Article Text
Abstract
Introduction/Background To investigate the correlation between the dose predicted by the treatment planning system using three-dimensional (3D)-reconstructed CT images and the dose measured by diode detectors, under clinical condition of high-dose-rate brachytherapy of the cervix uteri.
Methodology During each application, 2 QED diode (1115000–2 and 1113000–2) are applied onto patient‘s skin at bladder (on top) and rectum level (side) with a bolus of at least 6 cm in water to mimic TPS calculation conditions. A CT-based HDR with a prescribed dose per fraction of 7 to CTV is performed. Measurements are carried both in water phantom and on patient’s skin and are compared to those calculated by the treatment planning system (Elekta Oncentra Brachy 4.5.2)
Results The preliminary measurements show a linear response for the examinated detectors and a good agreement between measures and calculations (min: 0.4%, max 1.5%). The observed trend between treatment sessions is in agreement with the expectations, making these diodes a suitable tool for in vivo dosimetry measurements.
Conclusion An important topic in brachytherapy clinical practice consists in determinate the dose to rectum and bladder, in order to correlate these data with acute and late toxicity of OARs. Preliminary results shows that accuracy and reproducibility of the measurement system is sufficient for clinical routine implementation. Therefore, further measurements are needed in order to make the protocol robust.
Disclosures The authors declare no competing interests.