Stock R G, Stone N N, Lo Y C, Malhado N, Kao J, DeWyngaert J K
Department of Radiation Oncology, Mount Sinai School of Medicine, New York, NY, USA.
Int J Radiat Oncol Biol Phys. 2000 Oct 1;48(3):899-906. doi: 10.1016/s0360-3016(00)00707-0.
An analysis of CT-based dosimetry was performed to assess the efficacy of the real time method of prostate implantation, explore the relationship of various dose descriptions and determine implant factors affecting outcome.
Between 7/95 and 8/99, 297 patients underwent (125)I implants for T1-T2 prostate cancer and had CT-based dosimetry performed (TG43 formalism). Dosimetry was performed 1 month postimplant. Using a dose-volume histogram, doses delivered to 100%, 95%, 90%, and 80% of the prostate (D100, D95, D90, D80, respectively) as well as percentages of the gland receiving 240 Gy, 160 Gy, 140 Gy (V240, V160, V140, respectively) were reported. Correlations between the various dose parameters and D90 were generated. The effect of the number of seeds implanted, seeds/volume, prostate volume, experience as assessed by time (8/01/99-date of implant), ultrasound probe (mechanical sector vs. dual phased electronic), and the ratio of the CT dosimetry prostate volume/ultrasound implant volume (CT/US vol) were analyzed.
The median D100, D95, D90, and D80 values were 10,200 cGy, 15,655 cGy, 17,578 cGy, and 19,873 cGy, respectively. The median V240, V160, and V140 were 56%, 94%, and 98%, respectively. Correlations of dose descriptions found a close relationship of D95, D80, V240, V160, and V140 with D90 with r values of 0.928, 0.973, 0.911, 0.816, and 0.733, respectively. D100 correlated poorly with D90 (r = 0.099). Using a stepwise regression analysis, CT/US vol ratio, prostate volume, and seed number were the only significant factors affecting D90 with CT/US vol ratio having the greatest effect. The dual-phased electronic probe was associated with fewer D90 values of less than 140 Gy (2%) compared to the mechanical sector probe (14%) (p = 0.02).
CT-based dosimetry results reveal the real-time implant technique to be an effective method of prostate implantation. Factors associated with more precise implantation, such as decreased postimplant edema, new technology, and increased number of seeds will lead to higher D90 values.
进行基于CT的剂量测定分析，以评估前列腺植入实时方法的疗效，探索各种剂量描述之间的关系，并确定影响结果的植入因素。
在1995年7月至1999年8月期间，297例T1 - T2期前列腺癌患者接受了碘-125植入治疗，并进行了基于CT的剂量测定（采用TG43形式主义）。剂量测定在植入后1个月进行。使用剂量体积直方图，报告给予前列腺100%、95%、90%和80%的剂量（分别为D100、D95、D90、D80）以及接受240 Gy、160 Gy、140 Gy的腺体百分比（分别为V240、V160、V140）。生成各种剂量参数与D90之间的相关性。分析植入的粒子数、粒子/体积、前列腺体积、根据时间（1999年8月1日 - 植入日期）评估的经验、超声探头（机械扇形探头与双相电子探头）以及CT剂量测定前列腺体积/超声植入体积之比（CT/US vol）的影响。
D100、D95、D90和D80的中位数分别为10200 cGy、15655 cGy、17578 cGy和19873 cGy。V240、V160和V140的中位数分别为56%、94%和98%。剂量描述的相关性发现D95、D80、V240、V160和V140与D90密切相关，r值分别为0.928、0.973、0.911、0.816和0.733。D100与D90的相关性较差（r = 0.099）。使用逐步回归分析，CT/US vol比、前列腺体积和粒子数是影响D90的唯一显著因素，其中CT/US vol比影响最大。与机械扇形探头（14%）相比，双相电子探头与D90值低于140 Gy的情况较少（2%）相关（p = 0.02）。
基于CT的剂量测定结果表明，实时植入技术是一种有效的前列腺植入方法。与更精确植入相关的因素，如植入后水肿减轻、新技术和粒子数增加，将导致更高的D90值。
