以CT图像为基础的宫颈癌三维腔内放疗

目的 探讨CT模拟图像引导下宫颈癌三维腔内放疗实施的可行性及意义。方法 对12例根治性放疗宫颈癌患者的55次腔内施源器置入CT图像,分别设计二维、三维计划,并行配对t检验、Wilcoxon符号秩检验、Pearson相关分析、Spearman相关分析。结果 三维计划双侧A点剂量、D₉₀、V₁₀₀、CI、CI′均高于二维(P=0.015、0.016、0.000、0.000、0.000),三维计划的膀胱、直肠点剂量及直肠D_{2 cm³}略高于二维计划,但热点剂量明显减少。两组计划的膀胱、乙状结肠、小肠D_{2 cm³}相近(P=0.140、0.123、0.214)。膀胱D_{2 cm³}明显高于膀胱点剂量(P=0.000)。乙状结肠D_{2 cm³}较直肠D_{2 cm³}与直肠最高3点剂量平均值更相关(r=0.314、0.63,P=0.000、0.000)。V₁₀₀与高危CTV体积呈线性关系(r=0.981,P=0.000)。膀胱D_{2 cm³}在膀胱体积>80 cm³后达430 cGy以上,小肠D_{2 cm³}在膀胱体积<115 cm³内变化不明显,一旦超过明显下降。结论 CT引导下宫颈癌三维腔内放疗较传统二维腔内放疗显著增加了靶区覆盖率、提高了适形度,但未明显增加OAR剂量且能及时发现减少OAR热点剂量。点剂量评估并不准确。可以通过膀胱体积调控膀胱、直肠、小肠剂量。     

局部晚期宫颈癌三维适形近距离治疗中ICRU参考点剂量与OAR体积剂量参数的关系研究

目的 比较局部晚期宫颈癌三维适形近距离治疗中膀胱、直肠不同充盈状态下OAR的ICRU参考点剂量与体积剂量参数之间关系。方法 MRI引导宫颈癌三维适形近距离治疗患者31例,共96分次,在TPS中确定ICRU直肠、膀胱参考点,记录其剂量,分别与直肠、膀胱体积剂量参数进行比较,配对t检验其差异。结果 膀胱D_ICRU小于膀胱D_{0.1 cm³}和D_{1 cm³}(P=0.000、0.000),大于D_{5 cm³}和D_{10 cm³}(P=0.000、0.000),与D_{2 cm³}相近(P=0.345)。膀胱充盈状态下,膀胱的D_ICRU小于膀胱D_{2 cm³}。直肠D_ICRU小于直肠D_{0.1 cm³}和D_{1 cm³}(P=0.000、0.002),大于D_{5 cm³}和D_{10 cm³}(P=0.000、0.000),与D_{2 cm³}相近(P=0.058)。膀胱、直肠ICRU参考点剂量与各自的D_{2 cm³}呈正相关。膀胱体积≥200 cm³,ICRU膀胱参考点会低估膀胱的D_{2 cm³}剂量。直肠体积≥37 cm³,ICRU直肠参考点会低估直肠的D_{2 cm³}剂量;直肠体积<37 cm³,ICRU直肠参考点会高估直肠的D_{2 cm³}剂量。结论 在三维适形近距离治疗中采用D_{2 cm³}作为评价OAR指标是基本安全的,但当膀胱、直肠处于排空状态时还需分别参考膀胱、直肠ICRU点剂量。     

儿童阴道横纹肌肉瘤60Co高剂量率三维后装治疗应用价值研究

目的 探讨⁶⁰Co高剂量率三维后装在儿童阴道横纹肌肉瘤放疗中的应用流程,并从剂量学角度分析可行性。方法 选取5例已行儿童阴道横纹肌肉瘤放疗患儿CT定位图像,分别设计3种治疗计划:计划A为3DCRT外照射,计划B为后装治疗,计划C为后装治疗联合外照射。根据EQD2评估CTV和OAR剂量学参数并单因素方差分析。结果 与计划A相比,计划C的CTV的D₉₀、D₅₀、D_mean更高(P=0.00),直肠、膀胱和股骨头剂量低,卵巢剂量略高(P=0.00)。与计划B相比,计划C的CTV 的D₉₀更高,D₅₀、D_mean较低,卵巢剂量较低,直肠、膀胱和股骨头剂量略高。计划B的直肠、膀胱D_{2 cm³}最低。结论 儿童阴道横纹肌肉瘤的放疗需根据原发肿瘤位置及手术后是否残留选择合适的治疗方式。CT引导的⁶⁰Co高剂量率三维后装治疗方式流程简单快捷,患儿耐受性好,靶区剂量高,正常组织保护好。     

多通道施源器用于晚期宫颈癌三维腔内放疗的剂量学研究

目的 探讨中晚期宫颈癌三维后装腔内放疗中三通道施源器的通道设计与OAR、靶区剂量间关系。方法 调取2015—2016年我院三维腔内治疗的15例中晚期宫颈癌数据,其中30次“阴道卵形两半球+宫腔管”的三通道施源器剂量参数纳入研究。在原靶区和OAR勾画、处方剂量不变基础上保留宫腔管单通道施源器,重新进行三维腔内照射设计的剂量参数作为对照组,配对t检验两组OAR剂量参数。结果 三通道、单通道施源器组直肠D_2cc分别为(387.8±96.8)、(340.8±88.1) cGy;两组膀胱和乙状结肠D_2cc分别为(443.2±87.5)、(719.4±243.0) cGy和(330.3±88.8)、(383.1±105.6) cGy。三通道组满足直肠(D_2cc≤500 cGy)、膀胱(D_2cc≤550 cGy)和乙状结肠(D_2cc≤500 cGy)计划限量,单通道组膀胱和乙状结肠D_2cc受量分别为大于和部分大于计划限量。单通道组膀胱和乙状结肠D_2cc受量高于三通道组(P均<0.05)。结论 宫颈癌三维腔内放疗中“阴道卵形两半球+宫腔管”三通道施源器比宫腔管单通道可有效降低膀胱和乙状结肠受量,有利于计划优化和剂量实施。     

局部晚期宫颈癌腔内联合组织间插植3D-IGBT的剂量学研究

目的 探讨CT引导下腔内联合组织间插植3D-IGBT局部晚期宫颈癌的剂量学优势。方法 分析2013—2014年于本院接受根治性外照射及腔内联合组织间插植3D-IGBT的局部晚期宫颈癌患者 45例,FIGO分期(2009年)为 Ⅰ_B2—Ⅳ_A期。同一患者行腔内联合组织间插植 ¹⁹²Ir治疗后,在原影像上去掉插植针作用,仅使用腔内施源器制定治疗计划。比较前后两组计划中高危CTV的 D_90%、中危CTV的 D_90%和膀胱、直肠、乙状结肠、小肠的 D_{2 cm³}剂量学差异,并行配对t检验。结果 共制定260次后装治疗计划, 其中腔内联合组织间插植治疗计划 130例、腔内治疗计划 130例。腔内联合组织间插植治疗较腔内治疗高危CTV的 D_90%、中危CTV的 D_90%显著增高(P=0.000、0.000),膀胱、直肠的 D_{2 cm³}显著降低(P=0.000、0.006)。结论 局部晚期宫颈癌使用腔内联合组织间插植3D-IGBT在获得更高靶区剂量的同时降低了膀胱、直肠受量。     

胸段食管癌VMAT计划的剂量学验证研究

目的 探讨VMAT计划在胸段食管癌放疗中的适应性。方法 应用0.6 cm³指形电离室和COMPASS三维剂量验证系统分别对 10例胸上段、10例胸中段食管癌的VMAT计划进行绝对剂量和相对剂量的验证。应用DVH比较靶区、肺、心脏和脊髓受照剂量和体积差异,并分析GTV、CTV、PTV和OAR的γ通过率。结果 胸上、中段食管癌的等中心处绝对剂量精确度均≥99%,GTV、PTV和OAR的γ通过率均≥97%。胸上段食管癌GTV、CTV、PTV的 D_95%、D_mean的验证差异均≤3%,脊髓 D_1%差异为2.21%,左肺和右肺的 V₅~V₃₀、D_mean的差异≤2%。胸中段食管癌的GTV、CTV、PTV和OAR的 D_95%、D_mean的验证差异≤2%,脊髓 D_1%差异为2.04%。左肺和右肺的 V₅~V₃₀以 V₁₀为界差异呈逐渐增大的趋势,处于1.5%以内。心脏 D_mean的差异为2.68%。结论 VMAT技术在胸段食管癌放疗中是适用的。     

环形施源器重建偏差对宫颈癌患者剂量影响分析

目的 研究在CT引导的三维后装中环形施源器(Nucletron#090.617)重建偏差对宫颈癌患者后装受照剂量的影响。方法 选取已完成治疗的根治性宫颈癌患者20例,在计划系统中模拟宫腔施源器,环形施源器和两者同时发生重建偏差时的剂量分布,重建偏差的方向分为施源器顶端方向(+)和施源器连接方向(-),重建偏差模拟±1、±2、±3 mm。统计CTV的D₁₀₀、D₉₀、D₅₀,膀胱、直肠、小肠的D_0.1cc、D_1cc、D_2cc,分析施源器重建偏差对三维后装剂量的影响。结果 宫腔施源器重建偏差对剂量的影响高于环形施源器。对于CTV评价参数,由施源器重建偏差导致的剂量偏差随统计体积的增大而增大。对于OAR评价参数,由施源器重建偏差导致的剂量偏差随统计体积的增大而减小。小肠剂量受施源器重建偏差影响最大。对CTV D₉₀、膀胱D_2cc、直肠D_2cc、小肠D_2cc,当环形施源器,宫腔施源器,二者同时发生3 mm重建偏差时产生的影响偏差分别为0.90%、1.62%、1.74%,1.33%、1.53%、1.78%,0.89%、1.85%、1.97%,0.86%、3.04%、3.50%。结论 三维后装中施源器重建偏差会对剂量产生一定的影响,为提高后装放疗的精确性,需要对施源器重建过程进行全面质量控制。     

宫颈癌多次计划CT引导三维近距离治疗可行性研究

目的 探讨宫颈癌患者多次计划CT引导的三维近距离治疗可行性及对危及器官剂量学影响。
方法 10例接受根治性放疗的Ⅱ_b~Ⅲ_b期宫颈癌患者每次腔内放疗前行CT扫描并勾画高危临床靶体积(HRCTV)及膀胱、直肠、乙状结肠。PLATO14.3计划系统设计,HRCTV采用D₉₀,危及器官采用D_{2 cm³}评价。处方剂量A点7 Gy单次后进行几何优化,直肠、乙状结肠D_{2 cm³}≤5 Gy,膀胱D_{2 cm³}≤5.5 Gy。第1次腔内治疗优化计划为标准计划,每次腔内放疗进行CT扫描制定几何优化计划。两组计划参数行独立样本t检验,危及器官体积与参数相关性采用Pearson法相关分析。
结果
标准计划与优化计划HRCTV的D₉₀相似(t=－0.03~－1.61,P=0.978~0.128),膀胱、直肠、乙状结肠D_{2 cm³}不同(t=－2.27~－3.35,P=0.049~0.004)。膀胱、直肠、乙状结肠体积与各自D_{2 cm³}均呈正相关(r=0.314、0.407、0.539,P=0.026、0.003、0.000)。
结论 CT引导的宫颈癌三维近距离治疗中多次计划有必要,危及器官体积对治疗CTV剂量无影响,但体积越大受照最多部位的D_{2 cm³}越高。     

宫颈癌常规放疗联合腔内三维放疗的初步研究

目的 探讨体外放疗联合CT影像为基础近距离放疗的宫颈癌患者DVH参数和治疗结果间关系。方法 2008—2011年间18例接受根治性放疗的Ⅱ_B—Ⅲ_B期宫颈癌患者进行了常规放疗加CT为基础的近距离三维放疗。观察两种放疗相加的高危CTV的D₉₀和直肠、膀胱的D_{2 cm³} 、D_{1 cm³} ,采用EQD₂进行剂量叠加。同时随访患者不良反应。结果 A点剂量为(93.0±5.5) Gy,高危CTV D₉₀为(73.6±11.9) Gy。患者中位随访时间为26个月,无复发病例。8例患者出现轻中度直肠晚期反应,其直肠D_{2 cm³} 、D_{1 cm³} 均高于无反应者[(87.4±3.8) Gy∶(75.8±7.4) Gy,P=0.004;(96.4±6.6) Gy∶(80.5±7.1) Gy,P=0.001]。结论 CT引导的宫颈癌三维近距离放疗高危CTV D₉₀剂量比文献报道略低,直肠D_{2 cm³} 建议<75 Gy。     

宫颈癌三维近距离治疗中两种常用施源器的剂量学比较

目的 对比研究环形施源器(Nucletron#090.617)和三管施源器(Nucletron#189.730)对宫颈癌患者三维近距离治疗受照剂量的影响。 方法 选取已完成治疗的根治性宫颈癌Ⅱ_B—Ⅳ_A期患者 40例,20例采用环形施源器,另外 20例采用三管施源器,分别统计三维近距离治疗计划中靶区 V_150% 、D₁₀₀和膀胱、直肠、小肠 D_{2 cc}。采用立独样本t检验方法对比分析两种施源器在宫颈癌三维近距离治疗中CTV和OAR的剂量。 结果 环形施源器和三管施源器的靶体积分别为(66.04±13.86) cm³、(65.67±15.08) cm³(P=0.052)。环形施源器中 D₁₀₀、V_150%分别为(3.71±0.34) Gy、0.54±0.02;三管施源器中 D₁₀₀、V_150%分别为(3.37±0.49) Gy、0.56±0.04(P=0.016、0.034)。环形施源器中膀胱、直肠、小肠 D_{2 cc}分别为(4.33±0.39)、(3.38±0.30)、(3.04±1.02) Gy,三管施源器的分别为(2.93±1.27)、(2.95±0.80)、(3.41±0.57) Gy (P=0.000、0.037、0.171)。 结论 宫颈癌三维近距离治疗中环形施源器靶区的覆盖度优于三管施源器,而膀胱、直肠受量同时也高于三管施源器,但小肠受量无差异。临床治疗中主要还是根据肿瘤的位置、侵犯范围以及阴道的条件来选择施源器。     

Design and Development of In-House Multichannel Applicator for HDR Vaginal Brachytherapy and Dosimetric Comparision with Single Channel Applicator

Introduction: Endometrial cancer (EC) is a leading cause of female cancer in developed countries. The total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymph node dissection is the primary management of endometrial cancer. Afterwards vaginal brachytherapy can be preferred either alone or combined with external beam radiotherapy to avoid the vault recurrence. This study was to assess the in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. The main objective of this study was to design and development of an in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. Materials and Methods: The multichannel applicator is a solid cylinder with 3 cm diameter, 13 cm length. It has a central channel surrounded by eight channels with a periphery arrangement in a single circle. We randomly selected eleven patients with endometrial carcinoma and 7Gy/per fraction of HDR dose was prescribed to CTV. Retrospectively, two 3D inverse treatment plans were created for each patient, with single channel loading and multichannel loading and the dose distribution of both plans could be compared. CTV coverage, rectum and bladder doses were compared. Results: The DVH analysis showed statistically significant difference between single and multichannel plan, that is for D95 of CTV (p=0.008), D100 of CTV (p=0.004) and 2cc of CTV (p=0.003). The p value for 1cc, 2cc and V70 are 0.003, 0.003 and 0.003 for rectum. On the other hand, bladder DVHs showed large difference between single and multichannel plan yet it is not statistically significant, and the p values for 1cc, 2cc and V 80 are 0.012, 0.009 and 0.225. Conclusion: The authors conclude that in house multichannel applicator with 3D inverse treatment planning techniques improves the dosimetric advantage over single channel applicators.     

Single or multi-channel vaginal cuff high-dose-rate brachytherapy: Is replanning necessary prior to each fraction?

PurposeAdjuvant high-dose-rate vaginal brachytherapy (VB) is commonly used in endometrial cancer. We evaluated the dosimetric and cost differences of using either a single plan or replan prior to each fraction for single- and multi-channel VB.Methods and MaterialsWe evaluated 84 fractions from 25 patients at our institution (16 single-channel patients each 3 fractions; 9 multi-channel patients each 4 fractions). All fractions were preceded by a computed tomographic (CT) simulation scan, after which a unique treatment plan was generated, dose points per International Commission on Radiation Units and Measurements (ICRU) 38. We calculated the dose to critical organs based on a decay-and-treat method utilizing the original catheter dwell-times for the initial fraction, and also the interfractional motion of the critical organ points between the initial and the subsequent CT scans.ResultsThe absolute mean dose difference was 14 cGy for bladder and 15 cGy for rectum between the replan and decay methods for single-channel, and 14 cGy for both organ points for the multi-channel cylinder. The bladder and rectum doses were not found to be significantly different between the replan and decay methods for either single-channel (bladder, P = .08; rectum, P = .19) or multi-channel cylinders (bladder, P = .85; rectum, P = .10). The mean interfractional displacement of the organ points between the initial and subsequent CT scans was 1.10 cm for the bladder and 0.67 cm for the rectum for single-channel, and 0.87 cm and 0.51 cm for multi-channel cylinders. The maximum interfractional motion was seen in the transverse plane for both organ points for both types of cylinders. At our institution, the decay method was 19% and 22% more cost-effective for single-channel and multi-channel cylinders, respectively.ConclusionsOur data show no dosimetric advantage, but higher costs, associated with replanning prior to each fraction for both single- and multi-channel VB. Fractional replanning should not be utilized on a routine basis.     

3D打印多通道施源器在宫颈癌术后患者近距离治疗中研究北大核心CSCD

目的比较3D打印多通道施源器与常规阴道单通道施源器用于近距离治疗的剂量学差异,为宫颈癌术后患者的近距离治疗提供一定的指导依据。方法选取25例自2019年1月—2020年11月接受^(192)Ir高剂量率近距离治疗的宫颈癌术后合并阴道上皮内瘤变Ⅲ级的患者,每位患者均采用3D打印多通道施源器和常规阴道单通道施源器进行CT扫描定位,并制定相应计划及评估,运用逆向剂量优化算法计算后得出剂量体积直方图,比较两组施源器用于近距离治疗时的高危临床靶区、膀胱及直肠受照剂量的差异,选择最优计划实施治疗。结果采用3D打印个体化多通道施源设计计划的D_(90)%、D_(100)%、V_(100)%、V_(150)%与常规单通道施源器设计的计划相比,差异均无统计学意义(P>0.05);膀胱、直肠的D2cm3与常规相比均明显降低,差异有统计学意义(均为P<0.05)。结论采用3D打印技术制作的多通道个体化施源器靶区适形性好,可更好地保护膀胱和直肠,有一定的治疗优势。     

Dosimetric and cost comparison of first fraction imaging versus fractional re-imaging on critical organ dose in vaginal cuff brachytherapy

PurposeVaginal cylinder high-dose-rate (HDR) brachytherapy is currently one of the most common procedures performed in the treatment of early-stage endometrial cancer. However, current recommendations by the American Brachytherapy Society regarding fractional re-imaging and dose calculation for organs at risk for HDR vaginal cuff brachytherapy are not well defined. In this study, we aim to compare a fractional re-imaging approach using computed tomographic (CT) scans prior to each fraction with a first fraction imaging-only approach with respect to bladder, rectal, and bowel dosimetry.Methods and MaterialsNineteen endometrial cancer patients undergoing vaginal cuff brachytherapy for endometrial cancer were imaged with CT scanning prior to every HDR fraction (fractional re-imaging [FRI]). Dose to the bowel, bladder, and rectum were calculated and compared with the estimated dose if imaging and planning were done only on the first fraction (first fraction imaging [FFI]).ResultsIn the analysis of FFI versus FRI, we observed mean bladder doses of 8.34 Gy vs 8.33 Gy (P = .98), mean rectal doses of 12.19 Gy versus 12.14 Gy (P = .81), and mean bowel doses of 2.82 Gy versus 2.76 Gy (P = .81). The FFI approach underestimated the FRI doses to the bladder, rectum, and bowel by 20% or more in 11%, 5%, and 29% of patients, respectively. Cost analysis revealed an estimated $663.06, or a 35% savings per patient treated with FFI.ConclusionsThere is no statistically significant difference in the mean dose to the bladder, rectum, or bowel in patients undergoing HDR vaginal cuff brachytherapy with a first fraction imaging scheme versus a fractional re-imaging scheme. These results indicate that fractional re-imaging is not necessary except in patients whose estimated dose to critical organs is near the maximum limit.     

Uncertainties when using only one MRI-based treatment plan for subsequent high-dose-rate tandem and ring applications in brachytherapy of cervix cancer.

BACKGROUND AND PURPOSE: This retrospective study compares individual MRI based 3D treatment planning for each intracavitary applicator insertion and the use of only one MRI treatment plan for cervical cancer brachytherapy. MATERIALS AND METHODS: GTV, high risk (HR) CTV and OAR were delineated and analysed for 14 patients. Data using the individual approach were taken from the actual irradiated plans. The "single plan procedure" was simulated by matching the dose distribution of the first plan to the MRI datasets of each subsequent implantation. Total doses from brachytherapy were added up and normalized to 2Gy fractionation (EQD2). RESULTS: The mean D90 for HR CTV was 6Gy higher when using one plan than when using individual treatment plans. The D(2cc) increased 3.5Gy for the bladder, 4.2Gy for the rectum and 5.8Gy for the sigmoid. The use of only one treatment plan would have resulted in 2, 1 and 5 extra cases exceeding total D(2cc) constraints for bladder (90Gy), rectum (75Gy) and sigmoid (75Gy), respectively. CONCLUSION: The use of only one treatment plan for several applications results in higher dose to target and OAR structures. CT, clinical examination and X-ray findings can help to reduce certain situations of overdosage, when individual MRI based treatment planning is not available for each fraction.     

宫颈癌术后阴道三维腔内近距离放射治疗两种施源器剂量学研究

目的: 比较宫颈癌根治术后行阴道三维腔内近距离治疗采用单通道柱状、双卵圆球两种施源器的剂量学差异，为宫颈癌术后行阴道三维腔内近距离放疗选择施源器提供参考。方法: 回顾性分析2018年6月12月于川北医学院附属医院肿瘤科完成阴道三维腔内近距离放射治疗的早期宫颈癌术后患者20例，每例患者均在接受宫颈癌根治手术后因有术后放疗指征，进行术后三维腔内近距离放射治疗。每例患者分别采用单通道柱状施源器、双卵圆球施源器行后装治疗各1次，不分先后。利用每例患者放疗时的实际CT定位资料，共40个CT定位资料，按照统一的靶区勾画标准重新勾画靶区（靶体积及危及器官）后制作近距离腔内放射治疗计划。分别统计两种施源器近距离治疗计划中靶区体积、D90、D100和膀胱、直肠体积及其D2cc。 采用独立样本t检验方法比较两种施源器在宫颈癌术后三维近距离治疗中靶区、危及器官剂量。 结果：阴道柱状施源器组和双卵圆球施源器组平均临床靶区体积分别为:（29.56±4.51）cm3、（31.68±3.16 ）cm3，差异无统计学意义(P=0.095)。柱状施源器组D90、D100分别为：（611.60±8.70）cGy、（414.38±47.16）cGy；双卵圆球施源器组D90、D100分别为：（608.19±7.30）cGy、（359.54±38.13）cGy，两组CTV D90约为 6Gy，差异无统计学意义（P=0.180）；D100差异有统计学意义（P =0.003）。柱状施源器组与双卵圆球施源器组直肠体积分别为：（53.03±10.70）cm3、（52.37±8.87）cm3，差异无统计学意义(P =0.213)；直肠D2cc分别为:（375.77±62.10）cGy、（341.57±38.43）cGy，差异有统计学意义（P=0.043）；膀胱体积分别为:（129.31±18.90）cm3、（123.14±13.15）cm3，差异无统计学意义（P=0.239）；膀胱D 2cc分别为：（391.13±62.94）cGy、（356.42±27.12）cGy，差异有统计学意义(P=0.032)。结论：宫颈癌根治术后阴道三维腔内近距离放射治疗中，与双卵圆球施源器相比，使用单通道柱状施源器靶区剂量分布更优，但膀胱、直肠受照剂量更高。因此在临床上，当直肠膀胱外照射受量较高、副反应较重可选择双卵圆球施源器，反之可选择单通道柱状施源器。     

局部晚期宫颈癌CT图像引导下192Ir三维腔内后装治疗剂量体积参数与疗效关系

目的 观察CT图像引导下192Ir三维腔内后装治疗的肿瘤靶区及危及器官受照射体积剂量参数与肿瘤局部控制率及晚期副反应之间关系.方法 10例局部晚期宫颈癌患者在完成盆腔外照射40 Gy及同期化疗后开始每周1次的CT图像引导下192Ir三维腔内后装治疗,每次治疗前进行CT扫描定位,勾画肿瘤靶区(GTV、CTV)和危及器官,利用PLATO治疗计划系统进行逆向治疗计划设计及优化,CTV单次处方剂量为6 Gy,治疗5～7次.结果 1年盆腔控制率为90%,1～2级放射性肠炎发生率为50%,无≥3级副反应.90%CTV等效生物剂量(BED)和相当于2 Gy分次的等效剂量(EQD2)分别为(95.50±7.81)Gy和(79.73±6.57)Gy(α/β=10).90%GTV的BED和EQD2分别为(101.86±7.27)Gy和(84.95±6.1)Gy(α/β=10).90%处方剂量对GTV、CTV的覆盖率分别为92%±4%、87%±7%.直肠、乙状结肠2 cm3体积受到的最小照射剂量分别为(74.97±1.64)、(67.93±4.30)Gy(EQD2,α/β=3).与二维治疗计划相比,三维治疗计划在没有改变A点剂量、直肠参考点剂量情况下提高了GTV、CTV的90%体积受照射剂量及90%处方剂量对GTV、CTV的覆盖率.结论 CT图像引导下192Ir三维腔内后装治疗提高了处方剂量对肿瘤靶区的覆盖率,1年盆腔控制率为90%且无严重副反应,远期疗效观察中.

Abstract：

Objective To investigate the correlation between dose volume histogram(DVH)of tumor targets and organs at risk(OAR)at CT-image based 192Ir brachytherapy and effects and complications for patients with locally advanced cervical cancer. Methods Ten patients with FIGO stage ⅢB cervical cancer received CT image-based 192Ir intracavitary brachytherapy after 54 Gy of three-dimentional four-field pelvic external beam radiotherapy and concurrent weekly cisplatin chemotherapy. Before each brachytherapy,CT images were acquired with applicators in place. Gross tumor volume(GTV), clinical target volume (CTV)and OAR were contoured and inverse treatment planning was designed and optimized by using PLATO treatment planning system. Conventional two-dimensional plans were also designed for comparison.The total intracavitary brachytherapy dose was 30 -42 Gy in 5 -7 fractions. The patients were followed, and the local control and complications were analyzed. The biologically equivalent dose(BED)and biologically equivalent dose in 2 Gy fractions(BED2)for GTV, CTV and OAR were calculated. The minimum dose in the most irradiated tissue volume 2 cm3(D2 cm3)adjacent to the applicator of the sigmoid colon, rectum,bladder and small bowel was determined from the DVH. Results The 1-year local pelvic control rate was 90% and grade 1-2 late complication of sigmoid colon and rectum was 50%. No grade 3 or more complications developed. On CT-image based planning, the BED and BED2 to 90% of the CTV(D90)were 95.50 Gy ± 7. 81 Gy and 79. 73 Gy ± 6. 57 Gy. The BED and BED2 to 90% of the GTV(D90)were 101.86 Gy ± 7.27 Gy and 84. 95 Gy ± 6. 1 Gy. The volume enclosed by 90% of prescribed dose(V90)for GTV and CTV were 92% ±4% and 87% ±7% respectively. The D2cm3 for rectum and sigmoid colon were 74. 97 Gy ±1.64 Gy and 67. 93 Gy ± 4. 30 Gy(EQD2, α/β = 3). Comparing with 2D brachytherapy plans , CT - image based planning has improved D90 and V90 for GTV and CTV with similar dose at point A and rectum reference point. Conclusions Computer tomography-image based 192Ir brachytherapy has resulted in the better dose distribution to the tumor targets with excellent tumor control and acceptable toxicity.     

Does inverse planning applied to Iridium192 high dose rate prostate brachytherapy improve the optimization of the dose afforded by the Paris system?

BACKGROUND AND PURPOSE: The purpose of the work is to analyse for 192Ir prostate brachytherapy (BT) some of the different steps in optimizing the dose delivered to the CTV, urethra and rectum. MATERIALS AND METHODS: Between 07/1998 and 12/2001, 166 patients were treated with 192Ir wires providing a low dose rate, according to the Paris system philosophy and with the 2D version of the treatment planning IsisR. 40-45 Gy were delivered after an external beam radiotherapy of 40 Gy. The maximum tolerable doses for BT were 25 Gy to the anterior third of the rectum on the whole length of the implant (R dose) and 52 Gy to the urethra on a 1cm length (Umax). A Umax/CTV dose ratio >1.3 represented a pejorative value as the planned dose of 40-45 Gy could not be achieved. On the other side a ratio 1.25 decreased significantly with optimization required on CTV contours and additional constraints on urethra while the R/CTV ratio was maintained under 0.55. For initial Umax/CTV >1.3 or >1.25 but 相似文献   

Comparaison entre Stump Cylinder et moule personnalisé, effet de la forme de l’applicateur sur la distribution de dose

PurposeThe purpose of this study was to compare the efficacy of two applicators used in high dose rate vaginal brachytherapy. The first is the Stump Cylinder used in the “brachycenter” department at the Middle East Institute of Health in Lebanon and the second is the custom mold used in the radiotherapy department at Tenon Hospital in France.Materials and methodA comparison of the clinical target volume and the doses received by the rectum and bladder was performed in order to determine the best method of treatment and to optimize the dose distribution. 95 patients were treated in both departments.ResultsThe average values of the D95% dose received by the CTV were respectively 89.43% for the Stump Cylinder and 110.16% for the custom mold. The conformity index was 0.84 for the Stump Cylinder while it was 0.97 for the custom mold, which ensures a better dose distribution. For the rectum, the maximum dose D2cc taken by volume was 71.23% for the Stump Cylinder and 79.51% for the custom mold. The bladder was better protected with Stump Cylinder with a D2cc value of 65.81% against 94.88% for the custom mold.ConclusionThe underdosing obtained using the Stump Cylinder was due to the shape of upper part of the cylinder which was not conform with the shape of the vaginal vault in women. A better protection of the organs at risk was observed with the Stump Cylinder since the dose taken by the rectum and bladder using a custom mold can reach the tolerance limits.