直肠癌IMRT中不同体位对靶区剂量覆盖影响

目的 探讨直肠癌IMRT中仰卧位和俯卧位对靶区剂量覆盖的影响,为直肠癌IMRT体位的选择提供参考。方法 选取24例接受术后辅助放疗的直肠癌患者,仰卧位和俯卧位各12例。所有患者在治疗前和治疗过程中(第1—4周)各扫描一组定位CT,分别定义为Plan、1W、2W、3W、4W。基于不同CT影像图像分别勾画OAR。PlanCT与第1—4周CT分别进行图像融合,将PlanCT的CTV和PTV分别拷贝至第1—4周CT上,将基于PlanCT的治疗计划分别拷贝至第1—4周CT,评估靶区处方剂量覆盖率并计算靶区剂量覆盖不合格率,同时在医科达MOSAIQ网络中读取每例患者每次治疗时加速器治疗床位置数据并计算床位总体偏差值。成对t检验比较2组数据差异,Pearson检验进行相关性分析。结果 在治疗过程中俯卧位患者的CTV、PTV靶区剂量覆盖不合格率高于仰卧位(19%：0%,70%：54%),总体偏差值与靶区剂量覆盖率存在显著相关性(r=-0.683,P=0.000)。俯卧位患者的总体偏差值为(1.23±0.76) cm明显大于仰卧位患者的(0.28±0.18) cm (P=0.001),其中y、z轴向偏差最为明显(P=0.003、0.003)。俯卧位患者小肠V5、V10明显小于仰卧位患者(P=0.003、0.004),其慢性不良反应也明显较少(P=0.041)。结论 直肠癌IMRT患者选择仰卧位能保持较好的靶区剂量覆盖率,而俯卧位因使用腹板装置会导致体位重复性变差,进而影响靶区剂量覆盖。尽管俯卧位联合腹板可以减少小肠耐受剂量,但应采取有效的保证患者体位重复性的措施。     

改进型腹板在直肠癌术后放疗中的应用

目的 简述改进型腹板在直肠癌术后放疗中的应用方法,并探讨其对摆位重复性的影响.方法 对改进型腹板的应用方法进行说明,运用锥形束CT对使用常规型腹板、改进型腹板放疗患者的分次内及分次间摆位误差分别进行测量,并对数据进行分析,得出结论.结果 运用常规型腹板患者分次内摆位误差在x轴差异无统计学意义（P＞0.05）,在v、z轴差异均有统计学意义（均P＜0.05）;分次间摆位误差在x轴差异无统计学意义（P＞0.05）,在v、z轴上差异均有统计学意义（均P＜0.05）.运用改进型腹板患者分次内摆位误差及分次间摆位误差在x、v、z轴上差异均无统计学意义（均P＞0.05）.结论 运用改进型腹板固定对摆位误差重复性的控制方面比常规型腹板更具有优势,有利于提高患者治疗的准确性.     

A significant decrease in rectal volume and diameter during prostate IMRT

Purpose

To record changes in rectal volume (RV) and diameter (RD) of patients with prostate adenocarcinoma prior to and at an interim period during radiotherapy, which could potentially affect treatment toxicity and tumor control.

Methods

Three hundred and fifteen patients treated with intensity modulated radiotherapy (IMRT) underwent planning CT scans before radiation and after 45 Gy. For each scan, RV and RD were recorded and compared using a two-tailed paired t-test. Robust linear regression analysis assessed correlation between initial RV and percent RV change.

Results

The mean change in RV was −8.62 cm³ and in RD was −0.19 cm³, (p < 0.05). A decrease ?10% in RV and RD was seen in 159 patients (50.5%) and 117 patients (37.1%), respectively. Patients with ?10% volume change had larger initial RVs than those with <10% decrease, (78.1 vs. 50.8 cm³, p < 0.0001).

Conclusions

A significant decrease in RV and RD occurs during prostate IMRT delivery. More than half of patients had decreased RV and over a third had decreased RD. This observation is pertinent to prostate localization, planning margins, and implies that dose-volume histogram (DVH) analysis of rectal irradiation based on pre-treatment CT scanning may inaccurately estimate the risk of rectal toxicity when the initial RV is larger than 70 cm³.     

Validity and reliability of the MSKCC Bowel Function instrument in a sample of Italian rectal cancer patients

Aims

The purpose of this study was to translate the Memorial Sloan Kettering Cancer Centre (MSKCC) Bowel Function Instrument into Italian and to test its psychometric validity and reliability in a sample of Italian rectal cancer patients.

Methods

The MSKCC questionnaire was translated into Italian using a standard procedure of double-back translation. Construct validity was tested using a factor analysis and internal reliability was estimated using the Cronbach’s alpha coefficient. Concurrent validity was determined by correlations with European Organisation for Research and Treatment of Cancer QLQ-C30 and QLQ-CR38 quality of life scales. A non-parametric analysis of variance was used to establish the discriminant validity of the questionnaire. Test-retest reliability was assessed using the intra-class correlation coefficient.

Results

124 rectal cancer patients participated in the validation study. The number of missing items was 2.2%. The factorial structure was found to be quite similar to the original one and the internal reliability was 0.7 for urgency, 0.6 for frequency, and 0.7 for dietary subscale. The test-retest reliability was acceptable with one exception: the dietary subscale showed a low reproducibility (ICC = 0.4). All three subscales showed a significant correlation with the QLQ-C30 and QLQ-CR38 domains and were able to discriminate several groups of clinical relevance.

Conclusions

The Italian version of the MSKCC Bowel Function Instrument shows acceptable psychometric properties and can be considered a valuable and specific instrument to assess bowel functions in rectal cancer patients, both for research purposes and in clinical practise.     

Target volume shape variation during irradiation of rectal cancer patients in supine position: Comparison with prone position

Purpose

To quantify the inter-fraction shape variation of the mesorectum for rectal cancer patients treated with 5 × 5 Gy in supine position and compare it to variation in prone position.

Methods and materials

For 28 patients a planning CT (pCT) and five daily cone-beam-CT (CBCT) scans were acquired in supine position. The mesorectal part of the CTV (MesoRect) was delineated on all scans. The shape variation was quantified by the distance between the pCT- and the CBCT delineations and stored in surface maps after online setup correction. Data were analyzed for male and female patients separately and compared to prone data.

Results

A large range of systematic, 1-8 mm (1SD), and random, 1-5 mm, shape variation was found, comparable to prone patients. Random-shape variation was comparable for male and female patients, while systematic variation was 3 mm larger for female patients.

Conclusions

Shape variation of the MesoRect is substantial, heterogeneous and different between male and female patients. Differences between supine and prone orientation, however, are small. Clinical margins should be differentiated in position along the cranio-caudal axis, in anterior-posterior direction and for gender. Margins should also be increased, even when online setup correction is used. Due to the small margin differences between prone and supine treatments, the setup choice should be determined on dose to the organs at risk.     

Dosimetric and toxicity comparison between prone and supine position IMRT for endometrial cancer

PURPOSE: To determine the dosimetric and toxicity differences between prone and supine position intensity-modulate radiotherapy in endometrial cancer patients treated with adjuvant radiotherapy. METHODS: Forty-seven consecutive endometrial cancer patients treated with adjuvant RT were analyzed. Of these, 21 were treated in prone position and 26 in the supine position. Dose-volume histograms for normal tissue structures and targets were compared between the two groups. Acute and chronic toxicity were also compared between the cohorts. RESULTS: The percentage of volume receiving 10, 20, 30, 40, 45, and 50 Gy for small bowel was 89.5%, 69%, 33%, 12.2%, 5%, and 0% in the prone group and 87.5%, 62.7%, 26.4%, 8%, 4.3%, and 0% in the supine group, respectively. The difference was not statistically significant. The dose-volume histograms for bladder and rectum were also comparable, except for a slightly greater percentage of volume receiving 10 Gy (1.5%) and 20 Gy (5%) for the rectum in the prone group. Acute small bowel toxicities were Grade 1 in 7 patients and Grade 2 in 14 patients in the prone group vs. Grade 1 in 6 patients and Grade 2 in 19 patients in the supine group. Chronic toxicity was Grade 1 in 7 patients and Grade 3 in 1 patient in the prone group and Grade 1 in 5 patients in the supine group. CONCLUSION: These preliminary results suggest that no difference exists in the dose to the normal tissue and toxicity between prone and supine intensity-modulated radiotherapy for endometrial cancer. Longer follow-up and more outcome studies are needed to determine whether any differences exist between the two approaches.     

高龄低位直肠癌患者保肛手术后控便功能分析

背景与目的:虽然保肛手术已在当前的直肠癌根治手术中占主导地位,但多数外科医生由于担心患者术后控便功能下降,都不愿向高龄低位直肠癌患者推荐低位吻合术。本研究对高龄低位直肠癌患者保肛术后肛门控便情况进行探讨和分析。方法:选取高龄低位直肠癌病例80例,分成两个年龄组,≥75岁年龄组39例,60￣74岁年龄组41例,收集患者的临床资料,包括治疗手段、并发症等。术后18个月内对患者肠道功能、控便情况及满意度等资料进行随访记录,并对两组患者术后控便情况进行比较。结果:术后18个月,79例(98.8%)患者生存,76例可评价肛门控便情况,其中≥75岁年龄组36例,60￣74岁年龄组40例。术后3个月肛门功能评价显示≥75岁年龄组较60￣74岁年龄组差(P<0.05),但术后半年时这种差异无统计学意义(P>0.05)。术后排便次数恢复正常的时间:≥75岁年龄组较60￣74岁年龄组虽有所延长,但无显著性差异(P>0.05)。≥75岁年龄组术后13例出现了Ⅰ度失禁的表现,与60￣74岁年龄组有显著性差异(P<0.05)。患者术后大便失禁经药物治疗后症状可缓解。结论:老年低位直肠癌患者保肛术后能保持较好的控便能力,高龄不应成为低位直肠癌保肛术的禁忌证。     

The effect of patient positioning (prone or supine) on the dose received by small bowel in pelvic radiotherapy in rectal cancer patients

PurposeThe small bowel is a main dose-limiting organ in pelvic radiotherapy in the patients with rectal cancer. Conventionally, pelvic radiotherapy of patients with rectal cancer is performed in the prone position.Material and MethodsThirty-nine patients underwent CT planning scan in the treatment position (20 patients in prone position group and 19 patients in supine position group). After radiation treatment planning optimization, the volumes of the irradiated small intestines were investigated.ResultsThe volume of irradiated small bowel was higher in the supine position (mean difference; 36,274 cm³). However, it was not statistically significant (P value = 0.187)ConclusionSupine position could be accepted for the patients undergoing preoperative rectal cancer chemo-radiation.     

碳纤维腹板在直肠癌术后放疗中的临床应用

目的:研究碳纤维腹板在直肠癌术后放疗中对小肠和膀胱的保护作用及放疗摆位的重复性.方法:选择直肠癌术后患者45例,其中应用腹板放疗组20例(A组),未应用腹板放疗(对照)组25例(B组),均采用三维适形放疗(threE-dimensional conformal radiation therapy,3D-CRT)技术,95%的计划靶体积(planning target volume, PTV)处方剂量为50 Gy/25次.A组患者采取单纯俯卧位(A1组)或加用腹板(A2组)进行2次CT定位扫描,通过剂量体积直方图观察PTV及小肠和膀胱受照射的剂量和体积.随机抽取A组和B组各10例患者,通过双曝光射野验证系统测量2组患者的摆位误差.同时,观察和记录所有患者在治疗过程中的急性放疗反应.结果:A1、A2组总PTV、总小肠体积、总膀胱体积及PTV平均受照射剂量差异均无统计学意义(P>0.05);A2组小肠平均受照射剂量、10%～100%各等剂量曲线包绕的小肠体积、膀胱平均受照射剂量和30%～100%各等剂量曲线包绕的膀胱体积均显著减少,差异有统计学意义(P<0.05).与B组相比,A组患者左-右和头-脚方向摆位误差减小,差异有统计学意义(P<0.05);前-后方向摆位误差也减小,但差异无统计学意义(P=0.705).A组患者中≥3级不良反应的发生率为15%(3/20),无治疗中断或终止;B组患者中≥3级不良反应的发生率为24%(6/25),因严重急性反应有2例患者中断治疗,1例患者终止治疗.结论:碳纤维腹板可显著减少直肠癌术后放疗中小肠和膀胱的受照射体积和剂量,且摆位重复性好,患者放疗反应减轻,值得临床推广应用.     

Rectal dose-volume differences using proton radiotherapy and a rectal balloon or water alone for the treatment of prostate cancer

PURPOSE: To describe dose-volume values with the use of water alone vs. a rectal balloon (RB) for the treatment of prostate cancer with proton therapy. MATERIALS AND METHODS: We analyzed 30 proton plans for 15 patients who underwent CT and MRI scans with an RB or water alone. Simulation was performed with a modified MRI endorectal coil and an RB with 100 mL of water or water alone. Doses of 78-82 gray equivalents were prescribed to the planning target volume. The two groups were compared for three structures: rectum, rectal wall (RW), and rectal wall 7 cm (RW7) at the level of the planning target volume. RESULTS: Rectum and RW volumes radiated to low, intermediate, and high doses were small: rectum V10, 33.7%; V50, 17.3%; and V70, 10.2%; RW V10, 32.4%; V50, 20.4%; and V70, 14.6%. The RB effectively increased the rectal volume for all cases (139.8 +/- 44.9 mL vs. 217.7 +/- 32.2 mL (p < 0.001). The RB also decreased the volume of the rectum radiated to doses V10-V65 (p < or = 0.05); RW for V10-V50; and RW7 for V10-V35. An absolute rectum V50 improvement >5% was seen for the RB in 5 of 15 cases, for a benefit of 9.2% +/- 2.3% compared with 2.4% +/- 1.3% for the remaining 10 cases (p < 0.001). Similar benefit was seen for the rectal wall. No benefit was seen for doses > or =70 gray equivalents for the rectum, RW, or RW7. No benefit of < or =1% was seen with an RB in 46% for the rectum V70 and in 40% for the rectal wall V70. CONCLUSIONS: Rectum and rectal wall doses with proton radiation were low whether using water or an RB. Selected patients will have a small but significant advantage with an RB; however, water alone was well tolerated and will be an alternative for most patients.     

Sphincter preservation in rectal cancer

Sphincter preservation is a major goal in the treatment of rectal cancer. For selected patients with T1–2 disease, local excision followed by postoperative combined modality therapy is a reasonable alternative to an abdominoperineal resection. However, for patients with T3 disease, the local recurrence with this approach is approximately 25% and they are treated more effectively with preoperative combined modality therapy. In patients who undergo a prospective clinical assessment and are declared to require an abdominoperineal resection, preoperative radiation therapy, either alone or when combined with chemotherapy, allows approximately 80% to undergo a low anterior resection/coloanal anastomosis. The majority have good-to-excellent sphincter function. These conservative approaches may be an alternative to an abdominoperineal resection in selected patients. Received: August 7, 1998     

Dosimetric analytic comparison of inverse and forward planned IMRT techniques in the treatment of head and neck cancer

PurposeOur aim was to investigate if, and to what degree, improvements of IMRT treatment plans generated by forward planning can be achieved with an inverse planning strategy for treatments of head and neck cancer.MethodsBetween June 2007 and April 2008, 19 patients with head-and-neck cancers were treated at KAAH and Oncology Center Jeddah, using forward planning intensity modulated radiation therapy (FP-IMRT). They received thirty fractions over six weeks, to simultaneously deliver 66 Gy to the gross tumor (CTV1), 60 Gy to the soft tissue and nodes adjacent to the previous volume (CTV2), and 54 Gy to elective nodes (CTV3). These are biologically equivalent to 70, 60, and 50 Gy, if given 2 Gy per fraction.These were retrospectively re-planned with an inverse planning algorithm (IP-IMRT). The main objective of the optimization process was sparing of the parotid glands, spinal cord, and brainstem beside adequate treatment of the planning target volume.ResultsHaving 95% and 98% of CTV1 to receive at least 95% and 90% of prescribed dose respectively was fulfilled in all cases in both groups with higher figures in group B (IP-IMRT) than in group A (FR-IMRT), more obvious in CTV2 and CTV3. The average maximum dose to the spinal cord was 45.1 Gy in group A, and 41.6 Gy in group B. The mean dose of both parotid glands was kept below 26 Gy in four patients in group A, but in all cases in group B.ConclusionIP-IMRT selectively spared critical organs to greater degree with better target coverage and should be considered the standard of treatment in head and neck tumors.     

Neoadjuvant chemoradiation with IMRT in resectable and borderline resectable pancreatic cancer

PurposeNeoadjuvant chemoradiation is an alternative to the surgery-first approach for resectable pancreatic cancer (PDA) and represents the standard of care for borderline resectable (BLR).Materials and methodsAll patients with resectable and BLR PDA treated with neoadjuvant chemoradiation using IMRT between 1/2009 and 11/2011 were reviewed. Patients were treated to a customized CTV which included the primary mass and regional vessels.ResultsNeoadjuvant chemoradiation was completed in 69 patients (39 BLR and 30 resectable). Induction chemotherapy was used in 32 (82%) of the 39 patients with BLR disease prior to chemoXRT. All resectable patients were treated with chemoXRT alone. Following neoadjuvant treatment, 48 (70%) of the 69 patients underwent successful pancreatic resection with 47 (98%) being margin negative (RO). In 30 of the BLR patients who had arterial abutment or SMV occlusion, 19 (63%) were surgically resected and all had RO resections. The cumulative incidence of local failure at 1 and 2 years was 2% (95% CI 0–6%) and 9% (95% CI 0.6–17%) respectively. The median overall survival for all patients, patients undergoing resection, and patients without resection were 20, 26 and 11 months respectively. Sixteen (23%) of the 69 patients are alive without disease with a median follow-up of 47 months (36–60).ConclusionNeoadjuvant chemoXRT can facilitate a margin negative resection in patients with localized PCa.     

Second cancer risk after 3D-CRT,IMRT and VMAT for breast cancer

Purpose

Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED).

Materials and methods

Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk.

Results

Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively.

Conclusion

Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively.