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。     

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。     

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。     

宫颈癌图像引导下调强放疗中危及器官变化对靶区的影响

目的 探讨晚期宫颈癌患者调强放疗中危及器官体积及位置变化对靶区的影响。方法 选取行图像引导下调强放疗宫颈癌患者16例，分别于放疗剂量达9 Gy/5f、18 Gy/10f、27 Gy/15f、36 Gy/20f及48.6 Gy/27f时用锥束CT（CBCT）扫描，采集CBCT图像，与原始治疗计划CT图像配准，分别在CT和CBCT图像中勾画大体肿瘤靶区及危及器官，比较危及器官体积、体积变化率及DICE相似度指数（dice's similarity coefficient，DSC） 。结果 放疗0~27分次膀胱、直肠、乙状结肠与小肠体积范围分别为88.48~195.49 cm³、40.41~42.93 cm³、792.85~907.86 cm³、38.49~49.05 cm³。膀胱0~27 分次体积变化差异有统计学意义（P=0.002），其余器官体积变化差异无统计学意义（P>0.05）。膀胱、直肠、乙状结肠及小肠0~27分次体积变化率和DSC差异均无统计学意义（P＞0.05）。膀胱、直肠体积变化率与宫颈靶区、宫体的DSC均呈负相关（P<0.05）。结论 宫颈癌调强放疗中膀胱、直肠等体积与位置变化较大，其变化可能影响宫颈靶区、子宫体的空间位置。     

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。     

CT引导下子宫内膜癌3D腔内近距离治疗计划的剂量学分析

目的 通过比较子宫内膜癌腔内近距离治疗3D计划和2D计划,探讨子宫内膜癌3D腔内近距离治疗的剂量学特性。方法 回顾性分析11例子宫内膜癌患者的39次3D近距离治疗计划并重新设计2D计划,从DVH上比较靶区V₁₅₀、D₉₀,膀胱、直肠、小肠及乙状结肠D_{2 cm³} 。采用配对t检验方法分析组间差异。结果 靶体积<60 cm³时,3D、2D计划靶区D₉₀分别为(551.17±90.33)、(574.15±117.18) cGy (P=0.390),随着靶体积增加3D计划的D₉₀增加(P=0.001)。3D、2D计划靶区V₁₅₀分别为(51.05±21.61)、(53.41±11.71) cm³(P=0.482)。当靶体积>60 cm³时,与2D计划相比,3D计划提高靶区覆盖同时增加了危及器官受量,但小肠受量增加不明显(P=0.128)。此外,不同计划模式下BMI增加对直肠、小肠、膀胱及乙状结肠的受量无显著影响,P值分别为0.239、0.198、0.744和0.834。结论 子宫内膜癌3D腔内近距离治疗与2D计划相比可显著提高较大靶区的覆盖范围,有效控制OAR受量,临床疗效与不良反应尚需进一步观察。     

宫颈癌三维适形近距离治疗膀胱体积变化对正常组织受量影响

目的 比较宫颈癌患者三维适形近距离治疗中膀胱体积改变对正常组织受量影响。方法 2012—2013年本院行宫颈癌根治性外照射+三维适形近距离治疗患者56例。行三维适形近距离治疗中分别将膀胱排空和充盈50、100、150 ml,比较不同膀胱充盈状态下直肠、小肠、乙状结肠及膀胱D₀.1 cm³、D₁.0 cm³、D₂.0 cm³并行配对t检验。结果 直肠D₀.1 cm³在膀胱充盈50、100 ml后较排空状态明显减少(P=0.000、0.000);小肠D₀.1 cm³和D₁.0.cm³及D₂.0 cm³在膀胱充盈50、100、150 ml较排空状态明显减少(P=0.008、0.000、0.000和0.000、0.000、0.000及0.000、0.000、0.000);膀胱D₀.1 cm³和D₁.0 cm³及D₂.0 cm³充盈100、150 ml后较排空状态明显增加(P=0.000、0.000和0.000、0.000及0.000、0.000)。结论 膀胱充盈状态改变了膀胱、小肠受量,对直肠、乙状结肠剂量影响较小;膀胱体积增加有利于降低小肠受量。在不改变膀胱受量前提下膀胱充盈50 ml较充盈100、150 ml更利于降低小肠受量。     

宫颈癌3DBT直肠实测剂量与参考剂量相关性研究

目的 探讨宫颈癌3DBT中直肠实测剂量与参考剂量的相关性, 评估直肠实测剂量的意义。方法 选取50例行宫颈癌根治性放疗患者, 在完成全盆腔外照射后行三维近距离治疗(3DBT)。依据ICRU38号报告推荐的直肠监测方法, 通过在体监测得到直肠实测剂量、参考点剂量(D_ICRU)及D_{2.0 cm³}, 在计划系统中得到计划剂量。应用配对t检验比较它们的差异, 采用Pearson法进行相关分析。结果 直肠实测剂量大于计划剂量(3.48∶3.25, P=0.000)、小于D_ICRU (3.48∶3.71, P=0.000)和D_{2.0 cm³}(3.48∶3.87, P=0.002)。直肠实测剂量与计划剂量存在线性关系, 二者偏差百分数为－20%~40%, 偏差平均数为8.16%, 其中63%宫颈癌患者偏差<±10%, 最大偏差达60%。实测剂量与D_ICRU相关性强(r=0.722)、与D_{2.0 cm³}相关性弱(r=0.284)。结论 宫颈癌3DBT中直肠实测剂量存在一定偏差, 但与计划剂量呈线性相关。实测剂量及计划剂量均会低估直肠剂量参考点剂量。直肠在体监测方法可作为有效的质量控制手段。     

子宫内膜癌单通道和六通道柱状施源器三维近距离照射的剂量学比较

目的 比较单通道和六通道柱状施源器2D、3D治疗计划靶区和正常组织照射剂量,评估三维近距离治疗在子宫内膜癌术后阴道内照射中的应用优势。方法 早期子宫内膜癌10例,分别置入六通道和单通道柱状施源器,CT模拟定位扫描后做治疗计划。CTV定义为阴道上段3 cm,黏膜下5 mm区域,处方剂量为5 Gy/次,共6次。分别制定不同施源器2D和3D治疗计划。比较两种施源器2D与3D计划CTV和OAR的剂量。结果 两种施源器2D、3D治疗计划均能很好满足CTV剂量要求。使用单通道施源器时3D计划可显著降低直肠D_{0.1 cm³}、D_{1.0 cm³}、D_{2.0 cm³}约18.2%、12.4%和10.7%。使用六通道施源器时,3D计划可显著降低直肠D_{0.1 cm³}、D_{1.0 cm³}、D_{2.0 cm³}和D_mean约36.6%、24.8%、20.4%和6.1%,并降低了膀胱和尿道D_mean。与单通道施源器3D计划相比,六通道施源器3D计划进一步降低了直肠、膀胱和小肠的照射剂量。结论 使用单通道或六通道柱状施源器进行阴道内照射时,2D和3D治疗计划均取得了很好的靶区剂量分布。3D治疗计划与2D治疗计划相比,能降低以直肠为主的OAR受量,六通道施源器3D计划进一步降低了直肠照射剂量。     

不同位置子宫颈癌三维与二维近距离放疗剂量学研究和最适治疗人群探讨

目的 通过对CT引导的宫颈癌三维与二维近距离放疗计划的剂量学比较,探讨不同位置子宫对危及器官剂量分布和靶区适形度的影响以及二维近距离放疗治疗宫颈癌的最适人群。方法 纳入我科30例宫颈癌患者的72 次三维近距离放疗计划,并重新设计二维计划,测量子宫位置前后、左右偏离角度。分别按照宫体前后偏离角度(T)及HRCTV体积(VHRCTV)将数据分为A、B、C、D及Ⅰ、Ⅱ、Ⅲ、Ⅳ组,以探寻二维计划最适子宫位置和HRCTV体积范围。统计采用配对t检验差异。结果 宫体前后偏离角度与两种计划的CI值及HRCTV D90无相关性(P值为0.077~0.633),与两种计划中膀胱D2 cm³呈正相关(P值为0.001~0.030),直肠D2 cm³呈负相关(P值为0.011~0.016)。B组(|T|≤10°)及Ⅲ组(VHRCTV为86~96 cm³)中两种计划危及器官参数及CI 值均相近(P值为0.040~0.463);而其他组均有不同程度上的差异(P值为0.000~0.940)。结论 子宫前后位置虽然不影响靶区适形度,但会干扰周围危及器官剂量分布,而当子宫位置接近平位(前后偏离角度≤10°)、靶区体积适当(VHRCTV为86~96 cm³)时两种计划的剂量学相近,此时最适采用二维近距离放疗。     

A comparison of ICRU point doses and volumetric doses of organs at risk (OARs) in brachytherapy for cervical cancer

Introduction: In brachytherapy for cervix cancer, doses to organs at risk (OARs) are traditionally calculated using the ICRU‐38 point doses to rectum and bladder. Three‐dimensional image‐guided brachytherapy allows assessment of OAR dose with dose volume histograms (DVHs). The purpose of this study was to analyse the correlation between DVHs and ICRU point doses. Methods: Using the PLATO? planning system, the bladder, rectum and sigmoid were retrospectively contoured on 62 CT datasets for 20 patients treated with definitive radiotherapy. The median external beam radiotherapy dose was 45 Gy. Brachytherapy was delivered using a CT‐MRI compatible tandem and ovoids to a median dose of 24 Gy in three fractions. DVHs were calculated, and the minimum dose to 2 cc of tissue receiving the highest dose (D_2cc) was recorded and compared with the ICRU point doses (D_ICRU). Results: The mean rectal D_ICRU was 4.01 Gy compared with D_2cc of 4.28 Gy. The mean bladder D_ICRU was 6.74 Gy compared with D_2cc of 8.65 Gy. The mean sigmoid D_2cc was 4.58 Gy. The mean dose ratios (D_2cc/D_ICRU) were 1.08 for rectum and 1.39 for bladder. D_ICRU correlated with D_2cc for rectum (r = 0.76, P = 0.001) and for bladder (r = 0.78, P = 0.01). Conclusion: OAR doses assessed by DVH criteria were higher than ICRU point doses. The significant correlation between D_2cc and D_ICRU has allowed us to set DVH dose constraints for CT‐based brachytherapy and thus begin the transition from two‐dimensional to three‐dimensional image‐guided brachytherapy planning.     

Three-dimensional high dose rate intracavitary image-guided brachytherapy for the treatment of cervical cancer using a hybrid magnetic resonance imaging/computed tomography approach: feasibility and early results

Aims

To evaluate the feasibility and outcome of image-guided brachytherapy (IGBT) for treating cervical cancer using magnetic resonance imaging (MRI)-based planning for the first fraction followed by computed tomography (CT)-based planning for subsequent fractions.

Materials and methods

Forty-four patients with cervical cancer were treated with three-dimensional high dose rate IGBT. The brachytherapy dose was 5.0–6.0 Gy × five fractions. All but five patients received concurrent weekly cisplatinum at 40 mg/m². All patients received external beam radiotherapy (EBRT) with a median dose of 45 Gy over 25 fractions. Total doses for the high-risk clinical target volume (HRCTV) and organs at risk, including the rectum, bladder and sigmoid, from EBRT and brachytherapy were summated and normalised to a biologically equivalent dose of 2 Gy per fraction (EQD₂). At 3 months after therapy, any early response was assessed with positron emission tomography (PET)/CT imaging.

Results

The mean D₉₀ for the HRCTV was 83.3 (3.0) Gy. The mean 2 cm³ dose to the bladder, rectum and sigmoid colon organs was 79.7 (5.1), 57.5 (4.4) and 66.8 (5.7) Gy, respectively. All but one (2.3%) patient had a complete response. Follow-up PET/CT was carried out in 41 (93.0%) patients, of whom 38 (92.5%) had a complete response. Of the 38 patients with a complete response on PET/CT, two had local recurrences at 6 and 8 months, respectively. Actuarial 2 year local control, disease-specific and overall survival rates were 88, 85 and 86%, respectively.

Conclusion

This is the first report of three-dimensional high dose rate IGBT for the treatment of cervical cancer using a hybrid MRI/CT approach. Early results have shown the feasibility of this approach with excellent local control. Additional studies are needed to assess long-term outcomes of local control and associated morbidities.     

膀胱体积变化对宫颈癌近距离放疗的影响

目的:分析膀胱体积变化对宫颈癌近距离治疗中肿瘤和正常组织受量的影响。方法:2015年1月至2017年12月于本院首诊的66例拟行根治性放疗的宫颈癌患者,治疗方案采用外照射放疗同期化疗加近距离治疗。均采用同期顺铂40 mg/m2每周方案化疗,外照射均采用常规分割外照射放疗,1.8~2 Gy/次,1次/天,5次/周,盆腔预防放疗剂量45 Gy/25次,阳性区域转移淋巴结处方剂量55~57.5 Gy/25次。后装采用三维自适应近距离放疗,A点剂量6 Gy每次,共4次,采用宫腔管和双侧阴道穹窿管或环形施源器,在定位CT图像上勾画高危临床靶区（high risk clinical tumor volume,HRCTV）、膀胱、直肠、乙状结肠,制定后装治疗计划后行近距离放疗。结果:后装近距离治疗期间,随着膀胱体积增大,膀胱D1cc、D2cc接受的放疗剂量逐渐升高,有显著统计学差异（P<0.001）,其中小于49.25 ml膀胱体积组膀胱受辐射量最小。而膀胱体积的变化不影响直肠D1cc和D2cc、乙状结肠D1cc和D2cc、HRCTV D90和HRCTV D95。随着后装次数的增加,膀胱体积有逐渐增加的趋势,虽然第一次后装时膀胱体积与第二、三次后装时膀胱体积无统计学差异,但是第一次后装时膀胱体积与第四次后装时膀胱体积有统计学差异(P=0.02)。结论:近距离治疗过程中控制膀胱体积可以减少膀胱受照射剂量,近距离治疗期间控制膀胱体积小于49.25 ml可能是一个更好地选择。     

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.     

Image and laparoscopic guided interstitial brachytherapy for locally advanced primary or recurrent gynaecological cancer using the adaptive GEC ESTRO target concept

Purpose

To retrospectively assess treatment outcome of image and laparoscopic guided interstitial pulsed dose rate brachytherapy (PDR-BT) for locally advanced gynaecological cancer using the adaptive GEC ESTRO target concept.

Materials and methods

Between June 2005 and December 2010, 28 consecutive patients were treated for locally advanced primary vaginal (nine), recurrent endometrial (12) or recurrent cervical cancer (seven) with combined external beam radiotherapy (EBRT) and interstitial PDR-BT. Treatment was initiated with whole pelvic EBRT to a median dose of 45 Gy followed by PDR-BT using the Martinez Universal Perineal Interstitial Template (MUPIT). All implants were virtually preplanned using MRI of the pelvis with a dummy MUPIT in situ. The GEC ESTRO high risk clinical target volume (HR CTV), intermediate risk clinical target volume (IR CTV) and the organs at risk (OAR) were contoured and a preplan for implantation was generated (BrachyVision, Varian). The subsequent implantation was performed under laparoscopic visualisation. Final contouring and treatment planning were done using a post-implant CT. Planning aim of PDR-BT was to deliver 30 Gy in 50 hourly pulses to HR CTV. Manual dose optimisation was performed with the aim of reaching a D90 > 80 Gy in the HR CTV calculated as the total biologically equivalent to 2 Gy fractions of EBRT and BT (EQD2). Dose to the OAR were evaluated using dose volume constraints for D_2cc of 90 Gy for bladder and 70 Gy for rectum and sigmoid.

Results

For HR CTV the median volume was 26 cm³ (7-91 cm³). Coverage of the HR CTV was 97% (90-100%) and D90 was 82 Gy (77-88 Gy). The D_2cc for bladder, rectum, and sigmoid were 65 Gy (47-81 Gy), 61 Gy (50-77 Gy), and 52 Gy (44-68 Gy), respectively. Median follow up was 18 months (6-61 months). The actuarial 2 years local control rate was 92% (SE 5), while disease-free survival and overall survival were 59% (SE 11) and 74%, respectively (SE 10). No complications to the laparoscopic guided implantation were encountered. Late grade 2 (CTC v 3.0) complications were recorded in nine (32%) patients. One patient had a grade 3 vaginal complication. No grade 4-5 complications have been recorded so far.

Conclusion

Image and laparoscopic guided interstitial PDR-BT using the GEC ESTRO target concept is applicable for locally advanced primary vaginal or recurrent endometrial and cervical cancer resulting in an excellent local control rate and limited morbidity.     

Single Magnetic Resonance Imaging vs Magnetic Resonance Imaging/Computed Tomography Planning in Cervical Cancer Brachytherapy

AimsTo compare differences in dose to the target volume and organs at risk (OARs) for ring and tandem brachytherapy using individualised magnetic resonance imaging (MRI)/computed tomography-based three-dimensional treatment plans for each application vs plans based on a single scan for all fractions.Materials and methodsThe study was carried out in 10 patients with carcinoma of the uterine cervix, treated with external beam radiotherapy and five fractions of high dose rate brachytherapy. Planning was carried out using MRI for the first fraction and computed tomography for each of the four subsequent fractions. The MRI-based plan was taken as the reference and the single-plan procedure was calculated by using the weights from the reference plan to calculate the dose distribution for each subsequent computed tomography-based plan. The high-risk clinical target volume (HRCTV) and OARs were delineated as per GEC-ESTRO guidelines. Total doses from external beam radiotherapy and brachytherapy were summated and normalised to a 2 Gy fraction size.ResultsThe mean D₉₀ for the HRCTV was 81.9 Gy when using one plan and 84 Gy when using individual treatment plans. Similarly, the mean D_2cc was 75.68 Gy vs 74.99 Gy for the bladder, 55.84 Gy vs 56.56 Gy for the rectum and 64.8 Gy vs 65.5 Gy for the sigmoid. Ring rotation was identified in three patients, resulting in a change in dwell positions, which otherwise could have led to either a high bladder dose or suboptimal coverage of the HRCTV.ConclusionsOur study has shown that a single-plan procedure achieved acceptable dosimetry in most patients. However, the individualised plan improved dosimetry by accounting for variations in applicator geometry and the position of critical organs.     

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.