Boosting imaging defined dominant prostatic tumors: A systematic review

Introduction

Dominant cancer foci within the prostate are associated with sites of local recurrence post radiotherapy. In this systematic review we sought to address the question: “what is the clinical evidence to support differential boosting to an imaging defined GTV volume within the prostate when delivered by external beam or brachytherapy”.

Materials and methods

A systematic review was conducted to identify clinical series reporting the use of radiation boosts to imaging defined GTVs.

Results

Thirteen papers describing 11 unique patient series and 833 patients in total were identified. Methods and details of GTV definition and treatment varied substantially between series. GTV boosts were on average 8 Gy (range 3–35 Gy) for external beam, or 150% for brachytherapy (range 130–155%) and GTV volumes were small (<10 ml). Reported toxicity rates were low and may reflect the modest boost doses, small volumes and conservative DVH constraints employed in most studies. Variability in patient populations, study methodologies and outcomes reporting precluded conclusions regarding efficacy.

Conclusions

Despite a large cohort of patients treated differential boosts to imaging defined intra-prostatic targets, conclusions regarding optimal techniques and/or efficacy of this approach are elusive, and this approach cannot be considered standard of care. There is a need to build consensus and evidence. Ongoing prospective randomized trials are underway and will help to better define the role of differential prostate boosts based on imaging defined GTVs.     

CT模拟定位中扫描层厚对肿瘤靶区体积的影响

目的研究CT扫描层厚对肿瘤靶区体积(GTV)的影响.方法在PQS-CT模拟定位机上,应用层厚分别为2mm、3 mm、5 mm、10 mm的条件,分别对埋入同一蜡块中的3个不同直径的物体进行扫描,然后在ACQSIM(虚拟模拟工作站)上逐层画出物体的外轮廓,最后利用工作站的统计功能计算出3个被测物体的前后径、左右径、上下径和体积.结果被测物体前后径、左右径在CT影像所测数值与实际测量数值的误差在0.5 mm以内,而上下径的CT数值与实际测量数值的误差大都在1 mm以上,被测物体体积和物体上下径的误差与扫描层厚呈正比例关系.结论临床医生在确定临床靶区体积(CTV)的上下径时,需要考虑GTV的上下径约有75%±61%扫描层厚厚度的范围是不确定的.扫描层厚越薄,扫描得到的肿瘤体积越接近实际的肿瘤体积.     

Inter-observer agreement in GTV delineation of bone metastases on CT and impact of MR imaging: A multicenter study

Background and purpose

The use of Stereotactic Body Radiotherapy (SBRT) for bone metastases is increasing rapidly. Therefore, knowledge of the inter-observer differences in tumor volume delineation is essential to guarantee precise dose delivery. The aim of this study is to compare inter-observer agreement in bone metastases delineated on different imaging modalities.

Advances in radiation therapy of head and neck cancer

Head and neck cancer is the fifth most common cancer in the USA. Although there have been major improvements in surgical and radiation techniques, the overall survival has not changed significantly in the last decade. The major changes occurring in recent years have been in the ability to preserve organs and to improve quality of life. The advances in radiation therapy include 3D conformal radiotherapy, intensity-modulated radiotherapy and, more recently, imaging-guided radiotherapy. In advanced head and neck cancer the addition of chemotherapy to radiation has concomitantly improved survival and facilitated higher rates of organ preservation. Clinical trials are needed to develop better strategies customized to subgroups defined by individual biological risk and imaging findings.     

PET／CT对头颈部癌放射治疗计划的临床价值

目的前瞻性研究以评估PET／CT对头颈部癌患者CT放射治疗计划和治疗模式的临床价值。方法24例头颈部癌患者（鼻咽癌6例、上颌窦癌5例、舌癌8例、牙龈癌5例）进入本研究。每例患者先在治疗体位下作CT平扫和增强扫描，然后行FDG-PET／CT检查。由同一放疗医师和物理师作CT和PET／CT放射治疗计划。每例患者的二个计划作对比，以评估PE丁／CT对CT放疗计划肿瘤区（GTV）体积、放疗野和治疗模式的影响。结果PET／CT检查后54．2％（13／24）的患者GTV体积变化≥15％。125％（3／24）的患者发生放射野改变：2例患者增加下颈部放射野（原CT扫描颈部阴性，PET／CT显示下颈部淋巴结阳性浓聚）；1例鼻咽癌放疗后复发患者原计划放射鼻咽部和颈部，PET／CT显示鼻咽部阴性和颈部阳性，取消鼻咽部放射野仅放疗颈部。该患者随访1年以上未发现肿瘤病灶。另2例患者PET／CT检查确定有远处转移（1例肺转移，1例骨转移），从而改变治疗方案为始息放疗和化疗。结论PET／CT检查使本组头颈部放疗患者的CT放疗计划和治疗模式产生明显改变，增加PET／CT检查具有很大的临床价值。     

18F-FDG PET-CT不同SUV阈值法与胰腺癌GTV靶区相关性研究

目的：随着精确放疗技术在胰腺癌治疗中应用越来越广泛,精确的图像引导技术也逐渐被关注。本研究旨在探讨不同标准化摄取值（standardized uptake values,SUV）阈值法勾画18氟-脱氧葡萄糖正电子发射断层扫描 CT（18 F-flu-orodeoxyglucose positron emission tomography CT,18 F-FDG PET-CT）图像上大体肿瘤体积（gross tumor volume,GTV）靶区与定位扫描增强 CT（contrast-enhanced CT,CECT）图像上 GTV 靶区的一致性,进一步明确 PET-CT 用于胰腺癌靶区勾画的最适方法,为胰腺癌精确放射治疗提供更多图像信息。方法选取2014-07-01—2015-06-30中国人民解放军空军总医院放疗科收治的39例经病理或临床确诊的胰腺恶性肿瘤患者。所有患者放疗前行18 F-FDG PET-CT 检查及腹部 CECT 扫描。依据不同阈值法测量出 PET-CT 图像显示肿块大小（GTV on PET-CT,PET／CT-GTV）。1）SUV相对百分比法：基于最大 SUV（maximum SUV,SUVmax ）,百分活性曲线所包绕的体素范围,包括 GTVpet15％、GTV-pet20％、GTVpet25％、GTVpet30％、GTVpet35％、GTVpet40％、GTVpet45％和 GTVpet50％;2）SUV 绝对值法：指 SUV 值超过预设值2．5所包绕的体素范围 GTVpet2．5）。测量出 CECT 上可见肿块大小（GTV on CT,CT-GTV）。将不同阈值法测出的 PET／CT-GTV 与相应 CT-GTV 进行对比分析。采用配对 t 检验对计量资料进行统计学分析。结果GTVpet 组随着百分比值增加体积在逐渐缩小。GTVpet25％、GTVpet30％和 GTVpet35％平均体积分别为（95．52±43．97）、（77．92±42.97）和（64．24±40．64）cm3;GTVpet2．5的平均体积为（18．6±26．56）cm3;而 GTVct 组平均体积为（80．09±46．07）cm3。对比分析 GTVpet 同 GTVct 体积间的一致性,结果显示 GTVpet30％与 GTVct 体积最为接近,P ＝0．996。同时基于 SUVmax30％阈值法勾画的 GTVpet30％体积较 GTVct 体积稍大,GTVpet30％组平均体积较 GTVct 体积大（0．22±5．2）cm3,95％ CI 为－10．31～10．77 cm3。GTVpet30％与 GTVct 间存在相关性,r ＝0．632,P ＜0．01;GTVpet2．5与GTVct 间不存在明显相关性,r＝0．257,P ＝0．21。胰腺癌18 F-FDG 代谢摄取普遍较低,采用 SUV2．5阈值法勾画 GTV-pet2．5普遍体积较小,甚至由于 SUVmax 都＜2．5而无法采用此方法勾画 GTV。结论采用 SUVmax30％阈值法勾画的GTVpet30％同 CECT 勾画的 GTVct 体积大小最为接近。但具体应用时根据个体代谢高低适度调整百分比一致性更好。     

多模态融合图像与病理学在盆腔肿瘤靶区勾画中的差异性研究

目的探讨CT、MRI及其融合图像的盆腔肿瘤勾画靶区（GTV）最大径与病理肿瘤实体的差异性。方法 （1）选取6例边界相对完整的术前盆腔肿瘤患者分别进行CT、MRI异机非同步扫描。CT和MRI图像数据行手工配准后传送至飞利浦公司PINNACLE V8.0放射治疗计划系统,行图像融合并由一位有经验的放疗科医师对患者的CT、MRI及融合图像肿瘤靶区（GTVs）进行勾画,并测量其最大径;（2）术后立即对实体肿瘤行速冻处理,并对实体肿瘤由外到里2mm一层行病理切片直到在镜下找到肿瘤细胞,测量镜下肿瘤的最大径并与（1）勾画的肿瘤靶区最大径比较分析。结果 DFUSION相对D实体平均缩小了0.205cm,约为D实体的2.80%、DCT和DMRI相对D实体平均缩小了0.548和0.458cm,约为D实体的7.48%和6.25%。结论通过融合图像勾画的GTV更接近于实体肿瘤,与单独CT或MRI图像相比优势明显。CT/MR图像融合技术有利于盆腔肿瘤靶区的确定,提高了临床对盆腔肿瘤靶区（GTV）勾画的准确率,利于患者的诊治。     

宫颈癌调强放疗中靶区退缩研究

目的研究宫颈癌患者放疗前后靶区的退缩情况。方法随机选取20例宫颈癌调强放疗患者,采集放疗前CT与放疗后CT图像,勾画出CTV及GTV肿瘤轮廓,分析其放疗后的退缩情况。结果20例患者的CTV及GTV肿瘤退缩明显,数据显示CTV平均退缩了17.3%,GTV肿瘤平均退缩了48.2%,并给临近危及器官吸收剂量带来影响。结论放疗期间CTV及GTV肿瘤退缩十分明显,应密切观察其退缩情况。对于个别GTV肿瘤较大的患者,其退缩对临近危机器官的影响不容忽略,必要时应重新制作治疗计划。