Two-dimensional Thermoluminescence Dosimetry Using Al2O3:Cr Ceramics for 4, 6, and 10 MV X-ray Beams

Despite their advantages, two-dimensional (2D) thermoluminescence dosimeters (TLDs) have not yet replaced film dosimeters owing to their nonuniformity and low repeatability. A 2D TLD based on Al2O3:Cr ceramics is a promising new reusable passive dosimeter. 2D Al2O3:Cr TLDs can be used for geometry check tests and dose distribution verification in robotic radiosurgery using monoenergetic X-ray beams. In this work, the dependence of energy on the field size and water depth of 2D Al2O3:Cr TLDs for 4, 6, and 10 MV X-ray beams was investigated, because multienergy X-ray beams are used in radiotherapy. Intensity-modulated radiotherapy plan verifications were performed using the TLDs. The TLDs were found to have a large field size dependence for each energy, but their water depth dependence was small at a water depth above 4 cm for each energy. The relative dose distributions were verified with high accuracy using the TLDs.