In-vivo Comparison of Planned and Measured Rectal Doses during Cobalt-60 HDR CT-based Intracavitary Brachytherapy Applications of Cervical Cancer Using the PTW 9112 Semiconductor Probe

Background: A semiconductor rectal probe was used to compare planned and measured rectal doses during Co-60 high dose rate (HDR) CT-based intracavitary brachytherapy applications (ICBT) of cervical cancer. Materials and Methods: A total of 22 HDR brachytherapy applications were included from 11 patients who were first treated with EBRT to the whole pelvis with a total prescribed dose of 50 Gy in 25 fractions. During each application, a PTW 9112 probe rectal probe having a series of five semiconductor diodes (R1 to R5) was inserted into the patient’s rectum and a CT-based HDR ICBT application with a prescribed dose per fraction of 7 or 7.5 Gy to HRCTV was performed. Measurements were carried in water phantom using PTW rectal and universal adaptor plugs. Doses measured in phantom and with patients were compared to those calculated by the treatment planning system. Results: The mean percentage dose difference ΔD (%) between calculated and measured values from phantom study were -5.29%, 1.89%, -2.72%, -4.76, and 0.72% for R1, R2, R3, R4, and R3 diodes, respectively and the overall mean ΔD (%) value with standard deviation (SD) was -2.03%±9.6%. From the patient study, a ΔD (%) that ranged from -19.5% to 24.0%, which corresponded to dose disparities between -0.77 Gy and 0.66 Gy. The median ΔD (%) ranged from 0.4% to 1.3%, or -0.03 to 0.05 Gy, respectively. ΔD (%) values exceeded 10% in approximately 26.4% of measurements (29 out of 110 in 22 applications). The location of Rmax in computed and measured values differs in 5 of 22 applications might be due to possible displacement of rectal probe between simulation and treatment. Conclusion: Despite the likely geometrical shift of measuring detectors between insertion and treatment, in-vivo dosimetry is feasible and can be used to estimate the dose to the rectum during HDR ICBT.     

CT引导下三管式腔内后装与腔内结合插植后装用于宫颈癌治疗的对比研究

目的:比较局部晚期宫颈癌采用标准三管施源器的腔内后装(tandem and ovoid)与腔内结合组织间插植后装的剂量学差异。方法:CT引导下的三维适形近距离治疗局部晚期宫颈癌患者20 例,间隔采用三管式腔内后装与腔内结合组织间插植共 72次。 按照施源器的不同分成 ２个组,每组 36 次,对靶区剂量、危及器官等进行比较。结果:在给予A点相同处方剂量的情况下,HR-CTV D90、D100在三管式腔内后装组与腔内结合组织间插植后装组中分别为（590.0±46.4）cGy、（471.2±66.2）cGy,（502.8±67.7）cGy、（335.9±46.0）cGy,P＜0．05),膀胱、直肠、乙状结肠D2cc均相近（P=0.85、0.28、0.53）。结论:采用腔内结合插植后装治疗局部晚期宫颈癌比三管式腔内后装可获得更高的靶区剂量,但长期疗效及晚期反应仍需进一步研究。     

准直器角度对宫颈癌 VMAT 的剂量学影响

目的：比较两种不同准直器角度对晚期宫颈癌 VMAT 计划的剂量学影响,为晚期宫颈癌 VMAT 计划的设计提供临床参考。方法：选择11例晚期宫颈癌患者,每例病人分别设计两种不同准直器角的双弧 VMAT计划,计划 A 和计划 B 的准直器角度分别为15°／345°和0°／90°。PTV 处方剂量为45Gy／（25f·1．8Gy）。所有计划都满足95％的靶区体积达到处方剂量要求。比较每个计划 PTV 的适形性指数（CI）与均匀性指数（HI）以及膀胱、直肠、股骨头和双肾的体积剂量（V30、V40、V50和 V18）和平均剂量（Dmean ）等参数。结果：两组计划靶区覆盖均能满足临床要求,但 B 计划的 CI 明显优于 A 组计划（0．75±0．03 vs 0．66±0．06;P ＜0．05）,并且有相似的均匀性指数。与 A 计划相比,B 计划在危及器官的体积剂量和平均剂量均明显低于前者（P ＜0．05）或者两者没有差别（P ＞0．05）。计划 A、B 两组膀胱和直肠的平均剂量（Dmean ）和体积剂量 V40分别为：（4500．70±218．28）cGy vs （4168．56±212．62）cGy（P ＝0．000）和（83．43％±11．73％）vs（61．46％±9．47％）（P ＝0．000）;（4836．12±313．33）cGy vs （4719．27±182．24）cGy（P＝0．121）和（97．05％±3．29％）vs （93．78％±6．60％）（P ＝0．066）。结论：对于晚期宫颈癌 VMAT 计划的设计,准直器角度为0°／90°的计划结果优于15°／345°的计划。不仅 PTV 的剂量分布有更好的适形性,而且能更好地保护危及器官。因此推荐使用0°／90°的准直器角度设计晚期宫颈癌的 VMAT 计划。     

CT Based 3-Dimensional Treatment Planning of Intracavitary Brachytherapy for Cancer of the Cervix : Comparison between Dose-Volume Histograms and ICRU Point Doses to the Rectum and Bladder

Background: CT based brachytherapy allows 3-dimensional (3D) assessment of organs at risk (OAR) doses with dose volume histograms (DVHs). The purpose of this study was to compare computed tomography (CT) based volumetric calculations and International Commission on Radiation Units and Measurements (ICRU) reference-point estimates of radiation doses to the bladder and rectum in patients with carcinoma of the cervix treated with high-dose-rate (HDR) intracavitary brachytherapy (ICBT). Materials and Methods: Between March2011 and May 2012, 20 patients were treated with 55 fractions of brachytherapy using tandem and ovoids and underwent post-implant CT scans. The external beam radiotherapy (EBRT) dose was 48.6Gy in 27 fractions. HDR brachytherapy was delivered to a dose of 21 Gy in three fractions. The ICRU bladder and rectum point doses along with 4 additional rectal points were recorded. The maximum dose (DMax) to rectum was the highest recorded dose at one of these five points. Using the HDRplus 2.6 brachyhtherapy treatment planning system, the bladder and rectum were retrospectively contoured on the 55 CT datasets. The DVHs for rectum and bladder were calculated and the minimum doses to the highest irradiated 2cc area of rectum and bladder were recorded (D2cc) for all individual fractions. The mean D2cc of rectum was compared to the means of ICRU rectal point and rectal DMax using the Student’s t-test. The mean D2cc of bladder was compared with the mean ICRU bladder point using the same statistical test .The total dose, combining EBRT and HDR brachytherapy, were biologically normalized to the conventional 2 Gy/fraction using the linear-quadratic model. (α/β value of 10 Gy for target, 3 Gy for organs at risk). Results: The total prescribed dose was 77.5 Gyα/β10. The mean dose to the rectum was 4.58±1.22 Gy for D2cc, 3.76±0.65 Gy at DICRU and 4.75±1.01 Gy at DMax. The mean rectal D2cc dose differed significantly from the mean dose calculated at the ICRU reference point (p<0.005); the mean difference was 0.82 Gy (0.48 -1.19Gy). The mean EQD2 was 68.52±7.24 Gyα/β3 for D2cc, 61.71±2.77 Gyα/β3 at DICRU and 69.24±6.02Gyα/β3 at DMax. The mean ratio of D2cc rectum to DICRU rectum was 1.25 and the mean ratio of D2cc rectum to DMax rectum was 0.98 for all individual fractions. The mean dose to the bladder was 6.00±1.90 Gy for D2cc and 5.10±2.03 Gy at DICRU. However, the mean D2cc dose did not differ significantly from the mean dose calculated at the ICRU reference point (p=0.307); the mean difference was 0.90 Gy (0.49-1.25Gy). The mean EQD2 was 81.85±13.03 Gyα/β3 for D2cc and 74.11±19.39 Gyα/β3 at DICRU. The mean ratio of D2cc bladder to DICRU bladder was 1.24. In the majority of applications, the maximum dose point was not the ICRU point. On average, the rectum received 77% and bladder received 92% of the prescribed dose. Conclusions: OARs doses assessed by DVH criteria were higher than ICRU point doses. Our data suggest that the estimated dose to the ICRU bladder pointmay be a reasonable surrogate for the D2cc and rectal DMax for D2cc. However, the dose to the ICRU rectal point does not appear to be a reasonable surrogate for the D2cc.     

Cancer of the uterine cervix: dosimetric guidelines for prevention of late rectal and rectosigmoid complications as a result of radiotherapeutic treatment

This paper is the report of a dosimetric study of 41 rectal and rectosigmoid complications after radiotherapeutic treatment (1974-1978) of 287 cervical uterine tumors. Treatment consisted of external irradiation (25 MeV linear accelerator) and intracavitary irradiation (Fletcher-Suit applicator) at different doses depending on tumor stage. Dosimetric measurements were expressed as the maximum rectal dose and mean rectal dose on the anterior surface of the rectum, as proposed by the Groupe Européen de Curiethérapie. Rectal doses were also studied as a function of intracavitary irradiation and intracavitary + external irradiation (maximum rectal and mean cumulative doses for each). The results show a significant difference in the state of the patients with and without complications, based on the dose reaching the rectum. The maximum and the mean cumulative rectal doses serve as one of the primary indicators for predicting complications. These values should therefore be determined before placement of intracavitary sources or, at the latest, before the second intracavitary application. We have shown that there is no fixed threshold dose, but that it varies from one region to another, depending on level of external irradiation. Our results argue in favor of adapting individual patient therapy based on simple precautions, which are adjustable to all treatment modalities. This method could lead to complete elimination of late rectal and rectosigmoid complications arising from radiotherapeutic treatment of cervical uterine cancer.     

Analysis of dosimetry and clinical efficacy of intracavitary/interstitial brachytherapy in locally advanced cervical cancer

Objective To study the dosimetric differences and short-term efficacy between intracavitary/interstitial brachytherapy (IC/ISBT) and conventional intracavitary brachytherapy (ICBT). Methods Forty-five patients with locally advanced cervical cancer were treated with IC/ISBT and ICBT. Points A (A1,A2), D90%, D100%, organs at risk, and the doses of bladder, colon, rectum and small intestine were calculated and the short-term efficacy was observed between two groups. Results Point A dose was significantly improved in IC/ISBT compared with ICBT (P<0.05). The D90% and D100% in IC/ISBT were significantly higher than those in ICBT (both P<0.05). After brachytherapy, IC/ISBT could obtain a significantly larger increase in target dose when residual tumor diameter was ≥3 cm compared with ICBT (P<0.05). The D2cm³ and D0.1cm³ of bladder, rectum, colon and small intestine did not significantly differ between IC/ISBT and ICBT (all P>0.05). The 1-,3-and 6-month clinical efficacy did not significantly differ between two technologies (all P>0.05). Conclusion During brachytherapy for locally advanced cervical cancer (residual tumor diameter ≥3 cm), IC/ISBT significantly increases the doses of target area and point A without increasing the dose of organs at risk or lowering the short-term clinical efficacy, which has significant dosimetric advantages.     

局部晚期宫颈癌后装腔内联合组织间插植剂量学及临床疗效分析

目的 研究后装腔内/组织间插植近距离治疗(IC/ISBT)与传统后装腔内近距离治疗(ICBT)相比较的剂量学差异及其近期疗效。方法 45例局部晚期宫颈癌患者采用IC/ISBT及ICBT方法进行后装近距离治疗,分别对两种治疗方法的A点(A1、A2)、D90%、D100%以及膀胱、结肠、直肠、小肠受量进行计算,同时观察近期疗效。结果 IC/ISBT比ICBT放疗A点剂量显著提升(P<0.05);并且IC/ISBT的D90%、D100%也均明显高于ICBT (P<0.05)。外照射后残存肿瘤直径≥3cm时,IC/ISBT比ICBT可获得较高的靶区剂量提升(P<0.05)。IC/ISBT与ICBT的膀胱、直肠、结肠、小肠D2cm³、D0.1cm³相近(P>0.05)。疗后1、3、6个月的近期疗效IC/ISBT与ICBT相近(P>0.05)。结论 局部晚期宫颈癌(残存肿瘤直径≥3cm)后装近距离治疗中IC/ISBT在不增加危及器官受量及降低近期疗效前提下显著地提高了靶区、A点剂量,具有明显剂量学优势。     

Rectal doses in intracavitary brachytherapy of gynecological malignancies: comparison of two dosimetric methods.

PURPOSE: To compare calculated rectal doses obtained by two dosimetric methods in intracavitary brachytherapy of gynecological malignancies. MATERIALS AND METHODS: This analysis included 124 intracavitary applications performed in 102 patients with cervical or endometrial cancer. The pelvic dose distribution based on orthogonal intracavitary placement films was calculated with the computer planning system. In each application the rectal dose was defined in the specific rectal point determined by both the use of a wire marker inserted into the rectum (R1) and by packing the vagina with radio-opaque gauze - the method recommended by the ICRU Report 38 (R2). The comparison included R1 and R2 doses as well as the respective radiobiological equivalent doses determined by the linear-quadratic model (r1 and r2). RESULTS: In 83% of applications the absolute value of R1 was lower than R2. The mean difference between R1 and R2 was 3.7 Gy (95% CI 3.03-4.41 Gy) and between r1 and r2 7.2 Gy (95% CI 5.77-8.56 Gy). These differences were significant (P<0.001 for both comparisons). The difference between the doses was not influenced by the type of applicator and remained significant even when a systemic+/-10% error of method was assumed. CONCLUSION: The rectal point dose determined with the use of rectal wire marker may be underestimated, therefore this method should be discouraged in gynecological brachytherapy.     

局部进展期宫颈癌四野盒式照射联合ICBT融合剂量学研究

目的:分析局部进展期宫颈癌(locally advanced cervical cancer,LACC)四野盒式照射联合腔内近距离放疗(intracavitary brachytherapy,ICBT)靶区和危及器官(organs at risk,OARs)融合剂量学分布.方法:20例LACC患者,行MRI和模拟CT扫描,融合MRI/CT图像,勾画靶区和OARs.设置四野/ICBT计划,单独计算靶区和OARs剂量,相加为几何剂量;叠加四野与ICBT形成融合计划,计算靶区和OARs融合剂量.计算ICBT对靶区和OARs剂量贡献.结果:几何计算导致低估靶区剂量和高估OARs剂量.除GTV外,ICBT对CTV和PTV也有贡献.膀胱充盈及空虚比较,靶区几何剂量低于融合剂量(P<0.05),OARs几何剂量高于融合剂量(P<0.05).膀胱充盈有利于降低OARs剂量.结论:LACC四野联合ICBT放疗融合剂量学评估可能优于几何评估,但有待进一步临床观察.膀胱保持一定容量有利于降低OARs剂量.     

宫颈癌腔内联合组织间插植治疗与三管式腔内后装治疗的剂量学比较

目的:比较腔内联合组织间插植治疗与三管式腔内后装治疗在宫颈癌后装近距离中的剂量学差异。方法:回顾性分析我院2017年2月至2017年12月后装治疗宫颈癌患者40例,FIGO分期为Ⅰb-Ⅳa期。其中20例患者采用核通Fletch三通道施源器进行三管式后装腔内治疗（ICBT）,20例患者采用核通Fletch宫腔管联合4针插植进行治疗（IC/ISBT）。在靶区D90尽量接近600 cGy条件下,评估单次后装治疗靶区适形指数（COIN）、均匀指数（HI）、膀胱及直肠的剂量学差异。结果:IC/ISBT组患者的高危CTV靶区COIN明显高于ICBT组（P=0.000）,而HI指数两组患者并无差异（P=0.917）。IC/ISBT组患者膀胱D1 cm3和D2 cm3剂量明显低于ICBT组（P=0.015,P=0.023）。IC/ISBT组患者直肠D1 cm3剂量明显低于ICBT组（P=0.040）,D2 cm3剂量也较ICBT组低（P=0.070）,但差异无统计学意义。两组患者总治疗时间差异无统计学意义（P=0.500）。结论:腔内联合4针插植治疗较三管式腔内放疗可以显著提高COIN而不改变靶区高剂量区范围和总治疗时间,并降低危及器官膀胱、直肠的受量。     

颈段、胸上段食管癌３ＤＣＲＴ／ＩＭＲＴ剂量学比较

目的　通过对颈段、胸上段食管癌三维适形（３ＤＣＲＴ）和调强（ＩＭＲＴ）放疗计划的剂量学比较,选择符合临床要求的最优方案。方法　１４例颈段、胸上段食管癌患者模拟定位后参考食管钡餐和内镜检查结果勾画ＧＴＶ,按照统一标准确定ＣＴＶ、ＰＴＶ,分别设计３ＤＣＲＴ、５野均匀分布ＩＭＲＴ-Ａ和５野非均匀分布ＩＭＲＴ-Ｂ共３套放疗计划,以９５％ＰＴＶ获得１００％处方剂量进行归一,分析各计划靶区剂量分布及危及器官受量的差异。结果　本组病例所有的ＩＭＲＴ计划均能满足治疗要求,而４例３ＤＣＲＴ计划不能满足要求,本研究仅对１０组可行计划进行进一步的剂量学比较。预防照射区（ＰＴＶ１）：３ＤＣＲＴ计划的剂量参数Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５分别为（５７２５±５４.９６）ｃＧｙ、（４７０３±２５.２６）ｃＧｙ、（５２０３±７１.７０）ｃＧｙ,明显高于ＩＭＲＴ-Ａ的（５３４８±２７.１４）ｃＧｙ、（４１５８±２７.３６）ｃＧｙ、（４９９６±５４.７４）ｃＧｙ和ＩＭＲＴ-Ｂ的（５２３２±２６.８５）ｃＧｙ、（４２８６±１２.１３）ｃＧｙ、（４９７９±３１.７８）ｃＧｙ（Ｐ＜０.０５）;３ＤＣＲＴＶ１０５为（８２.９５±３.０２）％,高于ＩＭＲＴ-Ａ的（７１.０７±６.６８）％和ＩＭＲＴ-Ｂ的（６９.５５±４.５６）％（Ｐ＜０.０５）,Ｖ１００、Ｖ９５无明显差异（Ｐ＞００５）。肿瘤区（ＰＴＶ２）：３套放疗计划的Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５、Ｖ_１０５、Ｖ_９５无明显差异（Ｐ＞０.０５）,而ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ的Ｖ_１００分别为（９５.２１±１.７８）％和（９６.１２±２.５５）％,均高于３ＤＣＲＴ的（８８.６９±１.８４）％（Ｐ＜０.０５）;ＩＭＲＴ-Ａ和ＩＭＲＴ-ＢＨＩ分别为１.０８±０.０１和１.０２±０.０１,低于３ＤＣＲＴ的１.１８±０.０３,差异有统计学意义（Ｐ＜０.０５）。除肺Ｖ５外,ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ脊髓Ｄ_ｍａｘ、肺Ｖ_２０、Ｖ_３０、ＭＬＤ分别为（３６４１±２３.４１）ｃＧｙ、（２２.０８±０.３１）％、（１１.０７±０.５１）％、（１０３４±３７.５１）ｃＧｙ和（３３０３±７５.３９）ｃＧｙ、（１９.８２±１.７４）％、（１０.１４±１.２０）％、（９８１±３８.１６）ｃＧｙ,均小于３ＤＣＲＴ的（４１１３±３８.２８）ｃＧｙ、（２８.０７±６.３０）％、（１９.７２±５.２６）％、（１３５６±３８.９１）ｃＧｙ,差异具有统计学意义（Ｐ＜０.０５）。ＩＭＲＴ计划剂量参数、体积参数、剂量分布均匀性无明显差别（Ｐ＞０.０５）;ＩＭＲＴ-Ｂ肺ＭＬＤ和脊髓Ｄｍａｘ较ＩＭＲＴ-Ａ低,差异具有统计学意义（Ｐ＜０.０５）。结论　颈段、胸上段食管癌放疗采用ＩＭＲＴ优于３ＤＣＲＴ,根据靶区形状非均匀布野ＩＭＲＴ可进一步降低肺和脊髓受照剂量。     

基于全卷积网络U-Net宫颈癌近距离治疗三维剂量分布预测研究

目的:基于全卷积网络U-Net预测宫颈癌近距离治疗(BT)感兴趣区(ROI)三维剂量分布,并评估其预测精度。方法:首先选取100例宫颈癌腔内结合组织间插植病例作为整个研究数据集,并将其划分为训练集(72例)、验证集(8例)、测试集(20例);然后利用U-Net建立模型,将是否包含宫腔管及插针作为区分因素训练两个模型;最...     

早期左乳腺癌保乳术后仰卧位和俯卧位照射的剂量学及放射损伤的比较

目的:通过比较早期左乳腺癌保乳术后仰卧位和俯卧位两种不同体位的调强治疗计划中危及器官的剂量学及急性放射损伤方面的差异性，为临床选择合适的体位固定方式提供依据。方法:选取2015年01月至2017年12月江苏省中医院收治的36例早期左乳腺癌保乳术后的患者，其中18例进行俯卧位固定方式的调强放疗，18例进行仰卧位固定方式的调强放疗，全乳房剂量为50 Gy/25 f,2 Gy/f,5 f/w。后对疤痕周围2 cm给予6 MeV电子线加量10 Gy/2.0 Gy/5次，5次/周。分别评估仰卧位及俯卧位两种治疗体位的计划中危及器官的剂量及急性放射性损伤的差异性，并对两组进行随访评估生存。结果:俯卧位组左肺Dmean（721.5±11.6）cGy、V5（20.4±1.4）%、V20（15.3±6.5）%，心脏平均剂量Dmean（468.6±60.4）cGy、V30（7.4±5.6）%；仰卧位组左肺Dmean（632.4±38.6）cGy、V5（35.5±1.3）%、V20（21.2±7.9）%，心脏平均剂量Dmean（532.2±17.9）cGy、V30（9.1±2.3）%。两组比较有统计学差异（P＜0.05），且俯卧位组左肺 Dmean、V5、V20，心脏平均剂量Dmean、V30优于仰卧位组。仰卧位及俯卧位组的术后2年局部复发率分别为5.6%（1/18），0%（0/18），无一例出现远处转移，无瘤生存率分别为94.4%、100%，2年生存率都为100%。两组无明显统计学差异（P＞0.05）。放射损伤方面，两组均未出现肺及心脏的急性放射性损伤，皮肤反应方面，均为1级皮肤反应，无一例出现2级及2级以上的皮肤损伤。俯卧位组及仰卧位组的皮肤损伤无明显差异。结论:相比于仰卧位放疗，在不减低生存的情况下，俯卧位放疗对肺及心脏保护得更好，且对皮肤的保护不劣于仰卧位组。     

A prospective study to assess the bladder distension effects on dosimetry in intracavitary brachytherapy of cervical cancer via computed tomography-assisted techniques.

BACKGROUND AND PURPOSE: Intracavitary brachytherapy (ICBT) is as important as external beam radiotherapy (EBRT) for the radical radiotherapy of uterine cervical cancer. The degree of urinary bladder distension during ICBT may affect the dose distribution in the bladder and rectum, to which an overdose may increase the chance of developing treatment-related complications. The purpose of this prospective study was to assess and quantify the impact of bladder distension on dosimetry in ICBT in patients with cervical cancer. PATIENTS AND METHODS: We recruited 20 patients with cervical cancer during a 12-month period. Inclusion criteria included pathological diagnosis of cervical cancer with IA to IIIB stages, and intact uterus. Patients were evaluated for brachytherapy after EBRT, and eligible individuals (cervical os could be identified clearly) were invited enter to this protocol to receive ICBT. In the first brachytherapy, bladder preparation (evacuation and distension by a Foley catheter) and CT scan were performed soon after the insertion of CT-compatible applicators. Then the bladder wall doses [median dose, maximum dose and dose-volume histograms (DVH)] were calculated via the PLATO computer planning system (Nucletron PLATO-RTS version 2.0). The individual data regarding doses and DVH were collected and compared. Bladder distension may shift the applicator position, and posterior displacement of the applicator system may increase the dose to the rectal wall, so this effect was also evaluated. RESULTS: All the continuous variables of these 20 patients followed a normal distribution. By paired t-test and multiple linear regression analysis, we found that bladder distension statistically significantly decreased the median bladder wall dose with an average reduction of 48% of the dose of an empty bladder (P<0.001), and the maximum dose did not change; on the other hand, the bladder distension did not have any adverse effects on the rectal wall doses. CONCLUSIONS: Using CT-assisted three-dimensional techniques to assess the bladder and rectal wall doses is feasible. Bladder distension reduces the median dose in the bladder wall, which may reduce treatment-related complications.     

Transperineal injection of hyaluronic acid in anterior perirectal fat to decrease rectal toxicity from radiation delivered with intensity modulated brachytherapy or EBRT for prostate cancer patients

PURPOSE: Rectal toxicity remains a serious complication affecting quality of life for prostate cancer patients treated with radiotherapy. We began an investigational trial injecting hyaluronic acid (HA) in the perirectal fat to increase the distance between the prostate and the anterior rectal wall. This is the first report using HA injection in oncology. METHODS AND MATERIALS: This is a trial of external beam radiation therapy with HDR brachytherapy boosts in prostate cancer. During the two high-dose-rate (HDR) fractions, thermoluminescent dosimeter dosimeters were placed in the urethra and in the rectum. Before the second HDR fraction, 3-7 mL (mean, 6 mL) of HA was injected under transrectal ultrasound guidance in the perirectal fat to systematically create a 1.5-cm space. Urethral and rectal HDR doses were calculated and measured. Computed tomography and magnetic resonance imaging were used to assess the stability of the new space. RESULTS: Twenty-seven patients enrolled in the study. No toxicity was produced from the HA or the injection. In follow-up computed tomography and magnetic resonance imaging, the HA injection did not migrate or change in mass/shape for close to 1 year. The mean distance between rectum and prostate was 2.0 cm along the entire length of the prostate. The median measured rectal dose, when normalized to the median urethral dose, demonstrated a decrease in dose from 47.1% to 39.2% (p < 0.001) with or without injection. For an HDR boost dose of 1150 cGy, the rectum mean Dmax reduction was from 708 cGy to 507 cGy, p < 0.001, and the rectum mean Dmean drop was from 608 to 442 cGy, p < 0.001 post-HA injection. CONCLUSION: The new 2-cm distance derived from the HA injection significantly decreased rectal dose in HDR brachytherapy. Because of the several-month duration of stability, the same distance was maintained during the course of external beam radiation therapy.     

Carcinoma of the cervix: analysis of bladder and rectal radiation dose and complications

From April 1969 through December 1980, 527 patients with epidermoid carcinoma of the cervix received radical radiation therapy at North Carolina Memorial Hospital (NCMH). The treatment was designed to deliver a combined dose (external beam plus intracavitary) of 7000-8000 cGy to Point A and 5000-6500 cGy to the pelvic lymph nodes depending upon the stage of the disease. The maximum dose to the bladder and to the rectum were calculated from the orthogonal intracavitary placement films with contrast material in these organs. Thirty-three cases of cystitis and fifty-eight cases of proctitis were recorded. The mean bladder dose for the group of patients with cystitis was higher, 6661 +/- 1309 cGy, than that for the patients without cystitis, 6298 +/- 1305 cGy, p = .19. The risk of cystitis increased as a function of bladder dose ranging from 3% for patients receiving less than or equal to 5000 cGy to the bladder to 12% for patients receiving greater than or equal to 8001 cGy to the bladder. A similar correlation was also found for rectal dose and proctitis. The mean rectal dose for the group of patients with proctitis was higher, 6907 +/- 981 cGy, than that for the patients without proctitis, 6381 +/- 1290 cGy, p = .003. The risk of proctitis increased as a function of rectal dose ranging from 2% for patients receiving less than or equal to 5000 cGy to the rectum to 18% for patients receiving greater than or equal to 8001 cGy to the rectum. A study of the severity of the cystitis as a function of bladder dose revealed a relationship between bladder dose and the severity of the complication (Grade I cystitis = 6600 +/- 1318 cGy vs Grade III cystitis = 6856 +/- 853 cGy). A dose-response relationship was found between the rectal dose and the severity of the complication (Grade I proctitis = 6810 +/- 906 cGy vs Grade III proctitis = 6997 +/- 1137 cGy). This relationship was statistically significant, p = .003. While there was no difference in the frequency of cystitis as a function of dose to the whole pelvis, the risk of proctitis did increase with increasing doses of external beam to the whole pelvis. It ranged from 3% for patients who received 2000 cGy or less to the whole pelvis to 14% for patients who received greater than 4000 cGy to the whole pelvis, p = .02.     

Computer tomography-assisted three-dimensional technique to assess rectal and bladder wall dose in intracavitary brachytherapy for uterine cervical cancer.

We used a computer tomography (CT)-assisted three-dimensional (3D) technique to assess dose to the rectum and bladder in intracavitary brachytherapy (ICBT) for patients with cervical cancer, and compared this technique with the conventional method. The results revealed that the difference in dose to the rectal and bladder wall between these two methods were significant. The CT-assisted technique is a feasible method, and it gives different results than the conventional method.     

局部中晚期宫颈癌宫旁插植放疗的临床疗效观察

目的 探讨腔内联合宫旁插植治疗(IC/ISBT)和腔内后装治疗(ICBT)对局部晚期宫颈癌的临床疗效.方法 选取经体外照射放疗(50 Gy/25 f)后肿瘤消退不明显且宫旁受侵的局部晚期(ⅡB～ⅢB期)宫颈癌患者100例.采用随机数字表法将患者分为ICBT组和IC/ISBT组,每组50例.然后进行CT,将图像传至Onc...     

Effect of bladder distension on dose distribution of intracavitary brachytherapy for cervical cancer: three-dimensional computed tomography plan evaluation

PURPOSE: To quantify the effect of bladder volume on the dose distribution during intracavitary brachytherapy for cervical cancer. METHODS AND PATIENTS: The study was performed on 10 women with cervical cancer who underwent brachytherapy treatment. After insertion of the brachytherapy applicator, the patients were transferred to the computed tomography unit. Two sets of computed tomography slices were taken, including the pelvis, one with an empty bladder and one after the bladder was filled with saline. The target and critical organs were delineated by the radiation oncologist and checked by the expert radiologist. The radiotherapy plan was run on the Plato planning system, version 14.1, to determine the dose distributions, dose-volume histograms, and maximal dose points. The doses and organ volumes were compared with the Wilcoxon signed ranks test on a personal computer using the Statistical Package for Social Sciences, version 11.0, statistical program. RESULTS: No significant difference regarding the dose distribution and target volumes between an empty or full bladder was observed. Bladder fullness significantly affected the dose to the small intestine, rectum, and bladder. The median of maximal doses to the small intestine was significantly greater with an empty bladder (493 vs. 284 cGy). Although dosimetry revealed lower doses for larger volumes of bladder, the median maximal dose to the bladder was significantly greater with a full bladder (993 vs. 925 cGy). The rectal doses were also affected by bladder distension. The median maximal dose was significantly lower in the distended bladder (481vs. 628 cGy). CONCLUSIONS: Bladder fullness changed the dose distributions to the bladder, rectum, and small intestine. The clinical importance of these changes is not known and an increase in the use of three-dimensional brachytherapy planning will highlight the answer to this question.     

螺旋断层放疗与常规放疗在全脑全脊髓照射中的剂量学比较

目的 探讨螺旋断层放疗（HT）与常规放疗（CRT）计划在全脑全脊髓照射中的剂量学特点,为临床选择不同的治疗方案提供依据。方法 选取行全脑全脊髓放疗患者的CT图像10例,勾画靶区及危及器官（OAR）后,分别传输至Xio-Release 4.62.00及HI·ART Version 4.0.4治疗计划系统,给予全中枢靶区（PTV CSI）36Gy／18f,根据RTOG 02-25标准限制OAR剂量。2组计划完成后,分别对靶区的均匀指数（HI）、适形指数（CI）、等剂量曲线覆盖程度、剂量体积直方图的分布和OAR的平均剂量（Dmean）及体积分数进行评估,并进行统计分析。结果 HT计划中计划靶区体积（PTV）的HI、CI优于CRT组（P＜0.05）;2组计划的靶区最大量（Dmax）、Dmean均大于处方剂量（36Gy）,其中HT组较CRT组更接近处方剂量（P＜0.05）;CRT和HT组的V95、V107分别为（98.0±1.2）％、（34.7±18.9）％和（99.2±0.3）％、（0.6±1.3）％,差异均有统计学意义（P＜0.05）。HT组除骨髓、Body外其他OAR的Dmean均低于CRT组,其中在眼球、心脏、Body中的差异有统计学意义（P＜0.05）;HT组除眼球外其他OAR的V5均高于CRT组,其中在肺、心脏、胃、肝脏、肾、骨髓、Body中的差异均有统计学意义（P＜005）;2组计划中OAR V10的差异较小（P＞0.05）;HT组除Body外其他OAR V20均低于CRT组,其中在眼球、肺、心脏、胃、肾、肝脏中的差异有统计学意义（P＜0.05）。结论在全脑全脊髓照射中,HT计划优于CRT计划,值得临床进一步推广,但正常组织低剂量区的提高对临床的影响尚有待进一步观察。