MAX meets ADAM: a dosimetric comparison between a voxel-based and a mathematical model for external exposure to photons

Kramer, Richard A.; Vieira, José Wilson; Khoury, Helen J.; Lima, Fernando Roberto de Andrade

doi:10.1088/0031-9155/49/6/002

Cited by 46 publications

(37 citation statements)

References 27 publications

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“…Methodologies for defining standard patients and ways of assessing organ doses have evolved from the use of tissue-equivalent plastic body phantoms containing organs, into which dosimeters could be inserted, to mathematic phantoms, for which Monte Carlo simulations are applied (18,19). The most common available standard includes an adult with a body mass of 70 kg; children aged 15, 10, and 5 years and 1 year; and newborns (both genders for all ages).…”

Section: Determinationmentioning

confidence: 99%

Quality Initiatives Radiation Risk: What You Should Know to Tell Your Patient

Verdun¹,

Bochud²,

Gundinchet³

et al. 2008

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The steady increase in the number of radiologic procedures being performed is undeniably having a beneficial impact on healthcare. However, it is also becoming common practice to quantify the health detriment from radiation exposure by calculating the number of cancer-related deaths inferred from the effective dose delivered to a given patient population. The inference of a certain number of expected deaths from the effective dose is to be discouraged, but it remains important as a means of raising professional awareness of the danger associated with ionizing radiation. The risk associated with a radiologic examination appears to be rather low compared with the natural risk. However, any added risk, no matter how small, is unacceptable if it does not benefit the patient. The concept of diagnostic reference levels should be used to reduce variations in practice among institutions and to promote optimal dose indicator ranges for specific imaging protocols. In general, the basic principles of radiation protection (eg, justification and optimization of a procedure) need to be respected to help counteract the unjustified explosion in the number of procedures being performed.

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Section: Determinationmentioning

confidence: 99%

Quality Initiatives Radiation Risk: What You Should Know to Tell Your Patient

Verdun¹,

Bochud²,

Gundinchet³

et al. 2008

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107

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“…For patients of the same height and mass as these models, the mass, density, size, and position of tissues in patients will vary from the model representations. 20 For patients of different heights and masses, there will be even greater variation.…”

Section: Iid Patient Modeling-tissue Mass Density Size and Positionmentioning

confidence: 99%

On the uncertainties in effective dose estimates of adult CT head scans

2008

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Estimates of the effective dose to adult patients from computed tomography (CT) head scanning can be calculated using a number of different methods. These estimates can be used for a variety of purposes, such as improving scanning protocols, comparing different CT imaging centers, and weighing the benefits of the scan against the risk of radiation-induced cancer. The question arises: What is the uncertainty in these effective dose estimates? This study calculates the uncertainty of effective dose estimates produced by three computer programs (CT-EXPO, CTDosimetry, and ImpactDose) and one method that makes use of dose-length product (DLP) values. Uncertainties were calculated in accordance with an internationally recognized uncertainty analysis guide. For each of the four methods, the smallest and largest overall uncertainties (stated at the 95% confidence interval) were: 20%-31% (CT-EXPO), 15%-28% (CTDosimetry), 20%-36% (ImpactDose), and 22%-32% (DLP), respectively. The overall uncertainties for each method vary due to differences in the uncertainties of factors used in each method. The smallest uncertainties apply when the CT dose index for the scanner has been measured using a calibrated pencil ionization chamber.

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“…Validation of this method of calculating the equivalent dose to the skin was reported in Kramer et al (2005b). Detailed descriptions of both voxel phantoms are given in Kramer et al (2003Kramer et al ( , 2004aKramer et al ( , 2004b).…”

Section: The Max and The Fax Phantomsmentioning

confidence: 99%

“…In order to understand the decrease of the effective dose shown in figure 1, one has to analyse the change of the equivalent dose to the organs and tissues contributing to the effective dose. At the time when a female adult voxel-based phantom was not available, such an analysis has been reported for the replacement of the ADAM phantom by the MAX phantom (Kramer et al 2004b). Here the analysis will include also the female phantoms EVA and FAX.…”

Section: External Exposuresmentioning

confidence: 99%

Comparison between effective doses for voxel-based and stylized exposure models from photon and electron irradiation

2005

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For the last two decades, the organ and tissue equivalent dose as well as effective dose conversion coefficients recommended by the International Commission on Radiological Protection (ICRP) have been determined with exposure models based on stylized MIRD5-type phantoms representing the human body with its radiosensitive organs and tissues according to the ICRP Reference Man released in Publication No. 23, on Monte Carlo codes sometimes simulating rather simplified radiation physics and on tissue compositions from different sources. Meanwhile the International Commission on Radiation Units and Measurements (ICRU) has published reference data for human tissue compositions in Publication No. 44, and the ICRP has released a new report on anatomical reference data in Publication No. 89. As a consequence many of the components of the traditional stylized exposure models used to determine the effective dose in the past have to be replaced: Monte Carlo codes, human phantoms and tissue compositions. This paper presents results of comprehensive investigations on the dosimetric consequences to be expected from the replacement of the traditional stylized exposure models by the voxel-based exposure models. Calculations have been performed with the EGS4 Monte Carlo code for external and internal exposures to photons and electrons with the stylized, gender-specific MIRD5-type phantoms ADAM and EVA on the one hand and with the recently developed tomographic or voxel-based phantoms MAX and FAX on the other hand for a variety of exposure conditions. Ratios of effective doses for the voxel-based and the stylized exposure models will be presented for external and internal exposures to photons and electrons as a function of the energy and the geometry of the radiation field. The data indicate that for the exposure conditions considered in these investigations the effective dose may change between +60% and -50% after the replacement of the traditional exposure models by the voxel-based exposure models.

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MAX meets ADAM: a dosimetric comparison between a voxel-based and a mathematical model for external exposure to photons

Cited by 46 publications

References 27 publications

Quality Initiatives Radiation Risk: What You Should Know to Tell Your Patient

Quality Initiatives Radiation Risk: What You Should Know to Tell Your Patient

On the uncertainties in effective dose estimates of adult CT head scans

Comparison between effective doses for voxel-based and stylized exposure models from photon and electron irradiation

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