Treatment plan evaluation using dose-volume histogram (DVH) and spatial dose-volume histogram (zDVH)

Objective: The dose–volume histogram (DVH) has been accepted as a tool for treatment-plan evaluation. However, DVH lacks spatial information. A new concept, the z-dependent dose–volume histogram (zDVH), is presented as a supplement to the DVH in three-dimensional (3D) treatment planning to provide the spatial variation, as well as the size and magnitude of the different dose regions within a region of interest.

Materials and Methods: Three-dimensional dose calculations were carried out with various plans for three disease sites: lung, breast, and prostate. DVHs were calculated for the entire volume. A zDVH is defined as a differential dose–volume histogram with respect to a computed tomographic (CT) slice position. In this study, zDVHs were calculated for each CT slice in the treatment field. DVHs and zDVHs were compared.

Results: In the irradiation of lung, DVH calculation indicated that the treatment plan satisfied the dose–volume constraint placed on the lung and zDVH of the lung revealed that a sizable fraction of the lung centered about the central axis (CAX) received a significant dose, a situation that warranted a modification of the treatment plan due to the removal of one lung. In the irradiation of breast with tangential fields, the DVH showed that about 7% of the breast volume received at least 110% of the prescribed dose (PD) and about 11% of the breast received less than 98% PD. However, the zDVHs of the breast volume in each of seven planes showed the existence of high-dose regions of 34% and 15%, respectively, of the volume in the two caudal-most planes and cold spots of about 40% in the two cephalic planes. In the treatment planning of prostate, DVHs showed that about 15% of the bladder and 40% of the rectum received 102% PD, whereas about 30% of the bladder and 50% of the rectum received the full dose. Taking into account the hollow structure of both the bladder and the rectum, the dose–surface histograms (DSH) showed larger hot-spot volume, about 37% of the bladder wall and 43% of the rectal wall. The zDVHs of the bladder revealed that the hot-spot region was superior to the central axis. The zDVHs of the rectum showed that the high-dose region was an 8-cm segment mostly superior to the central axis. The serial array-like of the rectum warrants a closer attention with regard to the complication probability of the organ.

Conclusions: Although DVH provides an averaged dose–volume information, zDVH provides differential dose–volume information with respect to the CT slice position. zDVH is a 2D analog of a 3D DVH and, in some situations, more superior. It provides additional information on plan evaluation that otherwise could not be appreciated. The zDVH may be used along with DVH for plan evaluation and for the correlation of radiation outcome.     

B型超声图像直方图的原理及临床应用

本文叙述了声像图的直方图形成原理及其分析方法。介绍了三种直方图取样方法,即:①点分析取样;②线分析取样;③面分析取样。描述了用以分析的谱线宽度、高次谱位、谱线包络线及统计数据等参数。 本法有助于鉴别各种液性、实质性、纤维化、钙化或结石及混合性病变。本法对超声诊断的量化分析具有十分重要的意义。     

Dosimetric Parameters in Partial Breast Irradiation Through Brachytherapy

The objective of this work is to evaluate biological models and dose homogeneity in a new partial breast irradiation method, the MammoSite RTS. The study is based on 11 patients who received the therapy. For each patient, we determined the dose volume distribution delivered to the breast. Based on these data, we estimate some important biological parameters. Eleven patients with early-stage, invasive, ductal breast cancer were treated using MammoSite RTS brachytherapy, which delivers radiation through a balloon placed in the lumpectomy bed. The radiation was provided by an Iridium-192 source, and 340 cGy were delivered per fraction twice daily. We calculated some commonly used dosimetric parameters, and evaluated the biological parameters tumor control probability (TCP) and normal tissue complication probability (NTCP). We also looked for correlations among these parameters. The average equivalent uniform dose (EUD), NTCP, and TCP were 43.66 Gy, 47.95%, and 91.78%, respectively. The coefficient of variation (CV) among the patients was very low for all 3 parameters. Two dose homogeneity indices (DHI and the S-index) are strongly correlated (r = −0.815). The area under the dose-volume histogram (DVH) and the treatment volume (TXV) also showed a strong correlation (r = 0.995, p < 0.0001). A simplified logit Poisson–EUD model is suitable for determining NTCP and TCP. Other factors such as the area under the DVH and dose homogeneity indices are also useful in planning radiotherapy treatments for early breast cancer.     

超声组织直方图频谱定量和彩色层换技术诊断分析肿块137例

目的 使用计算机photoshop技术，观察研究静态肿块组织特性以提高超声的诊断能力。方法 应用Interword智能图文管理系统，将B超获取的诊断图像，经二次处理软件包manage格式，对B超组织图像包块进行分析。结果 通过对肿块组织直方图测定和彩色变换处理，提供了频谱数据及彩色图像的信息，直方图各灰阶参数在诊断肿块组织特性中发挥了重要作用，为临床诊治提供了客观的半定量化指标。结论 应用此计算机技术，具有简便可行，且提高静态脏器及肿物性质的诊断能力。     

Clinical application of a new method that segments the region of interest into multiple layers for RF amplitude histogram analysis in the cirrhotic liver

Purpose We used texture analysis in conjunction with an alternative method of analyzing the amplitude histogram using a radiofrequency (RF) signal to differentiate ultrasonograms of normal and cirrhotic livers. This method segments the region of interest (ROI) into multiple layers (sub-ROIs). In each sub-ROI of a homogeneous medium, the histogram of enveloped-amplitude of RF backscattered echoes resembles a Rayleigh distribution. Theoretically, the values of the signal-to-noise ratio (SNR), skewness, and kurtosis for Rayleigh statistics are constant and independent of the mean scattering intensity, which is contributed by such undesirable effects as tissue attenuation, beam diffraction, and incident waveforms. These values, which averaged overall sub-ROI, should provide an unbiased estimator.Methods We studied 36 normal livers and 28 cirrhotic livers, all confirmed by clinical findings including laboratory and pathology data; the SNR, skewness, and kurtosis values of the disease groups were compared. At the same time, these values were estimated using the conventional method, which did not segment the ROI into multiple sub-ROIs. The unpaired t-test was used to determine statistical significance.Results With the new method, all values obtained from cirrhotic livers differed significantly from those obtained from normal livers, and the standard deviation of these values was smaller than those obtained using the conventional method.Conclusions These results suggest that the new method can be used to diagnose the cirrhotic liver objectively.This article is translated from the Japanese version, which was published in J Med Ultrasonics 2001;28:J25–33     

脑部CT平扫图像直方图分析鉴别肿瘤性与非肿瘤性脑出血

目的 观察脑部CT平扫图像直方图分析鉴别诊断肿瘤性与非肿瘤性脑出血的价值。方法 收集116例非肿瘤性脑出血（非肿瘤组）和44例肿瘤性脑出血（肿瘤组），分析其脑部CT平扫图像直方图，获得病灶的直方图参数，包括最小值，第5、25、50、75、95百分位CT值、最大值、标准差、平均值、偏度和峰度。比较2组间直方图参数的差异，以ROC曲线分析各参数鉴别诊断肿瘤性与非肿瘤性脑出血的效能。结果 肿瘤组最大值、第5、25、50、75、95百分位CT值、平均值、标准差均小于非肿瘤组（P均<0.05），偏度和峰度大于非肿瘤组（P均<0.05），最小值与非肿瘤组差异无统计学意义（P>0.05）。ROC曲线分析结果显示，最大值、第25、50、75、95百分位CT值、平均值及标准差鉴别肿瘤性与非肿瘤性脑出血的诊断价值中等，其中第50百分位CT值的AUC最高（0.82），敏感度和特异度分别为0.92和0.68。结论 脑部CT平扫图像直方图分析可作为鉴别诊断肿瘤性与非肿瘤性脑出血的辅助手段。     

磁共振联合超声鉴别诊断子宫内膜间质肉瘤与变性子宫肌瘤

目的:应用磁共振联合超声鉴别诊断子宫内膜间质肉瘤（ESS）与变性子宫肌瘤。方法:回顾性分析ESS患者19例和变性子宫肌瘤患者36例。分析患者磁共振直方图（T2WI肿瘤最大层面直方图）及彩超检测结果特征,并对两种方法联合诊断的灵敏度与特异度进行分析。结果与结论:ESS患者与变性子宫肌瘤患者临床表现近似,但各具特征;ESS患者年龄更高,绝经女性所占比例更高,且肿物最大直径相对更大。超声检测肿瘤基本特征可见,ESS患者肿瘤边界模糊的比例更高,以中强度回声为主,瘤体结构多为实性,血流丰富,红色样变比例也较高。对比之下,变性子宫肌瘤患者回声多为低强度,肿瘤结构多为其他结构,血流稀疏,脂肪样变比例相对更高。同时,受试对象MRI检测T2W1肿瘤最大层面直方图相关参数,在ESS患者和变性子宫肌瘤患者中可见在平均值、方差、偏度、峰度以及几个不同的百分位数（P1、P10、P50、P90）的差异均存在统计学意义（P<0.05）。直方图（P50）联合超声检查的灵敏度和特异度均较高,效力最佳。