Outcomes of risk-adapted fractionated stereotactic radiotherapy for stage I non-small-cell lung cancer

PURPOSE: High local control rates can be achieved using stereotactic radiotherapy in Stage I non-small-cell lung cancer (NSCLC), but reports have suggested that toxicity may be of concern. We evaluated early clinical outcomes of "risk-adapted" fractionation schemes in patients treated in a single institution. METHODS AND MATERIALS: Of 206 patients with Stage I NSCLC, 81% were unfit to undergo surgery and the rest refused surgery. Pathologic confirmation of malignancy was obtained in 31% of patients. All other patients had new or growing 18F-fluorodeoxyglucose positron emission tomography positive lesions with radiologic characteristics of malignancy. Planning four-dimensional computed tomography scans were performed and fractionation schemes used (3 x 20 Gy, 5 x 12 Gy, and 8 x 7.5 Gy) were determined by T stage and risk of normal tissue toxicity. RESULTS: Median overall survival was 34 months, with 1- and 2-year survivals of 81% and 64%, respectively. Disease-free survival (DFS) at 1 and 2 years was 83% and 68%, respectively, and DFS correlated with T stage (p = 0.002). Local failure was observed in 7 patients (3%). The crude regional failure rate was 9%; isolated regional recurrence was observed in 4%. The distant progression-free survival at 1 and 2 years was 85% and 77%, respectively. SRT was well tolerated and severe late toxicity was observed in less than 3% of patients. CONCLUSIONS: SRT is well tolerated in patients with extensive comorbidity with high local control rates and minimal toxicity. Early outcomes are not inferior to those reported for conventional radiotherapy. In view of patient convenience, such risk-adapted SRT schedules should be considered treatment of choice in patients presenting with medically inoperable Stage I NSCLC.     

Variability of four-dimensional computed tomography patient models

PURPOSE: To quantify the interfractional variability in lung tumor trajectory and mean position during the course of radiation therapy. METHODS AND MATERIALS: Repeat four-dimensional (4D) cone-beam computed tomography (CBCT) scans (median, nine scans/patient) routinely acquired during the course of treatment were analyzed for 56 patients with lung cancer. Tumor motion was assessed by using local rigid registration of a region of interest in the 3D planning CT to each phase in the 4D CBCT. Displacements of the mean tumor position relative to the planned position (baseline variations) were obtained by using time-weighted averaging of the motion curve. RESULTS: The tumor trajectory shape was found to be stable interfractionally, with mean variability not exceeding 1 mm (1 SD) in each direction for the inhale and exhale phases. Interfractional baseline variations, however, were large, with 1.6- (left-right), 3.9- (cranial-caudal), and 2.8-mm (anterior-posterior) systematic variations (1 SD) and 1.2- (left-right), 2.4- (cranial-caudal) and 2.2-mm (anterior-posterior) random variations. Eliminating baseline variations by using soft-tissue guidance decreases planning target volume margins by approximately 50% compared with bony anatomy-driven protocols for conventional fractionation schemes. CONCLUSIONS: Systematic and random baseline variations constitute a substantial portion of the geometric variability present in the treatment of patients with lung cancer and require generous safety margins when relying on accurate setup/immobilization or bony anatomy-driven correction strategies. The 4D-CBCT has the ability to accurately monitor tumor trajectory shape and baseline variations and drive image-guided correction strategies that allows safe margin reduction.     

Four-dimensional ultrasound in prenatal diagnosis: leading edge in imaging technology

Since the introduction of the three-dimensional imaging technique, significant improvements have been undertaken. With the development of computer technology, calculation times become shorter and the software becomes more sophisticated. In the initial years, three-dimensional ultrasound allowed the production of only still volumes. Thus, scans only represented one single moment within the total examination. Serial re-scanning is one of the newest developments in three-dimensional ultrasound. In the volume-rendering mode, still imaging now may be replaced by three-dimensional ultrasound 'movies'. This technique may also be called four-dimensional ultrasound' or live three-dimensional ultrasound'. However, a frame rate of about 10 frames per second would be necessary to bring this technique to 'real-time' mode. Possible applications in prenatal diagnosis are examinations of the fetal extremities, fetal face and may be fetal behavior. Among the many advantages of four-dimensional ultrasound, improvement in imaging and the shorter training time for beginners to the three-dimensional technique are the most important.     

Dosimetric evaluation of MLC-based dynamic tumor tracking radiotherapy using digital phantom: Desired setup margin for tracking radiotherapy

The purpose of this study is to evaluate the dosimetric impact of the margin on the multileaf collimator-based dynamic tumor tracking plan. Furthermore, an equivalent setup margin (EM) of the tracking plan was determined according to the gated plan. A 4-dimensional extended cardiac-torso was used to create 9 digital phantom datasets of different tumor diameters (TDs) of 1, 3, and 5?cm and motion ranges (MRs) of 1, 2, and 3?cm. For each dataset, respiratory gating (30% to 70% phase) and tumor tracking treatment plans were prepared using 8-field 3-dimensional conformal radiation therapy by 4-dimensional dose calculation. The total lung V20 was calculated to evaluate the dosimetric impact for each case and to estimate the EM with the same impact on lung V20 obtained with the gating plan with a setup margin of 5?mm. The EMs for {TD?=?1?cm, MR?=?1?cm}, {TD?=?1?cm, MR?=?2?cm}, and {TD?=?1?cm, MR?=?3?cm} were estimated as 5.00, 4.16, and 4.24?mm, respectively. The EMs for {TD?=?5?cm, MR?=?1?cm}, {TD?=?5?cm, MR?=?2?cm}, and {TD?=?5?cm, MR?=?3?cm} were estimated as 4.24?mm, 6.35?mm, and 7.49?mm, respectively. This result showed that with a larger MR, the EM was found to be increased. In addition, with a larger TD, the EM became smaller. Our result showing the EMs provided the desired accuracy for multileaf collimator-based dynamic tumor tracking radiotherapy.     

四维超声心动图评价二尖瓣脱垂

采用经胸壁与经食管检查途径获取二维数据，对１０例正常人及２０例二尖瓣脱垂患者的二尖瓣装置及返流束进行了四维（动态三维）超声心动图重建。结果显示，正常二尖瓣装置呈＂马鞍＂形结构，瓣膜附着于瓣环前后缘处靠近左房，位置较高，内外侧结合部附着处靠近左室，位置较低。收缩期二尖瓣前后叶对合良好，四维超声心动图可从左房、左室侧及四腔切面等多个方位显示二尖辩脱垂病变的立体结构关系，脱垂部位、形状、程度及活动情况均可清晰显示，并可对返流束进行四维重建，显示其立体形态及动态变化。对全面理解二尖瓣脱垂的病理改变、提高诊断率、协助制定治疗方案及评价疗效有重要价值。     

经会阴四维超声观察新生儿体重及不同的分娩方式对产妇盆底结构的近期影响

【摘要】目的 应用经会阴四维超声观察新生儿体重及不同的分娩方式引起盆底结构改变的图像特征。方法 对2016年5月至2016年12月在我院初产的产妇于产后第42天依照新生儿体重及分娩方式不同分：巨大新生儿自然分娩组40 例、巨大新生儿剖宫产组55 例,以及对照组：正常体重新生儿自然分娩组150 例、正常体重新生儿剖宫产组150 例（均初产,于产后第42天）均进行盆底超声检查,观察并记录静息、缩肛和Valsalva动作三个时态下膀胱颈、子宫颈、直肠肛管形态及活动度。四维图像重建后观察三个时态下肛提肌裂口形态及连续性,并测量肛提肌裂口面积,记录超声检查结果并与进行统计分析。结果 经自然分娩的巨大新生儿组与自然分娩正常新生儿组比较膀胱颈活动度和三个状态下的肛提肌裂口均明显增大,子宫下垂发病率也增加,而直肠膨出发病率和Valsalva状态下膀胱后角、膀胱颈倾斜角和膀胱颈旋转角均没有明显统计学差别。剖宫产 的巨大新生儿组与剖腹产的正常体重新生儿组比较仅膀胱颈活动度和膀胱颈旋转角增大,余各指标无统计学差别。巨大新生儿自然分娩组与剖宫产组比较,仅Valsalva状态下膀胱后角和直肠膨出发病率无统计学差异,余各指标均明显增大。结论 与正常体重新生儿组比较,巨大新生儿组对产妇盆底结构的近期影响较明显,尤其是自然分娩的巨大新生儿组。     

Three-dimensional electrode displacement elastography using the Siemens C7F2 fourSight four-dimensional ultrasound transducer

Because ablation therapy alters the elastic modulus of tissues, emerging strain imaging methods may enable clinicians for the first time to have readily available, cost-effective, real-time guidance to identify the location and boundaries of thermal lesions. Electrode displacement elastography is a method of strain imaging tailored specifically to ultrasound-guided electrode-based ablative therapies (e.g., radio-frequency ablation). Here tissue deformation is achieved by applying minute perturbations to the unconstrained end of the treatment electrode, resulting in localized motion around the end of the electrode embedded in tissue. In this article, we present a method for three-dimensional (3D) elastographic reconstruction from volumetric data acquired using the C7F2 fourSight four-dimensional ultrasound transducer, provided by Siemens Medical Solutions USA, Inc. (Issaquah, WA, USA). Lesion reconstruction is demonstrated for a spherical inclusion centered in a tissue-mimicking phantom, which simulates a thermal lesion embedded in a normal tissue background. Elastographic reconstruction is also performed for a thermal lesion created in vitro in canine liver using radio-frequency ablation. Postprocessing is done on the acquired raw radio-frequency data to form surface-rendered 3D elastograms of the inclusion. Elastographic volume estimates of the inclusion compare reasonably well with the actual known inclusion volume, with 3D electrode displacement elastography slightly underestimating the true inclusion volume.