The contribution of optically stimulated luminescence dosimetry in quality control in radiotherapy

Resumo

In 2011, Brazil will have more than 489,000 new cases of cancer. Of these patients, a considerable contingent will be submitted to radiotherapy procedures. Thus, efficient systems that guarantee the quality of the beams used in radiotherapy procedures are extremely important because collaborate with the overall success of treatment. This paper presents the use of OSL (optically stimulated luminescence) dosimetry procedures in quality control in radiotherapy, making verification of the symmetry of treatment of radioactive fields emitted by linear accelerators. The use of OSL dosimetry was compared to procedures performed daily, using ionization chambers. Dosimeters of aluminum oxide doped with carbon (Al2O3: C) were distributed on a map, with the delimitation of a field 20x20 cm arranged as follows: one in the center of the field; four equidistant distributed, forming a square 10x10 cm; and 4 remaining distributed equidistant, forming a square of 20x20 cm. This arrangement is similar to equipment used for checking the symmetry of radioactive fields using ionization chambers. The analysis of data obtained in the symmetry axis X made a variation of 0.2% in OSL dosimetry while using the equipment provided with an ionization chamber, 0.1%. Noting the Y axis, the variation of data for OSL dosimetry was 0.04% and ionization chambers, 0.1%. The use of OSL dosimetry proved to be simple, with accessible instrumentation and making a possible reinterpretation of the data obtained. However, the data suggest that the broader performance of procedures using OSL dosimetry, seeking greater familiarity with the system, can reduce the variation in results.