WE‐E‐BRD‐08: Next‐Generation Deformable Patient Modeling for Monte Carlo Assessment of Organ Doses

Abstract

Purpose: Whole‐body patient models of various sizes and postures are needed for the assessment of organ doses in CT imaging, internal nuclear medicine and external‐beam radiation treatment procedures. This paper discusses a deformable mesh‐based modeling method to create patient‐specific phantoms that are morphed by changing to 5th‐ to 95th‐percentiles of body height and weight, as well as internal organ volume and masse. Method and Materials: The mesh‐based reference adult male and female phantoms were deformed by mainly two different percentile data: 1) the whole‐body size percentile data which were defined by the anthropometric parameters such as height and weight from the National Health and Nutrition Examination Survey (NHANES). 2) individual internal organ percentile data which were derived by the cumulative pattern analysis based on the International Commission on Radiological Protection (ICRP) 23 and 89 references. These mesh‐based percentile phantoms were converted into the voxel‐based phantoms. The final step is to link the voxel phantom with correct tissue density and elemental composition, so that radiation transport through the human‐body phantom was modeled correctly in a Monte Carlo code. Results: The whole‐body size percentile models have been created by the NHANES anthropometric data and the details of organ percentiles derived from ICRP references. The deformability of the RPI reference adult phantoms has been shown through the demonstration of percentiles‐ and postures‐specific adult models. Conclusion: A next generation deformable patient modeling method has been demonstrated. With the mesh deformation algorithms, the individual organs are able to be deformed to match the volumes and masses with desired organ percentiles. The flexible modeling allows patients to be represented in various sizes and postures for the purpose of Monte Carlo dose calculations. This study also identified the need for further research to develop method to run Monte Carlo calculations in mesh geometry directly.

Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

“…The percentile data for most major internal organs were based directly on the ICRP Publications 23 and 89 (ICRP 1975(ICRP , 2002. It was assumed that the distribution of major internal organ volume and mass follows the Gaussian normal distribution (Na et al 2009b). The percentile data of each major internal organ were then derived from the cumulative pattern analysis for a normal distribution (Zelen and Severo 1972).…”

Studying the effects of the lung mass on the absorbed dose to the lung due to the administration of131I for therapeutic purposes

“…After studying the difference in the lung mass in different people, it is vital to determine the range of the changes and its distribution. According to Na's reports, which were published in 2009 and 2010, the mass (or the volume) normal distribution of the organs follows the Gaussian distribution with high reliability (Na et al, 2009(Na et al, , 2010. The International Commission on Radiological Protection Publication 89 provided the standard anatomical and physiological information together with statistical data of some of the organs to protect patients from radiation (ICRP, 2002).…”

Development of a Library of Adult Computational Phantoms Based on Anthropometric Indexes

“…In another study, an automated algorithm was developed to generate an adult phantom library using polygon mesh surfaces where the Rensselaer Polytechnic Institute (RPI) adult male and adult female models [4] were extended into a library representing morphometric diversities in the US population for the 19-year old males and females. The organ masses were assumed to follow a Gaussian normal distribution [11] according to the mean and standard deviation compiled from various sources [5].…”