A novel method for the evaluation of uncertainty in dose-volume histogram computation

PURPOSE: Dose-volume histograms (DVHs) are a useful tool in state-of-the-art radiotherapy treatment planning, and it is essential to recognize their limitations. Even after a specific dose-calculation model is optimized, dose distributions computed by using treatment-planning systems are affected by several sources of uncertainty, such as algorithm limitations, measurement uncertainty in the data used to model the beam, and residual differences between measured and computed dose. This report presents a novel method to take them into account. METHODS AND MATERIALS: To take into account the effect of associated uncertainties, a probabilistic approach using a new kind of histogram, a dose-expected volume histogram, is introduced. The expected value of the volume in the region of interest receiving an absorbed dose equal to or greater than a certain value is found by using the probability distribution of the dose at each point. A rectangular probability distribution is assumed for this point dose, and a formulation that accounts for uncertainties associated with point dose is presented for practical computations. RESULTS: This method is applied to a set of DVHs for different regions of interest, including 6 brain patients, 8 lung patients, 8 pelvis patients, and 6 prostate patients planned for intensity-modulated radiation therapy. CONCLUSIONS: Results show a greater effect on planning target volume coverage than in organs at risk. In cases of steep DVH gradients, such as planning target volumes, this new method shows the largest differences with the corresponding DVH; thus, the effect of the uncertainty is larger.     

盆腔肿瘤调强与三维适形放疗肠道勾画与剂量-体积限制的研究进展

在盆腔肿瘤的放射治疗过程中,肠道损伤是重要的不良反应.随着调强放射治疗(IMRT)等精准放疗技术的广泛应用,正常组织器官的受照剂量已大幅下降.然而,肠道的不良反应仍限制了靶区剂量的提高.故在给予病灶足够照射剂量的同时,对肠道等重要危及器官(OAR)的保护变得更加重要.目前多数研究采用基于肠管的勾画方法,采用小肠+结肠勾...     

三维适形放疗局部晚期非小细胞肺癌的放射性肺炎风险因素研究

目的分析三维适形放疗(3DCRT)的ⅢA和ⅢB期非小细胞肺癌病例,分别评估≥2、3级放射性肺炎的发生与临床及剂量学参数的关系。方法107例病理组织学证实的ⅢA、ⅢB期非小细胞肺癌接受了平均60(26-74)Gy的3DCRT,其中42例单纯放疗,65例序贯放化疗。记录各临床因素及剂量体积直方图(DVH)参数,观察放疗结束3个月内发生的≥2级放射性肺炎(RP)和≥3级的放射性肺炎(SRP)。分级采用NCICTC3.0标准,统计用SPSS10.0软件包。结果107例共发生放射性肺炎39例,其中2级26例,3级10例,5级3例,SRP标准的13例。对RP单因素分析显示MLD、IMLD、CMLD、IV20-IV35、CV10、CV15、CV40、CV50及V10-V35有统计学意义(P=0.004、0.009、0.047、0.010、0.008、0.014、0.031、0.022、0.016、0.023、0.026、0.048、0.006、0.002、0.027、0.032、0.043),多因素分析显示V20是惟一RP发生的预测因子(P=0.005)。对SRP单因素分析显示MLD、IV20、IV25、IV30、CV5、CV10、V10、V15、V20、V30有统计学意义(P=0.005),多因素分析显示CV10是惟一SRP发生的预测因子(P=0.028)。结论对Ⅲ期非小细胞肺癌3DCRT,DVH参数与放射性肺炎的发生明显相关,其中V20、CV10分别是预测RP、SRP的剂量学指标。     

A new electrophysiologic triad for identification and localization of the critical isthmus in atrial flutter

IntroductionAtypical atrial flutter (AFL) is a supraventricular arrhythmia that can be treated with catheter ablation. However, this strategy yields suboptimal results and the best approach is yet to be defined. Carto® electroanatomical mapping (EAM) version 7 displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to activation and voltage maps. Using these EAM tools, the study aimed to assess the ability of an electrophysiologic triad to identify and localize the critical isthmus in AFL.MethodsRetrospective analysis using Carto® EAM of a single center registry of individuals who underwent left AFL ablation over one year. Subjects with non-left AFL, no high-density EAM, under 2000 points or no left atrium wall or structure mapping were excluded. Sites where arrhythmia is terminated via ablation were compared to an electrophysiologic triad comprising areas of low-voltage (0.05 to 0.3 mV), deep histogram valleys (LAT-valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-valley duration, which included 10% or more of the TCL. The longest LAT-valley was designated as the primary valley, while additional valleys were named as secondary.ResultsA total of nine subjects (six men, median age 75, interquartile range 71-76 years) were included. All patients presented with left AFL and 66% had a history of ablation for atrial fibrillation and/or flutter. The median TCL and collected points were 254 ms (220-290) and 3300 (IQR 2410-3926) points, respectively. All individuals with AFL presented with at least one LAT-valley on the analyzed histograms, which corresponded to heterogeneous low voltage areas (0.05 to 0.3 mV) and affected more than 10% of TCL. Six of the nine patients presented with a secondary LAT-valley. All arrhythmias were terminated successfully following radiofrequency ablation at the primary LAT-valley location. After a minimum three-month follow-up all patients remained in sinus rhythm.ConclusionAn electrophysiologic triad identified the critical isthmus in AFL for all patients. Further studies are needed to assess the usefulness of this algorithm in improving catheter ablation outcomes.     

放疗计划自动分析系统的开发研究

目的开发一款放疗计划自动分析系统,通过智能解析Pinnacle3治疗计划系统(TPS)的治疗计划底层数据,实现放疗计划剂量参数的自动化分析。方法将12例接受放射治疗的食管癌患者的治疗计划纳入研究。自动分析系统自动检索Pinnacle3 TPS数据库,获取12例治疗计划原始数据,并自动解析底层原始数据,重建轮廓、射野和剂量参数,并重新计算剂量分布和"剂量-体积"直方图。通过与在线TPS中原始计划输出体积和剂量数据进行对比,来评估新系统重新计算体积和剂量数据的准确性。结果自动分析系统成功解析治疗计划的底层数据,并重建治疗计划参数。新系统计算轮廓的体积与原计划的体积偏差≤0.1%;重新计算GTV、PGTV、CTV和PTV的Dmax、Dmean、D95和D50等参数,与原计划的剂量偏差≤1.0%;重新计算ROIs的Dmax和Dmean,与原计划的剂量偏差<5%。结论自动分析系统可直接分析Pinnacle3 TPS治疗计划的底层数据,重建治疗计划,计算轮廓体积和剂量参数,与原计划的剂量偏差满足临床要求。     

Shape and position of the haploid peak in flow cytometric sperm histograms for the assessment of andrological diseases

Ejaculates from 45 patients with various andrological diseases and from healthy men were analyzed by flow cytometric DNA measurements. The sperm histograms obtained by this method were subjected to mathematical analysis. The height, width and position of the haploid (1 C) peak proved to be a useful criterion for the discrimination of spermatozoa from patients with heterogeneous testicular disorders (SHTD, "mixed atrophy") and homogeneous testicular disorders (SETD) with delivery of immature spermiogenetic cells as compared to healthy persons.     

动态增强MRI定量参数及其直方图在乳腺癌中的研究进展

乳腺癌的高度异质性影响患者预后。动态增强(DCE)MRI定量参数直方图可反映乳腺癌异质性相关信息。本文就DCE-MRI定量参数及其直方图用于乳腺癌的研究进展进行综述。