Body Size-Specific Effective Dose Conversion Coefficients for Ct Scans

Romanyukha, A.; Folio, Les; Lamart, Stéphanie; Simon, Steven L.; Lee, Choonsik

doi:10.1093/rpd/ncv511

Cited by 40 publications

(34 citation statements)

References 19 publications

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“…Such values do not conform to the definition of E, based on the reference phantoms, and need to be distinguished from the reference quantity. Nevertheless, with appropriate validation, these calculations could perform a useful function, in providing a measure that could be termed patient-specific or size-specific E [17].…”

Section: Calculation Of E Based On Reference Phantomsmentioning

confidence: 99%

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Effective dose from radiation exposure in medicine: Past, present, and future

2020

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Effective dose (E) has been developed by the International Commission on Radiological Protection (ICRP) as a dose quantity with a link to risks of health detriment, mainly cancer. It is based on reference phantoms representing average individuals, but this is often forgotten in its application to medical exposures, for which its use sometimes goes beyond the intended purpose. There has been much debate about issues involved in the use of E in medicine and ICRP is preparing a publication with more information on this application. This article aims to describe the development of E and explain how it should be used in medicine. It discusses some of the issues that arise when E is applied to medical exposures and provides information on how its use might evolve in the future. The article concludes with responses to some frequently asked questions about uses of E that are in line with the forthcoming ICRP publication. The main use of E in medicine is in meaningful comparison of doses from different types of procedure not possible with measurable dose quantities. However, it can be used, with appropriate care, as a measure of possible cancer risks. When considering E to individual patients, it is important to note that the dose received will differ from that assessed for reference phantoms, and the risk per Sv is likely to be greater on average in children and less in older adults. Newer techniques allow the calculation of patient-specific E which should be distinguished from the reference quantity.

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Section: Calculation Of E Based On Reference Phantomsmentioning

confidence: 99%

“…If doses to organs and tissues of individuals are combined using the tissue weighting factors [16,17], then an alternative term, such as patient-specific E should be used. This would be a derivative of E that differs from the actual value of E which is a defined quantity relating to the reference phantoms [2].…”

mentioning

confidence: 99%

Effective dose from radiation exposure in medicine: Past, present, and future

2020

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“…3 shows, as an example, the dependences of CC E on the patient's body weight modeled by both stylized and hybrid phantoms in the case of abdomen CT examination. 17,24 The parameter values in Eq. 7are quite close for both sets of computational models (see Table II).…”

Section: B Weight Dependence Of the Conversion Coefficientsmentioning

confidence: 99%

“…To derive body size-specific CC E from the age specific CC E it was regressed the "effective diameters" of the ICRP phantoms on the age-specific CC E where "effective diameter" was determined as the mean of the anteroposterior and lateral dimensions on an axial image of the hybrid phantoms at the centre of the scan coverage. 24 Regression fits (in the form a simple empirical exponential model) were derived for different CT scan types.…”

Section: Introductionmentioning

confidence: 99%

“…The next step was to calculate body size‐specific CC E which assess effective dose more precisely and on a more individual level than the conventional age‐specific CC E and, hence, improve awareness of the true exposure, which is important for the clinical community to understand. To derive body size‐specific CC E from the age specific CC E it was regressed the “effective diameters” of the ICRP phantoms on the age‐specific CC E where “effective diameter” was determined as the mean of the anteroposterior and lateral dimensions on an axial image of the hybrid phantoms at the centre of the scan coverage 24 . Regression fits (in the form a simple empirical exponential model) were derived for different CT scan types.…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Patient‐weight dependence of the effective dose conversion coefficients for diagnostic x‐ray imaging procedures

Голиков

Дружинина

2020

Medical Physics

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The aim of this study was to provide a method and reference data for the evaluation of the weight dependence of the conversion coefficients from air collision kerma integrated over beam area to the effective dose for patients undergoing diagnostic x-ray examinations. Method: A simple physics-based analytical model was developed in order to calculate the weight dependence of the effective dose conversion coefficients based on existing values of the conversion coefficients between patient effective dose and air collision kerma integrated over beam area calculated by the Monte Carlo method on the base of computational MIRD-5-type stylized models. Results: The analytical expressions that make possible taking into account a patient's weight when assessing the effective dose were presented. The following categories of diagnostic x-ray examinations are considered: CT; plain radiography; cardiac angiography; fluoroscopy. The results indicate that the weight dependence of the effective dose conversion coefficients for different categories of diagnostic x-ray examinations has the same form. Correction factor for evaluation of the new value of the effective dose conversion coefficient for a patient with weight W pa. when we know its value for a standard patient with weight W st. depends on the ratios of their weights (W st. /W pat.) and fractions of the incident energy which is imparted to a patient. Conclusions: The paper presents an approach and necessary data for the estimation of the weight dependence of the effective dose conversion coefficients for patients undergoing different diagnostic x-ray examinations.

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Effect of tin spectral filtration on organ and effective dose in CT colonography and CT lung cancer screening

Fong,

Herts,

Primak

et al. 2023

Medical Physics

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BackgroundStudies of tin spectral filtration have demonstrated potential in reducing radiation dose while maintaining image quality for unenhanced computed tomography (CT) scans. The extent of dose reduction, however, was commonly measured using the change in the scanner's reported CTDIvol. This method does not account for how tin filtration affects patient organ and effective dose.PurposeTo investigate the effect of tin filtration on patient organ and effective dose for CT Lung Cancer Screening (LCS) and CT Colonography (CTC).MethodsA previously‐developed Monte Carlo program was adapted to model a 96‐row CT scanner (Somatom Force, Siemens Healthineers) with tin filtration capabilities at 100 kV (100Sn) and 150 kV (150Sn). The program was then validated using experimental CTDIvol measurements at all available kV (70–150 kV) and tin‐filtered kV options (100Sn and 150Sn). After validation, the program simulated LCS scans of the chest and CTC scan of the abdomen‐pelvis for a population of 53 computational patient models from the extended cardiac‐torso family. Each scan was performed using three different spectra: 120 kV, 100Sn, and 150Sn. CTDIvol‐normalized organ doses and DLP‐normalized effective doses, commonly referred to as dose conversion factors, were compared between the different spectra.ResultsFor all LCS and CTC scans, CTDIvol‐normalized organ doses and DLP‐normalized effective doses increased with increasing beam hardness (120 kV, 100Sn, 150 Sn). For LCS, relative for 120 kV, conversion factors for 100Sn produced a median increase in effective dose of 9%, with organ dose increases of 8% to lung, 5% to breast, 15% to thyroid, and 3% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 20%, with organ dose increases of 16%, 18%, 26%, and 12% to these same organs, respectively. For CTC, relative for 120 kV, conversion factors for 100Sn produced a median increase in effective dose of 12%, with organ dose increases of 9% to colon, 10% to liver, 11% to stomach, and 4% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 21%, with organ dose increases of 16%, 17%, 19%, and 10% to these same organs, respectively.ConclusionsResults show that dose conversion factors are greater when using tin filtration and should be considered when evaluating tin's potential for dose reduction.

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Body Size-Specific Effective Dose Conversion Coefficients for Ct Scans

Cited by 40 publications

References 19 publications

Effective dose from radiation exposure in medicine: Past, present, and future

Effective dose from radiation exposure in medicine: Past, present, and future

Technical Note: Patient‐weight dependence of the effective dose conversion coefficients for diagnostic x‐ray imaging procedures

Effect of tin spectral filtration on organ and effective dose in CT colonography and CT lung cancer screening

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