What information can we gain from performing adaptive radiotherapy of head and neck cancer patients from the past 10 years?

The aim of the review was to present the current literature status about replanning regarding anatomical and dosimetric changes in the target and OARs in the head and neck region during radiotherapy, to discuss and to analyze factors influencing the decision for adaptive radiotherapy of head and neck cancer patients. Significant progress has been made in head and neck patients’ evaluation and qualification for adapted radiotherapy over the past ten years. Many factors leading to anatomical and dosimetric changes during treatment have been identified. Based on the literature, the most common factors triggering re-plan are weight loss, tumor and nodal changes, and parotid glands shrinkage. The fluctuations in dose distribution in the clinical area are significant predictive factors for patients’ quality of life and the possibility of recovery. It has been shown that re-planning influence clinical outcomes: local control, disease free survival and overall survival. Regarding literature studies, it seems that adaptive radiotherapy would be the most beneficial for tumors of immense volume or those in the nearest proximity of the OARs. All researchers agree that the timing of re-planning is a crucial challenge, and there are still no clear consensus guidelines for time or criteria of re-planning. Nowadays, thanks to significant technological progress, the decision is mostly made based on observation and supported with IGRT verification. Although further research is still needed, adaptive strategies are evolving and now became the state of the art of modern radiotherapy.     

Magnetron Sputtered CsPbCl3 Perovskite Detectors as Real-Time Dosimeters for Clinical Radiotherapy

The aim of this study is to investigate the feasibility of manufacturing thin real-time relative dosimeters for clinical radiotherapy (RT) with potential applications for transmission monitoring in vivo dosimetry and pre-treatment dose verifications. Thin (≈1 μm) layers of a high sensitivity, wide bandgap semiconductor, the inorganic perovskite CsPbCl₃, have been grown for the first time by magnetron sputtering on plastic substrates equipped with electrode arrays. Prototype devices have been tested in real-time configuration to evaluate the dose delivered by a 6 MV photon beam from a linear accelerator. Linearity of the charge with the dose has been verified over three order of magnitudes, linearity of the current signal with the dose rate has been also successfully tested in the range 0.5-4.3 Gy/min. The combination of high sensitivity per unit volume and wide bandgap provides high signal-to-noise ratios, up to 70, even at moderate applied voltages. The Schottky diode configuration allows the detector to operate without bias voltage (null bias).The blocking-barrier structure allows to confine the active volume within sub-millimetric sizes, a quite attractive feature in view to increase granularity and achieve the high spatial resolutions required in modern RT techniques. All the above-mentioned features indeed pave the way to a novel generation of flexible, transmission, real time dosimeters for clinical radiotherapy.     

放疗干预对宫颈癌荷瘤小鼠的抑瘤作用及对Th1/Th2免疫细胞比例的影响

目的探讨放疗干预对宫颈癌荷瘤小鼠的抑瘤作用及其对辅助性T细胞1(Th1)/Th2细胞比例的影响。方法建立宫颈癌荷瘤小鼠模型,随机分为荷瘤组和放疗组,每组各10只,另设对照组10只。放疗组进行放疗干预14天,荷瘤组和对照组不治疗。放疗后4、6、8、10、12、14天测量肿瘤体积;末次治疗后,ELISA法测定血清干扰素-γ(IFN-γ)、白介素-2(IL-2)、IL-4、IL-10含量;计算抑瘤率、胸腺指数和脾脏指数;HE染色观察肿瘤组织学变化;TUNEL染色观察肿瘤组织细胞凋亡情况;流式细胞术检测脾脏Th1/Th2细胞比例;RT-qPCR和Western blot检测脾脏T盒子转录因子(T-bet)、GATA结合蛋白3(GABA-3)mRNA和蛋白表达。结果与荷瘤组比较,放疗组小鼠4、6、8、10、12、14天肿瘤体积及瘤质量减小,血清IL-2、IFN-γ升高,IL-4、IL-10降低,胸腺指数、脾脏指数升高,Th1细胞比例、Th1/Th2增加,Th2细胞比例减少,T-bet mRNA和蛋白及T-bet/GATA-3表达升高,GATA-3 mRNA和蛋白表达降低(P<0.05)。HE染色显示,荷瘤组肿瘤细胞数量较多,核大深染,无明显坏死;放疗组肿瘤细胞数量减少,出现大量坏死组织。TUNEL染色显示,荷瘤组TUNEL阳性细胞较少,放疗组TUNEL阳性细胞明显增多。结论放疗对宫颈癌荷瘤小鼠具有明显抑瘤作用,可能是通过调节T-bet/GATA-3表达,促进Th1/Th2分化平衡,增强机体免疫功能发挥作用。     

局部晚期乳腺癌新辅助放疗研究进展

乳腺癌发病率居世界女性癌症发病率首位,随着医学技术的进步,乳腺癌患者总生存率得到了提高,但是局部晚期乳腺癌的治疗仍然是棘手的临床问题。对于局部晚期乳腺癌,术后辅助放疗是常规治疗手段,而新辅助放疗在局部晚期乳腺癌治疗中地位尚不明确,本文综述局部晚期乳腺癌新辅助放疗的相关研究进展,希望为局部晚期乳腺癌的治疗提供参考。     

放射治疗记录与验证系统质量控制指南

放疗记录与验证系统(RVS)是一套用于防止医用电子加速器等放疗设备治疗参数设置错误,并且记录所有放疗阶段执行参数的医用计算机软件控制系统。为确保患者的治疗安全,必须对记录与验证系统采取必要的质量控制措施。本指南内容涉及:RVS安装和参数设定过程中的质量控制;RVS的验收测试;RVS在临床使用过程中的持续质量控制;使用RVS过程中的典型错误类型;执行RVS验收测试的具体测试例。     

发泡胶在鼻咽癌放疗中对剂量分布的影响

目的：研究在鼻咽癌放射治疗中应用发泡胶进行体位固定对剂量分布的影响。方法：随机选取11例应用头颈肩热塑膜联合发泡胶进行体位固定的鼻咽癌患者，在Pinnacle计划系统中将空白CT值设置到发泡胶的CT值以下，以确保发泡胶的CT值被计算在内，作为第一组计划（Plan_F）。同时，复制第一组计划并在定位图像上勾画出发泡胶，设置发泡胶的CT值为0，在不改变射野分布、权重及计划跳数的情况下重新计算剂量分布，作为第二组计划（Plan_N）。比较两组计划的靶区及周围正常组织的剂量分布。结果：对于靶区（GTVnx、GTVnd、GTVrpn、PGTVnx、CTV1、PTV1、CTV2、PTV2）的最小剂量Dmin，最大剂量Dmax，平均剂量Dmean去除发泡胶之后，所测 255组数据中仅有6组数据出现减小（约占2.4%），Dmin、Dmax和Dmean的变化度（%）（X±SD）依次为0.215±0.969、 0.395±0.623和 0.442±0.178，其中除了GTVrpn的Dmin（P=0.727）和Dmax（P=0.142），PGTVnx的Dmin（P=0.623），CTV1 Dmin（P=0.713），CTV2 Dmax（P=0.066），其他评估指标皆显示发泡胶使用组剂量低于去除发泡胶组（P＜0.05）；而对于周围正常组织（脑干、脊髓、左右晶体、左右视神经和腮腺）的Dmean和Dmax去除发泡胶之后，所测的154组数据中仅有14组数据出现减小（约占9.1%），Dmax和Dmean的变化度（%）（X±SD）依次为0.194±0.192 和0.129±0.128，其中除了左、右晶体的平均剂量Dmean（P值分别为0.123和0.06），其余各项指标同样显示发泡胶使用组剂量低于去除发泡胶组（P＜0.05）。结论：发泡胶的使用降低了实际治疗过程中受照部位的剂量，但发泡胶对剂量变化的影响都在目前临床可接受的范围之内。     

胸腺瘤术后辅助放疗的现状及进展

手术切除是胸腺瘤最重要的治疗手段,然而,术后辅助放疗的作用一直存在不同争议。二维放疗时代多数获益不明显,精准放疗技术已使肿瘤放疗发生了较大的变化,胸腺瘤术后放疗价值也可能在改变。目前,放疗在手术切缘阳性或无法行手术切除者的作用是肯定的;在完整手术切除者中,Masaoka-Koga分期Ⅰ期患者无需术后辅助放疗,Ⅱ期患者术后辅助放疗作用争议较大,如果放疗宜考虑Ⅱb期、大体积、B2/B3型等因素;Ⅲ期术后辅助放疗也存在争议,但是多数结果倾向行术后放疗。术后辅助放疗宜采用精准放疗技术,照射范围建议瘤床三维外扩0.5 cm,肿瘤累及的纵隔胸膜及沿纵隔胸膜前后、头脚方向0.5～1.0 cm,肺侧纵隔胸膜为0.5 cm以内,以及肿瘤周血管壁和部分血管间隙,避免包括过多的正常组织。剂量在完全切除时为45~50Gy,非完全切除为54~60Gy或稍高,可能会使放疗获益增加和风险下降。质子、重离子等新型放疗技术的应用可获得剂量学方面的优势,是否能转化为临床获益还需进一步探究。     

Substantial Volume Changes and Plan Adaptations During Preoperative Radiation Therapy in Extremity Soft Tissue Sarcoma Patients

Purpose

Many authors suggest that extremity soft tissue sarcomas (ESTS) do not change significantly in size during preoperative radiation therapy (RT). This cone beam computed tomography study investigates the justification to deliver the entire course with 1 initial RT plan by observing anatomic changes during RT.