Fabrication of tissue compensators for megavoltage beams using tissue equivalent materials

Irregular body surface of the patient give rise to inhomogeneous dose distributions around the target volume. Homogeneous dose distribution can be obtained using tissue compensators. Preparation of tissue compensators with aluminium or lead blocks is a tedious method and commercially available devices are expensive. A compensator device has been designed to use a tissue equivalent material to be kept at shield tray level, which accounts for divergence of radiation beam. The reduced size of such tissue compensator obtained at much longer distance from the skin exhibits minimum risk of electron contamination. Experimental verifications were carried out for a tissue compensator by determining transmission at different off axis points for confirmation of the accuracy of the device. This paper presents the design of tissue compensator device and methods to prepare the tissue compensators using tissue equivalent materials. (author). 6 refs., 3 figs