Simple method of stereotactic radiotherapy without stereotactic body frame for extracranial tumors

Thirty-five patients with metastatic lung cancer(46 lesions) and twenty patients with primary lung cancer (21 lesions) have been treated with a simple method of stereotactic radiotherapy (SRT) without stereotactic body frame. Tumor size ranged from 1-4 cm in diameter. We used Vac-Lok cushion(Med-Tek) as a immobilization system. To be sure to include the respiratory movement of tumor to planning target volume(PTV), every patients were examined by fluoroscopy and radio-opaque catheters with the same length of tumor movement were attached on the anterior and lateral chest wall before CT simulation. A gold grain was implanted into a tumor that was invisible on fluoroscopy, as a radiomaker. Protocol of 60 Gy/8 fractions/2 weeks and 45 Gy/3 fractions/3-6 days were mainly used. The median follow-up period was 15 months for primary lung cancer and 19 months for metastatic lung cancer. Local control rates were 91% for metastatic lung cancer, 89% for primary lung cancer and 85% for T1, 2N0M0 cases. All patients developed mild pneumonitis or fibrosis about 4.5 months after SRT just in the treatment volume. Only three patients was symptomatic.     

立体定向调强放射治疗剂量验证结果分析

目的 研究测量数据插值、计划系统剂量计算网格及剂量评估阈值等因素对立体定向调强放射治疗患者计划的剂量验证结果的影响。方法 回顾性分析了50例立体定向放射治疗的患者放疗计划的剂量验证结果。剂量验证设备采用MatriXX及配套MultiCube固体水模。测量数据分别选择线性插值（1.00 mm）和不插值（7.62 mm）两种分辨率;计划系统剂量计算网格分别选择1.0、2.5和4.0 mm;剂量评估阈值分别选择10%、20%和30%,γ评估标准分别选择2%/2 mm、3%/2 mm和3%/3 mm,分析不同因素选择对平面剂量验证结果的影响。结果 测量数据插值选择线性插值和不插值,2%/2 mm标准下,γ平均通过率分别为（86.3±7.3）%和（93.7±5.5）%;3%/2 mm标准下,γ平均通过率分别为（94.1±4.4）%和（97.7±3.9）%;3%/3 mm标准下,γ平均通过率分别为（97.7 ±2.2）%和（99.1±1.7）%。相比1.0 mm的剂量计算网格,使用2.5 mm计算网格,3种标准下γ平均通过率分别降低3.8%、1.9%和0.8%（t=8.41、9.06、5.30,P<0.05）,4.0 mm分别降低6.5%、6.0%和3.5%（t=-13.76、-13.15、-9.80,P<0.05）,差异有统计学意义。相比剂量评估阈值为10%,当阈值设置为20%时,2%/2 mm、3%/2 mm和3%/3 mm标准下,γ平均通过率分别降低2.4%、1.0%和0.6%（t=-8.60、-5.86、-4.68,P<0.05）;当阈值设置为30%,3种标准下γ平均通过率分别降低4.0%、1.7%和0.9%（t=-9.45、-6.66、-5.06,P<0.05）,差异有统计学意义。结论 测量数据插值、剂量计算网格大小及剂量评估阈值对立体定向放射治疗患者计划剂量验证结果均有明显影响,因此在进行立体定向放射治疗患者计划剂量验证时需要考虑这些因素。     

Prognostic factors in stereotactic body radiotherapy of lung metastases

Purpose

The aim of this study was to evaluate prognostic factors in patients with lung metastases who undergo lung stereotactic body radiotherapy (SBRT).

Materials and methods

A total of 87 patients with 129 lung metastases who underwent SBRT between November 2004 and May 2012 were enrolled in this retrospective study. The patient collective consisted of 54 men (62.1%) and 33 women (37.9%); the median age was 65 years (range 36–88). The Karnofsky performance index was ≥70% (median 90%) for all cases, but one (60%). Adverse effects were categorized using the CTCAE 4.0 classification system. Retrospective analyses regarding patients’ characteristics, progression-free survival (PFS), overall survival (OS), disease-specific survival (DSS), and local tumor control rates (LTC) were performed.

Results

On univariate and multivariate analysis OS, DSS, and PFS were significantly (p?<?0.05) better for patients with ≤3 lung metastases; no extrathoracic metastases at the time of the SBRT; a gross tumor volume (GTV) <7.7?cm³ and patients that received a staging that included positron emission tomography with fluorine 18 fluorodeoxyglucose/computed tomography (FDG-PET/CT) imaging. Furthermore, a longer OS was observed if newly diagnosed metastases during follow-up were limited to the lung (median survival: 43.7 months versus 21.7 months; p?=?0.023).

Conclusion

The number and pattern of metastases, and the size of the target volume are strong predictors for the outcome of patients receiving SBRT of lung tumors. FDG-PET/CT should be part of pretherapeutic staging before SBRT.

     

立体定向放射治疗在妇科肿瘤中的应用进展

立体定向放射治疗（SBRT）是近年来兴起的放疗新技术,该技术的优点在于它能够在控制正常组织剂量的前提下提高肿瘤组织的剂量。SBRT在妇科肿瘤中的应用主要集中在盆腔复发灶、腹主动脉旁转移淋巴结、远处转移灶的局部治疗,可获得良好的局部控制,甚至一些患者有长期无病生存的可能。尽管SBRT有严格的剂量限制,但放疗后野内复发灶治疗后出现严重不良反应的概率较高。SBRT可以作为局部晚期宫颈癌体外放疗结束后,因某些因素而无法实施后装治疗的替代治疗。     

Rib fracture following stereotactic body radiotherapy: a potential pitfall

Although the incidence of rib fractures after conventional radiotherapy is generally low (<2%), rib fractures are a relatively common complication of stereotactic body radiotherapy. For malignancy adjacent to the chest wall, the incidence of rib fractures after stereotactic body radiotherapy is as high as 10%. Unrecognized bone fractures can mimic bone metastases on bone scintigraphy, can lead to extensive workup, and can even lead to consideration of unnecessary systemic chemotherapy, as treatment decisions can be based on imaging findings alone. Nuclear medicine physicians and diagnostic radiologists should always consider rib fracture in the differential diagnosis.     

立体定向放射治疗体部肿瘤(附96例随访分析)

目的:通过临床随访观察,确定用立体定向分次放射治疗(Fractionted Stereotactic Radiotherapy,FSRT)体部肿瘤的近期疗效。对象与方法:96例体部肿瘤患者,其中38例肺癌、12例肝癌、11例胰腺癌、6例纵隔恶性肿瘤、6例食管癌、5例胃癌、5例胆管癌、6例直肠癌、3例宫颈癌和卵巢癌、4例椎骨转移瘤,继确诊和/或手术后,均经x线立体定向分次放射治疗。全部病例中67例(70％)经术前经皮穿刺针吸活组织检查或术后病理组织学检查证实,其余病例由临床、CT和/或磁共振等影像资料证实。用体箱、负压袋固定患者后CT扫描定位,X线立体定向放射治疗计划系统设计并优化治疗计划,加速器旋转照射。部分病人结合常规放射治疗。结果:X线立体定向放射治疗后1～3周内,90例(近94％)表现出临床症状明显改善,而且在此期间未发现1例严重并发症或死亡。肺癌患者随访CT检查32例,其中29例于FSRT后1～6个月肿瘤消失,2例肿瘤体积缩小50％以上,只有1例肿瘤大小无变化,有效率近97％。FSRT对其他肿瘤也有明显疗效,不仅可使原发癌灶缩小或消失,而且可使有癌转移的淋巴结消失。结论:FSRT是一种安全、无痛苦的、且能保持器官原有形态、结构及功能的治疗体部肿瘤的方法,它不仅适合于早期肿瘤患者,而且尤其适合于那些年老体弱,不能耐受手术的或术后残     

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。     

Multi-fractionated stereotactic radiotherapy

Precision and accuracy of a patient's treatment are key advantages of single-fraction stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMS) and some small brain metastases. These advantages are equally valuable in fractionated treatment of the pituitary, brain metastases and brain boost fields. The need to implement the preciseness from stereotactic radiosurgery to fractionated treatments was recognized. Using our experience with single-fraction stereotactic radiosurgery as a model, we developed a multi-fractionated stereotactic radiotherapy technique that allows us to immobilize a patient daily and implement important existing devices such as the Brown-Roberts-Wells (BRW) angiographic localizer, CT scan localizer, and non-coplanar shaped field treatment planning. Development of this technique also allows us to achieve reproducible patient positioning based on immobilization techniques using polyurethane foam immobilization and heat moldable plastic technology without the necessity of the invasive technique of skull fixation. The development, implementation and dosimetry of this technique will be discussed in this paper.     

Dosimetric comparison of robotic- and LINAC-based treatment of spine stereotactic body radiotherapy

To determine which treatment technique and modality would offer better dosimetric results and be preferable for spinal stereotactic body therapy (SBRT) depending on the three different regions of the vertebrae. Linear accelerator (LINAC)- and CyberKnife (CK)-based treatment techniques were compared in terms of their dosimetric quality, treatment efficiency, and delivery accuracy. Thirty previously treated patients were included in this study. Intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques were used for LINAC-based treatment, whereas CK-based treatment plans were generated for two different collimator systems: fixed and multileaf collimator (MLC). The plans were compared based on spinal cord sparing, dose homogeneity, conformity index (CI), gradient index (GI), monitor unit (MU), and beam-on time. The percentage volumes of V2Gy, V5Gy (representing volume low of the dose spillage region), V10Gy, and V20Gy (representing the volume of the high-dose spillage region) of the healthy tissue were analyzed. The CI and GI of the VMAT plans were better than those of the IMRT plans. For spinal cord sparing, the VMAT and MLC-based CK (CK-MLC) techniques were superior. The percentage of low-dose spillage regions was the lowest for IMRT and fixed cone-based CK (CK-FIX) plans. The percentage of the high-dose spillage region was the lowest for the VMAT and CK-MLC plans. In terms of treatment efficiency, the VMAT and CK-MLC plans were superior to the IMRT and CK-FIX plans. The VMAT technique lowered the MU and beam-on time values. The plan delivery accuracy of the VMAT and CK-FIX plans was better than that of the IMRT plans. VMAT is the best option for LINAC-based spinal SBRT. For CK-based spinal SBRT, MLC-based plans are preferred. If the clinic has both treatment modalities and the patient can tolerate long treatment times, CK-MLC-based treatment should be chosen because of its superiority in sparing the spinal cord and sharp dose fall-off.     

立体定向放疗在非小细胞肺癌治疗中的应用

体部立体定向放疗（stereotactic body radiation therapy,SBRT）是指应用单次或少数多次给予靶区高剂量照射的治疗方式。和常规放疗相比,具有分割剂量大、精度高等特点。其在肺部肿瘤中的应用可归纳为以下3点：①对于因高龄或合并严重心肺等内科疾病不能手术或不愿接受手术的早期（T_1-2N₀M₀）非小细胞肺癌（non-small cell lung cancer,NSCLC）,SBRT已确立标准治疗的地位。②对于可手术的早期NSCLC,SBRT初步应用的结果并不逊于手术。③对于肺内孤立转移灶（1~3个）,在全身治疗的基础上给与SBRT已逐步被接受。本文对此作一综述。     

Influence of respiration on dose calculation in stereotactic body radiotherapy of the lung

Our purpose in this study was to evaluate the variation in calculated doses caused by respiration in stereotactic body radiotherapy (SBRT) of the lung. The study targeted ten patients who underwent SBRT for lung tumors. CT images were acquired during free breathing and in the inhalation and exhalation phases. We compared the CT image at inhalation with the image at exhalation so as to measure the change in lung volume, variation in the CT value, and displacement of the chest wall. The lung volume change was shown to be correlated with the maximum of the chest wall motion and with the variation in the CT value. A statistically significant difference was observed in the CT values between inhalation and exhalation (p < 0.05). The total dose variation at the isocenter was confined within ±2 %. However, the dose from individual beams can vary significantly when the chest wall moves more than 10 mm in natural breathing.     

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.     

再程立体定向放射治疗的应用

肿瘤经放射治疗或者多种方法联合治疗后,局部复发经常出现,但局部再程放疗仅适用于少数病人,因其会引起潜在的严重并发症,特别是对大体积的肿瘤进行再程放疗时。采用立体定向放射治疗(SBRT)对复发的椎体转移瘤、头颈部肿瘤、盆腔肿瘤进行再程放疗,不仅能够提高局部控制率并减轻症状,同时还能够减少正常组织不良反应。SBRT在临床上是一种安全有效的方法,建议将SBRT作为控制局部症状的重要治疗手段。     

立体定向放射治疗在结直肠癌肝肺寡转移中的应用进展

结直肠癌是全球范围内最常见的恶性肿瘤之一,远处转移是导致结直肠癌患者死亡的主要原因。不同于广泛性转移,寡转移是肿瘤转移过程中的一种中间状态,积极治疗预后较好。随着放疗技术的进步,立体定向放射治疗在肿瘤局部治疗中发挥着越来越大的作用。本文就结直肠癌肝肺寡转移立体定向放射治疗现状进行综述。     

立体定向放疗计划验证模体在脑转移瘤HyperArc技术中的应用研究

目的 探究StereoPhan(SP)模体与SRS MapCHECK(SMC)半导体矩阵用于脑转移瘤患者HyperArc(HA)计划剂量验证的可行性。方法 选取16例在北京协和医院接受HA放射治疗的脑转移瘤患者为研究对象,分别将电离室和SMC半导体矩阵插入SP模体,测量患者的HA验证计划的点剂量与平面剂量,并与治疗计划系统(TPS)计算数据对比,平面剂量的γ分析标准取2 mm/3%、2 mm/2%、1 mm/3%和1 mm/2%。结果 16例患者的点剂量平均偏差是1.33%±0.84%,平面剂量γ通过率在2 mm/3%、2 mm/2%的标准下依次为99.72%±0.46%、98.93%±1.32%,在 1 mm/3% 、1 mm/2%的标准下依次为98.85%±1.79%、97.13%±3.19%。结论 SP模体与SMC半导体矩阵适合用于开展脑转移瘤患者HA计划的剂量验证工作,在进行点剂量和平面剂量验证时,可以分别采用3%和1mm/2%的分析标准。     

肺癌立体定向放疗偏中心计划设计剂量学研究

目的研究不同程度的偏中心计划对肺癌立体定向放疗(SBRT)计划质量和执行准确度的影响, 为肺癌SBRT的临床计划设计提供参考。方法首先, 选取10例肺癌SBRT患者, 将计划等中心置于肿瘤质心位置, 设计等中心参考计划。将计划等中心置于偏离肿瘤质心1、3、5、8及10 cm位置, 设计偏中心计划, 共计60个, 分析这些偏中心计划相对于参考计划的剂量学差异。然后, 引入不同程度的位置误差(0～5 mm), 利用Octavius 4D高分辨率剂量验证系统, 测量这些计划的伽马通过率(GPR), 完成240次计划验证, 分析参考计划和偏中心计划的执行准确度对位置误差的鲁棒性。结果偏中心计划的剂量梯度指标略差于等中心计划, 差异无统计学意义(P>0.05)。随着偏中心距离增加, 正常肺平均剂量(MLD)和V20以及支气管Dmax略微有升高趋势。MLD在偏中心距离1、3和10 cm, 较等中心计划分别升高了0.8%、0.8%和1.9%, 差异具有统计学意义(z=-2.34～-1.99, P<0.05), V20在偏中心距离1、5和10 cm, 较等中心计划分别增加了2.0%、2.5...     

The use of RapidArc volumetric-modulated arc therapy to deliver stereotactic radiosurgery and stereotactic body radiotherapy to intracranial and extracranial targets

Twenty-three targets in 16 patients treated with stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) were analyzed in terms of dosimetric homogeneity, target conformity, organ-at-risk (OAR) sparing, monitor unit (MU) usage, and beam-on time per fraction using RapidArc volumetric-modulated arc therapy (VMAT) vs. multifield sliding-window intensity-modulated radiation therapy (IMRT). Patients underwent computed tomography simulation with site-specific immobilization. Magnetic resonance imaging fusion and optical tracking were incorporated as clinically indicated. Treatment planning was performed using Eclipse v8.6 to generate sliding-window IMRT and 1-arc and 2-arc RapidArc plans. Dosimetric parameters used for target analysis were RTOG conformity index (CI_RTOG), homogeneity index (HI_RTOG), inverse Paddick Conformity Index (PCI), D_mean and D5–D95. OAR sparing was analyzed in terms of D_max and D_mean. Treatment delivery was evaluated based on measured beam-on times delivered on a Varian Trilogy linear accelerator and recorded MU values. Dosimetric conformity, homogeneity, and OAR sparing were comparable between IMRT, 1-arc RapidArc and 2-arc RapidArc plans. Mean beam-on times ± SD for IMRT and 1-arc and 2-arc treatments were 10.5 ± 7.3, 2.6 ± 1.6, and 3.0 ± 1.1 minutes, respectively. Mean MUs were 3041, 1774, and 1676 for IMRT, 1-, and 2-arc plans, respectively. Although dosimetric conformity, homogeneity, and OAR sparing were similar between these techniques, SRS and SBRT fractions treated with RapidArc were delivered with substantially less beam-on time and fewer MUs than IMRT. The rapid delivery of SRS and SBRT with RapidArc improved workflow on the linac with these otherwise time-consuming treatments and limited the potential for intrafraction organ and patient motion, which can cause significant dosimetric errors. These clinically important advantages make image-guided RapidArc useful in the delivery of SRS and SBRT to intracranial and extracranial targets.     

Dynamic hybrid-phase computed tomography simulation in lung stereotactic body radiotherapy: A feasibility study

To assess the feasibility of dynamic hybrid-phase computed tomography (CT_DHP) simulation when patients undergo lung stereotactic body radiation therapy (SBRT). Eighteen non-small-cell lung-cancer patients were immobilised in a stereotactic body frame with abdominal compression. All underwent dynamic hybrid-phase CT scans that were compared with cone-beam CT (CBCT). We also determined the internal target volume (ITV) and evaluated the following four metrics: the “AND” function in the Boolean module of Eclipse, volume overlap (VO), Dice similarity coefficient (DSC), and dose-volume histogram. The average ITV values of 4DCT_DHP and 3D-CBCT were respectively 12.82±10.42 and 14.6±12.18 cm³ (n=72, p<0.001), and the average ITV value of AND was 11.7±10.1 cm³. The average planning target volume (PTV) of 4DCT_DHP and 3D-CBCT was 25.63±18.04 and 28.00±19.82 cm³ (n=72, p<0.001). The median AND difference between ITV and PTV was significant (p<0.01) and had a significantly linear distribution (R²=0.991 for ITV, R²=0.972 for PTV). The average VO of PTV was greater than that of ITV (0.81±0.096; 0.78±0.11). We also observed that the average DSC in PTV (0.83±0.066) was greater than that in ITV (0.81±0.084). The average results indicated that 97.9%±3.44 of ITVCBCT was covered by 95% of the prescribed dose. The average minimum, maximum and mean percentage doses of ITV_CBCT were 87.9%±9.46, 107.3%±1.57, and 101.3%±1.12, respectively. This paper has demonstrated that dynamic hybrid-phase CT simulation for patients undergoing lung SBRT and also published evaluation metrics in scientific analysis. Our approach also has the advantage of adequate margin and fewer phases in CT simulation.     

Positioning accuracy for lung stereotactic body radiotherapy patients determined by on-treatment cone-beam CT imaging

Stereotactic body radiotherapy for early stage non-small cell lung cancer is an emerging treatment option in the UK. Since relatively few high-dose ablative fractions are delivered to a small target volume, the consequences of a geometric miss are potentially severe. This paper presents the results of treatment delivery set-up data collected using Elekta Synergy (Elekta, Crawley, UK) cone-beam CT imaging for 17 patients immobilised using the Bodyfix system (Medical Intelligence, Schwabmuenchen, Germany). Images were acquired on the linear accelerator at initial patient treatment set-up, following any position correction adjustments, and post-treatment. These were matched to the localisation CT scan using the Elekta XVI software. In total, 71 fractions were analysed for patient set-up errors. The mean vector error at initial set-up was calculated as 5.3 ± 2.7 mm, which was significantly reduced to 1.4 ± 0.7 mm following image guided correction. Post-treatment the corresponding value was 2.1 ± 1.2 mm. The use of the Bodyfix abdominal compression plate on 5 patients to reduce the range of tumour excursion during respiration produced mean longitudinal set-up corrections of -4.4 ± 4.5 mm compared with -0.7 ± 2.6 mm without compression for the remaining 12 patients. The use of abdominal compression led to a greater variation in set-up errors and a shift in the mean value.