Objective To define the planning target volume (PTV) margins in intensity-modulated radiotherapy (IMRT) for prostate cancer without imaging guidance using B-mode acquisition and targeting (BAT) ultrasound-based prostate localization. Methods Ten patients with prostate cancer underwent BAT ultrasound alignment before each IMRT session. The set-up deviations, each consisting of isocenter displacements in 3 directions (anterior-posterior, right-left lateral, and superior-inferior), were recorded for a total of 225 times and analyzed with Kolmogorov-Smimov (K-S) method. Results The isocenter shift in each direction, which represented an average from all the patients, was 3.56 ±2.71 mm, 4.08 ±3.99 mm, and 3.20 ±2.92 mm in the lateral (RL), anteroposterior (AP), and superior-inferior (SI) dimensions, respectively, and the deviations in each direction conformed to a normal distribution (P=0.806, P=0.061, and P=0.106, respectively). In the absence of imaging guidance for IMRT for prostate cancer, the PTV margin should expand by 8.97 mm in the right, 1.87 mm in the left, 12.05 mm in the anterior, 3.91 mm in the posterior, 9.06 mm in the superior and 2.66 mm in the inferior to allow 95% isodose curve to cover 90% of the clinical target volume. Conclusion The ultrasound imagining guided localization, with simple operation, nonirradiation and small systemic error, can be real-time corrected.%目的 探索麻醉代谢过程中听觉系统相关参数的变化,为动物实验中麻醉效果的正确评估建立监测指标.方法 选取4～6周的BALB/C小鼠,手术方法暴露下丘组织,用乌拉坦进行麻醉,选取纯音作为刺激条件,记录麻醉代谢过程中小鼠下丘的听觉局部电位波形,并用matlab软件提取波形的潜伏期和幅度数值,分析二者随麻醉剂的代谢而呈现的变化.结果 与幅度相比,小鼠听觉局部电位的潜伏期数值变异性小,且与时间有较好的相关性.在乌拉坦代谢过程中,潜伏期随麻醉代谢过程逐渐下降,其中前2h下降较快,后期逐渐趋于稳定.结论 听觉局部电位的潜伏期比幅度更适合作为麻醉效果的监测指标.
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