A body-size-dependent series of Chinese adult standing phantoms for radiation dosimetry.

Phantoms of different sizes, which have been indicated by several studies, have a significant impact on the accuracy of dose calculations. Therefore, it is necessary to establish a body-size-dependent series of Chinese standing adult phantoms to improve the accuracy of radiation dosimetry. In this study, the Chinese reference polygon-mesh phantom CRAM S/CRAF S have been refined first. And a method for automatically constructing lymph nodes in a mesh phantom has been proposed. Then based on the refined phantoms, this study has developed 42 anthropometric standing adult computational phantoms, 21 models for each gender, with a height range of 145-185 cm, and weight as a function of BMI corresponding to healthy, overweight, and obese. The parameters were extracted from the National Occupational Health Standards (GBZ) document of the People's Republic of China, which covers more than 90% of the Chinese population. For a given body height and mass, scale in proportion to a factor to reflect the change of adipose tissue and the internal organs. The rest part is adjusted manually to match the target parameters. In addition, the constructed body-size-specific phantoms have been implemented into the in-house THUDose Monte Carlo code to calculate the dose coefficients for photon external exposures, which in the antero-posterior, postero-anterior, right lateral geometries. The results showed that organ dose coefficients varied significantly with body size at low energies (< 2 MeV) and high energies (> 8 MeV), due to the differences in anatomy. Organ dose coefficient differences between a phantom of a given size and a reference phantom vary by up to 40% at the same height and up to 400% at different heights. The influence of body size differences on the dose coefficients demonstrates that the body-size-dependent Chinese adult phantoms have great promise for a wide range of applications in radiation dosimetry.