Chew Meng-Sang, Xue Jinyu, Houser Chris, Misic Vladimir, Cao Junsheng, Cornwell Thomas, Handler Jay, Yu Yan, Gressen Eric
Department of Radiation Oncology, Cooper University Hospital, Camden, NJ; Department of Mechanical Engineering, Lehigh University, Bethlehem, PA.
Department of Radiation Oncology, Cooper University Hospital, Camden, NJ.
Brachytherapy. 2009 Apr-Jun;8(2):255-264. doi: 10.1016/j.brachy.2008.11.008. Epub 2009 Feb 11.
To study the impact of seed localization, as performed by different observers using linked (125)I seeds, on postimplant dosimetry in prostate brachytherapy and, to compare transrectal ultrasound (TRUS)-based with CT-based approach for the dosimetric outcomes.
Nineteen permanent prostate implants were conducted using linked (125)I seeds. Postimplant TRUS and CT images were acquired and prostate glands were, after implantation, delineated on all images by a single oncologist, who had performed all 19 seeding procedures. Six observers independently localized the seeds on both TRUS and CT images, from which the principle dosimetric parameters V(100) (volume of prostate that received the prescribed dose), V(150) (volume of prostate that received 150% of the prescribed dose), and D(90) (minimal dose delivered to 90% of the prostate) were directly calculated for each patient. A single-factor analysis of variance was first applied to determine interobserver variability in seed localization. A nonparametric comparison of the approach using TRUS and CT was then carried out by the Wilcoxon paired-sample test.
Analysis from the analysis of variance for TRUS showed that the null hypothesis for equal means, could not be rejected for all six observers based on a significance level alpha=0.05. TRUS-based and CT-based approaches were then cross compared by the Wilcoxon paired-sample test, which suggested that the null hypothesis was insignificant for V(100) and D(90), but was significant for V(150).
Both TRUS- and CT-imaging modalities provided indistinguishable postimplant dosimetry results as far as V(100) and D(90) were concerned. There was comparable observer independence between TRUS- and CT-based seed localization for linked-seed implant procedures. With other advantages that TRUS-imaging modality had over CT in the evaluation of postimplant dosimetry, TRUS would be a preferred choice in conjunction with linked seeds for intraoperative procedures in prostate brachytherapy.
研究不同观察者使用链状（125）I 粒子进行粒子定位对前列腺近距离放射治疗中植入后剂量测定的影响，并比较基于经直肠超声（TRUS）和基于 CT 的方法在剂量测定结果方面的差异。
使用链状（125）I 粒子进行了 19 例永久性前列腺植入。植入后获取了 TRUS 和 CT 图像，植入后由一名完成了所有 19 次粒子植入操作的肿瘤学家在所有图像上勾勒出前列腺。六名观察者分别在 TRUS 和 CT 图像上独立定位粒子，然后直接为每位患者计算主要剂量测定参数 V（100）（接受规定剂量的前列腺体积）、V（150）（接受规定剂量 150%的前列腺体积）和 D（90）（输送到 90%前列腺的最小剂量）。首先应用单因素方差分析来确定观察者在粒子定位方面的变异性。然后通过 Wilcoxon 配对样本检验对使用 TRUS 和 CT 的方法进行非参数比较。
对 TRUS 的方差分析表明，基于显著性水平α=0.05，不能拒绝所有六名观察者均值相等的原假设。然后通过 Wilcoxon 配对样本检验对基于 TRUS 和基于 CT 的方法进行交叉比较，结果表明原假设对于 V（100）和 D（90）不显著，但对于 V（150）显著。
就 V（100）和 D（90）而言，TRUS 和 CT 成像方式提供的植入后剂量测定结果难以区分。对于链状粒子植入程序，基于 TRUS 和基于 CT 的粒子定位在观察者独立性方面具有可比性。鉴于 TRUS 成像方式在评估植入后剂量测定方面比 CT 具有其他优势，TRUS 将是前列腺近距离放射治疗术中与链状粒子联合使用的首选。
