{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T00:07:43Z","timestamp":1769558863004,"version":"3.49.0"},"reference-count":28,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2023,6,7]],"date-time":"2023-06-07T00:00:00Z","timestamp":1686096000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2023,8]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>It is challenging to assess the accuracy of volume CT Dose Index (<jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic>) when the axial scan modes corresponding to a helical scan protocol are not available. An alternative approach was proposed to directly measure  using helical acquisitions and relatively small differences (&lt;\u00a020%) from <jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic> were observed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Purpose<\/jats:title><jats:p>To visually demonstrate the 3D dose distribution for both axial and helical CT acquisitions and quantitively compare  and <jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic>.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>3D dose distribution within the standard CTDI phantoms (16 and 32\u00a0cm diameter) from a single CT projection, <jats:italic>D<jats:sub>p<\/jats:sub><\/jats:italic>(<jats:italic>x<\/jats:italic>,<jats:italic>y<\/jats:italic>,<jats:italic>z<\/jats:italic>) was first generated using Monte Carlo simulation (GEANT4) with 9\u00d710<jats:sup>8<\/jats:sup> photons per combination of tube voltage (80\u2013140\u00a0kV), collimation width (1\u20138\u00a0cm), and z\u2010axis location of the central ray of the x\u2010ray beam, with a spatial resolution of 1 mm<jats:sup>3<\/jats:sup>. These dose distributions from one single projection were analytically ensembled to simulate 3D dose volumes <jats:italic>D<jats:sub>A<\/jats:sub><\/jats:italic>(<jats:italic>x<\/jats:italic>,<jats:italic>y<\/jats:italic>,<jats:italic>z<\/jats:italic>) and <jats:italic>D<jats:sub>H<\/jats:sub><\/jats:italic>(<jats:italic>x<\/jats:italic>,<jats:italic>y<\/jats:italic>,<jats:italic>z<\/jats:italic>) for axial and helical scans, respectively, with different helical pitches (0.3\u20132) and scan lengths (100\u2013150\u00a0mm). 2D planar dose distributions were obtained by integrating the inside 100\u00a0mm of the dose volumes. <jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic> and were calculated using the planar dose data at corresponding pencil chamber locations and the percentage differences (PD) were reported.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>High spatial resolution 3D CT dose volumes were generated and visualized. PDs between  and <jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic> had strong dependency on scan length and peripheral chamber locations, with subtle dependency on collimation width and pitch. PDs were mostly within the range of\u00a0\u00b1\u00a03% for a scan length of 150\u00a0mm with four peripheral chamber locations.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>With a scan length covering the entire phantom length,  directly measured from helical scans can serve as an alternative to <jats:italic>CTDI<jats:sub>vol<\/jats:sub><\/jats:italic> only if all four peripheral locations were measured.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.16530","type":"journal-article","created":{"date-parts":[[2023,6,7]],"date-time":"2023-06-07T12:44:10Z","timestamp":1686141850000},"page":"4797-4808","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Visualization and comparison of CT dose distribution between axial and helical acquisitions"],"prefix":"10.1002","volume":"50","author":[{"given":"Kai","family":"Yang","sequence":"first","affiliation":[{"name":"Division of Diagnostic Imaging Physics Department of Radiology Massachusetts General Hospital  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xinhua","family":"Li","sequence":"additional","affiliation":[{"name":"Division of Diagnostic Imaging Physics Department of Radiology Massachusetts General Hospital  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lifeng","family":"Yu","sequence":"additional","affiliation":[{"name":"Department of Radiology Mayo Clinic  Rochester Minnesota USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Baojun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Radiology Boston University Medical Center  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Theodore A.","family":"Marschall","sequence":"additional","affiliation":[{"name":"Division of Diagnostic Imaging Physics Department of Radiology Massachusetts General Hospital  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bob","family":"Liu","sequence":"additional","affiliation":[{"name":"Division of Diagnostic Imaging Physics Department of Radiology Massachusetts General Hospital  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2023,6,7]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.37206\/97"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.37206\/109"},{"key":"e_1_2_8_4_1","first-page":"3","article-title":"The CTDI paradigm: a practical explanation for medical physicists","author":"Dixon RL","year":"2010","journal-title":"J Am Coll Radiol"},{"key":"e_1_2_8_5_1","first-page":"791","volume-title":"Radiation Dose in X\u2010ray Computed Tomography. 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