{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T22:16:25Z","timestamp":1783116985298,"version":"3.54.6"},"reference-count":34,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T00:00:00Z","timestamp":1776297600000},"content-version":"vor","delay-in-days":15,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T00:00:00Z","timestamp":1775001600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Estimating effective dose (E) for CT is often done with dose\u2010length product (DLP) and effective dose conversion factors, a.k.a.\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors. Previous studies have primarily focused on\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factor values derived from certain fixed\u2010sized phantoms but have not extensively explored all the contributing factors and associated variations in E.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>\n                      In this study, we investigated the contributing factors and variations of E using\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors as surrogates in adult and pediatric CT exams and provided empirical formula to estimate a comprehensive new set of\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Effective dose was estimated using NCICT (National Cancer Institute, USA), including organ and effective dose conversion coefficient library estimated by Monte\u2010Carlo radiation transport techniques. The\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors were derived as a surrogate of DLP\u2010normalized E, via E\/DLP (unit: mSv\/mGy\u00b7cm). We examined the variations of effective dose estimates for different phantom and scan parameters represented by the calculations of\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors. This included variations in patient sex, weight, height, kVp, and scan length across typical adult and pediatric CT examinations of anatomical regions such as the head, neck, chest, abdomen, and pelvis. Multivariable regression analyses with\/without standardization were conducted to evaluate the significance of the dependency of\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors on the studied parameters. Tube current modulation (TCM) parameters, modeled as a function of patient attenuation using variable modulation strengths, were also incorporated to reflect realistic clinical CT dose variations.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The variations of DLP\u2010normalized E were substantially affected by multiple factors, exceeding 100% for adults (weight for adult pelvis) and more than 200% for pediatrics (height for pediatric head). The analysis of standardized regression coefficients revealed that patient weight is the most critical factor, except for head scans in adults, where scan length and patient height are the main determinants. In pediatric CT, both patient weight and height had critical impact. Similarly, for pediatric head CT scans, patient height and scan length are the dominant factors, as observed in adults. Consequently, the\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors have a wide range, from 0.0099 to 0.0357 mSv\/mGy\u00b7cm for adult chest and from 0.0085 to 0.0363 mSv\/mGy\u00b7cm for adult abdomen. Empirical formulas to estimate\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factors were obtained based on multi\u2010variable regression with adjusted R square ranging from 0.71 to 0.93. Based on NCICT's TCM model, the use of TCM resulted in an additional average variation of 110% in the\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factor compared to non\u2010TCM results.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      Our study demonstrated the large variations of DLP\u2010normalized effective dose. Standardized coefficients revealed that patient weight, height and\/or scan length were the most crucial determinants. Depending on the specific TCM model used, even greater variations may be observed. This work also provided a practical framework for estimating CT effective dose using the traditional\n                      <jats:italic>k<\/jats:italic>\n                      \u2010factor method with updated new conversion factors.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70432","type":"journal-article","created":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T08:59:41Z","timestamp":1776329981000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Determinants and expected differences in the calculation of CT effective dose conversion factors for various phantom sizes and scan parameters"],"prefix":"10.1002","volume":"53","author":[{"given":"Renxin","family":"Chu","sequence":"first","affiliation":[{"name":"Department of Radiology Boston Children's Hospital  Boston Massachusetts USA"},{"name":"Department of Radiology UVA Health University Hospital  Charlottesville Virginia USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jelena","family":"Mihailovic","sequence":"additional","affiliation":[{"name":"Department of Radiology Mayo Clinic  Rochester Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Choonsik","family":"Lee","sequence":"additional","affiliation":[{"name":"Division of Cancer Epidemiology and Genetics, National Cancer Institute National Institutes of Health  Rockville Maryland USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lifeng","family":"Yu","sequence":"additional","affiliation":[{"name":"Department of Radiology Mayo Clinic  Rochester Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Da","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Radiology Boston Children's Hospital  Boston Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kai","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Radiology Massachusetts General Hospital  Boston Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,4,16]]},"reference":[{"issue":"1","key":"e_1_2_10_2_1","first-page":"1","article-title":"1990 recommendations of the International Commission on Radiological Protection. ICRP publication 60","volume":"21","year":"1991","journal-title":"Ann ICRP"},{"key":"e_1_2_10_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.icrp.2007.10.003"},{"key":"e_1_2_10_4_1","doi-asserted-by":"publisher","DOI":"10.1097\/HP.0000000000000674"},{"key":"e_1_2_10_5_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr\/22942198"},{"key":"e_1_2_10_6_1","doi-asserted-by":"publisher","DOI":"10.1093\/oxfordjournals.rpd.a032542"},{"key":"e_1_2_10_7_1","doi-asserted-by":"publisher","DOI":"10.37206\/97"},{"key":"e_1_2_10_8_1","doi-asserted-by":"publisher","DOI":"10.1148\/radiol.10100047"},{"key":"e_1_2_10_9_1","doi-asserted-by":"publisher","DOI":"10.1093\/rpd\/ncv511"},{"key":"e_1_2_10_10_1","volume-title":"Medical Radiation Exposure of Patients in the United States: Recommendations of the National Council on Radiation Protection and Measurements","author":"National Council on Radiation Protection and Measurements","year":"2019"},{"key":"e_1_2_10_11_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr\/93277434"},{"key":"e_1_2_10_12_1","volume-title":"Doses from computed tomography (CT) examinations in the UK\u20142011 review. Public Health England Report PHE\u2010CRCE\u2010013","author":"Shrimpton PC","year":"2014"},{"key":"e_1_2_10_13_1","volume-title":"Survey of CT practice in the UK. Part 2: dosimetric aspects. National Radiological Protection Board Report NRPB R249","author":"Shrimpton PC","year":"1991"},{"key":"e_1_2_10_14_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr.20150346"},{"key":"e_1_2_10_15_1","doi-asserted-by":"publisher","DOI":"10.31661\/jbpe.v0i0.2301\u20101586"},{"key":"e_1_2_10_16_1","doi-asserted-by":"crossref","unstructured":"FisherHL SnyderWS.Distribution of dose in the body from a source of gamma rays distributed uniformly in an organ. In:Proceedings of the First International Congress of Radiation Protection.Elsevier;1968:1473\u20101486. doi:10.1016\/B978\u20101\u20104832\u20108312\u20108.50220\u20104","DOI":"10.1016\/B978-1-4832-8312-8.50220-4"},{"key":"e_1_2_10_17_1","doi-asserted-by":"crossref","unstructured":"CristyM.Mathematical Phantoms Representing Children of Various Ages for Use in Estimates of Internal Dose.1980. NUREG\/CR\u20101159 ORNL\/NUREG\/TM\u2010367 5308345. doi:10.2172\/5308345","DOI":"10.2172\/5308345"},{"key":"e_1_2_10_18_1","volume-title":"The Calculation of Dose from External Photon Exposures Using Reference Human Phantoms and Monte\u2010Carlo Methods Pt 1","author":"Kramer R","year":"1982"},{"key":"e_1_2_10_19_1","volume-title":"Specific absorbed fractions of Energy at Various Ages from Internal Photon Sources: 7. Adult Male","author":"Cristy M","year":"1987"},{"issue":"3","key":"e_1_2_10_20_1","first-page":"5","article-title":"Basic anatomical and physiological data for use in radiological protection: reference values. a report of age\u2010 and gender\u2010related differences in the anatomical and physiological characteristics of reference individuals. ICRP Publication 89","volume":"32","year":"2002","journal-title":"Ann ICRP"},{"key":"e_1_2_10_21_1","doi-asserted-by":"publisher","DOI":"10.1093\/rpd\/ncm269"},{"key":"e_1_2_10_22_1","volume-title":"The Monte Carlo Method: Versatility Unbounded in a Dynamic Computing World","author":"Zankl M","year":"2005"},{"key":"e_1_2_10_23_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.icrp.2011.10.001"},{"issue":"3","key":"e_1_2_10_24_1","first-page":"1","article-title":"Conversion coefficients for use in radiological protection against external radiation. adopted by the ICRP and ICRU in september 1995","volume":"26","year":"1996","journal-title":"Ann ICRP"},{"key":"e_1_2_10_25_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/52\/12\/001"},{"key":"e_1_2_10_26_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/54\/19\/015"},{"key":"e_1_2_10_27_1","doi-asserted-by":"publisher","DOI":"10.1109\/JPROC.2009.2022417"},{"key":"e_1_2_10_28_1","doi-asserted-by":"publisher","DOI":"10.1109\/23.910837"},{"key":"e_1_2_10_29_1","volume-title":"Development and Application of the New Dynamic NURBS\u2010Based Cardiac\u2010Torso (NCAT) Phantom","author":"Segars WP","year":"2001"},{"key":"e_1_2_10_30_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3480985"},{"key":"e_1_2_10_31_1","doi-asserted-by":"publisher","DOI":"10.1088\/0952\u20104746\/35\/4\/891"},{"key":"e_1_2_10_32_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106498\/ad6faa"},{"key":"e_1_2_10_33_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/ab3eaa"},{"key":"e_1_2_10_34_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/59\/16\/4525"},{"key":"e_1_2_10_35_1","doi-asserted-by":"publisher","DOI":"10.1088\/2057\u20101976\/ac9845"}],"container-title":["Medical Physics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/mp.70432","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/mp.70432","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/mp.70432","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T21:26:01Z","timestamp":1783113961000},"score":1,"resource":{"primary":{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/10.1002\/mp.70432"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4]]},"references-count":34,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2026,4]]}},"alternative-id":["10.1002\/mp.70432"],"URL":"https:\/\/doi.org\/10.1002\/mp.70432","archive":["Portico"],"relation":{},"ISSN":["0094-2405","2473-4209"],"issn-type":[{"value":"0094-2405","type":"print"},{"value":"2473-4209","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4]]},"assertion":[{"value":"2025-11-11","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-03-21","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-04-16","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70432"}}