Abstract
The work of general Hounsfield unit (HU) value conversion material library has a prominent advantage in reflecting the multiplicity of tissue material compositions. For the sake of conquering the impact of limitations of imaging energy resolution and spatial resolution, while bearing in mind the accuracy and conservatism of BNCT dose calculation and assessment, a HU conversion material library for organs at risk (OAR) is established. The region of interest (ROI) is assigned to the OAR material library to build Monte Carlo model, which can be evolved into a homogeneous material with a single composition or a heterogeneous material with multiple compositions. A benchmark comparison of a coarse model with conventional fixed material library versus a refined model of HU-based converting approach coupled with an improved OAR-related ingrained material library within ROI was performed on practical glioma and head-and-neck tumor cases. Comparing the refined model with the coarse model showed that the minimum bioequivalent dose rate and physical absorbed dose rate of tumor differed by more than 3.6%, the health tissue maximum bioequivalent dose rate differed by 12.9%, and the maximum physical absorbed dose rate of the health tissue differed by 5.9%. Elemental compositions and mass densities influence the dose distribution. Delicately defined material compositions should be applied to ensure the trustworthiness of the calculated dose. Taking into account individual patient differences, improved material modeling strategies allow for simulations that are closer to the patient’s authentic physical condition, thereby more accurately assessing health tissue dose limit and tumor prescribed dose.