New Deformity Outline on the Breast Radiation Therapy for diminishing Absorbed Dose Ratio

Abstract

Breast cancer is one of the most common malignant diseases in women. After tumor mass surgery, radiation therapy is regularly taken into account the gold standard for the treatment. Kilo to Mega voltage photons have been suggested due to their characteristic depth dose build-up regime, reducing the dose to the breast skin to a fraction of the maximum dose exposure. During treatment, mean glandular dose is commonly used as a criterion for identifying radiation risks. Here, two outlines in cubic-rectangular (CR) and cylindrical- taper (CT) outlines were modelled together with corresponding assumptions using Monte-Carlo simulation and the recorded absorbed dose ratio (ADR) values were compared via defined a positron source by 511 keV energy. The results showed that the amounts of absorption and scattering cross-sections next to the ADR amount decreased as the height of the CR outline decreased. The average dose ratio amount in the CR outline was reduced by about 96% compared to that in the CT outline. By increasing the positron source distance from the nipple, the ADR amounts decreased for both outlines. The amount of accumulated dose ratio decreased harshly in the CR outline rather than in the CT outline. This study can be useful to examine breast tissue deformity in treatment planning.