磁共振影像对勾画大体肿瘤体积的影响

在确定中枢神经系统和头颈部不规则肿瘤时,磁共振影像MRI比CT影像有优势,特别是位于后窝或颅底的肿瘤、增强不明显的肿瘤、星形细胞瘤,若放射治疗医生直接在CT影像上勾画大体肿瘤体积（GTV）,则必须参考磁共振影像胶片;若把MRI影像套准在CT影像上,放射治疗医生不仅能直接在MRI上勾画GTV,而且能有效减小不同医生在勾画GTV时产生的偏差.     

不同HR-CTV下单纯腔内治疗与腔内联合组织间插植治疗在宫颈癌三维后装治疗中的对比研究

目的 研究不同高危临床靶体积（HR-CTV）下单纯腔内治疗与腔内联合组织间插植（腔内+插植）治疗技术在宫颈癌三维后装治疗中的剂量学差异,并探讨HR-CTV是否存在阈值。 方法 回顾性分析2019年10月至2021年2月于广西医科大学第四附属医院接受根治性放疗的100例中晚期宫颈癌患者的临床资料,年龄35~63岁,中位年龄51岁。根据后装治疗技术不同将患者分为单纯腔内治疗组（45例）、腔内+插植治疗组（55例）。按患者每个计划的HR-CTV大小分为6个体积范围进行分析,即HR-CTV≤40 cm3、40 cm380 cm3。 采用独立样本t检验比较2种后装治疗技术在不同体积范围内的靶区和危及器官（OAR）的剂量学参数。 结果 当HR-CTV≤40 cm3时,单纯腔内治疗组的靶区剂量（D₉₀、D₁₀₀）、靶区覆盖度（V₁₀₀）及靶区高量（D₅₀、V₁₅₀、V₂₀₀）均高于腔内+插植治疗组,且差异均有统计学意义（t=2.826~3.927,均P<0.05）,但靶区适形指数（CI）、OAR膀胱和直肠D_{2 cm3}（2 cm3的OAR体积接受的最低照射剂量）的差异均无统计学意义（t=0.186、1.871、0.258,均P>0.05）。当70 cm380 cm3时,腔内+插植治疗组的靶区剂量（D₉₀、D₁₀₀）、靶区覆盖度（V₁₀₀）、CI、OAR直肠和膀胱D_{2 cm3}剂量均显著优于单纯腔内治疗组,且差异均有统计学意义（t=?6.872~3.782,均P<0.05）,而2种治疗技术的靶区高量（D₅₀、V₁₅₀、V₂₀₀）相近,差异无统计学意义（t=0.613~1.918,均P>0.05）。当40 cm390、D₁₀₀）、靶区覆盖度（V₁₀₀ ）以及直肠D_{2 cm3}的差异均无统计学意义（t=?1.759~0.710,均P>0.05）,但腔内+插植治疗组的CI显著优于单纯腔内治疗组,且差异均有统计学意义（t=?2.590、?4.577、?3.144,均P<0.05）。 结论 对于小体积靶区（≤40 cm3）,单纯腔内治疗技术在不增加OAR剂量的情况下能更好地提高靶区剂量和靶区内高剂量体积;当靶区体积较大特别是>70 cm3时,腔内+插植治疗技术能在显著提高靶区处方剂量和适形度的同时更好地保护OAR。     

定位CT图像和CT/MR扩散加权成像融合图像对食管癌放疗GTV勾画的比较

目的 比较定位CT图像和CT与磁共振扩散加权成像(MR DWI)融合图像(CT/MR DWI)对食管癌放疗GTV勾画的差异.方法 收集经细胞学或组织病理学证实的20例行根治性放疗的食管鳞癌患者,由6名放疗科医师分别在Pinnacle工作站的定位CT图像上和CT/MR DWI融合图像上勾画食管癌原发灶GTV,不包括转移淋巴结.计算GTV体积的均数、标准差、变异系数(CV=标准差/均数),最大值与最小值的比(Ratio=最大值/最小值).比较两组间GTV体积的变异系数CV和最大值与最小值的比值(Ratio)的差异.结果 CT图像上勾画的GTV体积最大差值为55.71 cm³,CT/MR DWI融合图像上勾画的GTV体积最大差值为13.89 cm³(F=12.80,P<0.05),两组GTV体积的变异系数分别为0.30±0.08和0.11±0.04,两组GTV体积最大值与最小值的比值分别为2.38±0.62和1.34±0.13,差异有统计学意义(Z=-3.92、-3.92,P<0.05).结论 和定位CT图像相比,CT/MR DWI图像融合显示食管癌GTV较为直观,能够在一定程度上提高判断病变范围的一致性,从而减少不同医师间勾画靶区差异性.     

内镜下钛夹植入对局部晚期食管癌术前放疗患者靶区勾画和剂量学参数的影响

目的 探讨内镜下钛夹植入对局部晚期食管癌术前放疗患者靶区勾画和剂量学参数的影响。 方法 回顾性分析2018年1月至2019年12月于联勤保障部队第九〇〇医院经超声胃镜及组织病理学检查确诊为局部晚期食管鳞癌的36例患者的临床资料,其中男性23例、女性13例,年龄18~65（43.7±6.9）岁。放疗前所有患者均在内镜下分别于食管病灶的上界和下界行钛夹植入术,在钛夹植入前后均行CT扫描定位和靶区勾画,比较钛夹植入前后的大体肿瘤体积（GTV）长度、GTV、肿瘤临床体积（CTV）和危及器官受照剂量的差异。将36例患者按照GTV上界和下界的误差分为精确组（误差<1 cm）和误差组（误差≥1 cm）,分析影响食管靶区勾画的因素。计量资料的比较采用配对样本t检验和独立样本t检验;采用χ2检验对精确组和误差组的临床病理特征进行单因素Logistic回归分析;采用Cox多因素回归模型分析影响靶区精确勾画的危险因素。 结果 36例患者均顺利在内镜下植入钛夹,4例（11.1%）出现上界钛夹脱落;术后病理完全缓解率为52.8%（19/36）。钛夹植入前患者GTV长度为（4.74±1.02） cm,大于钛夹植入后的（3.98±0.79） cm,二者的差异有统计学意义（t=9.472,P<0.05）。钛夹植入前患者的GTV和CTV分别为（28.87±3.21） cm3和（72.46±6.37） cm3,均大于钛夹植入后的（24.59±2.67） cm3和（56.37±4.52） cm3,且差异均有统计学意义（t=6.726、7.696,均P<0.05）。钛夹植入前的双肺V₁₀、V₂₀（接受10、20 Gy照射剂量的肺体积占全肺总体积的百分比）和脊髓的受照剂量均高于钛夹植入后[（21.64±1.57）%对（17.32±0.96）%、（14.87±2.32）%对（11.69±1.84）%、（28.87±3.21） Gy对（24.59±2.67） Gy],且差异均有统计学意义（t=8.05、7.64、?2.43,均P<0.01）。单因素Logistic回归分析结果显示,年龄、肿瘤位置、饮酒史、GTV长度与GTV的勾画精确度存在相关性（χ2=5.64、11.57、13.33、8.23,均P<0.01）。Cox多因素回归分析结果显示,肿瘤位置 [相对危险度（RR）=0.296,95%置信区间:0.137~0.586,P<0.001]和GTV长度（RR=2.313,95%置信区间:1.280~4.875,P<0.01）是影响GTV精确勾画的独立危险因素。 结论 内镜下钛夹植入在局部晚期食管癌术前放疗中具有重要价值,可精确引导CT定位下靶区勾画的范围并减少正常器官的受照剂量。     

呼吸门控PET/CT对于肺癌放疗靶区勾画的指导

目的 目的通过对肺部肿瘤进行呼吸门控PET/CT研究,给予肺部肿瘤放疗靶区勾画指导,最终使患者接受合理的照射靶区。 方法 对20个恶性结节进行呼吸门控PET/CT与常规PET/CT采集,比较肺部不同位置结节的平均四维PET体积与三维PET体积的差别,以及平均四维CT体积与三维CT体积的差别。以平均四维体积与三维体积的相对差值作为体积间的差异, 分别从结节位置、运动幅度研究其对四维体积与三维体积的影响。 结果 用两种方法测得的平均四维PET体积比三维PET体积大17.2%。体积相对差值与结节呼吸运动幅度及结节位置有关。下肺和肺门病灶平均四维PET体积与三维PET体积的平均差值为26.5%,远远大于上肺和胸膜病灶的平均差值（2.7%）。当结节呼吸运动幅度大于3 mm时,四维与三维PET体积差值的平均值为24.3%;小于3 mm时,平均值为1.8%。平均四维CT体积比三维CT体积大3.9%,体积差值范围为0.2~5.9 cm3,体积比值为1.10依0.32。只有在下肺,平均四维CT体积明显大于三维CT体积,平均差值为11.3%。 结论 对于靠近肝脾的下肺结节,用平均四维PET勾画肿瘤靶区更精确些;对于肺门周围的结节,考虑平均四维PET体积作为肿瘤靶区;对于上肺和胸膜的结节,建议采用低剂量呼吸门控扫描且已经考虑了呼吸运动的平均四维CT体积勾画靶区。     

18F-FDG PET/CT代谢体积与病理体积对比确定宫颈癌最大标准摄取值的最佳百分阈值

目的 通过18F-氟代脱氧葡萄糖正电子发射型计算机断层扫描仪(18F-FDG PET/CT)代谢体积与病理体积的比较,确定宫颈癌最大标准摄取值(SUMmax)的最佳百分阈值.方法 12例宫颈癌患者术前行PET/CT,经PET图像选取肿瘤SUVmax的10％、15％、20％、25％、30％、35％、40％、45％、50％等不同阈值勾画肿瘤边界,生成相应的PET大体肿瘤体积(PET GTV).术后进行病理切片,确定每层切片肿瘤边缘及面积,由面积乘以切片厚度计算每张切片的肿瘤体积,累积所有切片的肿瘤体积作为全部肿瘤的病理大体体积(病理GTV).将与肿瘤病理GTV最接近的PET GTV确定为最佳PET GTV值,将其对应的SUVmax阈值称为最佳百分阈值.结果 12例患者的最佳SUVmax阈值为40.83％±6.34％(30％～50％).以SUVmax的41％阈值勾画肿瘤边界所得PET GTV与病理GTV比较,差异无统计学意义(P=0.352),并且两者有较好的相关性(r=0.99,P=0.000).结论 通过病理体积确定的PET最佳SUVmax阈值能准确指导宫颈癌靶区的勾画,对提高三维适形调强放疗疗效具有重要意义.     

68Ga-PSMA-11 PET/CT代谢体积参数在不同风险分层的初诊前列腺癌患者中的差异研究

目的 探究68Ga-前列腺特异性膜抗原(PSMA)-11 PET/CT代谢体积参数在不同风险分层的初诊前列腺癌（PCa）患者中的差异。 方法 回顾性分析2019年1月至12月于海军军区大学第一附属医院经前列腺活体组织穿刺检查结果确诊后行68Ga-PSMA-11 PET/CT检查的85例未经治疗的PCa患者的影像及临床资料,患者年龄49~88（69.1±7.7）岁。根据是否发生肿瘤转移和美国国立综合癌症网络指南推荐的风险分层将患者分别分为无转移组和转移组、低中风险组和高风险组;以格里森评分（GS）8分为临界值,将患者分为GS<8分组和GS≥ 8分组;以血清前列腺特异抗原（PSA）20 ng/mL为临界值,将患者分为PSA≤20 ng/mL组和PSA>20 ng/mL组;根据临床分期的不同,将患者分为临床T1~T2期组和临床T3~T4期组。采用三维勾画法在68Ga-PMSA-11 PET/CT图像上自动测量和勾画肿瘤病灶感兴趣区,计算最大标准化摄取值（SUV_max）、原发PSMA肿瘤体积（PSMA-TV_原发）、全身PSMA肿瘤体积（PSMA-TV_全身）、原发PSMA肿瘤总量（TL-PSMA_原发）、全身PSMA肿瘤总量（TL-PSMA_全身）。组间代谢体积参数的比较采用两独立样本非参数Mann-Whitney秩和检验。 结果 85例患者68Ga-PSMA-11 PET/CT显像结果均呈阳性,其中无转移组46例（54.1%）、转移组39例（45.9%）;低中风险组15例（17.6%）、高风险组70例（82.4%）。转移组的SUV_max、PSMA-TV_原发、PSMA-TV_全身、TL-PSMA_原发、TL-PSMA_全身的中位数均高于无转移组（16.2对9.8,39.5 cm3对10.8 cm3,58.8 cm3对10.8 cm3,318.4 cm3对37.2 cm3,628.0 cm3对37.2 cm3）,且差异均有统计学意义（Z=?6.301~?2.580,均P<0.05）;高风险组的SUV_max、PSMA-TV_原发、PSMA-TV_全身、TL-PSMA_原发、TL-PSMA_全身的中位数均高于低中风险组（13.8对4.2,16.5 cm3对8.4 cm3,21.9 cm3对11.4 cm3,146.1 cm3对27.4 cm3,229.6 cm3对28.6 cm3）,且差异均有统计学意义（Z=?4.242~?2.438,均P<0.05）;GS≥8分组的SUV_max、PSMA-TV_原发、PSMA-TV_全身、TL-PSMA_原发、TL-PSMA_全身的中位数均高于GS<8分组（14.8对9.9,16.5 cm3对12.5 cm3,23.9 cm3对14.3 cm3,146.1 cm3对36.3 cm3,229.6 cm3对36.3 cm3）,除PSMA-TV_原发外,差异均有统计学意义（Z=?2.850~?2.074,均P<0.05）;PSA>20 ng/mL组的SUV_max、PSMA-TV_原发、PSMA-TV_全身、TL-PSMA_原发、TL-PSMA_全身的中位数均高于PSA≤20 ng/mL组（16.2对 6.4,24.7 cm3对8.2 cm3,41.4 cm3对10.2 cm3,253.9 cm3对28.0 cm3,361.5 cm3对29.7 cm3）,且差异均有统计学意义（Z=?6.279~?3.948,均P<0.001）;临床T3~T4期组的SUV_max、PSMA-TV_原发、PSMA-TV_全身、TL-PSMA_原发、TL-PSMA_全身的中位数均高于临床T1~T2期组（16.6对9.3,34.9 cm3对10.7 cm3,62.3 cm3对14.3 cm3,303.5 cm3对32.6 cm3,482.1 cm3对45.9 cm3）,且差异均有统计学意义（Z=?4.889~?3.629,均P<0.001）。 结论 转移组和高风险组的初诊前列腺癌患者68Ga-PSMA-11 PET/CT的代谢体积参数显著高于无转移组及低中风险组患者。     

双层探测器光谱CT在中央型肺癌合并肺不张精准放疗中的应用价值

目的探讨双层探测器光谱CT(DLSDCT)在中央型肺癌(CLC)合并肺不张精准放疗中的价值。方法回顾性分析2020年4月至2021年11月山东第一医科大学第三附属医院及山东省肿瘤医院经病理证实的26例CLC合并肺不张患者的临床及影像资料(DLSDCT、PET-CT及放疗模拟定位CT图像)。26例患者中男21例, 女5例, 年龄36～82岁。2名医师分别在DLSDCT、PET-CT及模拟定位CT图像上评估CLC可识别率, 并勾画大体肿瘤体积(GTV), 测量GTV值(GTVDLSDCT、GTVPET-CT、GTVCT)。采用配对样本Friedman检验比较3种图像GTV的差异, 两两比较采用SNK检验并经Bonferroni校正。采用组内相关系数(ICC)比较2名医师间测量GTV值的一致性。结果 PET-CT、DLSDCT、放疗模拟定位CT图像上CLC可识别率分别为100%(26/26)、80.77%(21/26)、11.54%(3/26), DLSDCT图像上CLC可识别率显著高于模拟定位增强CT(χ2=16.06, P<0.001)。模拟定位CT图像、PET-CT图像、DLSD...     

基于四维CT探讨腹部加压对周围型肺部肿瘤立体定向放疗靶区位移及外扩边界的影响

目的基于四维CT(4DCT)探讨腹部加压对周围型肺部肿瘤立体定向放疗(SBRT)靶区位移幅度、靶区体积大小及外扩边界的影响。方法前瞻性收集拟行SBRT的周围型肺部肿瘤患者,CT模拟定位时依次完成腹部加压3DCT、腹部加压4DCT(4DCT_com)、自由呼吸4DCT(4DCT_free)扫描,并于照射前行腹部加压锥形束CT(CBCT_com)扫描。4DCT图像重建生成最大密度投影(MIP)图像。在上述图像上分别勾画大体肿瘤体积(GTV)并重建肿瘤内大体靶体积(IGTV),在IGTV MIP_com基础上分别均匀外扩5、4、3 mm构建计划靶区(PTV)MIP_com。按所在肺叶位置将肿瘤分为全组、肺上中叶组和肺下叶组。结果对于全组肿瘤靶区,与自由呼吸状态比较,加压使靶区中位三维运动矢量减少30.92%;对于肺上中叶和下叶靶区,加压分别使靶区中位三维运动矢量增加3.42%和减少18.80%。无论全组还是上中叶或是下叶组,肿瘤各方向位移及三维运动矢量差异均无统计学意义(P>0.05)。腹部加压使IGTV的体积显著减少,IGTV MIP_com、IGTV MIP_free和IGTV10_com、IGTV10_free中位体积分别为4.01、5.36 cm³和6.59、7.65 cm³,差异均有统计学意义(Z=-3.45、-3.14,P<0.01)。PTV MIPcom外扩5 mm时IGTV CBCT_com对PTV MIP_com的包含度为100%,外扩4、3 mm时包含度≥95%的比例分别为100%、83.33%。结论腹部加压技术改变了患者呼吸模式,减少腹式呼吸的同时增加了胸式呼吸;IGTV MIP和IGTV10的体积减小,为SBRT患者PTV的缩小创造了条件;临床上采用腹部加压技术实施SBRT时基于4DCT的IGTV外扩4 mm形成的PTV显示了临床精准放疗的趋势。     

基于放疗中重复4D-CT扫描胸段食管癌肿瘤靶区体积变化的研究

靶区确定及适应性修正是食管癌精确放疗的核心环节。放疗过程中靶区体积及位移变化是靶区修改和计划修正的依据,相对于三维CT(3D-CT),四维CT(4D-CT)扫描既可以获得不包含运动信息的肿瘤靶区,如基于单时相图像勾画所得大体肿瘤体积(GTV),又可以获得包含放疗分次内全部运动信息的肿瘤靶区,如基于全部时相GTV融合所得内大体肿瘤体积(IGTV)或基于最大密度投影(maximum intensity projection, MIP)图像勾画所得相应IGTV。本研究基于重复4D-CT扫描探讨放疗疗程中靶区体积变化。     

CT-fluoroscopy guided interstitial brachytherapy with image-based treatment planning for unresectable locally recurrent rectal carcinoma

PURPOSE: The aim of the study is to develop high-dose-rate (HDR) conformal interstitial brachytherapy by means of combined CT-fluoroscopy guidance with CT-based treatment planning for locally recurrent rectal carcinoma. METHODS AND MATERIALS: Brachytherapy needle insertion was guided with a helical CT scanner providing continuous fluoroscopy reconstruction. A video monitor placed adjacent to the CT gantry simultaneously allowed the operator to see the process of needle insertion. Final CT images were transferred by an online system to the treatment-planning computer, which reconstructed the implant needles and organ contours. The doses in planning target volume were normalized and geometrically optimized. The patients received a brachytherapy dose at 5 Gy twice daily with a hypofractionated accelerated schedule at a total dose of 30-50 Gy with or without external radiation therapy. Eighteen patients were treated with this procedure. RESULTS: Ten to thirty-six needles (average, 17.3) were successfully placed to the planning target volume in each patient. The average time for CT fluoroscopy was 357 seconds for each procedure. No accident was seen at needle insertion, but 2 patients developed incomplete peroneal nerve palsy after needle removal, but gradually recovered. CT-based treatment planning was faster and more accurate than projection reconstruction with conventional radiograms. Analysis of the dose volume histogram showed conformal dose distribution to the target, while avoiding normal structures. CONCLUSION: CT fluoroscopy guidance ensures safety and increases the accuracy of needle placement in brachytherapy. Conformal high-dose-rate (HDR) interstitial brachytherapy with CT-based treatment planning is a method worth considering for locally recurrent rectal cancer.     

Comparison of intracavitary brachytherapy and stereotactic body radiotherapy dose distribution for cervical cancer

PurposeTo compare the dose distribution characteristics of stereotactic body radiotherapy (SBRT) with intracavitary high-dose-rate (HDR) brachytherapy in patients with cervical carcinoma.Methods and MaterialsHDR intracavitary brachytherapy treatment plans for 11 women with cervical carcinoma were evaluated in this analysis. The total HDR brachytherapy dose was 28 Gy given in four fractions. HDR brachytherapy was delivered with the microSelectron HDR therapy unit (Nucletron B. V., Veenendaal, The Netherlands). SBRT plans for each patient were generated with MultiPlan for CyberKnife Robotic Radiosurgery System (Accuray Inc., Sunnyvale, CA). The dose distributions, dose–volume histograms, and maximum dose points of the target and critical organs were recorded for both plans.ResultsSBRT yielded significantly better target coverage; the median target coverage for the 100% isodose line was 50.7% for HDR brachytherapy plans, whereas it was 99.1% for SBRT plans. The dose distributions for critical organs were similar in both types of plans. The exceptions were the 25% isodose being significantly better in brachytherapy plans for rectum, and the 100% isodose exposure being higher in brachytherapy plans for rectum, bladder, and sigmoid colon. Some significant differences were also found in maximum doses received by a 2-cc volume of bladder in favor of SBRT plans. In addition, maximum bone marrow doses were significantly higher in SBRT plans.ConclusionSBRT plans achieved better target coverage and better dose distributions to critical organs except bone marrow compared with HDR brachytherapy plans in patients with locally advanced cervical cancer.     

Evaluation of an MR-only interstitial gynecologic brachytherapy workflow using MR-line marker for catheter reconstruction

PurposeMagnetic resonance imaging (MRI) offers excellent soft-tissue contrast enabling the contouring of targets and organs at risk (OARs) during gynecological interstitial brachytherapy procedure. Despite its benefit, one of the main challenges toward MRI-only workflows is that the implanted catheters are not reliably visualized on MR images. This study aims to evaluate the feasibility of MR-only workflow using an in-house MR line marker during interstitial gynecological high-dose-rate (HDR) brachytherapy.Methods and MaterialsTen patients diagnosed with locally advanced cervical cancer treated with HDR brachytherapy were included in this study. The hybrid CT/MR-treated plan was used as the study reference plan. Five users manually reconstructed the catheter's path on MR images (3D T1- and T2-weighted). Subsequently, the dwell positions from the users’ plans were superimposed on the reference plans to evaluate the dosimetric impact of the using MR-only for catheter reconstruction in comparison with hybrid CT/MR approach. Variability of dwell positions between users and reconstruction time was also evaluated.ResultsMore than 96.90% of catheter reconstruction variations were < 2 mm. No statistical differences were reported between MR-only and hybrid CT/MR in gross tumor volume D₉₈ and high-risk clinical target volume D₉₀, respectively. For the OARs (bladder, sigmoid, rectum, and bowel), no significant changes were observed in any dose metrics between MR-only and hybrid CT/MR. The average reconstruction time was 51 ± 10 minutes across all ten patients.ConclusionThe feasibility of MR-only workflow using MR line marker during interstitial gynecological HDR brachytherapy has been validated in this study. The results show that the MR-only workflow is equivalent to the conventional hybrid CT/MR approach in terms of gross tumor volume and high-risk clinical target volume coverage and respecting of OARs dose limits.     

CT-Based Interstitial HDR Brachytherapy

PURPOSE: Development, application and evaluation of a CT-guided implantation technique and a fully CT-based treatment planning procedure for brachytherapy. METHODS AND MATERIALS: A brachytherapy procedure based on CT-guided implantation technique and CT-based treatment planning has been developed and clinical evaluated. For this purpose a software system (PROMETHEUS) for the 3D reconstruction of brachytherapy catheters and patient anatomy using only CT scans has been developed. An interface for the Nucletron PLATO BPS treatment planning system for optimization and calculation of dose distribution has been devised. The planning target volume(s) are defined as sets of points using contouring tools and are used for optimization of the 3D dose distribution. Dose-volume histogram based analysis of the dose distribution (COIN analysis) enables a clinically realistic evaluation of the brachytherapy application to be made. The CT-guided implantation of catheters and the CT-based treatment planning procedure has been performed for interstitial brachytherapy and for different tumor sites in 197 patients between 1996 and 1997. RESULTS: The accuracy of the CT reconstruction was tested using first a quality assurance phantom and second, a simulated interstitial implant of 12 needles. These were compared with the results of reconstruction using radiographs. Both methods gave comparable results with regard to accuracy, but the CT based reconstruction was faster. Clinical feasibility was proved in pre-irradiated recurrences of brain tumors, in pretreated recurrences or metastatic disease, and in breast carcinomas. The tumor volumes treated were in the range 5.1 to 2,741 cm3. Analysis of implant quality showed a slightly significant lower COIN value for the bone implants, but no differences with respect to the planning target volume. CONCLUSIONS: The Offenbach system, incorporating the PROMETHEUS software for interstitial HDR brachytherapy has proved to be extremely valuable in routine clinical practice for many tumor sites. Our CT-guided implantation technique together with a fully CT-based planning system has enabled conformal brachytherapy treatment to become routine.     

Image fusion of CT and MRI data enables improved target volume definition in 3D-brachytherapy treatment planning

PURPOSE: To integrate MRI into CT-based 3D-brachytherapy treatment planning using a software system for image registration and fusion. METHODS AND MATERIALS: Sixteen patients with recurrent head-and-neck cancer, vulvar cancer, liposarcoma, and cervical cancer were treated with interstitial (n=12) and endocavitary (n=4) brachytherapy. CT and MRI scans were performed after implantation and prior to treatment planning. Image registration to integrate the CT and MR information into a single geometric framework was performed using a software algorithm based on mutual information. Conventional 3D-brachytherapy planning based on CT-information alone was compared to brachytherapy planning based on fused CT and MRI data. The accuracy of the image fusion was measured using predefined corresponding landmarks in the CT and MRI data. RESULTS: The presented automated algorithm proved to be robust and reliable (mean registration error 1.8 mm, range 0.8-4.1 mm, SD 0.9 mm). Tumor visualization was difficult using CT alone in all cases. Brachytherapy treatment planning based on fused CT and MRI data enabled better definition of target volume and risk structures as compared to treatment planning based on CT alone. CONCLUSIONS: Image registration and fusion is feasible for afterloading brachytherapy treatment planning. Treatment planning based on fused CT and MRI data resulted in improved target volume and risk structure definition.     

局部晚期宫颈癌腔内放疗联合组织间插植的剂量学研究

目的 比较局部晚期宫颈癌单纯腔内放疗与腔内联合组织间插植放疗的剂量学差异。方法 2016年5月—2017年3月局部晚期宫颈癌患者共35例,均行根治性放疗,治疗方法为外照射+腔内联合组织间插植放疗。调强放射治疗处方剂量为46.8~50.4 Gy/26~28次,1.8 Gy/次。腔内联合组织间插植放疗剂量为7 Gy/次,1次/周,共4次。同一患者首先置入三管式后装放疗施源器,采集CT图像制定治疗计划,取出三管式施源器后,置入宫腔管并植入插植针,再次采集图像制定放疗计划。分别评价比较两组计划中靶区及危及器官的受照剂量差别。结果 共制定212次后装放疗计划,其中单纯腔内治疗计划106例,腔内联合组织间插植治疗计划106例。腔内联合组织间插植放疗组计划较单纯腔内放疗组的靶区剂量明显升高,高危临床靶区（CTV）的D₉₀、中危CTV的D₉₀均显著增高（t=-6.01、-2.73,P<0.05）,膀胱、直肠、乙状结肠的D_{2 cm³}显著降低（t=3.07、4.52、2.91,P<0.05）。结论 局部晚期宫颈癌应用腔内联合插植放疗可以明显提高靶区剂量,并降低危及器官膀胱、直肠和乙状结肠的受照剂量。     

Palliative Interstitial HDR Brachytherapy for Recurrent Rectal Cancer

PURPOSE: To report the methods and clinical results of CT-based interstitial high-dose-rate (HDR) brachytherapy procedures for the palliative treatment of recurrent rectal cancer. PATIENTS AND METHODS: A total of 44 brachytherapy implants were performed in 38 patients. CT-guided catheter implants were performed in 34 patients under local anesthesia and sedation, and four patients were implanted intraoperatively. Of 40 CT-guided implants, 20 were done using metallic needles introduced via the sacrum and 20 were transperineal implants of plastic tubes in the presacral region. Postimplant CT scans were used for three-dimensional (3-D) conformal brachytherapy planning. Patients implanted with metallic needles were given a single fraction of 10-15 Gy using HDR (192)Ir, and those who received transperineal implants of plastic catheters were given fractionated brachytherapy, 5 Gy twice daily to a total dose of 30-40 Gy. The median tumor volume was 225 cm(3) with a range of 41-2,103 cm(3). RESULTS: After a median follow-up of 23.4 months, a total of 13/38 patients were alive. The median postbrachytherapy survival was 15 months with 18 of the 25 deaths due to distant metastases. Tumor response was as follows: 6/38 partial remission, 28/38 stable disease, and 4/38 local progression. A planning target volume (PTV) coverage > 85% was achieved in 42/44 implants. The treatment was well tolerated, and no acute complications were observed. One patient developed a fistula after 8 months. Pain relief was recorded in 34 patients (89.5%), and the median duration of this palliative effect was 5 months with a range of 1-13 months. CONCLUSIONS: Interstitial HDR brachytherapy is a valuable tool for the delivery of high doses and achieves effective palliation in recurrent rectal carcinoma.     

3T multiparametric MRI–guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PurposeTo evaluate the role of 3T-MRI–guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter.Methods and MaterialsWe retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups.ResultsSeventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D₉₀ (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D_2cc (Gy) for organs at risk was comparable. No Grades 3–4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively.ConclusionsThe mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.     

Optimization of conformal avoidance: a comparative study of prone vs. supine interstitial high-dose-rate breast brachytherapy

PURPOSE: Several recent studies indicate high-dose-rate (HDR) breast brachytherapy as an alternative to standard external beam radiation therapy for partial breast irradiation with high dose conformality to the target. However, this article presents an exploration of the possibility of achieving higher conformal avoidance of sensitive structures through detailed and comparative 3D CT-based anatomical dose distribution of a patient in supine and prone positions. METHODS AND MATERIALS: A patient treated with accelerated partial breast HDR breast brachytherapy in the supine position was selected for two CT-based analyses, one in the supine and one in the prone position. The optimized plan (Nucletron HDR planning station) for each position was achieved using graphical optimization with local adjustment of isodose lines to cover the planned target volume (PTV, lumpectomy with 2 cm margin) with 100% of the prescribed dose (34 Gy in 10 fractions) while minimizing the hot spots. Cumulative dose-volume histograms (DVH) were analyzed for the PTV, lung, skin, pectoral muscle, and chest wall. RESULTS: The PTV received 100% of prescribed dose in both the prone and supine positions. A significant (>40%) dose reduction was achieved in the lung in the prone treatment position. Similar dose reductions were also achieved for prone pectoral muscle, chest wall, and breast skin, irradiating less volume with high doses. Pectoral muscle, lumpectomy, and the breast skin showed prominent differences in shape and displacement in the prone compared with the supine position. CONCLUSION: CT-based treatment planning allowed calculations of volumetric dose distribution to the target and all sensitive structures with proper visualization and volumetric delineation of organs of interest. The treatment plan shows significant dose reduction may be possible in various sensitive structures if the patient is treated with HDR brachytherapy in the prone position.