Dose measurements in a thorax phantom at 3DCRT breast radiation therapy

Abstract

background:The anthropomorphic and anthropometric phantom developed by the research group NrI (Núcleo de radiações Ionizantes) can reproduce the effects of the interactions of radiation occurring in the human body. The whole internal radiation transport phenomena can be depicted by film dosimeters in breast rT. Our goal was to provide a dosimetric comparison of a radiation therapy (rT) plan in a 4MV 3D-conformal rT (4MV-3DcrT) and experimental data measured in a breast phantom. Materials and methods:The rT modality was two parallel opposing fields for the left breast with a prescribed dose of 2.0 Gy in 25 fractions. The therapy planning system (Tps) was performed on caT3D software. The dose readings at points of interest (pOI) pre-established in Tps were recorded. an anthropometric thorax-phantom with removal breast was used. eBT2 radiochromic films were inserted into the ipisilateral breast, contralateral breast, lungs, heart and skin. The irradiation was carried out on 4/80 Varian linear accelerator at 4MV. results:The mean dose at the Oar's presented statistically significant differences (p < 0.001) of 34.24%, 37.96% and 63.47% for ipsilateral lung, contralateral lung, and heart, respectively. The films placed at the skin-surface interface in the ipsilateral breast also showed statistically significant differences (p < 0.001) of 16.43%, -10.16%, -14.79% and 15.67% in the four quadrants, respectively. In contrast, the pTV dosimeters, representative of the left breast volume, encompassed by the electronic equilibrium, presented a non-significant difference with Tps, p = 0.20 and p = 0.90. conclusion:There was a non-significant difference of doses in pTV with electronic equilibrium; although no match is achieved outside electronic equilibrium.

Dosimetry Evaluation of Treatment Planning Systems in Patient-Specific 3D Printed Anthropomorphic Phantom for Breast Cancer after Mastectomy using a Single-Beam 3D-CRT Technique for Megavoltage Electron Radiation Therapy

“…Radiation therapy for breast cancer covers various tissues with very different densities, such as bone, lung, soft tissue, air, and very complex anatomy [ 9 ]. Meanwhile, some treatment planning systems (TPSs) have limitations for predicting low-density areas [ 9 ].…”

“…As an initial study on breast cancer individuals, an object similar to patients was needed in the medical world as a substitute called phantoms, used in quality control (QC) or quality tests on a linear accelerator (Linac) [ 10 ]. Therefore, dose measurements of the internal organs through detectors in phantoms will show the impact of the radiation interaction on the human being [ 9 ].…”