Abstract
With advances in high-dose-rate (HDR) brachytherapy, the importance of quality assurance (QA) is increasing to ensure safe delivery of the treatment by measuring dose distribution and positioning the source with much closer intervals for highly active sources. However, conventional QA is time-consuming, involving the use of several different measurement tools. Here, we developed simple QA method for HDR brachytherapy based on the imaging of Cherenkov emission and evaluated its performance. Light emission from pure water irradiated by an 192Ir γ-ray source was captured using a charge-coupled device camera. Monte Carlo calculations showed that the observed light was primarily Cherenkov emissions produced by Compton-scattered electrons from the γ-rays. The uncorrected Cherenkov light distribution, which was 5% on average except near the source (within 7 mm from the centre), agreed with the dose distribution calculated using the treatment planning system. The accuracy was attributed to isotropic radiation and short-range Compton electrons. The source positional interval, as measured from the light images, was comparable to the expected intervals, yielding spatial resolution similar to that permitted by conventional film measurements. The method should be highly suitable for quick and easy QA investigations of HDR brachytherapy as it allows simultaneous measurements of dose distribution, source strength, and source position using a single image.
Highlights
With advances in high-dose-rate (HDR) brachytherapy, the importance of quality assurance (QA) is increasing to ensure safe delivery of the treatment by measuring dose distribution and positioning the source with much closer intervals for highly active sources
The importance of QA is increasing with these advances in HDR brachytherapy as it tends toward smaller steps and significantly shorter dwell times for highly active sources, which are driven using remote afterloaders[17,18]
Treatment plans are planned with a treatment planning system (TPS), which calculates dose distribution in the patient body, and the plans are converted to treatment parameters, and transferred to a treatment machine[1]
Summary
With advances in high-dose-rate (HDR) brachytherapy, the importance of quality assurance (QA) is increasing to ensure safe delivery of the treatment by measuring dose distribution and positioning the source with much closer intervals for highly active sources. Treatment plans are planned with a treatment planning system (TPS), which calculates dose distribution in the patient body, and the plans are converted to treatment parameters (such as source positions and dwell times for brachytherapy), and transferred to a treatment machine[1]. The goal of quality assurance (QA) for radiation therapy is to ensure that each treatment is consistently administrated and that the radiation oncologist’s clinical intent, i.e., planned dose distribution, is accurately realised while guaranteeing patient safety[5,6,7]. Correct workings of the treatment machine are regularly checked to ensure that the parameters are within tolerance[5,6,7]
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