We investigated the potential use of two new borate matrices for quality assurance (QA) tests in radiotherapy. Both matrices, MgB₄O₇:Ce, Li (MBO) and Ce-doped 80MgB₂O₄–20MgB₄O₇ (80-20MBO), were doped with 0.5% cerium oxide. The following dosimetric properties of these materials prepared as pellets were tested: optically stimulated luminescence (OSL) sensitivity, dose response, fading, reproducibility, and the supralinearity index. Subsequently, the pellets were exposed to a 6 MV photon beam, and the percentage depth dose (PDD) curve, OSL response to different dose rates, and radiation field size dependencies were compared with those obtained with a reference detector (ionization chamber, I.C.) used in QA. The results indicated a higher OSL sensitivity of 80–20MBO as compared with MBO, on the order of 6- to 8-fold. The dose response of MBO presented a linear behavior within the range evaluated (20 mGy–2 Gy), unlike 80-20MBO, which had a supralinear behavior. The OSL signal of 80–20MBO was also marked by 60% fading within 5 h post irradiation; afterwards, the OSL signal stabilized. A better reproducibility of 80–20MBO compared with MBO was also observed. No dose rate dependence of the OSL response was observed; moreover, a maximum 5% standard deviation was seen in this test. For the field size tests, the pellets over-responded by 3.1% (80-20MBO) and 3.4% (MBO), in a 3 × 3 cm² field, compared with the I.C. For the PDD, a high deviation was observed if compared with the I.C. data at the build-up region (at a depth d ≤ 2 cm), maximum 4.3% and 7.8% for 80-20MBO and MBO, respectively, and beyond this value, good agreement among detectors was seen. Our preliminary results indicate the potential utility of these pellets in QA for radiotherapy.

我们调查了两种新的硼酸盐基质在放射治疗中质量保证（QA）测试中的潜在用途。两种基质，MgB ₄ O ₇：Ce，Li（MBO）和Ce掺杂的80MgB ₂ O ₄ –20MgB ₄ O ₇（80-20MBO），掺有0.5％的氧化铈。测试了制备为颗粒的这些材料的以下剂量学特性：光激发发光（OSL）灵敏度，剂量响应，褪色，可再现性和超线性指数。随后，将沉淀暴露于6 MV光子束，并将百分比深度剂量（PDD）曲线，OSL对不同剂量率的响应以及辐射场大小依赖性与参考检测器（电离室，IC）获得的值进行比较在质量检查中使用。结果表明，与MBO相比，OSL灵敏度更高，为80-20MBO，约为6到8倍。与具有超线性行为的80-20MBO不同，MBO的剂量响应在所评估的范围内（20 mGy–2 Gy）呈现线性行为。照射后5 h内80-60MBO的OSL信号也以60％褪色为特征；之后，OSL信号稳定下来。与MBO相比，还观察到80-20MBO更好的重现性。没有观察到OSL反应的剂量率依赖性；此外，在该测试中看到最大5％的标准偏差。对于田间尺寸测试，在3×3厘米内，药丸反应过度，分别为3.1％（80-20MBO）和3.4％（MBO）²场，与IC相比对于PDD，如果与集结区域（深度d≤2 cm处）的IC数据相比，则观察到较高的偏差，对于80-20MBO和MBO，最大偏差为4.3％和7.8％分别，并且超出此值，检测器之间看到了良好的一致性。我们的初步结果表明这些颗粒在放射治疗质量保证中的潜在用途。