食管癌患者放射治疗中照射体积和时间与外周血淋巴细胞绝对值的相关性研究

摘要 目的：探究照射体积和时间与食管癌患者外周血淋巴细胞绝对值的相关性。方法：本研究方案将纳入2019年1月~2019年12月蚌埠医学院第一附属医院放疗科收治的放疗或同步放化疗食管癌患者84例,其中单独放疗患者24例,同步放化疗患者60例,采用血液细胞分析仪测定患者放疗期间每周复查外周血白细胞（WBC）、中性粒细胞（N）、淋巴细胞（L）、血红蛋白（HB）及血小板（PLT）计数等指标。Pearson相关性分析照射时间、剂量及体积与外周血指标之间的相关性。结果：食管癌放疗患者,包括同步放化疗及单纯放疗亚组,在治疗1-6周,照射时间与外周血指标均无相关性（P>0.05）。但在放疗第5-6周,患者放疗剂量与WBC、N、L、HB呈负相关（P<0.05）,同步放化疗亚组患者照射剂量与WBC、N、L、HB呈负相关（P<0.05）。在治疗1-4周,不同照射剂量下各梯度照射剂量对应照射体积与外周血指标均无相关性（P>0.05）。但在第5-6周时,患者不同梯度照射剂量下各照射体积与WBC、N呈负相关（P<0.05）,同时在20Gy-60Gy照射剂量,尤其20Gy和30Gy照射剂量下照射体积与L呈负相关（P<0.05）。同步放化疗亚组患者不同照射剂量下各照射体积与WBC、N呈负相关（P<0.05）,同时在20Gy-60Gy照射剂量下照射体积与L呈负相关（P<0.05）,而且在60Gy照射剂量下照射体积与HB呈负相关（P<0.05）。结论：放疗患者特别是同步放化疗亚组患者照射体积、照射剂量与食管癌患者外周血淋巴细胞计数成负相关,基线淋巴细胞与食管癌患者外周血淋巴细胞计数成正相关,而照射时间与食管癌患者外周血淋巴细胞计数无相关性。     

食管癌组织CDC25B的表达与临床病理参数及放疗敏感性的关系研究

摘要 目的：探讨食管癌组织中细胞分裂周期蛋白25B （CDC25B）表达特点,分析其与食管癌临床病理参数和放疗敏感性的关系。方法：选择2015年1月至2018年1月我院收集的60例食管癌患者癌组织、癌旁组织的石蜡标本,采用免疫组化法检测食管癌组织和癌旁组织中CDC25B表达,分析CDC25B表达与食管癌临床病理参数的关系。所有患者均接受放疗或放化疗治疗,观察不同疗效患者CDC25B表达差异,分析CDC25B对食管癌放疗敏感性的预测价值。结果：食管癌组织中CDC25B阳性表达率高于癌旁组织（P<0.05）。CDC25B阳性表达与食管癌分化程度、TNM分期、淋巴结转移有关（P<0.05）。放疗敏感组CDC25B阳性表达率低于放疗抗拒组（P<0.05）。CDC25B预测食管癌放疗敏感性的曲线下面积（AUC）为0.718（95%CI：0.580~0.856）,灵敏度为60%,特异度为68%。结论：食管癌患者CDC25B表达上调,CDC25B阳性表达与食管癌分化程度、TNM分期、淋巴结转移恶性侵袭行为有关,CDC25B可作为食管癌放疗敏感性评估的辅助指标。     

应用KV-CBCT分析鼻咽癌调强放射治疗的摆位误差

目的:应用KV-CBCT分析鼻咽癌调强放射治疗时的摆位误差,为鼻咽癌调强放射治疗计划设计时CTV外扩PTV边界的大小提供参考。方法:选取30例IMRT的鼻咽癌患者,治疗过程中每周一次应用KV-CBCT采集患者治疗前的CT图像,将所得图像与定位CT图像进行匹配,分别测定X、Y、Z轴三个方向的摆位误差。结果:30例患者共拍摄168次KV-CBCT,获得168组摆位误差结果,群体摆位误差分别为X轴-0.15±1.43 mm,Y轴0.20±1.58 mm,Z轴-0.21±1.65 mm;根据Van Herk公式计算得到各方向的CTV-PTV外放边界值X、Y、Z轴分别为3.1 mm、3.3 mm和3.4 mm。结论:应用KV-CBCT影像系统可实时测量摆位误差并在线进行纠正,减小摆位误差,为CTV-PTV外放边界提供参考。     

调强放射治疗对食管癌患者外周血Treg细胞、血清肿瘤标志物及应激激素水平的影响

摘要 目的：观察调强放射（IMRT）治疗对食管癌患者外周血调节性T细胞（Treg）细胞、血清肿瘤标志物及应激激素水平的影响。方法：选取2019年9月~2021年3月期间自贡市第一人民医院收治的食管癌患者80例,按照随机数字表法将患者分为对照组（普通适形放疗,40例）和研究组（IMRT治疗,40例）。对比两组临床总有效率、外周血Treg细胞比例、血清肿瘤标志物及应激激素水平,观察放疗期间出现的不良反应。结果：研究组的临床总有效率高于对照组（P<0.05）。两组放疗后癌胚抗原（CEA）、糖类抗原 199（CA199）、细胞角蛋白19片段（CYFRA21-1）均下降,且研究组低于对照组（P<0.05）。两组放疗后生长激素（GH）、催乳素（PRL）均下降,且研究组低于对照组（P<0.05）。两组放疗后外周血Treg细胞占CD4⁺T细胞的比例下降,且研究组较对照组低（P<0.05）。不良反应发生率两组组间对比,未见显著性差异（P>0.05）。结论：食管癌患者采用IMRT治疗,可有效降低外周血Treg细胞比例、血清肿瘤标志物及应激激素水平,疗效较好,具有一定的临床应用价值。     

食管癌调强放射治疗的初期疗效及急性放射性肺损伤的影响因素分析

摘要 目的：探讨食管癌调强放射治疗的初期疗效及急性放射性肺损伤的影响因素。方法：选取2015年1月-2019年1月在我院进行调强放射治疗的食管癌患者322例,评价食管癌调强放射治疗后一个月的疗效;按照是否发生急性放射性肺损伤（RILI）分为急性RILI组和无急性RILI组,采用多因素Logistic回归分析分析急性RILI的影响因素。结果：调强放射治疗的完全缓解和部分缓解的患者占98.45%;322例患者中90例（27.95%）出现急性RILI,其中36例（11.18%）出现2级及以上的急性RILI;急性RILI组和无急性RILI组间卡氏（KPS）评分、淋巴结转移、基础肺疾病、V5、V10、V20、V30和全肺平均剂量（MLD）差异有统计学意义（P<0.05）;多因素Logistic回归分析显示,KPS评分<80分、有淋巴结转移、有基础肺疾病,V5≥60%、V10≥40%、V20≥28%、V30≥20%和MLD≥10Gy是食管癌调强放射治疗后急性放射性肺损伤的危险因素（P<0.05）。结论：使用调强放射治疗技术治疗食管癌的初期疗效较好,治疗过程中,应充分考虑病患的临床特征,优化放疗方案和靶区,减少急性RILI的发生,提高食管癌患者放疗后的生存质量。     

三维适形调强放疗联合榄香烯注射液对食管癌患者血清肿瘤标志物和T淋巴细胞亚群的影响

摘要 目的：探讨三维适形调强放疗联合榄香烯注射液对食管癌患者血清肿瘤标志物和T淋巴细胞亚群的影响。方法：选取我院于2016年8月到2019年12月期间接诊的食管癌患者60例,根据随机数字表法分为对照组（n=30）和研究组（n=30）,对照组患者予以三维适形调强放疗,研究组在对照组基础上联合榄香烯注射液治疗,比较两组患者疗效、生存质量、血清肿瘤标志物、T淋巴细胞亚群以及不良反应。结果：研究组患者治疗6周后的临床总有效率为63.33%（19/30）,高于对照组患者的36.67%（11/30）（P<0.05）。两组治疗6周后血清癌胚抗原（CEA）、糖类抗原199（CA199）水平均较治疗前降低,且研究组低于对照组（P<0.05）。两组患者治疗6周后CD3⁺、CD4⁺、CD4⁺/CD8⁺水平均下降,但研究组高于对照组（P<0.05）,CD8⁺水平均升高,但研究组低于对照组（P<0.05）。两组治疗6周后卡劳夫斯基（KPS）评分均较治疗前升高,且研究组高于对照组（P<0.05）。两组不良反应发生率对比未见统计学差异（P>0.05）。结论：三维适形调强放疗联合榄香烯注射液治疗食管癌患者,疗效较好,可有效阻止疾病进展,改善患者生存质量和降低血清肿瘤标志物水平,减轻机体免疫抑制,且不增加不良反应发生率。     

头颈部恶性肿瘤患者放疗后吞咽困难的危险因素分析及吞咽功能训练的临床应用价值

摘要 目的：分析头颈部恶性肿瘤（HNC）患者放疗后吞咽困难的危险因素,并观察吞咽功能训练的临床应用效果。方法：选择2020年4月~2022年5月期间在华中科技大学同济医学院附属同济医院接受放疗的HNC患者150例。采用自制调查量表获取患者的一般资料,采用单因素和多因素Logistic分析HNC患者放疗后吞咽困难的危险因素,并观察吞咽功能训练的临床应用效果。结果：本研究中150例HNC患者,放疗后出现吞咽困难的有93例,吞咽困难发生率为62.00%。根据放疗后是否出现吞咽困难将患者分为无吞咽困难组（n=57）和吞咽困难组（n=93）。单因素分析显示,HNC患者放疗后吞咽困难与文化程度、婚姻状况、高血压、糖尿病、高脂血症、居住地、体质量指数无关（P>0.05）,而与年龄、性别、吸烟史、饮酒史、肿瘤分期、肿瘤位置、累积放疗剂量有关（P<0.05）。多因素Logistic回归分析,结果显示：年龄偏大、男性、吸烟史、饮酒史、肿瘤分期为III期、肿瘤位置为颈部肿瘤、累积放疗剂量偏高是HNC患者放疗后吞咽困难的危险因素（P<0.05）。HNC患者干预1个月后、干预2个月后安德森吞咽困难量表（MDADI）评分较干预前下降,功能性经口摄食量表（FOIS）评分较干预前升高（P<0.05）。结论：HNC患者放疗后吞咽困难的发生率较高,年龄、性别、吸烟史、饮酒史、肿瘤分期、肿瘤位置、累积放疗剂量等均是其影响因素。HNC患者放疗期间给予吞咽功能训练,可有效改善患者的吞咽状况。     

食管癌三维适形放疗和常规放疗比较

目的对比研究三维适形放疗（3DCRT）和常规模拟机定位放疗两种不同方法在食管癌放射治疗中的优缺点。方法 20例食管癌患者采用3DCRT方法进行治疗,应用同一治疗计划系统,制定适形放疗和常规模拟机定位放疗方案。结果与常规模拟定位机定位放疗相比,食管癌照射中3DCRT有最好的剂量分布,既可明显提高靶区的剂量,同时能较好地保护正常组织。结论食管癌的适形放疗技术能降低正常组织的放射损伤和并发症,提高放疗治疗的适形度,改善靶区的剂量分布。     

立体定向放疗联合内分泌治疗对转移性激素敏感性前列腺癌患者免疫功能和生活质量的影响

摘要 目的：探讨立体定向放疗（SBRT）联合内分泌治疗对转移性激素敏感性前列腺癌患者生活质量、免疫功能的影响。方法：选取我院2015年2月~2017年2月期间收治的转移性激素敏感性前列腺癌患者100例,根据信封抽签法将患者分为对照组（50例）和放疗组（50例）,对照组给予内分泌治疗,放疗组在对照组的基础上联合SBRT治疗。对比两组前列腺特异性抗原（PSA）进展时间、PSA缓解率、治疗期间不良反应状况、3年生存率、免疫功能（CD3⁺、CD4⁺、CD8⁺、CD4⁺/CD8⁺）和扩展性前列腺癌复合指数量表（EPIC）各项评分。结果：随访3年,对照组有2例失访、放疗组有3例失访,放疗组的PSA进展时间长于对照组（P<0.05）,放疗组的3年生存率高于对照组（P<0.05）。治疗后,两组CD3⁺、CD4⁺/CD8⁺、CD4⁺均下降,但放疗组较对照组升高（P<0.05）,两组治疗后CD8⁺均升高,但放疗组较对照组降低（P<0.05）。治疗后6个月,放疗组性功能、激素功能、泌尿功能、肠道功能领域评分均高于对照组（P<0.05）。两组不良反应总发生率、PSA缓解率组间对比无差异（P>0.05）。结论：SBRT联合内分泌治疗转移性激素敏感性前列腺癌患者,可延长患者PSA进展时间,减轻免疫抑制,提高患者生活质量,同时还可改善患者的预后,患者耐受性良好。     

不同剂量右美托咪定联合丙泊酚全凭静脉麻醉对食管癌根治术患者炎症因子、氧化应激和术后谵妄的影响

摘要 目的：探讨不同剂量右美托咪定联合丙泊酚全凭静脉麻醉对食管癌根治术患者炎症因子、氧化应激和术后谵妄的影响。方法：选择南京医科大学附属宿迁第一人民医院2019年1月~2021年12月期间120例择期行食管癌根治术的患者。按照随机数字表法将患者分为对照组（41例,丙泊酚全凭静脉麻醉）、低剂量组（40例,对照组基础上联合0.50 μg/kg右美托咪定麻醉）、高剂量组（39例,对照组基础上联合1.00 μg/kg右美托咪定麻醉）。对比三组神经损伤指标、炎症因子、氧化应激相关指标,同时记录三组不良反应发生率和术后谵妄发生率。结果：高剂量组、低剂量组T2~T4时间点S100β蛋白、神经元特异性烯醇化酶（NSE）低于对照组,且高剂量组低于低剂量组（P<0.05）。高剂量组、低剂量组T2~T4时间点肿瘤坏死因子-α（TNF-α）、C反应蛋白（CRP）、白介素-6（IL-6）、白介素-1β（IL-1β）低于对照组,且高剂量组低于低剂量组（P<0.05）。高剂量组、低剂量组T2~T4时间点超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）高于对照组,且高剂量组高于低剂量组（P<0.05）。高剂量组、低剂量组T2~T4时间点丙二醛（MDA）低于对照组,且高剂量组低于低剂量组（P<0.05）。三组麻醉期间不良反应发生率对比无差异（P>0.05）。高剂量组的术后谵妄发生率低于低剂量组、对照组（P<0.05）。结论：1.00 μg/kg剂量的右美托咪定联合丙泊酚全凭静脉麻醉用于食管癌根治术患者麻醉效果较好,可降低术后谵妄发生率,有效控制氧化应激和炎症因子水平。     

食管癌调强放疗并发放射性肺损伤的危险因素分析

目的:分析食管癌调强放疗并发放射性肺损伤的危险因素。方法:以2015年2月-2018年2月于青海医学院附属医院接受调强放疗的食管癌患者100例为研究对象。分别收集患者年龄、性别、吸烟史、同步化疗情况、卡氏评分、肿瘤分期等资料以及放射剂量学因素V5、V10、V20、V30、Dmean情况,并采用单因素和多因素Logistic回归分析分析食管癌调强放疗并发放射性肺损伤的危险因素。结果:100例患者中发生放射性肺损伤人数为27例,发生率为27.00%。其中1级20例,2级7例。经单因素分析可得:食管癌调强放疗并发放射性肺损伤与卡氏评分、V5、V10、V20、V30以及Dmean有关(P0.05);与性别、年龄、吸烟史、同步化疗、肿瘤分期无关(P0.05)。经多因素Logistic回归分析可得:卡氏评分80分、V5≥60%、V10≥40%、V20≥25%、V30≥20%、Dmean≥10%均是食管癌调强放疗患者并发放射性肺损伤的独立危险因素(P0.05)。结论:食管癌调强放疗并发放射性肺损伤的发生率较高,且与卡氏评分以及放射剂量学因素V5、V10、V20、V30、Dmean密切相关。临床工作中可通过控制肺组织的照射剂量,减少放射性肺损伤发生风险。     

Perturbation analysis of 4D dose distribution for scanned carbon-ion beam radiotherapy

PurposeTo evaluate the patients’ set-up error-induced perturbation effects on 4D dose distributions (4DDD) of range-adapted internal target volume-based (raITV) treatment plan using lung and liver 4DCT data sets.MethodsWe enrolled 20 patients with lung and liver cancer treated with respiratory-gated carbon-ion beam scanning therapy. PTVs were generated by adding a 2 mm range-adapted set-up margin on the raITVs. Set-up errors were simulated by shifting the beam isocenter in three translational directions of ±2 mm, ±4 mm, and ±6 mm. 4DDDs were calculated for both nominal and isocenter-shifted situations. Dose metrics of CTV dose coverage (D95) and normal tissue sparing were evaluated. Statistical significance with p < 0.01 was considered by Wilcoxon signed rank test.ResultsThe CTV dose coverage was more sensitive to set-up errors for lung cases than for liver cases, and more serious in superior-inferior direction. The sufficient CTV-D95 > 98% could be achieved with set-up errors less than ±2 mm in all shift directions both for lung and liver cases. With the increase of set-up error, the CTV dose coverage decreased gradually. The clinical criterial of CTV-D95 > 95% could not be fulfilled with set-up error reached to ±4 mm for lung cases, and ±6 mm for liver cases. OAR doses did not have a significant difference with each set-up error for both lung and liver cases.ConclusionsThe range-adapted set-up margin successfully prevented dose degradation of 4DDDs in the presence of the same magnitude of set-up error for raITV-based carbon-ion beam scanning therapy.     

Evaluation of set-up errors in head and neck radiotherapy using electronic portal imaging

IntroductionThe aim of this study was to evaluate three-dimensional (3D) set-up errors and propose optimum margins for planning target volume (PTV) coverage in head and neck radiotherapy.MethodsThirty-five patients were included in the study. The total number of portal images studied was 632. Population systematic (Σ) and random (σ) errors for the patients with head and neck cancer were evaluated based on the portal images in the caudocranial longitudinal (CC) and left-right lateral (LR) direction measured in the anterior-posterior (AP) field, as well as from the images in the caudocranial longitudinal (CC) and dorsoventral lateral (DV) direction measured in the lateral (LAT) field. The values for the clinical-to-planning target volume (CTV-PTV) margins were calculated using ICRU Report 62 recommendations, along with Stroom's and van Herk's formulae.ResultsThe standard deviations of systematic set-up errors (Σ) ranged from 1.51 to 1.93 mm while the standard deviations of random set-up (σ) errors fell in between 1.77 and 1.86 mm. The mean 3D vector length of displacement was 2.66 mm. PTV margins calculated according to ICRU, Stroom's and van Herk's models were comprised between 1.95 and 6.16 mm in the three acquisition directions.Discussion and conclusionsBased on our results we can conclude that a 6-mm extension of CTV to PTV margin, as the lower limit, is enough to ensure that 90% of the patients treated for head and neck cancer will receive a minimum cumulative CTV dose greater than or equal to 95% of the prescribed dose.     

Marker Configuration Model-Based Roentgen Fluoroscopic Analysis

It remains unknown if and how the polyethylene bearing in mobile bearing knees moves during dynamic activities with respect to the tibial base plate. Marker Configuration Model-Based Roentgen Fluoroscopic Analysis (MCM-based RFA) uses a marker configuration model of inserted tantalum markers in order to accurately estimate the pose of an implant or bone using single plane Roentgen images or fluoroscopic images. The goal of this study is to assess the accuracy of (MCM-Based RFA) in a standard fluoroscopic set-up using phantom experiments and to determine the error propagation with computer simulations. The experimental set-up of the phantom study was calibrated using a calibration box equipped with 600 tantalum markers, which corrected for image distortion and determined the focus position. In the computer simulation study the influence of image distortion, MC-model accuracy, focus position, the relative distance between MC-models and MC-model configuration on the accuracy of MCM-Based RFA were assessed. The phantom study established that the in-plane accuracy of MCM-Based RFA is 0.1 mm and the out-of-plane accuracy is 0.9 mm. The rotational accuracy is 0.1 degrees. A ninth-order polynomial model was used to correct for image distortion. Marker-Based RFA was estimated to have, in a worst case scenario, an in vivo translational accuracy of 0.14 mm (x-axis), 0.17 mm (y-axis), 1.9 mm (z-axis), respectively, and a rotational accuracy of 0.3 degrees. When using fluoroscopy to study kinematics, image distortion and the accuracy of models are important factors, which influence the accuracy of the measurements. MCM-Based RFA has the potential to be an accurate, clinically useful tool for studying kinematics after total joint replacement using standard equipment.     

Feasibility of intensity-modulated radiotherapy to treat gastric cancer

AimTo present a proposed gastric cancer intensity-modulated radiotherapy (IMRT) treatment planning protocol for an institution that have not introduced volumetric modulated arc therapy in clinical practice. A secondary aim was to determine the impact of 2DkV set-up corrections on target coverage and organ at risk (OAR).Methods and MaterialsTwenty consecutive patients were treated with a specially-designed non-coplanar 7-field IMRT technique. The isocenter-shift method was used to estimate the impact of 2DkV-based set-up corrections on the original base plan (BP) coverage. An alternative plan was simulated (SP) by taking into account isocenter shifts. The SP and BP were compared using dose-volume histogram (DVH) plots calculated for the internal target volume (ITV) and OARs.ResultsBoth plans delivered a similar mean dose to the ITV (100.32 vs. 100.40%), with no significant differences between the plans in internal target coverage (5.37 vs. 4.96%). Similarly, no significant differences were observed between the maximal dose to the spinal cord (67.70 and 67.09%, respectively) and volume received 50% of the prescribed dose of: the liver (62.11 vs. 59.84%), the right (17.62 vs. 18.58%) and left kidney (29.40 vs. 30.48%). Set-up margins (SM) were computed as 7.80 mm, 10.17 mm and 6.71 mm in the left-right, cranio-caudal and anterior-posterior directions, respectively.ConclusionPresented IMRT protocol (OAR dose constraints with selected SM verified by 2DkV verification) for stomach treatment provided optimal dose distribution for the target and the critical organs. Comparison of DVH for the base and the modified plan (which considered set-up uncertainties) showed no significant differences.     

Set-up errors and planning margins in planar and CBCT image-guided radiotherapy using three different imaging systems: A clinical study for prostate and head-and-neck cancer

PurposeThe purpose of this work is to compare the positioning accuracy achieved by three different imaging techniques and planar vs. CBCT imaging for two common IGRT indications.MethodsA collective of prostate cancer and head-and-neck cancer patients treated at our institution during the year 2013 was retrospectively analyzed. For all treatment fractions (3078 in total), the kind of acquired set-up image and the performed couch shift before treatment were assessed. The distribution of couch corrections was compared for three different imaging systems available at our institution: the treatment beam line operating at 6 MV, a dedicated imaging beam line of nominally 1 MV, and the kVision system at 70–121 kV. Shifts were analyzed for planar and cone-beam CT images. Based on the set-up corrections, CTV to PTV expansion margins were calculated.ResultsThe difference in set-up corrections performed for the three energies and both techniques (planar vs. CBCT) was not significant for head-and-neck cancer patients. For prostate cancer all shifts had equal variance. Averages ranged from −0.7 to +0.7 mm. The set-up margins calculated on the basis of the observed shifts are 4.0 mm (AP) and 3.8 mm (SI, LR) for the head-and-neck PTV and 6.6 mm (SI), 6.7 mm (AP) and 7.9 mm (LR) for the prostate cancer patients.ConclusionsFor three different linac-based imaging energies and planar/CBCT imaging, no relevant differences in set-up shifts were observed. The suggested set-up margins for these indications are of the order of 4 mm for head-and-neck and 6–8 mm for prostate treatment.     

Translational and rotational localization errors in cone-beam CT based image-guided lung stereotactic radiotherapy

PurposeAccurate localization is crucial in delivering safe and effective stereotactic body radiation therapy (SBRT). The aim of this study was to analyse the accuracy of image-guidance using the cone-beam computed tomography (CBCT) of the VERO system in 57 patients treated for lung SBRT and to calculate the treatment margins.Materials and methodsThe internal target volume (ITV) was obtained by contouring the tumor on maximum and mean intensity projection CT images reconstructed from a respiration correlated 4D-CT. Translational and rotational tumor localization errors were identified by comparing the manual registration of the ITV to the motion-blurred tumor on the CBCT and they were corrected by means of the robotic couch and the ring rotation. A verification CBCT was acquired after correction in order to evaluate residual errors.ResultsThe mean 3D vector at initial set-up was 6.6 ± 2.3 mm, which was significantly reduced to 1.6 ± 0.8 mm after 6D automatic correction. 94% of the rotational errors were within 3°. The PTV margins used to compensate for residual tumor localization errors were 3.1, 3.5 and 3.3 mm in the LR, SI and AP directions, respectively.ConclusionsOn-line image guidance with the ITV–CBCT matching technique and automatic 6D correction of the VERO system allowed a very accurate tumor localization in lung SBRT.     

Adaptive volumetric modulated arc treatment planning for esophageal cancers using cone beam computed tomography

PurposeTo assess the potential of cone beam CT (CBCT) derived adaptive RapidArc treatment for esophageal cancers in reducing the dose to organs at risk (OAR).Methods and materialsTen patients with esophageal cancer were CT scanned in free breathing pattern. The PTV is generated by adding a 3D margin of 1 cm to the CTV as per ICRU 62 recommendations. The double arc RapidArc plan (Clin_RA) was generated for the PTV. Patients were setup using kV orthogonal images and kV-CBCT scan was acquired daily during first week of therapy, then weekly. These images were exported to the Eclipse TPS. The adaptive CTV which includes tumor and involved nodes was delineated in each CBCT image set for the length of the PTV. The composite CTV from first week CBCT was generated using Boolean union operator and 5 mm margin was added circumferentially to generate adaptive PTV (PTV1). Adaptive RapidArc plan (Adap_RA) was generated. NTCP and DVH of the OARs of the two plans were compared. Similarly, PTV2 was generated from weekly CBCT. PTV2 was evaluated for the coverage of 95% isodose of Adap_RA plan.ResultsThe PTV1 and PTV2 volumes covered by 95% isodose in adaptive plans were 93.51 ± 1.17% and 94.59 ± 1.43% respectively. The lung V_10Gy, V_20Gy and mean dose in Adap_RA plan was reduced by 17.43% (p = 0.0012), 34.64% (p = 0.0019) and 16.50% (p = 0.0002) respectively compared to Clin_RA. The Adap_RA plan reduces the heart D_35% and mean dose by 17.35% (p = 0.0011) and 17.16% (p = 0.0012). No significant reduction in spinal cord and liver doses were observed. NTCP for the lung (0.42% vs. 0.08%) and heart (1.39% vs. 0.090%) was reduced significantly in adaptive plans.ConclusionThe adaptive re-planning strategy based on the first week CBCT dataset significantly reduces the doses and NTCP to OARs.     

Phase correlation applied to the 3D registration of CT and CBCT image volumes

PurposeIn this study, a 3D phase correlation algorithm was investigated to test feasibility for use in determining the anatomical changes that occur throughout a patient's radiotherapy treatment. The algorithm determines the transformations between two image volumes through analysis in the Fourier domain and has not previously been used in radiotherapy for 3D registration of CT and CBCT volumes.MethodsVarious known transformations were applied to a patient's prostate CT image volume to create 12 different test cases. The mean absolute error and standard deviation were determined by evaluating the difference between the known contours and those calculated from the registration process on a point-by-point basis. Similar evaluations were performed on images with increasing levels of noise added. The improvement in structure overlap offered by the algorithm in registering clinical CBCT to CT images was evaluated using the Dice Similarity Coefficient (DSC).ResultsA mean error of 2.35 (σ = 1.54) mm was calculated for the 12 deformations applied. When increasing levels of noise were introduced to the images, the mean errors were observed to rise up to a maximum increase of 1.77 mm. For CBCT to CT registration, maximum improvements in the DSC of 0.09 and 0.46 were observed for the bladder and rectum, respectively.ConclusionsThe Fourier-based 3D phase correlation registration algorithm investigated displayed promising results in CT to CT and CT to CBCT registration, offers potential in terms of efficiency and robustness to noise, and is suitable for use in radiotherapy for monitoring patient anatomy throughout treatment.