An analysis of geometrical aspects of fabrication of irregular shielding blocks for large portal radiotherapy

This article deals with the inaccuracy in the volume shielded, if shielding blocks are fabricated with the mantle cutting machine using different distances obtained during planning radiography. However, there is no compromise in the volume of irradiation for curative radiotherapy. The concept of partially shielded volume in the regions to be shielded is brought out when blocks fabricated by the tray shift technique are used for treatment. (author). 7 refs., 4 figs., 4 tabs