these shortcomings, and investigate how different CBCT devices perform under certain conditions, is to use the contrast-to-noise-ratio (CNR) as an objective measure of image quality. In science and engineering, the signal-to-noise ratio (SNR) is a measure that compares the level of a desired signal to the level of background noise, CNR measure of image quality is based on image contrast rather than the raw signal. Using CNR instead of observers in image quality assessments may reduce the possibility of observer influence due to individual preferences. The difference in CNR values has been used in several articles to assess and compare image quality and optimization using different device settings <xref rid="bib0060" ref-type="bibr">[12]</xref>, <xref rid="bib0065" ref-type="bibr">[13]</xref>, <xref rid="bib0070" ref-type="bibr">[14]</xref>, <xref rid="bib0075" ref-type="bibr">[15]</xref>, <xref rid="bib0080" ref-type="bibr">[16]</xref>, <xref rid="bib0085" ref-type="bibr">[17]</xref>.</p><p>However, until today there is, to our knowledge, no study that has investigated the influence of patient position on CNR value and thus, its effect on image quality in CBCTs for dental applications.</p><p>The head position of the patient may influence the amount of tissue volume that the cone shaped radiation field has to pass to get to the detector. Since the radiation field is rotating around the patient head during exposure this may influence the amount of photons that reach the detector and hence the image building process.</p><p>Therefore the aim of this <italic>in vitro</italic> study was to evaluate how a deviation of the hard palate from the horizontal plane, affects the image quality, using two different CBCT devices. Further, to investigate the influence of different exposure parameter settings and field of views (FOVs).</p></sec><sec id="sec0010"><label>2</label><title>Materials and methods</title><sec id="sec0015"><label>2.1</label><title>Test object</title><p>The Sectional Head Phantom, SK150 (RANDO, The Phantom Laboratory, Salem, NY, USA) a human skull embedded in acrylic material (<italic>i.e.</italic> polyurethane) to simulate soft tissue, was used. The phantom was placed with the hard palate parallel to the horizontal plane and in a 20 ° backward tilted position (<xref rid="fig0005" ref-type="fig">Fig. 1</xref>).<fig id="fig0005"><label>Fig. 1</label><caption><p>Illustrates the difference in the phantom head position.</p></caption><alt-text id="at0005">Fig. 1</alt-text><graphic xlink:href="gr1"></graphic></fig></p></sec><sec id="sec0020"><label>2.2</label><title>CBCT imaging</title><p>Two different CBCT devices were used: Accuitomo <sup>®</sup> F 80 and Veraviewepocs<sup>®</sup> 3D R 100 (J. Morita Mfg. Corp. Kyto, Japan). The phantom head was examined with different FOVs, voxel sizes and slice thicknesses (<xref rid="tbl0005" ref-type="table">Table 1</xref>). The small FOVs (40 mm × 40 mm) were identical but the area of the large FOVs (80 mm × 80 mm and 100 mm × 80 mm) differed between the CBCT devices (<xref rid="fig0010" ref-type="fig">Fig. 2</xref>A and B) due to the reuleaux shape of the large FOV in Veraviewepocs <xref rid="bib0090" ref-type="bibr">[18]</xref>. The exposure parameters used in the first set of scans were 75, 80, 85, and 90 kV with a constant tube current of 5 mA. Then the mA value was varied at 2 and 8 together with different kV settings 80, 85 and 90. In total 80 examinations were performed.<fig id="fig0010"><label>Fig. 2</label><caption><p>Illustrates the difference between the areas of the large FOV in (A) Accuitomo and (B) Veraviewepocs. The Veraview has a rouleaux shape that is more adjusted the shape of the jaws.</p></caption><alt-text id="at0010">Fig. 2</alt-text><graphic xlink:href="gr2"></graphic></fig><table-wrap id="tbl0005" position="float"><label>Table 1</label><caption><p>Specifications for the different image parameter settings for the different CBCT-devices.</p></caption><alt-text id="at0020">Table 1</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left">Device</th><th align="left">Voxel size (mm)</th><th align="left">Slice thickness (mm)</th><th align="left">No of axial slices in each scan</th><th align="left">No of projections during scan</th><th align="left">Exposure time (s)</th></tr></thead><tbody><tr><td align="left">Accuitomo<xref rid="tblfn0005" ref-type="table-fn">a</xref> 40 mm × 40 mm</td><td align="left">0.125</td><td align="left">0.375</td><td align="left">107</td><td align="left">586</td><td align="left">17.5</td></tr><tr><td align="left">Veraview<xref rid="tblfn0010" ref-type="table-fn">b</xref> 40 mm × 40 mm</td><td align="left">0.125</td><td align="left">0.375</td><td align="left">115</td><td align="left">342</td><td align="left">9.4</td></tr><tr><td align="left">Accuitomo<xref rid="tblfn0005" ref-type="table-fn">a</xref> 80 mm × 80 mm</td><td align="left">0.160</td><td align="left">0.480</td><td align="left">167</td><td align="left">586</td><td align="left">17.5</td></tr><tr><td align="left">Veraview<xref rid="tblfn0010" ref-type="table-fn">b</xref> 100 mm × 80 mm<xref rid="tblfn0015" ref-type="table-fn">c</xref></td><td align="left">0.160</td><td align="left">0.480</td><td align="left">167</td><td align="left">342</td><td align="left">9.4</td></tr></tbody></table><table-wrap-foot><fn id="tblfn0005"><label>a</label><p id="npar0005">Accuitomo F80.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0010"><label>b</label><p id="npar0010">Veraviewepocs 3D R100.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0015"><label>c</label><p id="npar0015">Reuleaux Full Arch is an area shaped like a convex triangle. By more closely matching the natural dental arch form, this FOV allows a more complete scan of the maxilla and mandible.</p></fn></table-wrap-foot></table-wrap></p><p>All the axial slices (data sets) were sent to Picture Archiving and Communication System (PACS) (IMPAX 6.5.3 AGFA Healthcare, Belgium). The software of this program was used to display the ROI in different locations in the axial slices. The images were presented on two equal 21″ medical monitors, (MDCC-2121 Barco, Kortrijk, Belgium) with a special graphic card MXRT5200.</p></sec><sec id="sec0025"><label>2.3</label><title>Calculation of CNR</title><p>In the small FOVs, ROIs were set at three different levels on one side of the mandibular bone and bilaterally in the large FOVs. The ROIs had a diameter of 2.2 mm and 2.0 mm, in small and large FOVs, respectively. The vertical distance between the axial scans holding the ROIs was 4.5 mm (10 and 12 slices for large and small FOVs, respectively). Soft tissue and cortical bone were selected separately in each ROI and at each level in all the selected images.</p><p>For each ROI the mean CT-value and the standard deviation (SD) were obtained, provided by the PACS software (<xref rid="fig0015" ref-type="fig">Fig. 3</xref>A and B). At every level CNR values were calculated using the formula:<disp-formula id="eq0005"><mml:math id="M1" altimg="si1.gif" overflow="scroll"><mml:mrow><mml:mtext>CNR</mml:mtext><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:msub><mml:mrow><mml:mtext>Mean CT value</mml:mtext></mml:mrow><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:mtext>cortical bone</mml:mtext><mml:mo stretchy="true">)</mml:mo></mml:mrow></mml:msub><mml:mtext> </mml:mtext><mml:mo>−</mml:mo><mml:msub><mml:mtext>Mean CT value</mml:mtext><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:mtext>soft tissue equivalent material</mml:mtext><mml:mo stretchy="true">)</mml:mo></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msqrt><mml:mrow><mml:msup><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:msub><mml:mrow><mml:mtext>SD</mml:mtext></mml:mrow><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:mtext>cortical bone</mml:mtext><mml:mo stretchy="true">)</mml:mo></mml:mrow></mml:msub><mml:mo stretchy="true">)</mml:mo></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msup><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:msub><mml:mrow><mml:mtext>SD</mml:mtext></mml:mrow><mml:mrow><mml:mo stretchy="true">(</mml:mo><mml:mtext>soft tissue equivalent material</mml:mtext><mml:mo stretchy="true">)</mml:mo></mml:mrow></mml:msub><mml:mo stretchy="true">)</mml:mo></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:msqrt></mml:mrow></mml:mfrac></mml:mrow></mml:math></disp-formula><fig id="fig0015"><label>Fig. 3</label><caption><p>The setting of different regions of interest (ROIs). Hounsfield value (HU) represent the CT value used to calculate the CNR and deviation (DEV) represent the standard deviation (SD) value also used in the same formula. Unilateral settings in the small FOV (A) and bilaterally in the large FOV (B).</p></caption><alt-text id="at0015">Fig. 3</alt-text><graphic xlink:href="gr3"></graphic></fig></p></sec><sec id="sec0030"><label>2.4</label><title>Calculation of radiation dose</title><p>To determine effective dose Monte Carlo (MC) simulations were used applying PCXMC 2.0 (STUK). This program calculates absorbed organ and effective doses in x-ray examinations based on measurable quantities, <italic>e.g.</italic> dose area product (DAP) or incident air kerma. The program uses a modified anatomic phantom based on a mathematical model described by Cristy and Eckerman <xref rid="bib0095" ref-type="bibr">[19]</xref>. When calculating the effective dose, the tissue weighting factors of both International Commission on Radiological Protection (ICRP) publications 60, 1991 and Publication 103, 2007 can be used. The technical specifications used in the PCXMC simulation program are presented in <xref rid="tbl0010" ref-type="table">Table 2</xref>. This software has been used for CBCT examinations and compared to metal-oxide semiconductor field-effect transistor (MOSFET) dosimeter devices in effective dose calculation <xref rid="bib0100" ref-type="bibr">[20]</xref>.<table-wrap id="tbl0010" position="float"><label>Table 2</label><caption><p>Technical specifications used in the PCXMC simulation program (version 2.0).</p></caption><alt-text id="at0025">Table 2</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left"></th><th align="left">Accuitomo F80</th><th align="left">Veraviewepocs 3D R100</th></tr></thead><tbody><tr><td align="left">Source-to-detector distance (mm)</td><td align="left">710</td><td align="left">519</td></tr><tr><td align="left">Source-to-isocenter distance (mm)</td><td align="left">500</td><td align="left">346</td></tr><tr><td align="left">Anod angle (°)</td><td align="left">5</td><td align="left">5</td></tr><tr><td align="left">Rotation angle (°)</td><td align="left">360</td><td align="left">180</td></tr><tr><td align="left" rowspan="2">Detector field (WxH, mm)</td><td align="left">67 × 67 (400 × 400)</td><td align="left">62 × 71 (400 × 400)</td></tr><tr><td align="left">117 × 123 (800 × 800)</td><td align="left">125 × 130 (100 × 80)</td></tr><tr><td align="left">Exposure time (s)</td><td align="left">17.5</td><td align="left">9.4</td></tr><tr><td align="left">Total filtration</td><td align="left">3.9 mm Al</td><td align="left">2.5 mm Al + 0.2 mm Cu</td></tr><tr><td align="left">Frames/basal images</td><td align="left">586</td><td align="left">343</td></tr></tbody></table></table-wrap></p><p>DAP values (<xref rid="tbl0015" ref-type="table">Table 3</xref>) were measured using equipment Doseguard nr. 481 (RTI Electronics AB, www.rtigroup.com) and KAP-meter VAcuDAP2002 nr 1590001 (VacuTec Meßtechnik GmbH). The calculated effective dose for each scanning protocol is presented in <xref rid="tbl0020" ref-type="table">Table 4</xref>.<table-wrap id="tbl0015" position="float"><label>Table 3</label><caption><p>Exposure parameters and DAP values (mGycm<sup>2</sup>).</p></caption><alt-text id="at0030">Table 3</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left"></th><th align="left">75 kV</th><th align="left">80 kV</th><th align="left">85 kV</th><th align="left">90 kV</th><th align="left">80 kV</th><th align="left">80 kV</th><th align="left">85 kV</th><th align="left">85 kV</th><th align="left">90 kV</th><th align="left">90 kV</th></tr><tr><th align="left"></th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">2 mA</th><th align="left">8 mA</th><th align="left">2 mA</th><th align="left">8 mA</th><th align="left">2 mA</th><th align="left">8 mA</th></tr></thead><tbody><tr><td align="left">Accuitomo<xref rid="tblfn0025" ref-type="table-fn">b</xref></td><td align="left" rowspan="2">288<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">329</td><td align="left" rowspan="2">367</td><td align="left" rowspan="2">410</td><td align="left" rowspan="2">137</td><td align="left" rowspan="2">519</td><td align="left" rowspan="2">153</td><td align="left" rowspan="2">581</td><td align="left" rowspan="2">164<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">656<xref rid="tblfn0020" ref-type="table-fn">a</xref></td></tr><tr><td align="left">40 mm × 40 mm</td></tr><tr><td align="left">Veraview<xref rid="tblfn0030" ref-type="table-fn">c</xref></td><td align="left" rowspan="2">166</td><td align="left" rowspan="2">201</td><td align="left" rowspan="2">236</td><td align="left" rowspan="2">276</td><td align="left" rowspan="2">84</td><td align="left" rowspan="2">318</td><td align="left" rowspan="2">98</td><td align="left" rowspan="2">377</td><td align="left" rowspan="2">110<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">441<xref rid="tblfn0020" ref-type="table-fn">a</xref></td></tr><tr><td align="left">40 mm × 40 mm</td></tr><tr><td align="left">Accuitomo<xref rid="tblfn0025" ref-type="table-fn">b</xref></td><td align="left" rowspan="2">1046<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">1212</td><td align="left" rowspan="2">1351</td><td align="left" rowspan="2">1531</td><td align="left" rowspan="2">504</td><td align="left" rowspan="2">1913</td><td align="left" rowspan="2">562</td><td align="left" rowspan="2">2139</td><td align="left" rowspan="2">612<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">2450<xref rid="tblfn0020" ref-type="table-fn">a</xref></td></tr><tr><td align="left">80 mm × 80 mm</td></tr><tr><td align="left">Veraview<xref rid="tblfn0030" ref-type="table-fn">c</xref></td><td align="left" rowspan="2">546</td><td align="left" rowspan="2">657</td><td align="left" rowspan="2">764</td><td align="left" rowspan="2">890</td><td align="left" rowspan="2">274</td><td align="left" rowspan="2">1040</td><td align="left" rowspan="2">319</td><td align="left" rowspan="2">1209</td><td align="left" rowspan="2">356<xref rid="tblfn0020" ref-type="table-fn">a</xref></td><td align="left" rowspan="2">1424<xref rid="tblfn0020" ref-type="table-fn">a</xref></td></tr><tr><td align="left">100 mm × 80 mm</td></tr></tbody></table><table-wrap-foot><fn id="tblfn0020"><label>a</label><p id="npar0020"><italic>Calculated values</italic> (extrapolated from measured values).</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0025"><label>b</label><p id="npar0025">Accuitomo F80.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0030"><label>c</label><p id="npar0030">Veraviewepocs 3D R100.</p></fn></table-wrap-foot></table-wrap><table-wrap id="tbl0020" position="float"><label>Table 4</label><caption><p>Calculated effective dose (E = DAP × E<sub>DLP</sub>) values (in mSv), based on weighting factors of ICRP Publication 103 (2007).</p></caption><alt-text id="at0035">Table 4</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left"></th><th align="left">E<sub>DLP</sub><xref rid="tblfn0035" ref-type="table-fn">a</xref></th><th align="left">75 kV</th><th align="left">80 kV</th><th align="left">85 kV</th><th align="left">90 kV</th><th align="left">80 kV</th><th align="left">80 kV</th><th align="left">85 kV</th><th align="left">85 kV</th><th align="left">90 kV</th><th align="left">90 kV</th></tr><tr><th align="left"></th><th align="left"></th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">5 mA</th><th align="left">2 mA</th><th align="left">8 mA</th><th align="left">2 mA</th><th align="left">8 mA</th><th align="left">2 mA</th><th align="left">8 mA</th></tr></thead><tbody><tr><td align="left">Accuitomo<xref rid="tblfn0040" ref-type="table-fn">b</xref></td><td align="left" rowspan="2">0.156</td><td align="left" rowspan="2">0.045</td><td align="left" rowspan="2">0.051</td><td align="left" rowspan="2">0.057</td><td align="left" rowspan="2">0.064</td><td align="left" rowspan="2">0.021</td><td align="left" rowspan="2">0.081</td><td align="left" rowspan="2">0.024</td><td align="left" rowspan="2">0.091</td><td align="left" rowspan="2">0.026</td><td align="left" rowspan="2">0.102</td></tr><tr><td align="left">40 mm × 40 mm</td></tr><tr><td align="left">Veraview<xref rid="tblfn0045" ref-type="table-fn">c</xref></td><td align="left" rowspan="2">0.212</td><td align="left" rowspan="2">0.035</td><td align="left" rowspan="2">0.043</td><td align="left" rowspan="2">0.050</td><td align="left" rowspan="2">0.059</td><td align="left" rowspan="2">0.018</td><td align="left" rowspan="2">0.067</td><td align="left" rowspan="2">0.021</td><td align="left" rowspan="2">0.080</td><td align="left" rowspan="2">0.023</td><td align="left" rowspan="2">0.093</td></tr><tr><td align="left">40 mm × 40 mm</td></tr><tr><td align="left">Accuitomo<xref rid="tblfn0040" ref-type="table-fn">b</xref></td><td align="left" rowspan="2">0.139</td><td align="left" rowspan="2">0.145</td><td align="left" rowspan="2">0.168</td><td align="left" rowspan="2">0.188</td><td align="left" rowspan="2">0.213</td><td align="left" rowspan="2">0.070</td><td align="left" rowspan="2">0.266</td><td align="left" rowspan="2">0.078</td><td align="left" rowspan="2">0.297</td><td align="left" rowspan="2">0.085</td><td align="left" rowspan="2">0.340</td></tr><tr><td align="left">80 mm × 80 mm</td></tr><tr><td align="left">Veraview<xref rid="tblfn0045" ref-type="table-fn">c</xref></td><td align="left" rowspan="2">0.166</td><td align="left" rowspan="2">0.091</td><td align="left" rowspan="2">0.109</td><td align="left" rowspan="2">0.127</td><td align="left" rowspan="2">0.148</td><td align="left" rowspan="2">0.045</td><td align="left" rowspan="2">0.173</td><td align="left" rowspan="2">0.053</td><td align="left" rowspan="2">0.201</td><td align="left" rowspan="2">0.059</td><td align="left" rowspan="2">0.236</td></tr><tr><td align="left">100 mm × 80 mm</td></tr></tbody></table><table-wrap-foot><fn id="tblfn0035"><label>a</label><p id="npar0035">Conversion factor. Calculated with PCXMC 2.0 program (mSv/Gycm<sup>2</sup>).</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0040"><label>b</label><p id="npar0040">Accuitomo F 80.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0045"><label>c</label><p id="npar0045">Veraviewepocs 3D R100.</p></fn></table-wrap-foot></table-wrap></p></sec><sec id="sec0035"><label>2.5</label><title>Statistics</title><p>Factor analysis was used to study the variability among the observed variables. Using the program SAS 9.3 (<sup>®</sup>SAS Institute Inc., Cary, NC, USA) and the procedure Proc. mixed.</p></sec></sec><sec id="sec0040"><label>3</label><title>Results</title><p>The effects of co-variation of different variables tested were analyzed and are presented in <xref rid="tbl0025" ref-type="table">Table 5</xref>.<table-wrap id="tbl0025" position="float"><label>Table 5</label><caption><p>Analysis of variance.</p></caption><alt-text id="at0040">Table 5</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left">Effect</th><th align="left">p-value</th></tr></thead><tbody><tr><td align="left">CBCT-device and kV</td><td align="left">0.9709</td></tr><tr><td align="left">CBCT-device and mA</td><td align="left">0.9001</td></tr><tr><td align="left">CBCT-device and FOV</td><td align="left">0.0016<xref rid="tblfn0050" ref-type="table-fn">*</xref></td></tr><tr><td align="left">CBCT-device and patient position</td><td align="left">0.0215<xref rid="tblfn0050" ref-type="table-fn">*</xref></td></tr><tr><td align="left">kV and mA</td><td align="left">0.6936</td></tr><tr><td align="left">kV and FOV</td><td align="left">0.9851</td></tr><tr><td align="left">kV and patient position</td><td align="left">0.7487</td></tr><tr><td align="left">mA and FOV</td><td align="left">0.0424<xref rid="tblfn0050" ref-type="table-fn">*</xref></td></tr><tr><td align="left">mA and patient position</td><td align="left">0.0829</td></tr><tr><td align="left">FOV and patient position</td><td align="left">0.0014<xref rid="tblfn0050" ref-type="table-fn">*</xref></td></tr></tbody></table><table-wrap-foot><fn id="tblfn0050"><label>*</label><p id="npar0050">Significant covariance.</p></fn></table-wrap-foot></table-wrap></p><p>Regardless of FOV or CBCT device, the tilted head position rendered the highest CNR mean values (<xref rid="tbl0030" ref-type="table">Table 6</xref>, <xref rid="tbl0035" ref-type="table">Table 7</xref>) indicating better image quality. Further analysis of the other variables CBCT device and FOV and then mA and FOV, showed that the large FOV of the Accuitomo and the small FOV in the Veraviewepocs rendered the highest CNR mean values. Analyzing mA and FOV, high CNR mean values were found in small FOVs at high mA settings and in large FOVs at low mA (<xref rid="tbl0040" ref-type="table">Table 8</xref>).<table-wrap id="tbl0030" position="float"><label>Table 6</label><caption><p>Mean CNR value analysing CBCT device and patient position.</p></caption><alt-text id="at0045">Table 6</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left">CBCT-device</th><th align="left">Patient position</th><th align="left">No of observations</th><th align="left">Mean CNR</th><th align="left">Std Error</th></tr></thead><tbody><tr><td align="left">Accuitomo F80</td><td align="left">Horisontally</td><td align="left">78</td><td align="left">7.21</td><td align="left">0.253</td></tr><tr><td align="left">Accuitomo F80</td><td align="left">Tilted</td><td align="left">78</td><td align="left">9.01</td><td align="left">0.253</td></tr><tr><td align="left">Veraviewepocs 3D R100</td><td align="left">Horisontally</td><td align="left">78</td><td align="left">7.87</td><td align="left">0.253</td></tr><tr><td align="left">Veraviewepocs 3D R100</td><td align="left">Tilted</td><td align="left">78</td><td align="left">8.50</td><td align="left">0.253</td></tr></tbody></table></table-wrap><table-wrap id="tbl0035" position="float"><label>Table 7</label><caption><p>Mean CNR value analysing FOV and patient position.</p></caption><alt-text id="at0050">Table 7</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left">FOV</th><th align="left">Patient position</th><th align="left">Number of observations</th><th align="left">Mean CNR</th><th align="left">Std Error</th></tr></thead><tbody><tr><td align="left">Small<xref rid="tblfn0055" ref-type="table-fn">a</xref></td><td align="left">Horisontal</td><td align="left">78</td><td align="left">7.33</td><td align="left">0.253</td></tr><tr><td align="left">Small<xref rid="tblfn0055" ref-type="table-fn">a</xref></td><td align="left">Tilted</td><td align="left">78</td><td align="left">9.35</td><td align="left">0.253</td></tr><tr><td align="left">Large<xref rid="tblfn0060" ref-type="table-fn">b</xref></td><td align="left">Horisontal</td><td align="left">78</td><td align="left">7.75</td><td align="left">0.253</td></tr><tr><td align="left">Large<xref rid="tblfn0060" ref-type="table-fn">b</xref></td><td align="left">Tilted</td><td align="left">78</td><td align="left">8.15</td><td align="left">0.253</td></tr></tbody></table><table-wrap-foot><fn id="tblfn0055"><label>a</label><p id="npar0055">40 mm × 40 mm Accuitomo F80 and Veraviewepocs 3D R100.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0060"><label>b</label><p id="npar0060">80 mm × 80 mm Accuitomo F80 and 100 mm × 80 mm Veraviewepocs 3D R100.</p></fn></table-wrap-foot></table-wrap><table-wrap id="tbl0040" position="float"><label>Table 8</label><caption><p>Mean CNR value analysing mA and FOV.</p></caption><alt-text id="at0055">Table 8</alt-text><table frame="hsides" rules="groups"><thead><tr><th align="left">mA</th><th align="left">FOV</th><th align="left">No of observations</th><th align="left">Mean CNR</th><th align="left">Std Error</th></tr></thead><tbody><tr><td align="left">2.00</td><td align="left">small<xref rid="tblfn0065" ref-type="table-fn">a</xref></td><td align="left">36</td><td align="left">6.44</td><td align="left">0.373</td></tr><tr><td align="left"></td><td align="left">large<xref rid="tblfn0070" ref-type="table-fn">b</xref></td><td align="left">36</td><td align="left">7.22</td><td align="left">0.373</td></tr><tr><td align="left">5.00</td><td align="left">small<xref rid="tblfn0065" ref-type="table-fn">a</xref></td><td align="left">84</td><td align="left">8.57</td><td align="left">0.244</td></tr><tr><td align="left"></td><td align="left">large<xref rid="tblfn0070" ref-type="table-fn">b</xref></td><td align="left">84</td><td align="left">7.91</td><td align="left">0.244</td></tr><tr><td align="left">8.00</td><td align="left">small<xref rid="tblfn0065" ref-type="table-fn">a</xref></td><td align="left">36</td><td align="left">9.71</td><td align="left">0.373</td></tr><tr><td align="left"></td><td align="left">large<xref rid="tblfn0070" ref-type="table-fn">b</xref></td><td align="left">36</td><td align="left">8.79</td><td align="left">0.373</td></tr></tbody></table><table-wrap-foot><fn id="tblfn0065"><label>a</label><p id="npar0065">40 mm × 40 mm Accuitomo F80 and Veraviewepocs 3D R100.</p></fn></table-wrap-foot><table-wrap-foot><fn id="tblfn0070"><label>b</label><p id="npar0070">80 mm × 80 mm Accuitomo F80 and 100 mm × 80 mm Veraviewepocs 3D R100.</p></fn></table-wrap-foot></table-wrap></p><p>In the large FOVs the effective dose varied to a larger extent between CBCT devices than in small FOVs where they were almost equal.</p></sec><sec id="sec0045"><label>4</label><title>Discussion</title><p>To approach a more objective evaluation of image quality CNR value can be calculated. Different scull and jaw models have been used <italic>in vitro</italic> to test this. In some studies the SEDENTEXCT (Safety and efficacy of a new and emerging dental X-ray modality) IQ (image quality) or polymethyl methacrylate phantoms were used <xref rid="bib0060" ref-type="bibr">[12]</xref>, <xref rid="bib0075" ref-type="bibr">[15]</xref>, others have used a maxillary or mandibular bone embedded in resin as a test object <xref rid="bib0065" ref-type="bibr">[13]</xref> or just a dry mandible together with an epoxy resin bone tissue substitute block <xref rid="bib0070" ref-type="bibr">[14]</xref>. Choi et al., <xref rid="bib0085" ref-type="bibr">[17]</xref> used SEDENTEXCT IQ phantom and a scull phantom with soft tissue replica for comparison of technical and diagnostic image quality and came to the conclusion that the CNR value has a significant association with subjective image quality. Pauwels et al. <xref rid="bib0105" ref-type="bibr">[22]</xref> reported on technical versus diagnostic image quality in dental CBCT imaging, where CNR values and observer scores for different anatomical landmarks were found to have a specific correlation for each CBCT device tested.</p><p>This study showed that the only significant variable with unanimous outcome was head position. The backward tilted position always rendered higher mean CNR values despite FOV or CBCT device. Findings by Bryant et al., <xref rid="bib0110" ref-type="bibr">[23]</xref>, showed that exo-mass <italic>i.e</italic>. the irradiated mass outside the actual FOV, could influence the CT value depending on its location in relation to the FOV. In small FOVs the exo-mass is larger. However, the total mass in a slice affects the uniformity of the density values. This could explain our findings that the tilted head position rendered higher CNR values.</p><p>Another finding was that the CNR values between the devices did not differ more despite the difference in number of basis images. The Accuitomo uses 586 compared to the Veraviewepocs 342. Bechara et al. <xref rid="bib0070" ref-type="bibr">[14]</xref> showed in a study that increasing the number of basis images increased the CNR value in small FOVs. But increasing the number of basis images not necessarily have a positive effect on the CNR value in large FOVs.</p><p>A recent study by Koivisto et al. <xref rid="bib0115" ref-type="bibr">[24]</xref> demonstrated that the image quality varies between different anatomical landmarks in the scull, except for the mandible were the image quality always was evaluated as good. Hence, the mandible may not be affected by surrounding structures to the same extent as other regions in the maxillofacial complex due to its location more apart from the scull base.</p><p>FOV and voxel size are other variables influencing image quality <xref rid="bib0065" ref-type="bibr">[13]</xref>, <xref rid="bib0115" ref-type="bibr">[24]</xref>, <xref rid="bib0120" ref-type="bibr">[25]</xref>, <xref rid="bib0125" ref-type="bibr">[26]</xref>, <xref rid="bib0130" ref-type="bibr">[27]</xref>. In this study we choose the mandible and a FOV not exceeding 100 mm × 80 mm and small voxel sizes. Excluding the variable head tilting from the statistical analysis, we obtained diverting findings regarding mean CNR values.</p><p>The phantom used did not have any fillings or metal components incorporated nor did it move during examinations. Thus, artifacts like beam hardening, exponential edge-gradient effect and motion <xref rid="bib0135" ref-type="bibr">[28]</xref> were not present and have no implications on the image quality in this study. The scan time is 9.4 s for Veraviewepocs and 17.5 s for Accuitomo. In a clinical situation a long exposure time could deteriorate the image quality if the patient cannot be fixated properly. A recent review by Spin-Neto 2016<xref rid="bib0140" ref-type="bibr">[29]</xref> concluded that investigations monitoring patients during CBCT reported a movement prevalence of 20% and artefact recognition, without knowledge of movement in the range of 4.5%–41.5%.</p><p>In a clinical situation it is of great importance to choose a FOV and an image resolution due to the clinical task. It is also important that the patient is positioned in a way that allows him or her not to move, even if it means tilting the head backward or positioning the head horizontally.</p><p>All other factors constant, the radiation dose is dependent on the FOV<xref rid="bib0145" ref-type="bibr">[30]</xref>. In our study the effective dose differed more in the large than in the small FOVs between CBCT devices, in favor of Veraviewepocs despite a larger FOV than Accuitomo. This may be an effect of the posteriorly directed projection, 180 ° rotation and the reuleaux shape.</p></sec><sec id="sec0050"><label>5</label><title>Conclusions</title><p>Head position can affect the image quality. Tilting the head backward rendered higher mean CNR values in the mandibular region regardless of CBCT device or FOV used indication an improved image quality. Other variables such as motion artefacts may have more influence on image quality in a clinical setting than the patient head position. This remains to be further investigated.</p></sec><sec id="sec0055"><title>Conflict of interest</title><p>None.</p></sec></body><back><ref-list id="bibl0005"><title>References</title><ref id="bib0005"><label>1</label><element-citation publication-type="journal" id="sbref0005"><person-group person-group-type="author"><name><surname>Mozzo</surname><given-names>P.</given-names></name><name><surname>Procacci</surname><given-names>C.</given-names></name><name><surname>Tacconi</surname><given-names>A.</given-names></name><name><surname>Martini</surname><given-names>P.T.</given-names></name><name><surname>Andreis</surname><given-names>I.A.</given-names></name></person-group><article-title>A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results</article-title><source>Eur. Radiol.</source><volume>8</volume><issue>9</issue><year>1998</year><fpage>1558</fpage><lpage>1564</lpage><pub-id pub-id-type="pmid">9866761</pub-id></element-citation></ref><ref id="bib0010"><label>2</label><element-citation publication-type="journal" id="sbref0010"><person-group person-group-type="author"><name><surname>Davies</surname><given-names>A.</given-names></name><name><surname>Patel</surname><given-names>S.</given-names></name><name><surname>Foschi</surname><given-names>F.</given-names></name><name><surname>Andiappan</surname><given-names>M.</given-names></name><name><surname>Mitchell</surname><given-names>P.J.</given-names></name><name><surname>Mannocci</surname><given-names>F.</given-names></name></person-group><article-title>The detection of periapical pathoses using digital periapical radiography and cone beam computed tomography in endodontically retreated teeth – part 2: a 1 year post-treatment follow-up</article-title><source>Int. Endod. J.</source><volume>49</volume><issue>7</issue><year>2016</year><fpage>623</fpage><lpage>635</lpage><pub-id pub-id-type="pmid">26174351</pub-id></element-citation></ref><ref id="bib0015"><label>3</label><element-citation publication-type="journal" id="sbref0015"><person-group person-group-type="author"><name><surname>Kapila</surname><given-names>S.D.</given-names></name><name><surname>Nervina</surname><given-names>J.M.</given-names></name></person-group><article-title>CBCT in orthodontics: assessment of treatment outcomes and indications for its use</article-title><source>Dentomaxillofac. Radiol.</source><volume>44</volume><issue>1</issue><year>2015</year><fpage>20140282</fpage><pub-id pub-id-type="pmid">25358833</pub-id></element-citation></ref><ref id="bib0020"><label>4</label><element-citation publication-type="journal" id="sbref0020"><person-group person-group-type="author"><name><surname>Chan</surname><given-names>H.L.</given-names></name><name><surname>Misch</surname><given-names>K.</given-names></name><name><surname>Wang</surname><given-names>H.L.</given-names></name></person-group><article-title>Dental imaging in implant treatment planning</article-title><source>Implant Dent.</source><volume>19</volume><issue>4</issue><year>2010</year><fpage>288</fpage><lpage>298</lpage><pub-id pub-id-type="pmid">20683285</pub-id></element-citation></ref><ref id="bib0025"><label>5</label><element-citation publication-type="journal" id="sbref0025"><person-group person-group-type="author"><name><surname>Bahadure</surname><given-names>R.N.</given-names></name><name><surname>Thosar</surname><given-names>N.</given-names></name><name><surname>Khubchandani</surname><given-names>M.</given-names></name></person-group><article-title>Orthodontic extrusion: diagnosis and treatment with CBCT in a pediatric patient</article-title><source>Gen. Dent.</source><volume>61</volume><issue>4</issue><year>2013</year><fpage>e5</fpage><lpage>7</lpage></element-citation></ref><ref id="bib0030"><label>6</label><element-citation publication-type="journal" id="sbref0030"><person-group person-group-type="author"><name><surname>Goodarzi Pour</surname><given-names>D.</given-names></name><name><surname>Romoozi</surname><given-names>E.</given-names></name><name><surname>Soleimani Shayesteh</surname><given-names>Y.</given-names></name></person-group><article-title>Accuracy of cone beam computed tomography for detection of bone loss</article-title><source>J. Dent.</source><volume>12</volume><issue>7</issue><year>2015</year><fpage>513</fpage><lpage>523</lpage></element-citation></ref><ref id="bib0035"><label>7</label><element-citation publication-type="journal" id="sbref0035"><person-group person-group-type="author"><name><surname>Nemtoi</surname><given-names>A.</given-names></name><name><surname>Czink</surname><given-names>C.</given-names></name><name><surname>Haba</surname><given-names>D.</given-names></name><name><surname>Gahleitner</surname><given-names>A.</given-names></name></person-group><article-title>Cone beam CT: a current overview of devices</article-title><source>Dentomaxillofac. Radiol.</source><volume>42</volume><issue>8</issue><year>2013</year><fpage>20120443</fpage><pub-id pub-id-type="pmid">23818529</pub-id></element-citation></ref><ref id="bib0040"><label>8</label><element-citation publication-type="journal" id="sbref0040"><person-group person-group-type="author"><name><surname>Pauwels</surname><given-names>R.</given-names></name><name><surname>Araki</surname><given-names>K.</given-names></name><name><surname>Siewerdsen</surname><given-names>J.H.</given-names></name><name><surname>Thongvigitmanee</surname><given-names>S.S.</given-names></name></person-group><article-title>Technical aspects of dental CBCT: state of the art</article-title><source>Dentomaxillofac. Radiol.</source><volume>44</volume><issue>1</issue><year>2015</year><fpage>20140224</fpage><pub-id pub-id-type="pmid">25263643</pub-id></element-citation></ref><ref id="bib0045"><label>9</label><element-citation publication-type="journal" id="sbref0045"><person-group person-group-type="author"><name><surname>Suomalainen</surname><given-names>A.</given-names></name><name><surname>Kiljunen</surname><given-names>T.</given-names></name><name><surname>Kaser</surname><given-names>Y.</given-names></name><name><surname>Peltola</surname><given-names>J.</given-names></name><name><surname>Kortesniemi</surname><given-names>M.</given-names></name></person-group><article-title>Dosimetry and image quality of four dental cone beam computed tomography scanners compared with multislice computed tomography scanners</article-title><source>Dentomaxillofac. Radiol.</source><volume>38</volume><issue>6</issue><year>2009</year><fpage>367</fpage><lpage>378</lpage><pub-id pub-id-type="pmid">19700530</pub-id></element-citation></ref><ref id="bib0050"><label>10</label><element-citation publication-type="journal" id="sbref0050"><person-group person-group-type="author"><name><surname>Bornstein</surname><given-names>M.M.</given-names></name><name><surname>Scarfe</surname><given-names>W.C.</given-names></name><name><surname>Vaughn</surname><given-names>V.M.</given-names></name><name><surname>Jacobs</surname><given-names>R.</given-names></name></person-group><article-title>Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks</article-title><source>Int. J. Oral Maxillofac. Implants</source><volume>29</volume><issue>Suppl</issue><year>2014</year><fpage>55</fpage><lpage>77</lpage><pub-id pub-id-type="pmid">24660190</pub-id></element-citation></ref><ref id="bib0055"><label>11</label><element-citation publication-type="journal" id="sbref0055"><person-group person-group-type="author"><name><surname>Horner</surname><given-names>K.</given-names></name><name><surname>O'Malley</surname><given-names>L.</given-names></name><name><surname>Taylor</surname><given-names>K.</given-names></name><name><surname>Glenny</surname><given-names>A.M.</given-names></name></person-group><article-title>Guidelines for clinical use of CBCT: a review</article-title><source>Dentomaxillofac. Radiol.</source><volume>44</volume><issue>1</issue><year>2015</year><fpage>20140225</fpage><pub-id pub-id-type="pmid">25270063</pub-id></element-citation></ref><ref id="bib0060"><label>12</label><element-citation publication-type="journal" id="sbref0060"><person-group person-group-type="author"><name><surname>Pauwels</surname><given-names>R.</given-names></name><name><surname>Silkosessak</surname><given-names>O.</given-names></name><name><surname>Jacobs</surname><given-names>R.</given-names></name><name><surname>Bogaerts</surname><given-names>R.</given-names></name><name><surname>Bosmans</surname><given-names>H.</given-names></name><name><surname>Panmekiate</surname><given-names>S.</given-names></name></person-group><article-title>A pragmatic approach to determine the optimal kVp in cone beam CT: balancing contrast-to-noise ratio and radiation dose</article-title><source>Dentomaxillofac. Radiol.</source><volume>43</volume><issue>5</issue><year>2014</year><fpage>20140059</fpage><pub-id pub-id-type="pmid">24708447</pub-id></element-citation></ref><ref id="bib0065"><label>13</label><element-citation publication-type="journal" id="sbref0065"><person-group person-group-type="author"><name><surname>Bechara</surname><given-names>B.</given-names></name><name><surname>McMahan</surname><given-names>C.A.</given-names></name><name><surname>Moore</surname><given-names>W.S.</given-names></name><name><surname>Noujeim</surname><given-names>M.</given-names></name><name><surname>Geha</surname><given-names>H.</given-names></name></person-group><article-title>Contrast-to-noise ratio with different large volumes in a cone-beam computerized tomography machine: an in vitro study</article-title><source>Oral Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>114</volume><issue>5</issue><year>2012</year><fpage>658</fpage><lpage>665</lpage><pub-id pub-id-type="pmid">23083479</pub-id></element-citation></ref><ref id="bib0070"><label>14</label><element-citation publication-type="journal" id="sbref0070"><person-group person-group-type="author"><name><surname>Bechara</surname><given-names>B.</given-names></name><name><surname>McMahan</surname><given-names>C.A.</given-names></name><name><surname>Moore</surname><given-names>W.S.</given-names></name><name><surname>Noujeim</surname><given-names>M.</given-names></name><name><surname>Geha</surname><given-names>H.</given-names></name><name><surname>Teixeira</surname><given-names>F.B.</given-names></name></person-group><article-title>Contrast-to-noise ratio difference in small field of view cone beam computed tomography machines</article-title><source>J. Oral Sci.</source><volume>54</volume><issue>3</issue><year>2012</year><fpage>227</fpage><lpage>232</lpage><pub-id pub-id-type="pmid">23047033</pub-id></element-citation></ref><ref id="bib0075"><label>15</label><element-citation publication-type="journal" id="sbref0075"><person-group person-group-type="author"><name><surname>Pauwels</surname><given-names>R.</given-names></name><name><surname>Stamatakis</surname><given-names>H.</given-names></name><name><surname>Manousaridis</surname><given-names>G.</given-names></name><name><surname>Walker</surname><given-names>A.</given-names></name><name><surname>Michielsen</surname><given-names>K.</given-names></name><name><surname>Bosmans</surname><given-names>H.</given-names></name><name><surname>Bogaerts</surname><given-names>R.</given-names></name><name><surname>Jacobs</surname><given-names>R.</given-names></name><name><surname>Horner</surname><given-names>K.</given-names></name><name><surname>Tsiklakis</surname><given-names>K.</given-names></name><name><surname>Consortium</surname><given-names>S.P.</given-names></name></person-group><article-title>Development and applicability of a quality control phantom for dental cone-beam CT</article-title><source>J. Appl. Clin. Med. Phys.</source><volume>12</volume><issue>4</issue><year>2011</year><fpage>3478</fpage><pub-id pub-id-type="pmid">22089004</pub-id></element-citation></ref><ref id="bib0080"><label>16</label><element-citation publication-type="journal" id="sbref0080"><person-group person-group-type="author"><name><surname>Kalender</surname><given-names>W.A.</given-names></name><name><surname>Deak</surname><given-names>P.</given-names></name><name><surname>Kellermeier</surname><given-names>M.</given-names></name><name><surname>van Straten</surname><given-names>M.</given-names></name><name><surname>Vollmar</surname><given-names>S.V.</given-names></name></person-group><article-title>Application- and patient size-dependent optimization of x-ray spectra for CT</article-title><source>Med. Phys.</source><volume>36</volume><issue>3</issue><year>2009</year><fpage>993</fpage><lpage>1007</lpage><pub-id pub-id-type="pmid">19378760</pub-id></element-citation></ref><ref id="bib0085"><label>17</label><element-citation publication-type="journal" id="sbref0085"><person-group person-group-type="author"><name><surname>Choi</surname><given-names>J.W.</given-names></name><name><surname>Lee</surname><given-names>S.S.</given-names></name><name><surname>Choi</surname><given-names>S.C.</given-names></name><name><surname>Heo</surname><given-names>M.S.</given-names></name><name><surname>Huh</surname><given-names>K.H.</given-names></name><name><surname>Yi</surname><given-names>W.J.</given-names></name><name><surname>Kang</surname><given-names>S.R.</given-names></name><name><surname>Han</surname><given-names>D.H.</given-names></name><name><surname>Kim</surname><given-names>E.K.</given-names></name></person-group><article-title>Relationship between physical factors and subjective image quality of cone-beam computed tomography images according to diagnostic task</article-title><source>Oral Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>119</volume><issue>3</issue><year>2015</year><fpage>357</fpage><lpage>365</lpage><pub-id pub-id-type="pmid">25592866</pub-id></element-citation></ref><ref id="bib0090"><label>18</label><element-citation publication-type="book" id="sbref0090"><person-group person-group-type="author"><name><surname>J. Morita Mfg. Corp</surname></name></person-group><chapter-title>Veraviewepocs 3D R100</chapter-title><year>2017</year><comment>http://global.morita.com/usa/cms/website.php?id=/en/products/dental/diagnostic_and_imaging_equipment/6054_veraviewepocs_3d.html. (Accessed March 24 2017)</comment></element-citation></ref><ref id="bib0095"><label>19</label><mixed-citation publication-type="other" id="oref0095">M.E. Cristy, K.F. Eckerman, Specific absorbed fractions of energy at various ages from internal photon sources. Methods, Volumes I – VII. Oak Ridge National Laboratory, Report No.: ORNL/TM-8381 Google Scholar, 1987.</mixed-citation></ref><ref id="bib0100"><label>20</label><element-citation publication-type="journal" id="sbref0100"><person-group person-group-type="author"><name><surname>Koivisto</surname><given-names>J.</given-names></name><name><surname>Kiljunen</surname><given-names>T.</given-names></name><name><surname>Tapiovaara</surname><given-names>M.</given-names></name><name><surname>Wolff</surname><given-names>J.</given-names></name><name><surname>Kortesniemi</surname><given-names>M.</given-names></name></person-group><article-title>Assessment of radiation exposure in dental cone-beam computerized tomography with the use of metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters and Monte Carlo simulations</article-title><source>Oral Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>114</volume><issue>3</issue><year>2012</year><fpage>393</fpage><lpage>400</lpage><pub-id pub-id-type="pmid">22862982</pub-id></element-citation></ref><ref id="bib0105"><label>22</label><mixed-citation publication-type="other" id="oref0105">R. Pauwels, L. Seynaeve, H. Bosmans, R. Bogaerts, R. Jacobs, Technical versus diagnostic image quality in dental CBCT imaging. Scientific Exhibit, Congress ECR 2013, Poster No.: C-2391, doi:10.1594/ecr2013/C-2391.</mixed-citation></ref><ref id="bib0110"><label>23</label><element-citation publication-type="journal" id="sbref0110"><person-group person-group-type="author"><name><surname>Bryant</surname><given-names>J.A.</given-names></name><name><surname>Drage</surname><given-names>N.A.</given-names></name><name><surname>Richmond</surname><given-names>S.</given-names></name></person-group><article-title>Study of the scan uniformity from an i-CAT cone beam computed tomography dental imaging system</article-title><source>Dentomaxillofac. Radiol.</source><volume>37</volume><issue>7</issue><year>2008</year><fpage>365</fpage><lpage>374</lpage><pub-id pub-id-type="pmid">18812597</pub-id></element-citation></ref><ref id="bib0115"><label>24</label><element-citation publication-type="journal" id="sbref0115"><person-group person-group-type="author"><name><surname>Koivisto</surname><given-names>J.</given-names></name><name><surname>Wolff</surname><given-names>J.</given-names></name><name><surname>Jarnstedt</surname><given-names>J.</given-names></name><name><surname>Dastidar</surname><given-names>P.</given-names></name><name><surname>Kortesniemi</surname><given-names>M.</given-names></name></person-group><article-title>Assessment of the effective dose in supine, prone, and oblique positions in the maxillofacial region using a novel combined extremity and maxillofacial cone beam computed tomography scanner</article-title><source>Oral Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>118</volume><issue>3</issue><year>2014</year><fpage>355</fpage><lpage>362</lpage><pub-id pub-id-type="pmid">25151590</pub-id></element-citation></ref><ref id="bib0120"><label>25</label><element-citation publication-type="journal" id="sbref0120"><person-group person-group-type="author"><name><surname>Katsumata</surname><given-names>A.</given-names></name><name><surname>Hirukawa</surname><given-names>A.</given-names></name><name><surname>Okumura</surname><given-names>S.</given-names></name><name><surname>Naitoh</surname><given-names>M.</given-names></name><name><surname>Fujishita</surname><given-names>M.</given-names></name><name><surname>Ariji</surname><given-names>E.</given-names></name><name><surname>Langlais</surname><given-names>R.P.</given-names></name></person-group><article-title>Relationship between density variability and imaging volume size in cone-beam computerized tomographic scanning of the maxillofacial region: an in vitro study</article-title><source>Oral Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>107</volume><issue>3</issue><year>2009</year><fpage>420</fpage><lpage>425</lpage></element-citation></ref><ref id="bib0125"><label>26</label><element-citation publication-type="journal" id="sbref0125"><person-group person-group-type="author"><name><surname>Ganguly</surname><given-names>R.</given-names></name><name><surname>Ramesh</surname><given-names>A.</given-names></name><name><surname>Pagni</surname><given-names>S.</given-names></name></person-group><article-title>The accuracy of linear measurements of maxillary and mandibular edentulous sites in cone-beam computed tomography images with different fields of view and voxel sizes under simulated clinical conditions</article-title><source>Imaging Sci. Dent.</source><volume>46</volume><issue>2</issue><year>2016</year><fpage>93</fpage><lpage>101</lpage><pub-id pub-id-type="pmid">27358816</pub-id></element-citation></ref><ref id="bib0130"><label>27</label><element-citation publication-type="journal" id="sbref0130"><person-group person-group-type="author"><name><surname>Spin-Neto</surname><given-names>R.</given-names></name><name><surname>Gotfredsen</surname><given-names>E.</given-names></name><name><surname>Wenzel</surname><given-names>A.</given-names></name></person-group><article-title>Impact of voxel size variation on CBCT-based diagnostic outcome in dentistry: a systematic review</article-title><source>J. Digit. Imaging</source><volume>26</volume><issue>4</issue><year>2013</year><fpage>813</fpage><lpage>820</lpage><pub-id pub-id-type="pmid">23254628</pub-id></element-citation></ref><ref id="bib0135"><label>28</label><element-citation publication-type="journal" id="sbref0135"><person-group person-group-type="author"><name><surname>Schulze</surname><given-names>R.</given-names></name><name><surname>Heil</surname><given-names>U.</given-names></name><name><surname>Gross</surname><given-names>D.</given-names></name><name><surname>Bruellmann</surname><given-names>D.D.</given-names></name><name><surname>Dranischnikow</surname><given-names>E.</given-names></name><name><surname>Schwanecke</surname><given-names>U.</given-names></name><name><surname>Schoemer</surname><given-names>E.</given-names></name></person-group><article-title>Artefacts in CBCT: a review</article-title><source>Dentomaxillofac. Radiol.</source><volume>40</volume><issue>5</issue><year>2011</year><fpage>265</fpage><lpage>273</lpage><pub-id pub-id-type="pmid">21697151</pub-id></element-citation></ref><ref id="bib0140"><label>29</label><element-citation publication-type="journal" id="sbref0140"><person-group person-group-type="author"><name><surname>Spin-Neto</surname><given-names>R.</given-names></name><name><surname>Wenzel</surname><given-names>A.</given-names></name></person-group><article-title>Patient movement and motion artefacts in cone beam computed tomography of the dentomaxillofacial region: a systematic literature review</article-title><source>Oral. Surg. Oral Med. Oral Pathol. Oral Radiol.</source><volume>121</volume><issue>4</issue><year>2016</year><fpage>425</fpage><lpage>433</lpage><pub-id pub-id-type="pmid">26972541</pub-id></element-citation></ref><ref id="bib0145"><label>30</label><element-citation publication-type="journal" id="sbref0145"><person-group person-group-type="author"><name><surname>Al-Okshi</surname><given-names>A.</given-names></name><name><surname>Lindh</surname><given-names>C.</given-names></name><name><surname>Sale</surname><given-names>H.</given-names></name><name><surname>Gunnarsson</surname><given-names>M.</given-names></name><name><surname>Rohlin</surname><given-names>M.</given-names></name></person-group><article-title>Effective dose of cone beam CT (CBCT) of the facial skeleton: a systematic review</article-title><source>Bri. J. Radiol.</source><volume>88</volume><issue>1045</issue><year>2015</year><fpage>20140658</fpage></element-citation></ref></ref-list><ack id="ack0005"><title>Acknowledgements</title><p><funding-source id="gs0005">Futurum, – Academy for Health and Care Region Jönköping County, Sweden</funding-source> and the <funding-source id="gs0010">National Clinical Research School in Odontology, Karolinska Institutet, Stockholm, Sweden</funding-source> have contributed with resources and funding.</p></ack></back></pmc></record>Pour manipuler ce document sous Unix (Dilib)
EXPLOR_STEP=$WICRI_ROOT/Wicri/Santé/explor/EdenteV2/Data/Pmc/Corpus
HfdSelect -h $EXPLOR_STEP/biblio.hfd -nk 002C46 | SxmlIndent | more
Ou
HfdSelect -h $EXPLOR_AREA/Data/Pmc/Corpus/biblio.hfd -nk 002C46 | SxmlIndent | more
Pour mettre un lien sur cette page dans le réseau Wicri
{{Explor lien
|wiki= Wicri/Santé
|area= EdenteV2
|flux= Pmc
|étape= Corpus
|type= RBID
|clé= PMC:5675893
|texte= Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices
}}
Pour générer des pages wiki
HfdIndexSelect -h $EXPLOR_AREA/Data/Pmc/Corpus/RBID.i -Sk "pubmed:29159206" \
| HfdSelect -Kh $EXPLOR_AREA/Data/Pmc/Corpus/biblio.hfd \
| NlmPubMed2Wicri -a EdenteV2
| This area was generated with Dilib version V0.6.32. |  |