Quality control in “Intensity Modulated Radiation Therapy-IMRT” using thermoluminescent dosimeters

Abstract

Introduction Quality assurance in radiation therapy included all actions for ensure the maximum dose for the target volume (tumour) and minimum dose for the healthy tissues. The use of thermoluminescent detectors for evaluation of the absorbed doses in treatments that involve the use of ionizing radiation is widespread and well established in clinical routine. The quality measures are employed to validate system performance, such as IMRT quality assurance (QA). An example for IMRT QA is the decision not to treat the patient if the comparison between a point-dose measurement and the planned value exceeds a predefi ned acceptance criterion (±5%). This work aimed the evaluation of absorbed doses with the use of thermoluminescent detectors (TLDs) of lithium fl uoride doped with magnesium and titanium (LiF:Mg,Ti) and a polymethylmethacrylate (PMMA) phantom in Intensity Modulated Radiation Therapy – IMRT planning. Methods In this study the PMMA phantom simulated a patient in treatment. The central cavity (rectangular format) was considered like target volume (tumour) and the others four cavities were considered like organs at risk. The TLDs were positioned inside the cavities; each cavity has an EVA mold for the positioning of TLDs.