Delineation of the QRS complex using the envelope of the e.c.g.

A new algorithm for QRS delineation has been developed. Based on the envelope of the e.c.g. signal a delineation function is defined, which yields a single positive pulse for each complex. From this function the onset and end of the QRS or, alternatively, a fiducial point is determined. To remove low-frequency component such as S-T abnormalities without distortion of the QRS complex, a filter with time-varying characteristics is used. The accuracy of the method has been evaluated in a test set of different QRS complexes obtained from coronary care patients. For QRS onset, the standard deviation of the difference between automated and manual determination was 7 ms in normal beats and 14 ms in ectopic beats. With simulated noise added to each waveform an average dispersion of 7 ms was observed in the recognition of the QRS onset at a signal-to-noise ratio of 15 dB. The corresponding dispersion in the location of a fiducial point was 2 ms. Using simulated e.c.g. data, the stability of the method is demonstrated for transitions between different waveform morphologies. Presented in part at ‘Computers in cardiology’, Florence, 23rd–25th September 1981     

Dose planning variations related to delineation variations in MRI-guided brachytherapy for locally advanced cervical cancer

PurposeTo examine the variability in prescribed dose due to contouring variations in intracavitary image-guided adaptive brachytherapy for cervical cancer. To identify correlations between dosimetric outcomes and delineation uncertainty metrics.Methods and MaterialsA data set from an EMBRACE sub-study on contouring uncertainties was used, consisting of magnetic resonance images of six patients with cervical cancer delineated by 10 experienced observers (target volumes and organs at risk). Two gold standard contours were generated, an expert consensus and the simultaneous truth and performance level estimation. Plans were individually optimised to all of the contour sets (12 in total). Plans were applied to the gold standard contour sets, and dose volume histogram parameters including D₉₀, D₉₈ and D_2cm³ were determined. The variability between plans was assessed. Dose volume histogram parameters and delineation uncertainty metrics were correlated using the Spearman's non-parametric rank correlation.ResultsThere is a dosimetric variability between observers, patients and the gold standard contour used for analysis. Approximately 3 Gy D₉₀ EQD2₁₀ variability (SD) was observed for the CTVHR and 1.2-3.6 Gy D_2cm³ EQD2₃ for the organs at risk. The maximum geometric dimensions of the delineations are most commonly correlated with dosimetry changes. Although the correlations are similar across gold standards, the direction of these correlations differs, indicating that the dosimetric outcomes are dependent on the contour that the plan is optimised to.ConclusionThis study highlights the dosimetric differences interobserver uncertainty in contouring can have for cervical cancer brachytherapy. The importance of carefully choosing a gold standard from which to benchmark is reiterated.     

18F-FDGPET/CT勾画鼻咽癌原发肿瘤体积最适阈值的研究

目的 寻找¹⁸F-FDG PET/CT勾画鼻咽癌大体肿瘤体积（GTV）的最适阈值。 方法 16例初诊鼻咽癌患者在治疗前接受¹⁸F-FDG PET/CT及MRI检查,将MRI/CT融合图像上勾画的肿瘤GTV定义为GTV_f,¹⁸F-FDG PET/CT勾画肿瘤范围为BTV。不同阈值条件下的BTV通过调整最大标准摄取值（SUV_max）的比例得到。将不同阈值条件下的BTV和GTV_f进行比较,当二者在体积及形态学上达到最佳匹配时对应的阈值水平为最适阈值（sTL）。sTL×SUV_max得到相应的最适标准摄取值（sSUV）。 结果 16例患者最适阈值sTL（%）为20.93±6.51, 相应的最适标准摄取值sSUV为2.27±0.48。 sTL与SUV_max呈负相关（R²=0.85,F=78.57,P<0.05）;sSUV与SUV_max呈正相关（R²=0.75,F=41.88,P<0.05）;sTL与GTV_f无相关性。 结论 利用SUV_max阈值法勾画鼻咽癌GTV是可行的,最适阈值不是一个固定数值,与SUV_max相关,与肿瘤体积没有明显相关性。     

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...     

AccuContour软件自动勾画胸腹部肿瘤患者两种胃结构比较

目的 使用基于深度学习的AccuContour软件自动勾画胸腹部肿瘤患者正常胃和胸腔胃结构,对勾画效果进行评估和比较.方法 选取36例胸腹部肿瘤患者,分为2组,其中18例正常胃患者为A组,其余18例食管癌术后胸腔胃患者为B组.使用AccuContour软件在患者的定位CT图像上自动勾画胃结构,对自动勾画和手工勾画的体积...     

基于SPECT/CT同机融合显像内乳前哨淋巴结分布探讨内乳淋巴引流区照射的靶区范围

目的 基于SPECT/CT同机融合显像的内乳前哨淋巴结（IM-SLN）位置分布,探讨内乳淋巴结（IMLN）引流区预防性照射的靶区范围。方法 回顾性选取2014-2018年709例初诊为乳腺癌并在术前对IM-SLN进行了SPECT/CT前哨淋巴结显像检查的患者,其中97例患者IM-SLN显像阳性,显像的IM-SLN总数为136枚。依据放射治疗肿瘤协作组（RTOG）和丹麦乳腺癌合作小组（DBCG）指南勾画IMLN临床靶区（CTV）,分别定义为CTV_RTOG和CTV_DBCG,确定CTV_RTOG及CTV_DBCG与IM-SLN的位置关系。结果 位于第1~5肋间的IM-SLN个数分别为55、41、33、6和1枚,第1~3肋间IM-SLN数占总数的94.9%。CTV_RTOG边缘到IM-SLN中心点及5 mm直径IM-SLN外侧缘的平均距离分别为4.10 mm（95%CI 3.54~4.65 mm）和6.40 mm（95%CI 5.81~6.98 mm）,两者比较差异有统计学意义（t=-30.486,P<0.05）,而CTV_DBCG到两者的平均距离分别为1.60 mm（95%CI 1.16~2.05 mm）和3.34 mm（95%CI 2.78~3.89 mm）,两者比较差异有统计学意义（t=-16.364,P<0.05）。CTV_RTOG边缘到IM-SLN中心点及5 mm直径IM-SLN外侧缘的平均距离均明显大于CTV_DBCG（t=16.640、19.815,P<0.05）。CTV_RTOG、CTV_DBCG分别可覆盖18.4%、60.3%的IM-SLN中心点。覆盖90%及100%的IM-SLN中心点时,CTV_RTOG需外扩8和15 mm,而CTV_DBCG需外扩5和13 mm。设定IM-SLN的直径为5 mm时,覆盖90%及100%的IM-SLN时,CTV_RTOG需外扩11和17 mm,而CTV_DBCG需外扩7和16 mm。结论 基于SPECT/CT显像图像上IM-SLN的分布,内乳淋巴结预防性照射靶区范围包括第1~3肋间是合理的;无论基于RTOG还是DBCG指南所勾画内乳靶区均不足以覆盖90%的IM-SLN。     

International guideline for the delineation of the clinical target volumes (CTV) for nasopharyngeal carcinoma

Purpose

Target delineation in nasopharyngeal carcinoma (NPC) often proves challenging because of the notoriously narrow therapeutic margin. High doses are needed to achieve optimal levels of tumour control, and dosimetric inadequacy remains one of the most important independent factors affecting treatment outcome.

利用四维锥形束CT指导肺癌内靶区的勾画

目的 研究四维锥形束CT(4D-CBCT)指导肺癌内靶区勾画的可行性。方法 简单随机法选取本院24例肺癌患者。平静呼吸下CT模拟定位获得CT图像,首次治疗前4D-CBCT扫描获得4D-CBCT中位图像,将4D图像重建算法更改为3D,获得3D-CBCT图像。图像融合算法取骨配准,分别在定位CT、4D-CBCT中位图像、3D-CBCT图像上勾画大体肿瘤靶区(GTV),定义GTV到临床靶区(CTV)的外扩边界为7 mm,获得CTV_CT、ITV_4D和ITV_3D,基于CTV_CT在三维方向上外扩5 mm得到ITV_CT。比较靶区间中心点位置、体积、相似度和相互包含关系的差异。结果 ITV_CT与ITV_3D在中下叶组的头脚方向上,靶区中心点位置差异有统计学意义(Z=-2.027,P<0.05)。在靶区体积方面,ITV_CT最大,与ITV_3D相比差异有统计学意义(Z=-2.941,P<0.05),ITV_4D最小,但与ITV_3D相比差异无统计学意义(P>0.05)。ITV_CT与ITV_3D相似度均数<75%,ITV_4D与ITV_3D相似度均数>90%(Z=-2.940、-2.975,P<0.05)。ITV_CT、ITV_4D未被ITV_3D包含的比例均数为40%和5%(Z=-2.952、-3.185,P<0.05)。结论 4D-CBCT的中位图像可以缩小内靶区的勾画范围,为肺癌的自适应放疗提供选择。     

314例儿童先天性心脏病分布特征描述

目的：掌握昆山市5岁以下儿童先天性心脏病流行情况和病例分布特征,为开展人群预防与疾病诊治提供依据。方法：对2008年8～12月期间完成的49901名5岁以下儿童先天性心脏病普查中确诊病例进行回顾性调查。结果：5岁以下儿童先天性心脏病检出率为6．29％o,男、女童检出率分别为6．47‰和6．11‰。差异无显著性（2=0．39,P值〉0．05）;先天性心脏病分布特点为随年龄增长先天性心脏病检出率降低,0-5岁儿童先天性心脏病病种前五位分别是ASD（27．07％）、VSD（23．89％）、ASD＋PDA（21．66％）、VSD＋PDA（6．69％）、PDA（5．73％）,其中,单纯的VSD与合并其他畸形的VSD相加后,占比36．94％;不同年龄组儿童先天性心脏病病种顺位有差异,0岁～组和1岁～组房间隔缺损占比最高,而其他3个年龄组以室间隔缺损为最高;ASD检出率男性高于女性。结论：本地区5岁以下儿童CHD检出率处于国内平均水平,但分布特征有差异,制订综合防治措施应结合本地区CHD分布特征,以提高防治效果,     

Proposition de sélection et délinéation des volumes cibles anatomocliniques tumoraux et ganglionnaire pour la radiothérapie des cancers de la glande sous-mandibulaire

This article provides a proposal for the selection and delineation of clinical target volumes for the treatment with radiation of submandibular glands tumours. This article does not deal with external radiotherapy indications but specifies the volumes to be treated if radiotherapy is chosen. High-risk and low-risk peritumoral clinical target volumes are described based on the probability of local tumoral spread. High-risk and low-risk clinical target volumes are illustrated on CT-scan slices. A proposal for the selection of nodal clinical target volumeis also proposed.