剂量体积联合等效均匀剂量优化在鼻咽癌调强放疗危及器官优化中的应用

目的 研究剂量体积优化（dose-volume, DV）联合等效均匀剂量（equivalent uniform dose, EUD）优化在鼻咽癌调强放疗危及器官优化中的应用。方法 选取西南医科大学附属医院肿瘤科放疗室鼻咽癌患者调强放疗计划55例,制作调强计划时优化方法分为常规DV优化法和DV与EUD联合优化法两种,比较两种优化方法优化后靶区与危及器官的受量。结果 常规DV优化和DV与EUD联合优化后肿瘤靶区处方剂量、均匀性指数与适形度指数之间差异均无统计学意义（均P>0.05）,危及器官平均剂量差异均有统计学意义,DV与EUD联合优化得到的危及器官平均剂量低于常规DV优化（均P<0.001）。结论 本研究将DV优化与EUD联合优化法成功应用于鼻咽癌调强放疗危及器官的优化中,并在此基础上提出一种调强计划危及器官受量的验收方法,减少调强放疗计划中人为主观因素对危及器官受量的影响。     

肺灌注显像联合剂量体积直方图参数预测放射性肺炎的临床研究

 目的　观察接受三维适形或调强放疗的肺癌患者放疗前后肺灌注显像的变化、肺受照射的剂量体积直方图（DVH）参数等,并结合临床因素,探讨其与放射性肺炎发生的相关性。方法　18例接受三维适形或调强放疗的肺癌患者放疗前后行肺灌注显像检查,比较照射前后肺灌注显像的变化。放射性肺炎的评价按美国肿瘤放疗协作组（RTOG）急性放射性肺炎标准评定。获得的CT与单光子发射CT（SPECT）肺灌注图像融合后,将等剂量曲线投影到SPECT图像,将传统的DVH转换成f-DVH。将f-DVH曲线中每例患者的V5、V10和V20所对应的灵敏度与特异度相加,取其最大值,寻找到曲线的界值。分析放疗前后肺灌注显像变化及肺受照射的DVH与放射性肺炎发生的相关性。结果　18例患者中,33.3 %（6／18）发生了2级以上放射性肺炎。放疗前后肺灌注受损加重者2级以上放射性肺炎发生率为62.5 %（5／8）,肺灌注受损改善者发生率为10.0 %（1／10）。f-DVH图曲线中V5、V10和V20的界值分别为53 %、41 %和27 %,以V5对中重度急性放射性肺炎的预测准确度最高。放疗前后肺灌注显像的变化联合全肺DVH参数V5是放射性肺炎最强的预测因素。结论　肺癌患者放疗前后肺灌注显像能反映患侧肺灌注功能的变化。放疗前后肺灌注显像的变化联合DVH参数V5有望作为预测放射性肺炎发生的指标。     

四种放疗计划优化方法在肺癌大分割放疗中的剂量学研究

目的 探讨物理优化与生物优化方法在肺癌大分割放疗中的剂量学差异。方法 选择10例非小细胞肺癌放疗病例,分别对每个病例使用物理函数(DV组)、生物函数-物理函数相结合(DV+EUD组、EUD+DV组)及生物函数(EUD组)优化方法重新进行VMAT计划设计;其中4个组计划约束函数不同,但约束条件与计算参数保持相同。通过计算与统计各项剂量学参数来评估4种计划优化方法在肺癌大分割放疗中的剂量学差异。结果 在靶区方面,EUD组与EUD+DV组的等效均匀剂量值相近,但这两组EUD值比另外两组分别高出2.8%~3.6%和3.2%~3.7%;EUD组与EUD+DV组的肿瘤控制率平均值也高于DV组和DV+EUD组(P<0.05)。均匀性指数值也不同(P<0.05),而适形指数值相近(P>0.05)。在危及器官方面,正常肺组织的EUD、V5、V10、V20、V30以及心脏与脊髓的剂量参数差异均相近(P>0.05),但靶区使用生物函数的两组其全肺平均剂量较另外两组的略低。结论 生物函数在提高靶区的EUD与肿瘤控制率以及保护肺组织方面都具有一定的优势,临床工作中可以此为参考选择生物函数优化方法。     

放疗前肺功能参数对非小细胞肺癌放射性肺炎的预测价值

目的 观察肺癌患者三维适形放疗后放射性肺炎的发生情况,探讨放疗前肺功能参数在预测非小细胞肺癌放射性肺炎方面的价值.方法 对81例接受三维适形放射治疗并符合入组条件的非小细胞肺癌患者进行放疗前基础肺功能测定,并记录剂量体积参数,观察放疗后放射性肺炎的发生情况,对患者临床资料、肺功能参数、剂量体积参数等指标进行单因素及多因素分析,评价肺功能参数预测放射性肺炎的价值.结果 全组患者中17例出现≥2级放射性肺炎,占21.0%(17/81),其中2级15例,3级2例,无4、5级放射性肺炎发生.单因素分析结果显示,放疗前肺功能指标FEV1.0、FEV1.0/FVC、DLCO及放疗计划指标PTV体积、双肺MLD、V5、V20、V30,均影响患者≥2级放射性肺炎的发生(P<0.05).≥2级放射性肺炎组患者肺功能参数FEV1.0、FEV1.0/FVC、DLCO指标值均低于0、1级放射性肺炎组,且有统计学意义(P<0.05).多因素分析结果显示:FEV1.0、FEV1.0/FVC、DLCO等相关肺功能指标值并非≥2级放射性肺炎的独立影响因素,仅双侧肺脏MLD、V5、V20及V30为患者≥2级放射性肺炎发生的独立影响因素(P<0.05).结论 基础肺功能参数FEV1.0、FEV1.0/FVC、DLCO在≥2级急性放射性肺炎预测方面具有一定价值,肺功能受损是放射性肺炎的高危因素,但并非影响放射性肺炎的独立因素.     

广义等效均匀剂量优化方法在鼻咽癌调强放射治疗计划中的应用研究

背景与目的:在制订鼻咽癌的调强放射治疗(intensity-modulated radiotherapy,IMRT)计划时,通过比较传统的剂量-体积(dose-volume,DV)物理优化方法,与联合运用DV物理优化方法和广义等效均匀剂量(generalized equivalent uniform dose optimization,gEUD)优化方法的鼻咽癌放疗计划中的剂量学差异,探讨不同的优化方法对IMRT计划中危及器官(organ at risk,OAR)的保护作用。方法:随机选取2019—2021年复旦大学附属眼耳鼻喉科医院收治的鼻咽癌患者50例,将每例计划都同时采用两组优化方案进行优化计算:A组仅采用传统的DV物理优化方法;B组采用联合DV优化和gEUD优化方法,其中gEUD的a值分别选取1、2、5、10和20。通过分别观察采用不同的优化方案及不同的a值所获得的腮腺和口腔等OAR的剂量数据结果,从而评估两组优化方案的剂量学差异。结果:比较分析两组方案的计划数据,其中靶区的剂量学指标差异无统计学意义(P>0.05)。但在腮腺和口腔的保护方面,B组优化方案的结果明显优于A...     

62例局部晚期NSCLC三维适形放射治疗中放射性肺炎相关因素分析

目的：探讨接受三维适形放射治疗局部晚期非小细胞肺癌（non-small cell lung cancer,NSCLC）患者发生放射性肺炎的相关因素。方法：62例不能手术切除局部晚期NSCLC患者放疗前1周行肺功能检测,分析患者性别、年龄、临床分期、病理类型、病变部位、同步化疗、吸烟状况、合并慢性阻塞性肺病与否、肿瘤位置、肿瘤体积和剂量参数V10、V20、V30以及肺功能指标与放射性肺炎的关系。结果：62例患者中11例发生放射性肺炎,其中3例发生于放疗中,8例发生于放疗后1个月内。单因素分析有统计学差异的相关因素为肺功能状态、肿瘤体积、肺剂量体积参数（P=0.002,P=0.000,P=0.032）;经过Logistic回归模型多因素分析,放疗前合并重度慢性阻塞性肺病、病变位于肺下叶、肿瘤直径〉5cm以及V30〉25%为放射性肺损伤发生的显著相关因素（P=0.047,P=0.035,P=0.040和0.002）。结论：放射性肺损伤是多因素综合影响结果,对肺部有慢性疾病患者应优选治疗方案,且控制肺V30〈25%。     

剂量体积联合等效均匀剂量优化在肝癌调强放疗中的应用

目的：探讨剂量-体积（dose-volume,DV）联合等效均匀剂量（Equivalent uniform dose，EUD）目标函数对肝癌调强放疗计划优化的影响。方法：随机选取20例原发性肝癌患者，对每例患者先做DV物理约束作为优化条件的计划，然后在保持物理约束条件不变的基础上，将危及器官增加最大EUD和靶区增加最小EUD的约束条件，重新优化计划。比较单纯使用DV目标函数优化计划和DV联合EUD目标函数优化计划对靶区和危及器官剂量学差异。结果：两组计划均能满足临床治疗要求。单纯DV优化和DV联合EUD优化（DV+EUD）的靶区剂量、CI和HI均无统计学差（P>0.05）；DV+EUD优化使正常肝的所受剂量较纯物理DV优化明显减小，同时肝，肾脏、胃、小肠等平均剂量也减低明显,差异具有统计学意义（P<0.05）。结论：DV+EUD优化应用到肝癌患者调强放射治疗中可以在满足靶区剂量临床要求的同时，更好地保护正常组织。     

62例局部晚期NSCLC三维适形放射治疗中放射性肺炎相关因素分析

目的:探讨接受三维适形放射治疗局部晚期非小细胞肺癌(non-small cell lung cancer,NSCLC)患者发生放射性肺炎的相关因素。方法:62例不能手术切除局部晚期NSCLC患者放疗前1周行肺功能检测,分析患者性别、年龄、临床分期、病理类型、病变部位、同步化疗、吸烟状况、合并慢性阻塞性肺病与否、肿瘤位置、肿瘤体积和剂量参数V10、V20、V30以及肺功能指标与放射性肺炎的关系。结果:62例患者中11例发生放射性肺炎,其中3例发生于放疗中,8例发生于放疗后1个月内。单因素分析有统计学差异的相关因素为肺功能状态、肿瘤体积、肺剂量体积参数(P=0.002,P=0.000,P=0.032);经过Logistic回归模型多因素分析,放疗前合并重度慢性阻塞性肺病、病变位于肺下叶、肿瘤直径>5cm以及V30>25%为放射性肺损伤发生的显著相关因素(P=0.047,P=0.035,P=0.040和0.002)。结论:放射性肺损伤是多因素综合影响结果,对肺部有慢性疾病患者应优选治疗方案,且控制肺V30<25%。     

非小细胞肺癌三维适形放疗放射性肺损伤剂量学因素分析

目的 观察非小细胞肺癌三维适形放疗患者急性放射性肺炎的发生情况,并分析其与各剂 量学因素的关系。方法 收集2010年6月—2010年12月间首程行三维适形放疗的非小细胞肺癌患者68 例。从治疗计划系统的剂量体积直方图中获取以下剂量学参数：处方剂量、平均肺剂量(MLD)、正常 肺体积剂量（V5~V50间隔5 Gy）等,分别采用单因素及多因素分析各个剂量学参数与放射性肺炎之 间的关系,并采用受试者工作特征曲线寻找预测界值。结果 V5是放射性肺炎发生的独立预后因素 （χ2=5.15,P=0.023）。患者肺脏的V5超过57%时放射性肺炎的发生率可能会增加。结论 临床医师 在审核治疗计划时,除了要考虑V20、V30、MLD等常用参数外,还应关注V5的大小。     

VMAT下肺等效均匀剂量预测RP价值研究

目的 对VMAT下基于肺等效均匀剂量的放射性肺炎预测价值的临床应用效果进行评价及最优化a值的搜寻。 方法 选取2015—2016年间接受过VMAT的 65例肺癌患者,根据放疗结束后有无RP分成两组,导出DVH等信息,用自编数值分析程序进行数据分析。分别计算a在-50~50区间两组肺等效均匀剂量值变化,找出两组相对肺等效均匀剂量值差距最大的a值。采用成组t检验对发生和未发生放射性肺炎的 V₅、V₂₀、V₃₀、MLD和肺等效均匀剂量(a_optimal)进行分析;采用Pearson相关分析法分析V_dose和肺等效均匀剂量(a_optimal)与RP之间关系;采用 Logistic回归方法建立疾病预测模型。 结果 a=0.3时发生和未发生组肺等效均匀剂量相对差取得最大值(627.94 cGy和510.23 cGy,相对剂量差 R=23.07%)。相对差R在-50~-5区间缓慢减少,在-5~0急剧增加且在a=0.3时取得最大值;在a从 0.3~4.0区间快速减小后直到研究终点50都趋于缓慢减小趋势。传统物理容积剂量阈值相关性分析也提示肺等效均匀剂量(a=0.3时)和 V₅、V₁₀、V₂₀、MLD有相关性(r=0.929,P<0.05)。 结论 采用VMAT技术进行胸部肿瘤放疗患者,肺等效均匀剂量(a=0.3时)能较好区分有无肺炎两组,建议肺等效均匀剂量限制在510 cGy内,肺等效均匀剂量和常规物理剂量相结合对非均匀照射条件下RP有一定临床预测价值。     

Dose-volume histogram analysis as predictor of radiation pneumonitis in primary lung cancer patients treated with radiotherapy

PURPOSE: To determine the relationship between various parameters derived from lung dose-volume histogram analysis and the risk of symptomatic radiation pneumonitis (RP) in patients undergoing radical radiotherapy for primary lung cancer. METHODS AND MATERIALS: The records of 156 patients with lung cancer who had been treated with radical radiotherapy (>/=45 Gy) and for whom dose-volume histogram data were available were reviewed. The incidence of symptomatic RP was correlated with a variety of parameters derived from the dose-volume histogram data, including the volume of lung receiving 10 Gy (V(10)) through 50 Gy (V(50)) and the mean lung dose (MLD). RESULTS: The rate of RP at 6 months was 15% (95% confidence interval 9-22%). On univariate analysis, only V(30) (p = 0.036) and MLD (p = 0.043) were statistically significantly related to RP. V(30) correlated highly positively with MLD (r = 0.96, p < 0.001). CONCLUSION: V(30) and MLD can be used to predict the risk of RP in lung cancer patients undergoing radical radiotherapy.     

Modeling radiation pneumonitis risk with clinical, dosimetric, and spatial parameters

PURPOSE: To determine the clinical, dosimetric, and spatial parameters that correlate with radiation pneumonitis. METHODS AND MATERIALS: Patients treated with high-dose radiation for non-small-cell lung cancer with three-dimensional treatment planning were reviewed for clinical information and radiation pneumonitis (RP) events. Three-dimensional treatment plans for 219 eligible patients were recovered. Treatment plan information, including parameters defining tumor position and dose-volume parameters, was extracted from non-heterogeneity-corrected dose distributions. Correlation to RP events was assessed by Spearman's rank correlation coefficient (R). Mathematical models were generated that correlate with RP. RESULTS: Of 219 patients, 52 required treatment for RP (median interval, 142 days). Tumor location was the most highly correlated parameter on univariate analysis (R = 0.24). Multiple dose-volume parameters were correlated with RP. Models most frequently selected by bootstrap resampling included tumor position, maximum dose, and D35 (minimum dose to the 35% volume receiving the highest doses) (R = 0.28). The most frequently selected two- or three-parameter models outperformed commonly used metrics, including V20 (fractional volume of normal lung receiving >20 Gy) and mean lung dose (R = 0.18). CONCLUSIONS: Inferior tumor position was highly correlated with pneumonitis events within our population. Models that account for inferior tumor position and dosimetric information, including both high- and low-dose regions (D(35), International Commission on Radiation Units and Measurements maximum dose), risk-stratify patients more accurately than any single dosimetric or clinical parameter.     

肺癌、纵隔肿瘤及食管癌放疗后放射性肺炎发生因素的对比研究

 目的　对肺癌（肺靶区）与纵隔肿瘤及食管癌（纵隔靶区）三维适形放疗中放射性肺炎（RP）发生的影响因素及剂量体积直方图（DVH）参数进行对比研究。方法　回顾性分析接受放射治疗的肺癌、纵隔肿瘤及食管癌患者83例的临床资料,采用χ2 检验对临床因素（性别、年龄、肿瘤部位、分期、化疗）与RP发生的相关性进行分析;分别对两靶区的DVH参数与RP的发生进行相关性分析;用t检验对肺靶区与纵隔靶区DVH参数进行比较。结果　≥2级 RP 发生率为36.5 %（31／81）。各临床因素与≥2级RP发生无关（χ2 值分别为0.377、0.215、0.018、0.717、0.215,均P＞0.05）。两靶区的DVH参数中,V5、V10、V20、V30、全肺平均剂量（MLD）与RP的发生均具有明显相关性。两靶区发生RP的患者V5[（50.9±17.8）%、（69.9±20.4）%]（t＝2.745,P＜0.05）、V10[（38.6±15.2）%、（53.5±18.8）%]（t＝2.434,P＜0.05）差异均有统计学意义,而V20（t＝0.388,P＞0.05）、V30（t＝0.005,P＞0.05）及MLD（t＝0.138,P＞0.05）差异均无统计学意义。两靶区未发生RP患者的DVH参数t检验后得到类似结果。结论　在肺靶区、纵隔靶区的放疗中,RP的发生与DVH参数密切相关,尤其是V20、V30及MLD对RP的发生有重要的影响。     

Evaluation of the Radiation Pneumonia Development Risk in Lung Cancer Cases

Background: Concurrent chemo-radiotherapy is the recommended standard treatment modality for patients with locally advanced lung cancer. The purpose of three-dimensional conformal radiotherapy (3DCRT) is to minimize normal tissue damage while a high dose can be delivered to the tumor. The most common dose limiting side effect of thoracic RT is radiation pneumonia (RP). In this study we evaluated the relationship between dose-volume histogram parameters and radiation pneumonitis. This study targeted prediction of the possible development of RP and evaluation of the relationship between dose-volume histogram (DVH) parameters and RP in patients undergoing 3DCRT. Materials and Methods: DVHs of 41 lung cancer patients treated with 3DCRT were evaluated with respect to the development of grade ≥ 2 RP by excluding gross tumor volume (GTV) and planned target volume (PTV) from total (TL) and ipsilateral (IPSI) lung volume. Results: Were admitted statistically significant for p<0.05. Conclusions: The cut-off values for V5, V13, V20, V30, V45 and the mean dose of TL-GTV; and V13, V20,V30 and the mean dose of TL-PTV were statistically significant for the development of Grade ≥2 RP. No statistically significant results related to the development of Grade ≥2 RP were observed for the ipsilateral lung and the evaluation of PTV volume. A controlled and careful evaluation of the dose-volumehistograms is important to assess Grade ≥2 RP development of the lung cancer patients treated with concurrent chemo-radiotherapy. In the light of the obtained data it can be said that RP development may be avoided by the proper analysis of the dose volume histograms and the application of optimal treatment plans.     

Potential for radiation therapy technology innovations to permit dose escalation for non-small-cell lung cancer

BACKGROUND: Innovations in radiation therapy (RT) technology could have the potential to allow for radiation dose escalation by evaluating tumor motion, minimizing and compensating for motion, and evaluating delivery technologies such as 3-dimensional (3D) conformal radiation therapy (CRT) and intensity-modulated RT (IMRT) using tomotherapy. MATERIALS AND METHODS: Ninety different RT plans were generated using 3 different treatment techniques for 10 patients. These were evaluated using dosimetric tools such as dose-volume histogram (DVH) analysis, tumor equivalent uniform dose (EUD), and dosimetric parameters predictive for lung toxicity, such as the volume of lung receiving > 20 Gy of radiation (V20) and the normalized mean total radiation dose to the lung (NTDmean). The 3 techniques studied included free breathing using 3D CRT, 3D CRT with maximum-inspiration breath-hold (MIBH) to minimize tumor motion, and IMRT delivery with MIBH; the combination of 3 separate planning treatment-volume sets resulted in the generation of 90 different treatment plans. To plan these, patients underwent treatment-planning computed tomography in MIBH and free breathing followed by simulation with measurement of tumor motion and generation/evaluation of DVHs, EUDs, V20, and NTDmean. RESULTS: Average tumor motion was 1.54 cm in the cephalocaudad directions, 1.26 cm in the anteroposterior directions, and 0.56 cm in the lateral directions between maximum inspiration and expiration. Maximum-inspiration breath-hold produced superior lung sparing evidenced by lower V20 and NTDmean values, and these parameters predicted lower modeled pneumonitis rates. Tomotherapy-based IMRT provided further lung sparing. CONCLUSION: Treatment in MIBH results in lower V20 and NTDmean values and lower modeled pneumonitis rates. This effect is enhanced by the use of IMRT. The use of MIBH with IMRT may therefore aid in escalating the dose in RT.     

Time and dose-related changes in lung perfusion after definitive radiotherapy for NSCLC

Background and purpose

To examine radiation-induced changes in regional lung perfusion per dose level in 58 non-small-cell lung cancer (NSCLC) patients treated with intensity-modulated radiotherapy (IMRT).

Optimizing radiation treatment plans for lung cancer using lung perfusion information.

PURPOSE: To study the impact of incorporation of lung perfusion information in the optimization of radical radiotherapy (RT) treatment plans for patients with medically inoperable non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: The treatment plans for a virtual phantom and for five NSCLC patients with typical defects of pre-RT lung perfusion were optimized to minimize geometrically determined parameters as the mean lung dose (MLD), the lung volume receiving more than 20 Gy (V20), and the functional equivalent of the MLD, using perfusion-weighted dose-volume histograms. For the patients the (perfusion-weighted) optimized plans were compared to the clinically applied treatment plans. RESULTS: The feasibility of perfusion-weighted optimization was demonstrated in the phantom. Using perfusion information resulted in an increase of the weights of those beams that were directed through the hypo-perfused lung regions both for the phantom and for the studied patients. The automatically optimized dose distributions were improved with respect to lung toxicity compared with the clinical treatment plans. For patients with one hypo-perfused hemi-thorax, the estimated gain in post-RT lung perfusion was 6% of the prescribed dose compared to the geometrically optimized plan. For patients with smaller perfusion defects, perfusion-weighted optimization resulted in the same plan as the geometrically optimized plan. CONCLUSION: Perfusion-weighted optimization resulted in clinically well applicable treatment plans, which cause less radiation damage to functioning lung for patients with large perfusion defects.     

Ⅲ+Ⅳ期非小细胞肺癌三维适形或调强放疗中复合指标预测放射性肺炎前瞻性临床研究

目的 探讨非小细胞肺癌三维适形或调强放疗正常肺V5和V10联合V20评价放射性肺炎(RP)的意义.方法 采用三维适形或调强后程加速超分割放疗经病理或细胞学证实初治非小细胞肺癌患者90例,其中Ⅲa期6例、Ⅲb期29例、Ⅳ期55例.放疗剂量61～80 Gy,中位数70 Gy.由剂量体积直方图计算全肺V5、V10、V20、V30、平均肺剂量(MLD),对侧肺V5、V10及同侧肺V30.用CTC3.0标准评估肺损伤.结果 90例患者中发生RP为1级29例、2级23例、3级5例、4级1例、5级1例.全肺V5、V10、V20、对侧肺V10、大体肿瘤体积(GTV)、计划靶体积、射野数目与≥1级RP相关(χ2=2.04、2.05、2.01、4.62、6.50、5.61、5.61,P=0.044、0.043、0.047、0.030、0.010、0.020、0.020),全肺V5、V10、V20和V30、MLD与≥2级RP相关(χ2=2.05、2.20、2.96、4.96、5.20,P=0.040、0.030、0.000、0.030、0.020).多因素分析显示GTV与≥1级RP发生相关(χ2=4.06,P=0.044),V20与≥2级RP发生相关(χ2=9.61,P=0.002).全肺V5、V10、V20的中位数分别为66%、48%、31%.V20>31%时≥2级RP概率增加,V20>31%+V10>48%+V5>66%时≥2级RP概率增加,V20>31%+V5>66%时≥2级RP概率增加;V20>31%时V10>48%与<48%比较RP概率相似,V20≤31%时V5>66%与<66%、V10>48%与<48%比较RP概率也相似.性别、年龄、临床分期、病理类型、治疗方式、KPS与≥1、2级RP无关.结论 肺V5、V10联合V20评价放射性肺炎的发生可能提高预测放射性肺炎的能力.     

Clinical dose-volume histogram analysis in predicting radiation pneumonitis in Hodgkin's lymphoma

PURPOSE: To quantify the incidence of radiation pneumonitis (RP) in a modern Hodgkin's lymphoma (HL) cohort, and to identify any clinically relevant parameters that may influence the risk of RP. METHODS AND MATERIALS: Between January 2003 and February 2005, 64 consecutive HL patients aged 18 years or older receiving radical mediastinal radiation therapy (RT) were retrospectively reviewed. Symptomatic cases of radiation pneumonitis were identified. Dose-volume histogram parameters, including V(13), V(20), V(30), and mean lung dose (MLD), were quantified. RESULTS: At a median follow-up of 2.1 years, the actuarial survival for all patients was 91% at 3 years. There were 2 (2/64) cases of Radiation Therapy Oncology Group (RTOG) Grade 2 RP (incidence 3.1%). Both index cases with corresponding V(20) values of 47.0% and 40.7% were located in the upper quartile (2/16 cases), defined by a V(20) value of > or =36%, an incidence of 12.5% (p = 0.03). Similarly for total MLD, both index cases with values of 17.6 Gy and 16.4 Gy, respectively, were located in the upper quartile defined by MLD > or =14.2 Gy, an incidence of 11.8% (2/17 cases, p = 0.02). CONCLUSIONS: Despite relatively high V(20) values in this study of HL patients, the incidence of RP was only 3%, lower compared with the lung cancer literature. We suggest the following clinically relevant parameters be considered in treatment plan assessment: a V(20) greater than 36% and an MLD greater than 14 Gy, over and above which the risk of RTOG Grade 2 or greater RP would be considered clinically significant.