Acquisition and display of radiation dose distributions using microcomputer technology

Abstract

In the commissioning or quality assurance of a medical linear accelerator or a computerized radiotherapy planning system, the traditional approach usually consists of acquiring and comparing one-dimensional dose profiles. This methodology is tedious and incomplete since only a portion of the radiation field can realistically be sampled. We have developed an automated measurement system which allows efficient measurement and display a complete two-dimensional dose distributions. The general purpose microcomputer used (IBM PC/XT compatible) can be interfaced economically to any water phantom dosimetry system equipped with a three axis scancontroller, and can also communicate data to the treatment planning system. This allows for direct comparison of measured with computed dose distributions, thus revealing discrepancies in the dose computation algorithms used. In this paper, we describe the interface between the microcomputer, a conventional water dosimetry system (Therados RFA-3), and a treatment planning computer. We report our early experience with acquiring dose distributions and show sample comparisons with computed results for megavoltage electron beams incident on homogeneous and heterogeneous systems.