Dynamic wedge dosimetry on a dual energy linear accelerator.

摘要

The dynamic wedge is created by moving one of the primary beam limiting collimators in a continuous fashion to create a continuously decreasing field width while the radiation beam is on. Because of this collimator motion, different segments of the treatment field will be exposed to the primary beam for different intervals of time. This process of shrinking the field width while modulating the collimator jaw velocity and dose rate creates the desired wedge-shaped isodose gradient across the treatment field. The amount of dose that is delivered to the patient as the collimator moves across the treatment field is controlled by pre-specified computer selected look-up tables.;Before a dynamic wedge option can be implemented clinically, it must be thoroughly tested by measuring pertinent beam characteristics, thereby determining the reliability of this technology. Unlike beam measurements in static field radiotherapy, dynamic beam radiatiotherapy requires the use of an integrating dosimetry technique. In this thesis data was accumulated with the use of film dosimetry and direct integration ionization chambers. Using such systems the dosimetric properties of the dynamic wedge installed on a dual energy Clinac 2300 C/D linear accelerator were investigated. (Abstract shortened by UMI.)