Correcting for the nonuniform boron distribution in a tumor for BNCT dose calculation

Abstract

Abstract Most BNCT treatment planning systems perform dose calculations based on the assumption of a homogeneous BPA distribution in tumors, which leads to dose distortion due to the difference between the TNR range measured in PET images and the target delineation in CT images of the treatment plan. The heterogeneous BPA distribution in the target of the treatment plan can be obtained by image fusion. This study provides a way to quantify a heterogeneous BPA distribution based on PET images. Theoretically, the same mean TNR for dose calculation by homogeneous or heterogeneous BPA distribution should get almost the same mean dose. However, slightly different mean doses are found due to the partial volume effect for a small target volume. The wider the BPA distribution is, the higher the impact on the DVH distribution is. Dose distribution with homogeneous boron distribution may be overestimated in low boron uptake regions by wrong boron concentration and neutron flux depression. To accurately give the tumor prescription dose and achieve better tumor control, for low dose regions of the tumor should be considered more BNCT treatments or combined with other treatment modalities. The heterogeneous boron distribution must be taken into consideration to have an accurate dose estimation. Therefore, the way how medical physicists and clinicians process the TNR in GTV should be refined, and the method demonstrated in the work provides a good reference.