Implementation of enhanced dynamic wedge using Theraplan.

The article discusses how to use the standard utility program on Theraplan to create physical wedges which are equivalent to each of the enhanced dynamic wedges. The user must first create segmented treatment tables for each wedge, using a spreadsheet, and then convert these tables to equivalent thicknesses of an arbitrary wedge material. These thicknesses are then supplied to Theraplan. The paper discusses the agreement achieved between Theraplan and measured data, and the quality assurance procedures which should be adopted.

Levels of leakage radiation from electron collimators of a linear accelerator.

The leakage radiation from electron applicators used with our linear accelerator has been measured. For the applicators 6 X 6 to 25 X 25 cm size, the leakage was measured in the plane of the patient and on the sides of the applicators with the available electron energies of 6, 9, 12, 15 and 18 MeV. The levels were significant. The highest leakage on the side was for the combination of 6 X 6-cm applicator and 9-MeV electrons (32%) and in the plane of the patient for 25 X 25-cm applicator with 18 MeV (10%) relative to the peak dose. Adding lead 1-2 mm, at appropriate locations inside the applicators has reduced the leakages to acceptable levels without affecting the beam parameters.