Use of a Radiotherapy Treatment-Planning Computer for Dosimetry of the AFRRI (Armed Forces Radiobiology Research Institute) Cobalt-60 Facility

摘要

This study examined the feasibility of using radiation therapy treatment-planning computer (TPC) designed for clinical radiotherapy, to calculate patterns of depth dose and tissue-to-air ratios (TAR's) for objects irradiated in the Cobalt-60 Facility at the Armed Forces Radiobiology Research Institute (AFRRI). The TPC was used to calculate patterns of depth dose for four cylindrical phantoms of different sizes. Patterns of whole-body depth dose and TAR's were calculated for cylindrical phantoms using a computer for treatment planning, and then compared to those measured in the Cobalt-60 Facility. The measured TAR's agreed well with the computer-calculated TAR's for one computational mode but not for another. The calculated and experimental depth-dose patterns agreed well at the central cross sections of the phantoms, but differed significantly at the cross sections near the end of the phantoms. These data demonstrate the degree of nonuniformity of dose in cylindrical phantoms irradiated in the Cobalt-60 Facility. They also point out the usefulness of a treatment-planning computer in characterizing distributions of depth dose.