Development of a shielding device for radiotherapy of breast cancer-bearing mice

Abstract

Breast cancer is the fifth most common cause of death worldwide. Currently, one of the standard treatments for breast cancer is radiation therapy (RT). On the other hand, mouse models have been used in pre-clinical studies for breast cancer RT, requiring dedicated shielding to exposure the breast region. In this work, we considered the values of the lead attenuation coefficient and the tenth reducing layer for a 60Co irradiator and developed a lead shielding device for breast cancer-bearing mice to be exposed to localized breast RT. Five-kg of lead were exposed to temperature of 340ºC and inserted into an aluminum mold previously adjusted to the dimensions of the device. After solidification, the device was shaped into a cylinder with dimension of 14 x 15 x 7 cm (height x width x thickness, respectively). A round cut-out for breast exposure of 1 cm in diameter was made at 5 cm from the basis of the device. For shielding device validation, we performed calibrations to establish a dose of 10 Gy in the target. Fifteen CaSO4:Dy thermoluminescent dosimeters were distributed along a 50 mL conical tube to simulate the mouse position inside the shielding. The shielding device was placed at a fixed distance of 10 cm from the target for optimal exposure time. After irradiation, the dosimeters were read on a thermoluminescent reader. According to our results, we were able to develop a body-shielding device that assured the required dose for RT of breast cancer in mice.

Development of custom lead shield and strainer for targeted irradiation for mice in the gamma cell chamber

“…Therefore, to minimize this pathological effect on the non-cancerous tissues, based on gamma shielding calculation, for 1.3 MeV energy of gamma-ray from Co 60 source with 1.133 kGy/ hour, the lead shielding requires a thickness of 5 cm for reducing one-tenth of the dose rate. Up to date, there are several different custom-made lead shields have been developed to suit different xenograft model such as orthotopic and flank 7 ; glioblastoma 10 , mouse flank 11 , and breast cancer shielding device 12 . All these shields are not only developed based on different models but also based on types of irradiator, either X-ray 7 , 11 or gamma-ray 10 .…”

Noninvasive Red Laser Intervention before Radiotherapy of Triple-negative Breast Cancer in a Murine Model

“…The total dose delivered to the breast tumor was 60 Gy split into 4 fractions of 15 Gy (one fraction per day). The mouse was inserted into a conical tube (50 mL) and shielded by a lead device, both of them with a hole in the breast region to allow irradiation of the tumor ( 24 ).…”