Out of Field Breast Doses as an Undesired Consequence of Cervical Cancer Radiotherapy
Yunus SARALI1,Makbule TAMBAŞ2,Canan KÖKSAL1,Uğur AKBAŞ1,Hatice Bilge BECERİR1
1Department of Medical Physics, İstanbul University, Çapa, Institute of Oncology, İstanbul-Turkey
2Department of Radiation Oncology, Okmeydanı Training and Research Hospital, İstanbul-Turkey
DOI : 10.5505/tjo.2019.2098 OBJECTIVE
Unwanted doses may occur in distant organs, outside of the region where we want to be irradiated in patients treated with radiotherapy. These doses cannot be accounted accurately by the treatment planning system (TPS) yet. In our study, the doses received by the breast tissue outside the field of irradiation are aimed to investigate dosimetrically in irradiation with three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT) techniques for cervical cancer.

The patient was simulated in Alderson Rando phantom and irradiated with three different techniques in Varian DHX (Rapidarc) linear accelerator with 48 Gy in 24 fractions. Doses that occur in the breast tissue were measured using thermoluminescent dosimeters and compared with each other and the data obtained from TPS.

The dose values in the right and left breasts were found to be statistically similar to each other (p>0.05), whereas significant differences were detected between different techniques. The mean calculated breast doses were 7.16±1.61 cGy in 3D-CRT, 27,75±3,88 cGy in IMRT and 12,20±2,65 cGy in VMAT, respectively.

The breast tissue doses are significantly lower in 3D-CRT and VMAT compared with IMRT. This finding should be considered while choosing a treatment technique, especially in young patients with cervical cancer. Keywords : Breast dose; cervical cancer radiotherapy; out-of-field dose; peripheral dose