容积旋转调强与固定野动态调强在上段食管癌治疗中的剂量学比较

目的 比较容积旋转调强（VMAT）与固定野动态调强（dIMRT）在上段食管癌放疗计划中的剂量学差异。方法 利用瓦里安Eclipse 8.6计划系统对10例上段食管癌患者分别设计单弧360°Rapid Arc放疗计划和五野均分的dIMRT放疗计划。利用剂量体积直方图（DVH）来统计GTV和PTV的相关剂量参数、适形指数（CI）、均匀性指数（HI）,肺、脊髓、正常组织的剂量体积参数,以及总机器跳数（MU）、总治疗时间。结果 Rapid Arc与dIMRT计划中GTV的D₂、D₉₈、HI、CI和V100差异均有统计学意义（P＜0.05）,PTV的D₂、HI、CI差异均有统计学意义（P＜0.05）,Rapid Arc计划的GTV和PTV更具优势;Rapid Arc和dIMRT脊髓D₁分别为（3644.15±72.89）cGy和（3810.69±97.51）cGy（P＜0.05）,肺V₂₀为（13.65±2.19）％和（15.14±1.24）％（P＞0.05）,平均剂量为（893.95±102.43）cGy和（882.86±120.67）cGy（P＞0.05）;Rapid Arc计划与dIMRT计划MU分别为482±36和763±89,治疗时间为（102±19）s和（336±41）s。结论 Rapid Arc计划可以达到或优于dIMRT计划的靶区剂量分布,具有较少MU和总治疗时间的优势,能够更好地降低危及器官的受照剂量,可以获得更好的靶区剂量均匀性和靶区适合度。     

动态调强和静态调强技术治疗中晚期宫颈癌剂量学比较

目的宫颈癌严重威胁着妇女的健康,调强放射治疗(intensity modulated radiotherapy,IMRT)联合后装放疗成为中晚期(ⅡB~ⅢB期)宫颈癌治疗的主要方法。本研究旨在比较动态调强放射治疗(dynamic intensity modulated radiotherapy,dIMRT)技术和强度等级不同的静态调强放射治疗(static intensity modulated radiotherapy,sIMRT)技术治疗中晚期宫颈癌时的剂量学特点,为临床应用提供参考。方法回顾性选取玉林市红十字会医院2017-10-09-2019-03-24收治的中晚期(ⅡB~ⅢB期)宫颈癌患者50例(其中ⅡB期17例,ⅢA期15例,ⅢB期18例),在增强定位CT影像上勾画靶区和危及器官。在Eclipse 10.0计划系统中基于同一套CT图像设计5野调强计划,选取dIMRT技术中的滑窗技术(Sliding Window,SW)和强度等级分别为13(Ec13),10(Ec10),7(Ec7)和5(Ec5)的sIMRT技术,处方剂量均为50Gy/25次,要求计划靶区95%的体积达到处方剂量。通过分析剂量-体积直方图(dose volume histogram,DVH)及传输参数,比较5种调强放射治疗方式中计划靶区的靶区适形指数(conformity index,CI)、均匀指数(homogeneity index,HI)、危及器官(膀胱、小肠和直肠)剂量分布和机器参数的差异。数据经Shapiro-Wilk法检验符合正态分布后,组间均值差异进行单因素方差分析,两两多重比较采用LSD法。用Pearson法分析sIMRT强度等级与子野数量的关系。结果5种计划的靶区最大剂量Dmax、平均剂量Dmean、HI值和CI值差异有统计学意义。其中,对于SW、Ec13、Ec10、Ec7和Ec5计划,Dmax值分别为(55.27±1.29)、(55.54±1.18)、(55.83±1.10)、(57.51±1.05)和(59.90±1.08)Gy,差异有统计学意义,F=154.844,P<0.01;HI值分别为1.06±0.01、1.06±0.01、1.07±0.01、1.09±0.01和1.12±0.02,差异有统计学意义,F=452.442,P<0.01;CI值分别为0.89±0.01、0.88±0.01、0.88±0.01、0.86±0.01和0.83±0.01,差异有统计学意义,F=107.928,P<0.01。相对于sIMRT,SW组的Dmean、HI值和CI值差异有统计学意义,均P<0.05。对于膀胱、小肠和直肠,5组计划中剂量体积V20、V30和V40差异无统计学意义,而最大剂量Dmax则差异有统计学意义,均P<0.01。Ec5计划中膀胱、小肠和直肠V50值的均值比SW计划中均值分别为13.58%、45.14%和36.20%。SW计划中传输时间为(6.82±0.55)min,机器跳数(monitor units,MUs)为(1090.9±88.7)MUs,比sIMRT技术数值大,差异有统计学意义,均P<0.01。对于sIMRT,强度等级越高,子野数量越多,治疗的实施时间越长。子野数量与强度等级呈线性关系。结论对于中晚期宫颈癌,dIMRT技术与强度等级≥10的sIMRT技术剂量分布相当。综合考虑,临床应用中优先选取dIMRT或者强度等级等于或接近于10的sIMRT。     

Consensus guidelines for delineation of clinical target volume for intensity-modulated pelvic radiotherapy in postoperative treatment of endometrial and cervical cancer

PURPOSE: To develop an atlas of the clinical target volume (CTV) definitions for postoperative radiotherapy of endometrial and cervical cancer to be used for planning pelvic intensity-modulated radiotherapy. METHODS AND MATERIALS: The Radiation Therapy Oncology Group led an international collaboration of cooperative groups in the development of the atlas. The groups included the Radiation Therapy Oncology Group, Gynecologic Oncology Group, National Cancer Institute of Canada, European Society of Therapeutic Radiology and Oncology, and American College of Radiology Imaging Network. The members of the group were asked by questionnaire to define the areas that were to be included in the CTV and to outline theses areas on individual computed tomography images. The initial formulation of the group began in late 2004 and culminated with a formal consensus conference in June 2005. RESULTS: The committee achieved a consensus CTV definition for postoperative therapy for endometrial and cervical cancer. The CTV should include the common, external, and internal iliac lymph node regions. The upper 3.0 cm of the vagina and paravaginal soft tissue lateral to the vagina should also be included. For patients with cervical cancer, or endometrial cancer with cervical stromal invasion, it is also recommended that the CTV include the presacral lymph node region. CONCLUSION: This report serves as an international template for the definition of the CTV for postoperative intensity-modulated radiotherapy for endometrial and cervical cancer.     

Assessment of extended-field radiotherapy for stage IIIC endometrial cancer using three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and helical tomotherapy

PURPOSE: To perform a dosimetric comparison of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and helical tomotherapy (HT) plans for pelvic and para-aortic RT in postoperative endometrial cancer patients; and to evaluate the integral dose (ID) received by critical structures within the radiation fields. METHODS AND MATERIALS: We selected 10 patients with Stage IIIC endometrial cancer. For each patient, three plans were created with 3D-CRT, IMRT, and HT. The IMRT and HT plans were both optimized to keep the mean dose to the planning target volume (PTV) the same as that with 3D-CRT. The dosimetry and ID for the critical structures were compared. A paired two-tailed Student t test was used for data analysis. RESULTS: Compared with the 3D-CRT plans, the IMRT plans resulted in lower IDs in the organs at risk (OARs), ranging from -3.49% to -17.59%. The HT plans showed a similar result except that the ID for the bowel increased 0.27%. The IMRT and HT plans both increased the IDs to normal tissue (see Table 1 and text for definition), pelvic bone, and spine (range, 3.31-19.7%). The IMRT and HT dosimetry showed superior PTV coverage and better OAR sparing than the 3D-CRT dosimetry. Compared directly with IMRT, HT showed similar PTV coverage, lower Ids, and a decreased dose to most OARs. CONCLUSION: Intensity-modulated RT and HT appear to achieve excellent PTV coverage and better sparing of OARs, but at the expense of increased IDs to normal tissue and skeleton. HT allows for additional improvement in dosimetry and sparing of most OARs.     

加速器模型和治疗计划系统对知识库计划模型的影响：一项基于宫颈癌适形调强放射放疗计划的研究

背景与目的：“RapidPlan”利用适形调强放射治疗（intensity-modulated radiotherapy,IMRT）中的患者解剖和剂量信息,以剂量体积直方图（dose-volume histogram,DVH）预测模型的方式来预测新计划的剂量分布。针对每种治疗计划系统（treatment planning system,TPS）和治疗机器模型分别建立知识库模型需耗费大量精力且选择繁琐,因此本研究评估基于特定TPS和加速器模型建立的知识库计划模型能否适用于其他TPS和加速器模型。方法：选取2015—2016年于复旦大学附属肿瘤医院采用IMRT技术治疗的50例临床治疗的宫颈癌患者的放疗资料,使用RapidPlan建立基于知识库的计划预测模型。训练数据均基于Pinnacle计划系统,机器模型采用Synergy加速器6 MV光子射线。使用该预测模型对15例宫颈癌病例进行预测,提取目标函数数值后,分别在3组不同的优化环境中重新优化以评估加速器模型和TPS对知识库计划模型的影响：① 与模型构建一致的TPS和加速器模型,即Pinnacle与Synergy;② TPS一致但加速器模型不一致,即Pinnacle与Truebeam;③ TPS和加速器模型都不一致,即Eclipse和Truebeam。评估方法为基于知识库模型生成的计划与相应环境下人工计划进行剂量学比较。结果：组2和组3中,知识库计划与人工计划得到相似质量的计划靶区（planning target volume,PTV）剂量覆盖,而在组1中知识库计划改善了PTV的D ₂ %（0.95 Gy,P<0.01）和剂量均一性指数（homogeneity index,HI）(0.02,P<0.01）。知识库计划降低了所有3组计划的膀胱V ₃₀ 、V ₄₅ 和平均剂量,同时知识库计划还降低了肠道的平均剂量。结论：基于知识库的计划模型对加速器和TPS的依赖并不显著。     

Comparison of three-dimensional versus intensity-modulated radiotherapy techniques to treat breast and axillary level III and supraclavicular nodes in a prone versus supine position

Background and purpose

To determine the optimal method of targeting breast and regional nodes in selected breast cancer patients after axillary dissection, we compared the results of IMRT versus no IMRT, and CT-informed versus clinically-placed fields, in supine and prone positions.

Materials and methods

Twelve consecutive breast cancer patients simulated both prone and supine provided the images for this study. Four techniques were used to target breast, level III axilla, and supraclavicular fossa in either position: a traditional three-field three-dimensional conformal radiotherapy (3DCRT) plan, a four-field 3DCRT plan using a posterior axillary boost field, and two techniques using a CT-informed target volume consisting of an optimized 3DCRT plan (CT-planned 3D) and an intensity-modulated radiotherapy (IMRT) plan. The prescribed dose was 50 Gy in 25 fractions.

Results

CT-planned 3D and IMRT techniques improved nodal PTV coverage. Supine, mean nodal PTV V50 was 50% (3-field), 59% (4-field), 92% (CT-planned 3D), and 94% (IMRT). Prone, V50 was 29% (3-field), 42% (4-field), 97% (CT-planned 3D), and 95% (IMRT). Prone positioning, compared to supine, and IMRT technique, compared to 3D, lowered ipsilateral lung V20.

Conclusions

Traditional 3DCRT plans provide inadequate nodal coverage. Prone IMRT technique resulted in optimal target coverage and reduced ipsilateral lung V20.     

Dosimetric comparison of bone marrow-sparing intensity-modulated radiotherapy versus conventional techniques for treatment of cervical cancer

PURPOSE: To compare bone marrow-sparing intensity-modulated pelvic radiotherapy (BMS-IMRT) with conventional (four-field box and anteroposterior-posteroanterior [AP-PA]) techniques in the treatment of cervical cancer. METHODS AND MATERIALS: The data from 7 cervical cancer patients treated with concurrent chemotherapy and IMRT without BMS were analyzed and compared with data using four-field box and AP-PA techniques. All plans were normalized to cover the planning target volume with the 99% isodose line. The clinical target volume consisted of the pelvic and presacral lymph nodes, uterus and cervix, upper vagina, and parametrial tissue. Normal tissues included bowel, bladder, and pelvic bone marrow (PBM), which comprised the lumbosacral spine and ilium and the ischium, pubis, and proximal femora (lower pelvis bone marrow). Dose-volume histograms for the planning target volume and normal tissues were compared for BMS-IMRT vs. four-field box and AP-PA plans. RESULTS: BMS-IMRT was superior to the four-field box technique in reducing the dose to the PBM, small bowel, rectum, and bladder. Compared with AP-PA plans, BMS-IMRT reduced the PBM volume receiving a dose >16.4 Gy. BMS-IMRT reduced the volume of ilium, lower pelvis bone marrow, and bowel receiving a dose >27.7, >18.7, and >21.1 Gy, respectively, but increased dose below these thresholds compared with the AP-PA plans. BMS-IMRT reduced the volume of lumbosacral spine bone marrow, rectum, small bowel, and bladder at all dose levels in all 7 patients. CONCLUSION: BMS-IMRT reduced irradiation of PBM compared with the four-field box technique. Compared with the AP-PA technique, BMS-IMRT reduced lumbosacral spine bone marrow irradiation and reduced the volume of PBM irradiated to high doses. Therefore BMS-IMRT might reduce acute hematologic toxicity compared with conventional techniques.     

Dosimetric predictors of acute hematologic toxicity in cervical cancer patients treated with concurrent cisplatin and intensity-modulated pelvic radiotherapy

PURPOSE: To identify dosimetric parameters associated with acute hematologic toxicity (HT) and chemotherapy delivery in cervical cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy. METHODS AND MATERIALS: We analyzed 37 cervical cancer patients receiving concurrent cisplatin (40 mg/m(2)/wk) and intensity-modulated pelvic radiotherapy. Pelvic bone marrow (BM) was contoured for each patient and divided into three subsites: lumbosacral spine, ilium, and lower pelvis. The volume of each region receiving 10, 20, 30, and > or =40 Gy (V(10), V(20), V(30), and V(40), respectively) was calculated. HT was graded according to the Radiation Therapy Oncology Group system. Multivariate regression models were used to test associations between dosimetric parameters and HT and chemotherapy delivery. RESULTS: Increased pelvic BM V(10) (BM-V(10)) was associated with an increased Grade 2 or worse leukopenia and neutropenia (odds ratio [OR], 2.09; 95% confidence interval [CI], 1.24-3.53; p = 0.006; and OR, 1.41; 95% CI, 1.02-1.94; p = 0.037, respectively). Patients with BM-V(10) > or =90% had higher rates of Grade 2 or worse leukopenia and neutropenia than did patients with BM-V(10) <90% (11.1% vs. 73.7%, p < 0.01; and 5.6% vs. 31.6%, p = 0.09) and were more likely to have chemotherapy held on univariate (16.7% vs. 47.4%, p = 0.08) and multivariate (OR, 32.2; 95% CI, 1.67-622; p = 0.02) analysis. No associations between HT and V(30) and V(40) were observed. Dosimetric parameters involving the lumbosacral spine and lower pelvis had stronger associations with HT than did those involving the ilium. CONCLUSION: The volume of pelvic BM receiving low-dose radiation is associated with HT and chemotherapy delivery in cervical cancer patients undergoing concurrent chemoradiotherapy.     

颈段、胸上段食管癌３ＤＣＲＴ／ＩＭＲＴ剂量学比较

目的　通过对颈段、胸上段食管癌三维适形（３ＤＣＲＴ）和调强（ＩＭＲＴ）放疗计划的剂量学比较,选择符合临床要求的最优方案。方法　１４例颈段、胸上段食管癌患者模拟定位后参考食管钡餐和内镜检查结果勾画ＧＴＶ,按照统一标准确定ＣＴＶ、ＰＴＶ,分别设计３ＤＣＲＴ、５野均匀分布ＩＭＲＴ-Ａ和５野非均匀分布ＩＭＲＴ-Ｂ共３套放疗计划,以９５％ＰＴＶ获得１００％处方剂量进行归一,分析各计划靶区剂量分布及危及器官受量的差异。结果　本组病例所有的ＩＭＲＴ计划均能满足治疗要求,而４例３ＤＣＲＴ计划不能满足要求,本研究仅对１０组可行计划进行进一步的剂量学比较。预防照射区（ＰＴＶ１）：３ＤＣＲＴ计划的剂量参数Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５分别为（５７２５±５４.９６）ｃＧｙ、（４７０３±２５.２６）ｃＧｙ、（５２０３±７１.７０）ｃＧｙ,明显高于ＩＭＲＴ-Ａ的（５３４８±２７.１４）ｃＧｙ、（４１５８±２７.３６）ｃＧｙ、（４９９６±５４.７４）ｃＧｙ和ＩＭＲＴ-Ｂ的（５２３２±２６.８５）ｃＧｙ、（４２８６±１２.１３）ｃＧｙ、（４９７９±３１.７８）ｃＧｙ（Ｐ＜０.０５）;３ＤＣＲＴＶ１０５为（８２.９５±３.０２）％,高于ＩＭＲＴ-Ａ的（７１.０７±６.６８）％和ＩＭＲＴ-Ｂ的（６９.５５±４.５６）％（Ｐ＜０.０５）,Ｖ１００、Ｖ９５无明显差异（Ｐ＞００５）。肿瘤区（ＰＴＶ２）：３套放疗计划的Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５、Ｖ_１０５、Ｖ_９５无明显差异（Ｐ＞０.０５）,而ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ的Ｖ_１００分别为（９５.２１±１.７８）％和（９６.１２±２.５５）％,均高于３ＤＣＲＴ的（８８.６９±１.８４）％（Ｐ＜０.０５）;ＩＭＲＴ-Ａ和ＩＭＲＴ-ＢＨＩ分别为１.０８±０.０１和１.０２±０.０１,低于３ＤＣＲＴ的１.１８±０.０３,差异有统计学意义（Ｐ＜０.０５）。除肺Ｖ５外,ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ脊髓Ｄ_ｍａｘ、肺Ｖ_２０、Ｖ_３０、ＭＬＤ分别为（３６４１±２３.４１）ｃＧｙ、（２２.０８±０.３１）％、（１１.０７±０.５１）％、（１０３４±３７.５１）ｃＧｙ和（３３０３±７５.３９）ｃＧｙ、（１９.８２±１.７４）％、（１０.１４±１.２０）％、（９８１±３８.１６）ｃＧｙ,均小于３ＤＣＲＴ的（４１１３±３８.２８）ｃＧｙ、（２８.０７±６.３０）％、（１９.７２±５.２６）％、（１３５６±３８.９１）ｃＧｙ,差异具有统计学意义（Ｐ＜０.０５）。ＩＭＲＴ计划剂量参数、体积参数、剂量分布均匀性无明显差别（Ｐ＞０.０５）;ＩＭＲＴ-Ｂ肺ＭＬＤ和脊髓Ｄｍａｘ较ＩＭＲＴ-Ａ低,差异具有统计学意义（Ｐ＜０.０５）。结论　颈段、胸上段食管癌放疗采用ＩＭＲＴ优于３ＤＣＲＴ,根据靶区形状非均匀布野ＩＭＲＴ可进一步降低肺和脊髓受照剂量。     

HT及IMRT在儿童全中枢放疗剂量学比较及二次致癌风险评估

目的 探讨HT及IMRT计划在儿童全中枢放疗中的剂量学特点,并根据EAR模型估算儿童全中枢放疗后二次致癌风险。方法 选取2012-2017年间接受全脑全脊髓照射患者CT图像15例,勾画靶区及OAR后分别完成IMRT及HT计划,t检验两种计划间靶区HI、CI和OAR的Dmax、Dmean及V10、V20并优化临床治疗方案。根据各器官DVH及EAR模型估算比较两种计划二次致癌风险。结果 两组计划在靶区覆盖度上均能达到临床要求(100%剂量≥95%靶体积),其中HT组HI优于IMRT组(P=0.000);CI上HT组并未显示优势。但HT组对于海马保护具有绝对优势,D2%和Dmean均明显低于IMRT组(P=0.000)。对OAR保护,HT在甲状腺的Dmax、Dmean、V20及心脏的Dmax、V10均小于IMRT (P=0.001、0.002、0.014及P=0.001、0.003)。在二次致癌方面,HT组相较于IMRT组对于甲状腺和肺脏的二次致癌风险更高,甲状腺和肺脏EAR分别为28.666∶26.926(P=0.010)和20.496∶18.922(P=0.003);对胃二次致癌风险似乎较高(P=0.248),对肝脏二次致癌风险相对较小(P=0.020)。结论 在儿童保护海马的全中枢放疗中HT计划优于IMRT计划。但HT对甲状腺和肺脏有较高二次致癌风险,在计划制定时应评估这些致癌风险及其他正常组织效应的平衡。     

Repeat CT imaging and replanning during the course of IMRT for head-and-neck cancer

PURPOSE: Many patients with head-and-neck (H&N) cancer have tumor shrinkage and/or weight loss during the course of radiotherapy. We conducted this retrospective study to determine the dosimetric effects of repeat computed tomography (CT) imaging and replanning during the course of intensity-modulated radiotherapy (IMRT) on both normal tissues and target volumes. METHODS AND MATERIALS: A retrospective chart review identified 13 patients with H&N cancer treated with IMRT who had repeat CT imaging and replanning during the course of radiotherapy. The first IMRT plan for each patient was generated based on the original planning CT scan acquired before the start of treatment. Because of tumor shrinkage or weight loss during radiotherapy, a second CT scan was acquired, and a new plan was generated and used to complete the course of IMRT. CT-CT fusion was used to correct patient positioning differences between the scans. By using a commercial inverse IMRT planning system, a hybrid IMRT plan was generated for each patient by applying the beam configurations of the first IMRT plan (including the intensity profile of each beam) to the anatomy of the second CT scan. The dose-volume histograms of the actual and hybrid IMRT plans were compared using analysis of variance methods for repeated measures. RESULTS: All patients had locally advanced, nonmetastatic Stage III or IV disease, including 6 nasopharynx, 6 oropharynx, and 1 unknown primary site. All patients were treated with concurrent platinum-based chemotherapy. When replanning vs. not replanning was compared, the hybrid IMRT plans (without replanning) demonstrated reduced doses to target volumes and increased doses to critical structures. The doses to 95% (D95) of the planning target volumes of the gross tumor volume (PTVGTV) and the clinical target volume (PTVCTV) were reduced in 92% of patients, by 0.8-6.3 Gy (p=0.02) and 0.2-7.4 Gy (p=0.003), respectively. The maximum dose (Dmax) to the spinal cord increased in all patients (range, 0.2-15.4 Gy; p=0.003) and the brainstem Dmax increased in 85% of patients without replanning (range, 0.6-8.1 Gy; p=0.007). CONCLUSIONS: Repeat CT imaging and replanning during the course of IMRT for selected patients with H&N cancer is essential to identify dosimetric changes and to ensure adequate doses to target volumes and safe doses to normal tissues. Future prospective studies with larger sample sizes will help to determine criteria for repeat CT imaging and IMRT replanning for H&N cancer patients undergoing radiotherapy.     

COMBINATION OF PRONE POSITION AND INTENSITY-MODULATED RADIATION THERAPY （IMRT） REDUCES SMALL BOWEL DOSES IN RADIATION THERAPY FOR GYNECOLOGIC MALIGNANCIES

Small bowel sequelae including obstruction, enteritis, and diarrhea, are among the most important acute and chronic toxicities in gynecologic carcinoma patients treated with pelvic radiotherapy[1, 2]. The total dose of radiation delivered to the pelvic organs by the whole pelvic external irradiation and intracavitary insertions is the most significant factor affecting the probability of these complications. The incidence of late bowel complications after pelvic irradiation isreported to be rel…     

非小细胞肺癌6MV-X射线和10MV-X射线调强放射治疗计划的剂量学比较

目的比较非小细胞肺癌（NSCLC）调强放射治疗（IMRT）计划中采用6MV-X和10MV-X射线治疗的剂量学差异。方法应用ADAC Pinnacle8治疗计划系统提供的卷积/迭加法对两种能量条件下相同靶区的IMRT计划进行剂量计算,通过剂量-体积直方图（DVH）参数（最大剂量、平均剂量和处方剂量）、均匀性指数（HI）以及适形指数（CI）,比较8例肺癌患者的6MV-X和10MV-X射线的IMRT计划的物理学参数。结果两者靶区的平均剂量、HI和CI之间差异比较无明显统计学差异,但6MV计划中高剂量覆盖靶区的程度优于10MV计划;正常肺组织、心脏、脊髓等危及器官（OAR）的受量基本相同。结论对于肺癌的放射治疗建议选用6MV-X射线。     

Patterns of failure and toxicity after intensity-modulated radiotherapy for head and neck cancer

PURPOSE: To determine the outcome of patients treated with intensity-modulated radiotherapy (IMRT) for head and neck cancer. METHODS AND MATERIALS: We reviewed the charts of 100 consecutive patients treated with IMRT for squamous cell carcinoma of the oropharynx (64%), nasopharynx (16%), hypopharynx (14%), and larynx (6%). Most patients were treated with a concomitant boost schedule to 72 Gy. Of the 100 patients, 54 (54%) received adjuvant chemotherapy, mostly concurrent cisplatin. The dosimetry plans for patients with either locoregional failure or Grade 4-5 complications were reviewed and fused over the computed tomography images corresponding with the location of the event. Marginal failures were defined as those that occurred at a region of high-dose falloff, where conventional fields would have provided better coverage. RESULTS: The median follow-up of living patients was 3.1 years (range, 1-5.2 years). The 3-year rate of local control, locoregional control, freedom from relapse, cause-specific survival, and overall survival for all patients was 89%, 87%, 72%, 78%, and 71%, respectively. The 3-year rate of freedom from relapse, cause-specific survival, and overall survival for the 64 oropharynx patients was 86%, 92%, and 84%, respectively. Of the 10 local failures, 2 occurred at the margin of the high-dose planning target volume. Both regional failures occurred within the planning target volume. No locoregional failures occurred outside the planning target volume. Of the 100 patients, 8 and 5 had Grade 4 and 5 complications from treatment, respectively. All patients with Grade 5 complications had received adjuvant chemotherapy. No attempt was made to discriminate between the complications from IMRT and other aspects of the patients' treatment. CONCLUSION: Intensity-modulated radiotherapy did not compromise the outcome compared with what we have achieved with conventional techniques. The 2 cases of recurrence in the high-dose gradient region highlight the potential hazard of approaches that involve highly conformal dose distributions.     

Clinical outcome of adjuvant treatment of endometrial cancer using aperture-based intensity-modulated radiotherapy

PURPOSE: To assess disease control and acute and chronic toxicity with aperture-based intensity-modulated radiotherapy (AB-IMRT) for postoperative pelvic irradiation of endometrial cancer. METHODS AND MATERIALS: Between January and July 2005, after hysterectomy for endometrial cancer, 15 patients received 45 Gy to the pelvis using AB-IMRT. The AB-IMRT plans were generated by an in-house treatment planning system (Ballista). The AB-IMRT plans were used for treatment and were dosimetrically compared with three other approaches: conventional four-field, enlarged four-field, and beamlet-based IMRT (BB-IMRT). Disease control and toxicity were prospectively recorded and compared with retrospective data from 30 patients treated with a conventional four-field technique. RESULTS: At a median follow-up of 27 months (range, 23-30), no relapse was noted among the AB-IMRT group compared with five relapses in the control group (p = 0.1). The characteristics of each group were similar, except for the mean body mass index, timing of brachytherapy, and applicator type used. Patients treated with AB-IMRT experienced more frequent Grade 2 or greater gastrointestinal acute toxicity (87% vs. 53%, p = 0.02). No statistically significant difference was noted between the two groups regarding the incidence or severity of chronic toxicities. AB-IMRT plans significantly improved target coverage (93% vs. 76% of planning target volume receiving 45 Gy for AB-IMRT vs. conventional four-field technique, respectively). The sparing of organs at risk was similar to that of BB-IMRT. CONCLUSION: The results of our study have shown that AB-IMRT provides excellent disease control with equivalent late toxicity compared with the conventional four-field technique. AB-IMRT provided treatment delivery and quality assurance advantages compared with BB-IMRT and could reduce the risk of second malignancy compared with BB-IMRT.