Dose variations caused by setup errors in intracranial stereotactic radiotherapy: A PRESAGE study

Stereotactic radiotherapy (SRT) requires tight margins around the tumor, thus producing a steep dose gradient between the tumor and the surrounding healthy tissue. Any setup errors might become clinically significant. To date, no study has been performed to evaluate the dosimetric variations caused by setup errors with a 3-dimensional dosimeter, the PRESAGE. This research aimed to evaluate the potential effect that setup errors have on the dose distribution of intracranial SRT. Computed tomography (CT) simulation of a CIRS radiosurgery head phantom was performed with 1.25-mm slice thickness. An ideal treatment plan was generated using Brainlab iPlan. A PRESAGE was made for every treatment with and without errors. A prescan using the optical CT scanner was carried out. Before treatment, the phantom was imaged using Brainlab ExacTrac. Actual radiotherapy treatments with and without errors were carried out with the Novalis treatment machine. Postscan was performed with an optical CT scanner to analyze the dose irradiation. The dose variation between treatments with and without errors was determined using a 3-dimensional gamma analysis. Errors are clinically insignificant when the passing ratio of the gamma analysis is 95% and above. Errors were clinically significant when the setup errors exceeded a 0.7-mm translation and a 0.5° rotation. The results showed that a 3-mm translation shift in the superior-inferior (SI), right-left (RL), and anterior-posterior (AP) directions and 2° couch rotation produced a passing ratio of 53.1%. Translational and rotational errors of 1.5 mm and 1°, respectively, generated a passing ratio of 62.2%. Translation shift of 0.7 mm in the directions of SI, RL, and AP and a 0.5° couch rotation produced a passing ratio of 96.2%. Preventing the occurrences of setup errors in intracranial SRT treatment is extremely important as errors greater than 0.7 mm and 0.5° alter the dose distribution. The geometrical displacements affect dose delivery to the tumor and the surrounding normal tissues.     

Dosimetric evaluation of MLC-based dynamic tumor tracking radiotherapy using digital phantom: Desired setup margin for tracking radiotherapy

The purpose of this study is to evaluate the dosimetric impact of the margin on the multileaf collimator-based dynamic tumor tracking plan. Furthermore, an equivalent setup margin (EM) of the tracking plan was determined according to the gated plan. A 4-dimensional extended cardiac-torso was used to create 9 digital phantom datasets of different tumor diameters (TDs) of 1, 3, and 5?cm and motion ranges (MRs) of 1, 2, and 3?cm. For each dataset, respiratory gating (30% to 70% phase) and tumor tracking treatment plans were prepared using 8-field 3-dimensional conformal radiation therapy by 4-dimensional dose calculation. The total lung V20 was calculated to evaluate the dosimetric impact for each case and to estimate the EM with the same impact on lung V20 obtained with the gating plan with a setup margin of 5?mm. The EMs for {TD?=?1?cm, MR?=?1?cm}, {TD?=?1?cm, MR?=?2?cm}, and {TD?=?1?cm, MR?=?3?cm} were estimated as 5.00, 4.16, and 4.24?mm, respectively. The EMs for {TD?=?5?cm, MR?=?1?cm}, {TD?=?5?cm, MR?=?2?cm}, and {TD?=?5?cm, MR?=?3?cm} were estimated as 4.24?mm, 6.35?mm, and 7.49?mm, respectively. This result showed that with a larger MR, the EM was found to be increased. In addition, with a larger TD, the EM became smaller. Our result showing the EMs provided the desired accuracy for multileaf collimator-based dynamic tumor tracking radiotherapy.     

ExacTrac X-射线图像引导系统在体部肿瘤放疗中的摆位误差和残余误差分析

目的 通过对体部肿瘤放射治疗的ExacTrac X-射线图像的回顾性分析,了解患者群体的摆位误差和残余误差分布情况,研究六维放射治疗床修正摆位误差的必要性和有效性。方法 通过配准数字重建图像（DRR）和ExacTrac图像引导系统拍摄的正交kV级验证像的骨性解剖结构,计算患者3个方向的平移误差和旋转误差以及对应的残余误差。结果 平移摆位误差为x（左右方向）：（2.27±2.02）mm,y（头脚方向）：（4.49±2.52）mm,z（腹背方向）：（2.27±1.37）mm;旋转摆位误差为Rx（矢状面）：（1.02±0.73）°,Ry（横断面）：（0.67±0.68）°,Rz（冠状面）：（0.76±0.84）°。残余平移误差x（r）：（0.27±0.48）mm,y（r）：（0.37±0.45）mm,z（r）：（0.22±0.30）mm;残余旋转误差为Rx（r）：（0.17±0.33）°,Ry（r）：（0.14±0.34）°,Rz（r）：（0.16±0.28）°。结论 对于体部放射治疗的患者,旋转误差和平移误差是同时存在的,不仅需要校准平移误差,旋转误差也不容忽视。ExacTrac X-射线图像引导系统能够有效纠正六自由度的摆位误差,并保证残余误差在较小的范围内,保证了体部肿瘤放疗的治疗精度。     

锥形束CT测量胸段食管癌调强放疗摆位误差对剂量学的影响

目的 应用千伏级锥形束CT(kV-CBCT)测量胸段食管癌调强放疗的摆位误差,探讨摆位误差对肿瘤靶体积和周围正常组织受照剂量的影响.方法 21例胸段食管癌患者经图像引导调强放疗,共获得173组CBCT摆位误差数据,利用这些数据在三维治疗计划系统中模拟患者的实际治疗过程,分析摆位误差对肿瘤靶区及周围正常组织受照剂量的影响.结果 21例患者左右、头脚、前后方向的摆位误差分别是(2.73 ±1.85)、(3.19±2.71)和(2.35±1.71)mm.摆位误差对患者GTV的剂量学影响不明显,但误差却使患者95％ PTV( D95％)接受的剂量与标准计划相比降低3.38 Gy,PTV最小剂量(Dmin)和平均剂量(Dmean)分别下降9.83和0.65 Gy,摆位误差的修正提高了计划靶区的适形度和剂量均匀性,标准计划相应值分别为(0.74±0.10)和(1.07±0.02),模拟计划相应值分别为(0.69±0.08)和(1.13±0.07),差异均有统计学意义(t=3.43和-3.91,P＜0.05);摆位误差对脊髓的最大剂量(Dmax)、双肺和心脏等周围正常组织受照剂量影响,差异无统计学意义(P＞0.05),模拟计划中脊髓的最大剂量均值为(42.20±4.97)Gy,标准计划为(41.37±2.75) Gy,摆位误差使部分患者脊髓最大剂量超过45 Gy,其中1例最大值达到52.8 Gy.结论 kV-CBCT图像引导胸段食管癌调强放疗可减小患者的摆位误差,提高PTV的受照剂量和治疗精度,摆位误差对双肺、脊髓和心脏受照剂量未见明显改变.     

有无均整器模式下脊柱转移瘤立体定向放疗计划的剂量学比较

目的 比较 6 MV X射线无均整器模式(FFF)和均整器模式(FF)下,脊柱转移瘤立体定向放疗(SBRT)计划的剂量学差异。方法 选取9例入组患者共12处脊柱转移灶分别设计FFF-SBRT和FF-SBRT计划,比较两组计划的靶区、危及器官和正常组织剂量体积直方图(DVH)、靶区适形度(CI)、机器跳数和治疗时间的差别。结果 两种模式下的计划均能满足临床治疗需要。靶区、危及器官、正常组织剂量分布相似。FFF-SBRT计划的机器跳数明显高于FF-SBRT计划(t=-5.20,P<0.01),实际治疗时间相当于FF-SBRT计划的1/2(t=17.27,P<0.01)。结论 两种模式均能满足临床治疗需求,FFF-SBRT计划的治疗时间更短,效率更高。临床试验注册中国临床试验注册中心,ChiCTR-TRC-14004281。     

肾细胞癌的立体定向体部放射治疗策略及进展

肾细胞癌(RCC)是泌尿生殖系统中侵袭性最高的恶性肿瘤之一,预后不佳,尤其是发生RCC转移的患者。传统观点一般认为肾细胞癌对放疗不敏感。立体定向体部放射治疗(SBRT)与常规放疗相比,具有高精准度、较高照射剂量、对周围组织损伤小等特点。近年来,SBRT在原发性及转移性RCC治疗中均展现了确切的疗效。SBRT联合靶向治疗以及免疫治疗等联合方案可以提高原发和晚期转移RCC患者的肿瘤局部控制率,且不良反应较小。本文就SBRT 联合靶向治疗以及免疫治疗的策略和进展等方面进行综述。     

射波刀治疗小肝癌前瞻性临床研究初步结果

目的 探讨射波刀-立体定向放疗技术治疗小肝癌的安全性和有效性。方法 前瞻性分析本院2014年6月至2016年12月应用立体定向放疗技术治疗33例小肝癌的患者资料,治疗后每3个月复查,采用修改后实体肿瘤疗效评价标准（mRECIST）进行疗效评价,采用常见不良反应事件评价标准（CTCAE）4.0分级标准评价治疗反应,采用Kaplan-Meier法计算生存率和局部控制（CR+PR+SD）率,并绘制生存曲线。结果 平均随访19.3（2.3~30.8）个月。截止随访日期,共有33个病例含33个靶点纳入研究。其中18个病灶（54.5%）完全缓解,7个病灶（21.2%）部分缓解,5个病灶（15.2%）稳定,3个（9.1%）进展。总有效（CR+PR）率为75.8%,局部控制率为90.9%。1年局部控制率为100%,2年局部控制率为83.6%,中位疾病无进展生存期（DPFS）为15.0个月。未照射肝脏体积≥ 1 000 ml、治疗前甲胎蛋白（AFP）<100 ng/ml、治疗后CTCAE分级≤ 1级均有助于延长生存期。V₅与2级及以上不良反应相关（P=0.015）。治疗后乏力、纳差、恶心、呕吐等胃肠道反应和肝损伤主要为1、2级不良反应,1例出现3级肝功能损伤在治疗半年后缓解,1例出现4级肝不良反应在治疗后1年治愈。结论 射波刀治疗小肝癌不良反应可耐受,局部控制效果好。     

Assessment of treatment response after lung stereotactic body radiotherapy using diffusion weighted magnetic resonance imaging and positron emission tomography: A pilot study

Background and purposeThere is no early predictor of treatment response after lung stereotactic body radiotherapy (SBRT). We conducted this pilot study to evaluate whether serial diffusion weighted magnetic resonance imaging (DW-MRI) or positron emission tomography (PET) could predict response after SBRT.Material and methodsEarly stage non-small cell lung cancer patients who received SBRT were eligible. DW-MRI and PET were undertaken pretreatment and every 3 months after SBRT in the first year. Patients with <1 year of follow-up were excluded from the analysis. The apparent diffusion coefficient (ADC) value and maximum standardized uptake value (SUV_max) of tumors were measured and compared between groups with or without local recurrence (LR).ResultsFifteen patients were enrolled and the data of 14 patients were analyzed. The median ADC value was significantly lower in patients with LR (n = 3) than in those without LR (n = 11) at 3 and 6 months (1.11 vs. 1.54 and 0.98 vs. 1.69 [×10⁻³ mm²/s]; p = 0.039 and 0.012, respectively) while there was no significant difference pretreatment and at 9 and 12 months after treatment. No significant difference was observed in the SUV_max at any time point.ConclusionsDW-MRI could be an early predictor of treatment response after lung SBRT.     

Prediction of clinical outcome after stereotactic body radiotherapy for non-small cell lung cancer using diffusion-weighted MRI and F-FDG PET

Purpose/objectives

To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for predicting disease progression (DP) among patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiotherapy (SBRT).

Materials/methods

Fifteen patients with histologically confirmed stage I NSCLC who underwent pre-treatment DW-MRI and PET and were treated with SBRT were enrolled. The mean apparent diffusion coefficient (ADC) value and maximum standardised uptake value (SUV_max) were measured at the target lesion and evaluated for correlations with DP.

Results

The median pre-treatment ADC value was 1.04 × 10⁻³ (range 0.83–1.29 × 10⁻³) mm²/s, and the median pre-treatment SUV_max was 9.9 (range 1.6–30). There was no correlation between the ADC value and SUV_max. The group with the lower ADC value (≤1.05 × 10⁻³ mm²/s) and that with a higher SUV_max (≥7.9) tended to have poor DP, but neither trend was statistically significant (p = 0.09 and 0.32, respectively). The combination of the ADC value and SUV_max was a statistically significant predictor of DP (p = 0.036).

Conclusion

A low ADC value on pre-treatment DW-MRI and a high SUV_max may be associated with poor DP in NSCLC patients treated with SBRT. Using both values in combination was a better predictor.     

胸腔镜肺叶切除术与立体定向放疗治疗早期非小细胞肺癌的疗效比较

目的 比较胸腔镜（VATS）肺叶切除术与立体定向放疗（SBRT）治疗早期非小细胞肺癌（NSCLC）患者的疗效。方法 回顾性分析了2012年1月至2016年12月在浙江省肿瘤医院接受VATS肺叶切除术或SBRT的早期NSCLC患者。根据年龄、性别、卡氏评分（KPS）、查尔森合并症指数（CCI）、肺功能和肿瘤直径对两种治疗患者进行倾向评分匹配（PSM）。对两组符合要求的病例总生存率（OS）、癌症特异性生存率（CSS）、局部控制率（LRC）和无病生存率（DFS）进行对比分析。结果 共纳入567例符合要求病例,其中VATS肺叶切除术458例,SBRT 109例。经倾向评分匹配后,每组分别纳入52例患者。中位随访时间44个月。手术组3年和5年的总生存率分别为94.2%和91.6%,SBRT组分别为88.6%和79.9%（P=0.097）。手术组和SBRT组的5年CSS差异无统计学意义（91.6% vs. 83.7%,P=0.270）。两组3年和5年期LRC相当（94.0%和85.9% vs.93.5%和93.5%,P=0.621）。两队列间5年DFS的差异无统计学意义（80.5% vs.79.0%,P=0.624）。手术组中,有5例患者（10%）出现≥ 3级治疗不良反应。1例患者术后30 d内因严重肺部感染导致的败血症死亡。SBRT组中,1例患者发生3级放射性肺炎,无4级或5级治疗相关不良反应。结论 SBRT或可作为代替VATS肺叶切除术治疗Ⅰ~Ⅱ期非小细胞肺癌的一种选择,但尚需进行随机试验进一步评估。     

Circumferential or sectored beam arrangements for stereotactic body radiation therapy (SBRT) of primary lung tumors: Effect on target and normal-structure dose-volume metrics

To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non–small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations. The prescribed dose (PD) was 60 Gy in 5 fractions to 95% of the planning target volume (PTV) (maximum PTV dose ~ 150% PD) for a 6-MV photon beam. Plan conformality, R₅₀ (ratio of volume circumscribed by the 50% isodose line and the PTV), and D_2 cm (D_max at a distance ≥2 cm beyond the PTV) were evaluated. For lungs, mean doses (mean lung dose [MLD]) and percent V₃₀/V₂₀/V₁₀/V₅ Gy were assessed. Spinal cord and esophagus D_max and D₅/D₅₀ were computed. Chest wall (CW) D_max and absolute V₃₀/V₂₀/V₁₀/V_5 Gy were reported. Sectored SBRT planning resulted in significant decrease in contralateral MLD and V₁₀/V_5 Gy, as well as contralateral CW D_max and V₁₀/V_5 Gy (all p < 0.001). Nominal reductions of D_max and D₅/D₅₀ for the spinal cord with sectored planning did not reach statistical significance for static-gantry IMRT, although VMAT metrics did show a statistically significant decrease (all p < 0.001). The respective measures for esophageal doses were significantly lower with sectored planning (p < 0.001). Despite comparable dose conformality, irrespective of planning configuration, R₅₀ significantly improved with IMRT-s/VMAT-c (p < 0.001/p = 0.008), whereas D_2 cm significantly improved with VMAT-c (p < 0.001). Plan delivery efficiency improved with sectored technique (p < 0.001); mean monitor unit (MU)/cGy of PD decreased from 5.8 ± 1.9 vs 5.3 ± 1.7 (IMRT) and 2.7 ± 0.4 vs 2.4 ± 0.3 (VMAT). The sectored configuration achieves unambiguous dosimetric advantages over circumferential arrangement in terms of esophageal, contralateral CW, and contralateral lung sparing, in addition to being more efficient at delivery.     

Dosimetric comparison of vaginal vault brachytherapy vs applicator-guided stereotactic body radiotherapy with volumetric modulated arc therapy and helical tomotherapy for endometrium cancer patients

We performed this dosimetric study to compare a nonstandard volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) techniques with high-dose rate (HDR) brachytherapy (BRT) plan of vaginal vault in patients with postoperative endometrial cancer (EC). Twelve postoperative patients with early stage EC were included in this study. Three plans were performed for each patient; dosimetric and radiobiological comparisons were made using dose-volume histograms and equivalent dose for determining the planning target volume (PTV) coverages in brachytherapy and external beam radiotherapy, and organs-at-risk (OARs) doses between three different delivery techniques. All the plans achieved adequate dose coverage for PTV; however, the VMAT plan yielded better dose conformity, and the HT plan showed better homogeneity for target volume. With respect to the OARs, the bladder D_2cc was significantly lower in the BRT plan than in the VMAT and HT plans, with the highest bladder D_2cc value being observed in the HT plan. However, no difference was observed in the rectum D_2cc of the three plans. Other major advantages of the BRT plan over the VMAT and HT plans were the relatively lower body integral doses and femoral head doses as well as the fact that the integral doses were significantly lower in the BRT plan than in the VMAT and HT plans. This is the first dosimetric comparison of vaginal vault treatment for EC with BRT, VMAT, and HT plans. Our analyses showed the feasibility of stereotactic body radiotherapy technique as an alternative to HDR-BRT for postoperative management of EC patients.     

局部晚期非小细胞肺癌同步加量调强放疗的回顾性分析

目的 分析采用同步加量调强放疗(SIB-IMRT)技术治疗局部晚期非小细胞肺癌(NSCLC)的疗效及安全性.方法 回顾分析2008年1月至2011年6月在我院胸部放疗科行SIB-IMRT治疗的局部晚期NSCLC 78例,其中,ⅢA期45例,ⅢB期33例.处方剂量为PTV 50.4 ～64.0 Gy/28 ～33次,单次剂量为1.8～2.1 Gy;IGTV为60.0 ～ 74.3 Gy/28 ～ 33次,单次剂量为2.0～2.5 Gy.主要观察指标为总有效率(ORR)、局部控制率(LCR)、总生存率(OS)、无疾病进展生存率(PFS)及3级及以上食管和肺损伤.结果 78例患者均按计划完成根治性放疗,IGTV剂量≥60 Gy.67例(85.9％)患者接受以顺铂或卡铂为基础的第三代细胞毒药物两药联合方案化疗,其中17例(21.8％)为同步放化疗,50例(64.1％)为序贯放化疗.全组ORR为69.2％,其中CR 11例(14.1％),PR 43例(55.1％),SD 22例(28.2％),PD 2例(2.6％).截至2012年10月,失访6例,随访率92.3％.72例可随访患者中已死亡50例,22例存活.1、2、3年局部控制率分别为88.4％、54.7％、28.6％,中位PFS为15.3个月(2.3 ～46.8个月),中位OS为27.3个月(5.8 ～49.3个月).1、2、3年无进展生存率分别为50.7％、27.6％、21.1％;1、2、3年总生存率分别为87.5％、56.6％、30.3％.在同步放化疗与非同步放化疗亚组中,中位OS分别为32.8个月和24.1个月,1、2、3年总生存率分别为94.7％、73.7％、47.3％和83.0％、50.5％、23.9％(x2=3.946,P＜0.05).全组共发生急性放射性食管损伤59例(75.6％),治疗相关性肺损伤(TRP)21例(26.9％),其中3级及以上放射性食管损伤19例(24.4％),3级及以上放射性肺损伤9例(11.5％).随访1年后,2例(2.6％)出现晚期3级肺损伤,食管无3级及以上晚期不良反应.结论 SIB-IMRT照射技术治疗局部晚期NSCLC疗效确切,安全性良好,值得临床进一步开展大样本前瞻性随机对照研究.     

Radiation injury of the lung after stereotactic body radiation therapy (SBRT) for lung cancer: A timeline and pattern of CT changes

Stereotactic body radiation therapy (SBRT) is a new radiotherapy treatment method that has been applied to the treatment of Stage I lung cancers in medically inoperable patients, with excellent clinical results. SBRT allows the delivery of a very high radiation dose to the target volume, while minimizing the dose to the adjacent normal tissues. As a consequence, CT findings after SBRT have different appearance, geographic extent and progression timeline compared to those following conventional radiation therapy for lung cancer. In particular, SBRT-induced changes are limited to the “shell” of normal tissue outside the tumor and have a complex shape. When SBRT-induced CT changes have a consolidation/mass-like appearance, the differentiation from tumor recurrence can be very difficult. An understanding of SBRT technique as it relates to the development of SBRT-induced lung injury and familiarity with the full spectrum of CT manifestations are important to facilitate diagnosis and management of lung cancer patients treated with this newly emerging radiotherapy method.     

Efficacy and safety of CT-guided 125I seed implantation as a salvage treatment for locally recurrent head and neck soft tissue sarcoma after surgery and external beam radiotherapy: A 12-year study at a single institution

ObjectivesThe objective of this study was to evaluate the efficacy and safety of CT-guided radioactive ¹²⁵I seed implantation as a salvage treatment for locally recurrent head and neck soft tissue sarcoma (HNSTS) after surgery and external beam radiotherapy.Methods and MaterialsFrom December 2006 to February 2018, 25 patients with locally recurrent HNSTS after surgery and external beam radiotherapy were enrolled. All the patients successfully underwent CT-guided ¹²⁵I seed implantation. The primary end points included the objective response rate (ORR) and local progression-free survival (LPFS). The secondary end points were survival (OS) and safety profiles.ResultsAfter ¹²⁵I seed implantation, the ORR was 76.0%. The 1-, 3-, and 5-year LPFS rates were 65.6%, 34.4%, and 22.9%, respectively, with the median LPFS of 16.0 months. The 1-, 3-, and 5-year OS rates were 70.8%, 46.6%, and 34.0%, respectively, with the median OS of 28.0 months. Furthermore, univariate analyses showed that the recurrent T stage and histological grade were prognostic factors of LPFS, whereas only the histological grade was a predictor of OS. The major adverse events were skin/mucosal toxicities, which were generally of lower grade (≤Grade 2) and were well tolerated.ConclusionsRadioactive ¹²⁵I seed implantation could be an effective and safe alternative treatment for locally recurrent HNSTS after failure of surgery and radiotherapy. Recurrent T stage and histological grade were the main factors influencing the efficacy.