Diode Dosimetric Characteristics Assessment for In-Vivo Dosimetry in Radiotherapy Treatment

Abstract

Diodes are radiation dosimetry system that has been applied widely in radiotherapy treatment and very useful for in-vivo dosimetry (IVD). It is duly important to understand the characteristic of detector before it can be used in clinical treatment. In this study, characteristics of diode model IBA dosimetry EDP-153G diode were analysed and compared to calibrated ionization chamber. 6 MV linear accelerator (Linac) was used with different field sizes (FS), Linac monitor unit (MU), tray field (TF), wedge field (WF) and source to surface distance (SSD). Actual diode thickness, diode reproducibility, perturbation effect and diode effect with radiation beam angle and temperature were performed. From the determination of diode dosimetric characteristic, a clinical treatment planning system (TPS) model Elekta Monaco and calibrated ionization chamber (IC) were used to verify the accuracy of diode reading in different setup conditions. Results of study showed wedge, SSD, angle of incidents and temperature were affected the accuracy of diode reading. Phantom measurement and simulation of patient treatment were less than 3%.