Measurements of Dose Distribution outside the Treatment Area in case of Radiotherapy Treatment using Polystyrene Phantom

TL;DR

This study measures off-field dose distributions in radiotherapy using a polystyrene phantom and TLD chips, providing data crucial for radiation protection and treatment planning.

Contribution

It introduces a method to quantify dose outside the treatment area for various teletherapy units using a fabricated phantom and TLD measurements.

Findings

Dose decreases with distance from field edge

Dose distribution depends on energy, field size, and shape

Parameterization of dose for Cobalt-60 beam

Abstract

Dose distribution (depthwise and laterally) to organs outside the radiotherapy treatment field can be significant and therefore is of clinical interest from the radiation protection point of view. In the present work, measurements were performed in a locally fabricated polystyrene phantom using TLD chips (LiF-100) for different teletherapy units (Cobalt-60 gamma ray, 120 kVp X-ray and 250 kVp X-ray) to estimate the dose distribution at distances up to 40 cm from the field edge along the central axes of the field size. Finally, the dose distribution for Cobalt-60 beam energy is parameterized as a function of depth, distance from field edge, and field size and shape.