淋巴瘤靶区勾画和计划设计指南北大核心CSCD

放疗是淋巴瘤综合治疗的重要组成,在不同病理亚型、不同化疗反应患者中可以实施根治性、巩固性或姑息性放疗。随着化疗演进和对放疗长期不良反应的研究,近10年淋巴瘤放疗靶区和剂量发生巨大变革。本指南针对中国发病率较高的淋巴瘤亚型,选择放疗科最常见的淋巴瘤放疗情形,结合国内外研究数据、当今国内外指南和专家意见,以当前最优化的放疗实施流程为目标,建立从体位固定、靶区勾画、处方剂量到计划制订和评估的标准操作流程,以推动临床应用、提高医疗质量、提高临床疗效并减少不良反应。     

淋巴瘤靶区勾画和计划设计指南

放疗是淋巴瘤综合治疗的重要组成,在不同病理亚型、不同化疗反应患者中可以实施根治性、巩固性或姑息性放疗。随着化疗演进和对放疗长期不良反应的研究,近10年淋巴瘤放疗靶区和剂量发生巨大变革。本指南针对中国发病率较高的淋巴瘤亚型,选择放疗科最常见的淋巴瘤放疗情形,结合国内外研究数据、当今国内外指南和专家意见,以当前最优化的放疗实施流程为目标,建立从体位固定、靶区勾画、处方剂量到计划制订和评估的标准操作流程,以推动临床应用、提高医疗质量、提高临床疗效并减少不良反应。     

Quality assurance in radiotherapy of breast cancer--variability in planning target volume delineation

The inter-physician and inter-patient variability in planning target volume delineation for the radiotherapy of breast cancer after conservative surgery is presented. Eleven experienced radiation oncologists determined the planning target volume (PTV) for four breast cancer patients. Delineation was based on CT slices taken at intervals of 15 mm. The variability in target volume delineation was determined by measuring the volumes in units of cc and the position of the drawn PTVs. Statistical analysis was based on X/R-charts and on Pareto chart and analysis. The maximum range in PTV for one patient was from 670 to 1200 cc. The observations of three physicians were in excess of the warning limit altogether 18 times. The methods used in this study clearly reveal inter-physician variability in PTV delineation and widest variations found are not acceptable. Training targeted to some physicians and more detailed and unambiguous protocols for PTV delineation are needed.     

乳腺癌术后放疗靶区勾画和计划设计指南

乳腺癌术后辅助放射治疗是乳腺癌综合治疗的重要组成部分,规范开展放射治疗对于乳腺癌患者的长期疗效和生活质量都至关重要。本指南涵盖了乳腺癌术后放疗适应证选择、定位、靶区和危及器官勾画、放疗剂量和分割方式、危及器官剂量限制、计划设计等全流程的质量标准,旨在提升国内各放疗单位开展乳腺癌术后放疗的规范化水平,为各单位结合本单位设备特点和患者治疗情况,制定更为细致的标准操作程序提供参考。     

乳腺癌术后放疗靶区勾画和计划设计指南北大核心CSCD

乳腺癌术后辅助放射治疗是乳腺癌综合治疗的重要组成部分,规范开展放射治疗对于乳腺癌患者的长期疗效和生活质量都至关重要。本指南涵盖了乳腺癌术后放疗适应证选择、定位、靶区和危及器官勾画、放疗剂量和分割方式、危及器官剂量限制、计划设计等全流程的质量标准,旨在提升国内各放疗单位开展乳腺癌术后放疗的规范化水平,为各单位结合本单位设备特点和患者治疗情况,制定更为细致的标准操作程序提供参考。     

Investigating the clinical aspects of using CT vs. CT-MRI images during organ delineation and treatment planning in prostate cancer radiotherapy

In order to apply highly conformal dose distributions, which are characterized by steep dose fall-offs, it is necessary to know the exact target location and extension. This study aims at evaluating the impact of using combined CT-MRI images in organ delineation compared to using CT images alone, on the clinical results. For 10 prostate cancer patients, the respective CT and MRI images at treatment position were acquired. The CTV was delineated using the CT and MRI images, separately, whereas bladder and rectum were delineated using the CT images alone. Based on the CT and MRI images, two CTVs were produced for each patient. The mutual information algorithm was used in the fusion of the two image sets. In this way, the structures drawn on the MRI images were transferred to the CT images in order to produce the treatment plans. For each set of structures of each patient, IMRT and 3D-CRT treatment plans were produced. The individual treatment plans were compared using the biologically effective uniform dose () and the complication-free tumor control probability (P(+)) concepts together with the DVHs of the targets and organs at risk and common dosimetric criteria. For the IMRT treatment, at the optimum dose level of the average CT and CT-MRI delineated CTV dose distributions, the P(+) values are 74.7% in both cases for a of 91.5 Gy and 92.1 Gy, respectively. The respective average total control probabilities, PB are 90.0% and 90.2%, whereas the corresponding average total complication probabilities, P(I) are 15.3% and 15.4%. Similarly, for the 3D-CRT treatment, the average P(+) values are 42.5% and 46.7%, respectively for a of 86.4 Gy and 86.7 Gy, respectively. The respective average P(B) values are 80.0% and 80.6%, whereas the corresponding average P(I) values are 37.4% and 33.8%, respectively. For both radiation modalities, the improvement mainly stems from the better sparing of rectum. According to these results, the expected clinical effectiveness of IMRT can be increased by a maximum ΔP(+) of around 0.9%, whereas of 3D-CRT by about 4.2% when combined CT-MRI delineation is performed instead of using CT images alone. It is apparent that in both IMRT and 3D-CRT radiation modalities, the better knowledge of the CTV extension improved the produced dose distribution. It is shown that the CTV is irradiated more effectively, while the complication probabilities of bladder and rectum, which is the principal organs at risk, are lower in the CT-MRI based treatment plans.     

The Dilemma of Target Delineation with PET/CT in Radiotherapy Planning for Malignant Tumors

Currently there are many unanswered questions concerning contouring a target with PET/CT in radiotherapy planning.Who should contour the PET volume-the radiation oncologist or the nuclear medicine physician?Which factors will contribute to the dual-observer variability between them?What should be taken as the optimal SUV threshold to demarcate a malignant tumor from the normal tissue?When the PET volume does not coincide with the local area CT findings,which portion should be contoured as the target?If a reginal lymph node draining area or a remote region is shown to be PET positive but CT negative,or PET negative but CT positive,how is the target identified and selected?Further studies concerning the relationship between PET/CT and the cancerous tissue are needed.The long-term clinical results showing an increased therapeutic ratio wil finaly verify the applicability of guidelines to contour the target with PET/CT in radiotherapy planning.     

前列腺癌重碳离子放疗计划与调强放疗计划的比较

目的比较前列腺癌重碳离子放疗（C-ion RT）与调强放疗（IMRT）在剂量学方面的差异。方法随机选取5例前列腺癌患者,分别设计4野共面的C-ion RT计划和7野共面的IMRT计划。剂量均采用百分剂量,95％的等剂量面必须包括100％的计划靶体积（PTV）。比较靶区剂量分布的适形度指数（CI）和异质性指数（IC）,根据剂量体积直方图（DVH）,比较相同剂量水平下C-ion RT计划与IMRT计划中周围器官及非靶区正常组织的照射体积。结果在C—-ion RT计划中,CI50%、CI94%、IC分别为3．36、1．20和0．03,与IMRT计划比较差异有统计学意义（P均〈0．01）,靶区剂量分布的CI和IC均优于IMRT计划。除了95％的剂量水平外,在10％、30％、50％、70％和90％剂量水平,采用C—ion RT均可明显减少直肠的受照射体积（P均〈0．05）,同时完全保护直肠的后壁;在任何剂量水平,C—ion RT可明显减少膀胱和非靶区正常组织的受照射体积（P均〈0．05）;在10％、20％、30％和40％剂量水平,C—ion RT可明显减少双侧股骨头的受照射体积（P均〈0．05）。结论在前列腺癌的放射治疗中,与IMRT计划相比,C—ion RT计划在剂量学方面有明显优势,C—ion RT的这些优势将能够进一步提高前列腺癌的局部控制率,减少放疗引起的并发症。     

ABAS软件勾画OAR临床前测试重要性研究

目的 对基于模板自动分区(ABAS)算法的图像勾画软件进行临床前测试,评估鼻咽癌放疗计划OAR勾画精度,为确定临床应用条件提供依据。方法 以放疗医师在22例鼻咽癌患者放疗计划CT图像上手工勾画的OAR结构为评价标准,分别对ABAS软件两种算法(General和Head/Neck)自动勾画的OAR进行以下测试:(1)每1例患者均拷贝1套图像,以原图像上手工勾画的轮廓为模板在拷贝图像上自动勾画,考察自动勾画对模板的还原能力;(2)以1例患者图像上手工勾画的轮廓为模板,对其余患者图像进行自动勾画,考察采用单一模板对不同患者图像自动勾画的准确度。评价指标包括各OAR的DSC、V_diff、DSC与勾画体积相关性,以及自动勾画加手工修改与单纯手工勾画的耗时差别。Wilcoxon符号秩检验,Spearman相关性分析。结果 Head/Neck算法对模板还原能力优于或相当于General算法,自动勾画DSC与所勾画结构体积大小呈正相关(r_s=0.879、0.939)。还原测试中体积>1 cm³器官自动勾画的DSC>0.8。使用Head/Neck算法基于单一模板的自动勾画中,脑干、颞叶、腮腺、下颌骨的DSC和V_diff平均值分别为0.81~0.90和2.73%~16.02%,颞颌关节和视交叉DSC为0.45~0.49。应用自动勾画加手工修改比单纯手工勾画可以节省68%时间。结论 临床前测试可以确定ABAS算法在特定临床应用条件的准确度和适用范围,所测试软件可帮助提高鼻咽癌放疗计划OAR勾画效率,但不适用于较小体积器官的勾画。     

Target volume delineation for partial breast radiotherapy planning: clinical characteristics associated with low interobserver concordance

PURPOSE: To examine variability in target volume delineation for partial breast radiotherapy planning and evaluate characteristics associated with low interobserver concordance. METHODS AND MATERIALS: Thirty patients who underwent planning CT for adjuvant breast radiotherapy formed the study cohort. Using a standardized scale to score seroma clarity and consensus contouring guidelines, three radiation oncologists independently graded seroma clarity and delineated seroma volumes for each case. Seroma geometric center coordinates, maximum diameters in three axes, and volumes were recorded. Conformity index (CI), the ratio of overlapping volume and encompassing delineated volume, was calculated for each case. Cases with CI 相似文献   

A method for generating large datasets of organ geometries for radiotherapy treatment planning studies

Background

With the rapidly increasing application of adaptive radiotherapy, large datasets of organ geometries based on the patient’s anatomy are desired to support clinical application or research work, such as image segmentation, re-planning, and organ deformation analysis. Sometimes only limited datasets are available in clinical practice. In this study, we propose a new method to generate large datasets of organ geometries to be utilized in adaptive radiotherapy.

Methods

Given a training dataset of organ shapes derived from daily cone-beam CT, we align them into a common coordinate frame and select one of the training surfaces as reference surface. A statistical shape model of organs was constructed, based on the establishment of point correspondence between surfaces and non-uniform rational B-spline (NURBS) representation. A principal component analysis is performed on the sampled surface points to capture the major variation modes of each organ.

Results

A set of principal components and their respective coefficients, which represent organ surface deformation, were obtained, and a statistical analysis of the coefficients was performed. New sets of statistically equivalent coefficients can be constructed and assigned to the principal components, resulting in a larger geometry dataset for the patient’s organs.

Conclusions

These generated organ geometries are realistic and statistically representative.     

Uncertainties in model-based outcome predictions for treatment planning

Purpose: Model-based treatment-plan-specific outcome predictions (such as normal tissue complication probability [NTCP] or the relative reduction in salivary function) are typically presented without reference to underlying uncertainties. We provide a method to assess the reliability of treatment-plan-specific dose–volume outcome model predictions.

Methods and Materials: A practical method is proposed for evaluating model prediction based on the original input data together with bootstrap-based estimates of parameter uncertainties. The general framework is applicable to continuous variable predictions (e.g., prediction of long-term salivary function) and dichotomous variable predictions (e.g., tumor control probability [TCP] or NTCP). Using bootstrap resampling, a histogram of the likelihood of alternative parameter values is generated. For a given patient and treatment plan we generate a histogram of alternative model results by computing the model predicted outcome for each parameter set in the bootstrap list. Residual uncertainty (“noise”) is accounted for by adding a random component to the computed outcome values. The residual noise distribution is estimated from the original fit between model predictions and patient data.

Results: The method is demonstrated using a continuous-endpoint model to predict long-term salivary function for head-and-neck cancer patients. Histograms represent the probabilities for the level of posttreatment salivary function based on the input clinical data, the salivary function model, and the three-dimensional dose distribution. For some patients there is significant uncertainty in the prediction of xerostomia, whereas for other patients the predictions are expected to be more reliable. In contrast, TCP and NTCP endpoints are dichotomous, and parameter uncertainties should be folded directly into the estimated probabilities, thereby improving the accuracy of the estimates. Using bootstrap parameter estimates, competing treatment plans can be ranked based on the probability that one plan is superior to another. Thus, reliability of plan ranking could also be assessed.

Conclusions: A comprehensive framework for incorporating uncertainties into treatment-plan-specific outcome predictions is described. Uncertainty histograms for continuous variable endpoint models provide a straightforward method for visual review of the reliability of outcome predictions for each treatment plan.     

Metal artefact reduction for accurate tumour delineation in radiotherapy

Background and purpose

Two techniques for metal artefact reduction for computed tomography were studied in order to identify their impact on tumour delineation in radiotherapy.

Guidelines for delineation of lymphatic clinical target volumes for high conformal radiotherapy: head and neck region

The success of radiotherapy depends on the accurate delineation of the clinical target volume. The delineation of the lymph node regions has most impact, especially for tumors in the head and neck region. The purpose of this article was the development an atlas for the delineation of the clinical target volume for patients, who should receive radiotherapy for a tumor of the head and neck region. Literature was reviewed for localisations of the adjacent lymph node regions and their lymph drain in dependence of the tumor entity. On this basis the lymph node regions were contoured on transversal CT slices. The probability for involvement was reviewed and a recommendation for the delineation of the CTV was generated.     

Automated beam angle and weight selection in radiotherapy treatment planning applied to pancreas tumors

PURPOSE: To extend and investigate the clinical value of a recently developed algorithm for automatic beam angle and beam weight selection, for irradiation of pancreas tumors. METHODS AND MATERIALS: The algorithm aims at generation of acceptable treatment plans, i.e., delivering the prescribed tumor dose while strictly obeying the imposed hard constraints for organs at risk and target. Extensions were made to minimize the beam number and/or to escalate the tumor dose. For 5 pancreas patients, the clinical value and the potential for beam number reduction and dose escalation were investigated. Comparisons were made with clinical plans and equiangular plans. RESULTS: Compared to clinical plans, the generated plans with the same number of beams yielded a substantial reduction in the dose to critical tissues. Using the algorithm, an escalated tumor dose of 58 Gy could be achieved for two cases. Maximum dose escalations required a minimum of 3 to 4 beam orientations. For 13 CT slices and an in-slice resolution of 0.5 cm, the total calculation times were 23-55 min, including precalculation of 180 input dose distributions (15 min). CONCLUSIONS: The algorithm yielded acceptable treatment plans with clinically feasible numbers of beams, even for escalated tumor doses. Generated plans were superior to the clinically applied plans and to equiangular setups. Calculation times were clinically acceptable. The algorithm is now increasingly used in clinical routine.     

Radical external radiotherapy for prostatic carcinoma

From 1965 through 1974, 88 patients with Stage B or C prostatic carcinoma were treated with radical megavoltage therapy. Treatment technique was small field arc alone for Stage B and 4 field box whole pelvis irradiation to 4400 or 5000 rad with small field rotational boost for Stage C. All were at risk for 5 years and 30 for 10 years or more. None of the 14 Stage B patients have died of cancer, although one is living with metastases. In Stage C (74 patients) uncorrected actuarial survival was 55% ± 5.8 (5 year) and 28% ± 6.5 (10 year). When corrected for intercurrent deaths, survival was 65 % ± 5.8 (5 year) and 37 % ± 8.1. Survival curves for those patients receiving 6000–6900 rad were not significantly different from those receiving 7000 rad or more. Local control may be better in the latter group, 82.7% (43/52) versus 71.4% (20/28), although this is, not significant. Thirty-one percent of local failures appeared after 5 years. Whole pelvis dose of 5000 rad was associated with a higher 5 and 10 year survival than 4400 rad but the difference was not statistically significant. Comparison between groups treated with radiation alone, versus radiation plus a simultaneous hormonal therapy showed no significant differences in survival, local control or complications. A group of 20 patients who failed hormonal therapy and were then irradiated did less well. Complications were generally mild, but early in the series 2 patients receiving 7500 rad developed ano-rectal necrosis; one of these patients died. More common problems were urethral stricture (12 % ) and ano-rectal stenosis (10%). Changes in technique in 1971 drastically reduced the subsequent complications. The failure of whole pelvic irradiation to improve on the 10 year results of local treatment is discussed.     

Impact of FDG-PET on lung cancer delineation for radiotherapy

Purpose: The purpose of this study is to assess the impact of fused diagnostic F‐18 2‐fluoro‐2‐deoxy‐D‐glucose (FDG) positron emission tomography (PET)/computed tomography (CT) and planning FDG‐PET/CT scans on voluming of lung cancer for radiotherapy. Methods: Five radiation oncologists (ROs), five radiation oncology trainees and a radiologist contoured five cases of non‐small cell lung cancer. The CT alone, the diagnostic FDG‐PET/CT and planning FDG‐PET/CT each registered to the CT, were used to contour three volumes. The concordance index (CI) was used to compare each volume with a reference RO. Results: Although there was considerable inter‐observer variability in CT contouring, there was no significant difference between mean volumes of the gross tumour volume for the RO and radiation oncology trainees using any technique. There was no increase in CI with the addition of PET/CT, either diagnostic or planning, for the RO. However, the volumes of the radiation oncology trainees showed a significant increase in CI from 65.8% with CT alone to 68.0% and 72.3% with diagnostic PET/CT and planning PET/CT, respectively (P = 0.028). Mean variation at the tumour/mediastinum interface was significantly reduced with addition of registered PET/CT. Conclusions: The concordance of RO with the reference RO did not significantly increase with use of integrated FDG PET/CT images. However, the contouring of radiation oncology trainees' became more concordant with the reference.     

Breast cancer after radiotherapy: Risk factors and suggestion for breast delineation as an organ at risk in the prepuberal girl

Patients who survive a cancer occurring during childhood or young adulthood, treated with radiation, are at a very high risk of chronic sequelae and secondary tumours. To reduce this radioinduced morbidity and mortality, efforts are put on reducing the burden of the treatments and a long-term monitoring of these patients is progressively organized. We present a general review of the literature about the risk factors for developing a secondary breast cancer, which is the most frequent secondary tumour in this population. We suggest that contouring the prepubescent breast as an organ at risk may help predict the risk and reduce the dose to the breasts using modern radiotherapy techniques.