Computed tomography overestimation of esophageal tumor length: Implications for radiotherapy planning

AIM:To assess the relationship between preoperative computed tomography(CT)and postoperative pathological measurements of esophageal tumor length and the prognostic significance of CT tumor length data.METHODS:A retrospective study was carried out in 56 patients who underwent curative esophagogastrectomy.Tumor lengths were measured on the immediate preoperative CT and on the post-operative resection specimens.Inter-and intra-observer variations in CT measurements were assessed.Survival data were collected.RESULTS:There was a weak correlation between CT and pathological tumor length(r=0.30,P=0.025).CT lengths were longer than pathological lengths in 68%(38/56)of patients with a mean difference of 1.67 cm(95%CI:1.18-2.97).The mean difference in measurements by two radiologists was 0.39 cm(95% CI:-0.59-1.44).The mean difference between repeat CT measured tumor length(intra-observer variation) were 0.04 cm(95%CI:-0.59-0.66)and 0.47 cm (95%CI:-0.53-1.47).When stratified,patients not receiving neoadjuvant chemotherapy showed a strong correlation between CT and pathological tumor length(r =0.69,P=0.0014,n=37)than patients that did(r= 0.13,P=0.43,n=19).Median survival with CT tumor length>5.6 cm was poorer than with smaller tumors,but the difference was not statistically significant.CONCLUSION:Esophageal tumor length assessed using CT does not reflect pathological tumor extent and should not be the only modality used for management decisions,particularly for planning radiotherapy.

Three-Tesla Magnetic Resonance and Computed Tomography Imaging in Three-Dimensional Conformal Radiotherapy for Localized Prostate Cancer

Aims and background: we evaluate CT-3Tesla MRI fusion in conformal radiotherapy for localized prostate cancer.Methods: 18 consecutive patients underwent a 3T MRI scan under radiotherapy planning conditions, after the CT scan. Bowel and bladder preparation were prescribed. CT and MR images were automatically fused;prostate and seminal vesicles were contoured on CT and on MRI, organs at risk were defined on CT-MRI fusion. Late rectal and sexual toxicity, differences in target volume between MRI and CT and differences in rectal and penile bulb dose distribution based on CT only or on CT-MRI fusion were evaluated.Results: one patient experienced a late rectal toxicity;no patient had sexual toxicity. The difference between the mean MRI and CT target volumes was statistically significant (p = 0.0001 paired Student's t-test). The dose-volume histogram (DVH) analysis shows a significant reduction of the dose received by the rectum and the penile bulb in MRI-plans compared to CT-plans.Conclusions: 3 Tesla MRI scan under radiotherapy planning conditions along with bowel preparation significantly improves the definition of the target volume sparing normal tissue irradiation.

Dosimetric consequences of tumor volume changes after kilovoltage cone-beam computed tomography for non-operative lung cancer during adaptive intensity-modulated radiotherapy or fractionated stereotactic radiotherapy

Objective The aim of this study was to investigate tumor volume changes with kilovoltage cone-beam computed tomography （kV-CBCT） and their dosimetric consequences for non-operative lung cancer during intensity-modulated radiotherapy （IMRT） or fractionated stereotactic radiotherapy. Methods Eighteen patients with non-operative lung cancer who received IMRT consisting of 1.8-2.2 Gy/fraction and five fractions per week or stereotactic radiotherapy with 5-8 Gy/fraction and three fractions a week were studied, kV-CBCT was performed once per week during IMRT and at every fraction during stereotactic radiotherapy. The gross tumor volume （GTV） was contoured on the kV-CBCT images, and adaptive treatment plans were created using merged kV-CBCT and primary planning computed tomogra- phy image sets. Tumor volume changes and dosimetric parameters, including the minimum dose to 95% （D95） or 1% （D1） of the planning target volume （PTV）, mean lung dose （MLD）, and volume of lung tissue that received more than 5 （Vs）, 10 （Vl0）, 20 （V20）, and 30 （V30） Gy were retrospectively analyzed. Results The average maximum change in GTV observed during IMRT or fractionated stereotactic radio- therapy was -25.85% （range, -13.09% --56.76%）. The D95 and Dr of PTV for the adaptive treatment plans in all patients were not significantly different from those for the initial or former adaptive treatment plans. In patients with tumor volume changes of 〉20% in the third or fourth week of treatment during IMRT, adap- tive treatment plans offered clinically meaningful decreases in MLD and V5, V10, V20, and V30; however, in patients with tumor volume changes of 〈 20% in the third or fourth week of treatment as well as in patients with stereotactic radiotherapy, there were no significant or clinically meaningful decreases in the dosimetric parameters. Conclusion Adaptive treatment planning for decreasing tumor volume during IMRT may be beneficial for patients who experience tumor volume changes of 〉20% in the third or fourth week of treatment.

The role of high-energy computed radiography(CR)in radiotherapy

Computed radiography(CR)imaging has high irradiation tolerance and it is easy to archive CR images along with other image information by Digital Imaging and Communications in Medicine(DICOM)format,and to process them.CR can be used in radiation Quality Control(QC)task and verification of treatment setting-up.In this paper,the role of high-energy CR in radiation oncology is studied.The patients were imaged by CR system and EPID before radiotherapy.All verification images were acquired with 1–2 MU(Monitor Unit)using 6 MV X-rays.QC for a linac was done with film and high-energy CR to collect the data on daily,weekly and monthly basis.The QC included Multileaf Collimators(MLC)calibration and mechanical iso-centre check.CR was also adapted to verify patient position,the film was used to compare with digitally reconstructed radiographs(DRR)and portal image from EPID. Treatment setting-up was verified based on the result of comparison.High quality verification images could be acquired by the CR system.Comparing to EPID,the results showed that the system was suitable for practical use to acquire daily verification images,and it was useful to fulfill part of quality assurance(QA)in radiation oncology.The quality of image acquired by the high-energy CR system is comparable or even better than DRRs and portal images. The final treatment set-up for the patients could be verified more accurately with the CR system.

Photon-counting computed tomography thermometry via material decomposition and machine learning

Thermal ablation procedures,such as high intensity focused ultrasound and radiofrequency ablation,are often used to eliminate tumors by minimally invasively heating a focal region.For this task,real-time 3D temperature visualization is key to target the diseased tissues while minimizing damage to the surroundings.Current computed tomography(CT)thermometry is based on energy-integrated CT,tissue-specific experimental data,and linear relationships between attenuation and temperature.In this paper,we develop a novel approach using photon-counting CT for material decomposition and a neural network to predict temperature based on thermal characteristics of base materials and spectral tomographic measurements of a volume of interest.In our feasibility study,distilled water,50 mmol/L CaCl2,and 600 mmol/L CaCl2 are chosen as the base materials.Their attenuations are measured in four discrete energy bins at various temperatures.The neural network trained on the experimental data achieves a mean absolute error of 3.97°C and 1.80°C on 300 mmol/L CaCl2 and a milk-based protein shake respectively.These experimental results indicate that our approach is promising for handling non-linear thermal properties for materials that are similar or dis-similar to our base materials.

Mucosa-associated lymphoid tissue lymphoma of the trachea treated with radiotherapy:A case report

BACKGROUND Mucosa-associated lymphoid tissue(MALT)lymphoma originates in the marginal zone of lymphoid tissue.lung is one of the most frequent non-gastrointestinal organs involved,here known as bronchus-associated lymphoid tissue(BALT)lymphoma.BALT lymphoma of unknown etiology,and most patients are asymptomatic.The treatment of BALT lymphoma is controversial.CASE SUMMARY A 55-year-old man admitted to hospital had a three-month history of progressively coughing up yellow sputum,chest stuffiness,and shortness of breath.Fiberoptic bronchoscopy revealed mucosal visible beaded bumps 4 cm from the tracheal carina at 9 o'clock and 3 o'clock,the right main bronchus,and the right upper lobe bronchus.Biopsy specimens showed MALT lymphoma.Computed tomography virtual bronchoscopy(CTVB)showed uneven main bronchial wall thickening and multiple nodular protrusion.BALT lymphoma stage IE was diagnosed after a staging examination.We treated the patient with radiotherapy(RT)alone.A total dose of 30.6 Gy/17 f/25 d was given.The patient had no obvious adverse reactions during RT.The CTVB was repeated after RT and showed that the right side of the trachea was slightly thickened.CTVB was repeated 1.5 mo after RT and again showed that the right side of the trachea was slightly thickened.Annual CTVB showed no signs of recurrence.The patient now has no symptoms.CONCLUSION BALT lymphoma is an uncommon disease and shows good prognosis.The treatment of BALT lymphoma is controversial.In recent years,less invasive diagnostic and therapeutic approaches have been emerging.RT was effective and safe in our case.The use of CTVB could provide a noninvasive,repeatable,and accurate method in diagnosis and follow-up.

数字化口腔定位支架在头颈部肿瘤放射治疗中的应用现状

在放射治疗中,由于射线不可避免地对正常细胞产生辐射作用,头颈部肿瘤患者常会发生严重的口腔并发症,例如:放射治疗诱发性口腔黏膜炎、张口困难、吞咽困难、放射性颌骨坏死和放射性龋病等。这些并发症会影响甚至中断放射治疗的进行,对放射治疗后患者的生活质量造成难以估量的影响。为减小放射治疗带来不利影响,近年来,国内外学者对口腔定位支架(OPS)开展了广泛的研究,其中传统型OPS对一些口腔并发症的预防起到明显的作用,但其在设计制作以及推广应用上存在一些不足,数字化OPS的研究应运而生。本文主要对数字化OPS的设计制作方法、口腔并发症的预防以及放射治疗摆位的影响进行总结分析,对其应用前景进行了展望。

兆伏级CT图像引导自适应放疗中生成合成CT研究

目的:开发一种基于深度学习神经网络的方法将宫颈癌MVCT图像转换为具有高信噪比和高对比度的伪kVCT图像,从而提供宫颈癌自适应放疗需要的患者三维解剖图像和定位信息,引导加速器实现精确放疗。方法:收集54例宫颈癌患者的MVCT和kVCT图像组成数据集,随机选择44例样本作为训练集,并将剩下的10例样本作为测试集。采用加入门控机制和多通道数据输入的循环生成对抗网络(CycleGAN)基于MVCT合成伪kVCT图像。采用平均绝对误差(MAE)、峰值信噪比(PSNR)和结构相似度指数(SSIM)等影像学成像质量评估参数,评估网络训练效果。结果:5通道MVCT-5通道kVCT图像与MVCT图像对比,MAE从(24.9±0.7)HU降至(17.8±0.3)HU,PSNR从(29.8±0.2)dB升至(30.7±0.2)dB,SSIM从0.841±0.007升至0.898±0.003。结论:该方法生成的伪kVCT在降噪和增强对比度方面具有优势,同时能够减少剂量计算中对额外MV-kVCT电子密度校准的需求。伪kVCT的剂量计算能力与MVCT相当,为伪kVCT影像应用于图像引导自适应放疗提供了可能。

控制扫描法对头颈部肿瘤患者精确CT定位扫描的效果研究

目的:研究控制扫描(CS)法精确确定放疗标记点CT层面的位置对头颈部肿瘤患者放疗的应用效果。方法:基于CS法制作标记点层面位置(MSP)计算程序,用于位置计算的企业微信程序,以及头颈部肿瘤患者(层厚3 mm)的CT定位扫描中。选取2020年10月至2022年3月南京医科大学附属南京医院收治的60例头颈部位肿瘤患者,将使用CS法行CT定位扫描的患者纳入观察组,使用常规方法行CT定位扫描的患者纳入对照组,每组30例。对两组CT定位扫描中3个金属标记点同时显示在同1层面的例数及含标记点CT图像的层数等进行对比分析。结果:观察组和对照组患者3个标记点同时显示在同1层面上的例数分别为26例和13例,观察组比对照组增加了13例(占43.4%),差异有统计学意义(χ^(2)=12.382,P<0.05);观察组和对照组含标记点CT图像仅1层的例数分别为4例和0例,观察组比对照组增加4例(占13.3%),差异有统计学意义(χ^(2)=2.411,P<0.05)。结论:使用CS法辅助头颈部肿瘤患者的放疗CT定位扫描,可精确计算得到CT定位扫描的目标起始位置,从而使放疗患者3个金属标记点的影像尽可能出现在同1个CT层面,具有较好的应用效果。能够有效提高放疗的便捷性和工作效率。

鼻咽癌放疗头颈部摆位误差及外轮廓变化对放疗剂量的影响

目的:采用千伏级锥形束CT(CBCT)获取分次间鼻咽癌调强放疗中的外轮廓变化及摆位误差,分析其对靶区及危及器官剂量分布的影响。方法:选取21例鼻咽癌患者,将全部患者的137次CBCT图像与定位CT图像匹配后得到左右、头脚、腹背方向的摆位误差数据。选取颈部3个不同层面,测量其外轮廓横切面宽度,并利用Pearson系数和独立样本t检验分析其对摆位误差的影响。基于CBCT影像制定模拟计划,分析摆位误差和外轮廓变化对放疗剂量的影响,并应用Mann-Whitney秩和检验进行显著性分析。结果:左右、头脚、腹背方向的摆位误差分别为(1.04±0.73)、(1.13±0.87)、(1.38±0.95)mm。A、B、C层面上的头颈部最大外轮廓变化率分别为15.36%、14.94%、14.99%。模拟计划显示GTV D_(98)、CTV1 D_(95)、CTV2 D_(95)靶区的模拟计划的剂量均小于执行的计划剂量,差异有统计学意义(P<0.05);脑干和脊髓的模拟计划D_(max)均大于计划剂量,差异有统计学意义(P<0.05)。结论:通过模拟计划可知,当摆位误差和外轮廓变化等不确定性因素存在时,靶区的剂量变化较大,其中GTV D_(98)最大减小11.49%,CTV1 D_(95)、CTV2 D_(95)最大变化率分别为12.88%、21.64%。除左右晶体和左腮腺之外,其余的危及器官和靶区剂量均有显著性差异,表明实际放疗中摆位误差和外轮廓变化的存在会对剂量分布造成显著影响。

宫颈癌容积旋转调强放射治疗中膀胱体积与剂量分布相关性研究

目的 探讨宫颈癌容积旋转调强放射治疗(IMRT)中膀胱体积改变对膀胱剂量学的影响。方法 选取2020年1月至2021年12月首都医科大学附属北京妇产医院放疗中心接受根治性同步放化疗的宫颈癌患者10例,均采用IMRT技术联合192 Ir高剂量率后装治疗。外照射第1周前5次每次放射治疗前行1次锥形束计算机断层扫描(CBCT),以后每周行1次CBCT,共收集100幅图像。基于CBCT图像重新勾画膀胱结构并移植至计划CT图像中,获取实际治疗时膀胱体积和剂量分布,并分析标准化膀胱体积(CBCT膀胱体积/CT膀胱体积)与标准化膀胱剂量(CBCT膀胱剂量/CT膀胱剂量)的相关性。结果 CBCT图像膀胱体积比计划CT图像小,标准化膀胱体积平均值为(0.96±0.31);受膀胱体积变化影响,CBCT图像膀胱剂量较计划CT图像高。标准化膀胱平均剂量和标准化V45平均值分别为(1.01±0.03)和(1.03±0.12)。标准化膀胱体积与标准化膀胱平均剂量无相关性(P>0.05)。标准化膀胱体积与标准化V45呈正相关(r=0.870,P=0.001)。结论 在宫颈癌IMRT治疗中,膀胱充盈程度的一致性较差。膀胱体积越大,膀胱剂量V45越大。基于图像引导放疗下,患者膀胱体积与定位时膀胱体积尽量保持一致,从而避免膀胱所受剂量过大。

肺部恶性肿瘤立体定向放射治疗后影像学动态变化规律

目的 肺部恶性肿瘤立体定向放射治疗(stereotactic radiation therapy,SRT)后计算机断层扫描(computed tomography,CT)图像的动态变化是一个复杂而连续的过程,容易引起误诊。探讨SRT后肿瘤及其周边正常肺组织的CT图像动态变化的规律。方法 回顾性分析2018—2021年在南京医科大学附属肿瘤医院接受SRT的104例肺部恶性肿瘤患者的临床资料,根据纳入条件,由研究者诊断小组对每次CT图像进行评估和动态比较,记录SRT后肿瘤本身及周边正常肺组织形态学变化和时序特征。结果 104例患者共109个病变。94个(86.2%)病灶呈现残存病灶与周边放射性肺损伤融合形成肿块样实变,可分为3个阶段。发生期:治疗后3个月(范围为1~9个月),胸部CT呈病灶周围絮状渗出性改变。发展期:治疗后4.5个月(范围为1.5~15.5个月),呈密度更高的斑片条索影和/或纤维化实变影。影像稳定前期:治疗后13个月(范围为5.5~39个月),呈纤维化实变逐渐吸收、固结或收缩并与病灶融合形成最终的肿块样实变,伴或不伴随纤维化移动,最终趋于稳定。15例(14.4%)患者周围肺组织无明显改变,仅表现为病灶本身变化,达到影像学稳定的中位时间为治疗后10个月(范围为2.5~15.5个月)。65个(59.6%)病灶影像稳定期肿块样实变长径比初始病变增加了20%以上。进入发展期时间越短,影像稳定阶段肿块样实变长径可能越大(P=0.021)。结论 SRT后肿瘤本身及周边正常肺组织通常会出现连续动态影像学改变,最终多数患者残存病灶与周边肺组织纤维化融合形成肿块样实变。多数患者肿块样实变长径较SRT前增加20%以上。

联合CT影像组学与深度学习特征建立列线图预测食管鳞癌放疗近期疗效

目的:探讨基于CT影像组学特征与深度学习特征建立列线图对食管癌放疗近期疗效的预测价值。方法:回顾性分析137例食管鳞癌患者的临床及影像资料。从CT图像中提取影像组学特征和深度学习特征。通过最小绝对收缩和选择算子方法分别对影像组学特征和深度学习特征进行降维并计算得到影像组学得分(Radscore)和深度学习得分(Deepscore)。采用多因素logistic回归分析建立预测模型,并绘制列线图。对列线图的校准度、诊断效能和临床价值进行评价。结果:筛选得到6个影像组学特征参与计算Radscore,6个深度学习特征参与计算Deepscore。多因素logistic回归结果显示Radscore、Deepscore、TNM分期为联合模型的独立预测因子。联合预测模型在训练集中预测食管鳞癌患者放疗近期疗效的曲线下面积(AUC)为0.904,高于临床模型(AUC=0.662)和影像组学模型(AUC=0.814),且AUC差异均有统计学意义(P<0.001、P=0.004)。验证集中联合模型的AUC为0.938,高于临床模型(AUC=0.644)和影像组学模型(AUC=0.852),联合模型与临床模型间AUC差异有统计学意义(P<0.001),与影像组学模型间AUC差异无统计学意义(P=0.091)。决策曲线分析发现联合预测列线图在0.1~0.9和0.97~0.99的阈值范围内表现出较好的临床实用性。结论:CT影像组学特征联合深度学习特征能较好地预测食管癌放疗近期疗效。

四维CT联合四维锥形束CT在肺癌立体定向放射治疗中的应用研究进展

以立体定向放射治疗(SBRT)为代表的高精度放射治疗在肺癌治疗的各个阶段发挥重要作用,而医学影像技术的进步、更加精确的剂量计算方法以及先进的影像及剂量验证算法的应用则为高精准放射治疗的实现提供保证。四维CT(4D CT)能够较好的显示肿瘤受呼吸影响的个体化运动,四维锥形束CT(4D-CBCT)作为勾画并获得肿瘤内靶区(ITV)的一种图像引导技术(IGRT),可以为实现精准治疗提供保证,上述两种技术结合能够纠正位移误差,实施监测肿瘤的运动范围并确保运动的靶区在照射范围内,是实施SBRT的保证。以肺癌精确放射治疗应用研究中的IGRT为切入点,综述4D CT联合4D-CBCT在肿瘤SBRT中的临床应用价值,旨在为肺癌的临床放射治疗提供参考。

基于Ethos自适应放射治疗系统不同成像算法的图像质量分析

目的:定量分析瓦里安Ethos自适应放射治疗(ART)系统上基于滤波反投影(FBP)和迭代重建(IR)技术的锥形束CT(CBCT)和迭代CBCT(iCBCT)的图像质量以及合成伪CT(sCT)的差异。方法:利用CT图像质量测试专用Catphan604模体,基于胸部扫描和腹部扫描完成CBCT和iCBCT各5次扫描,获取4套图像,每套图像包括CBCT图像、基于CBCT合成的sCT、iCBCT图像、基于iCBCT合成的sCT,分析其噪声功率谱(NPS)、图像均匀性指数(UI)、调制传递函数(MTF)、低对比度可见度(LCV)和对比度噪声比(CNR)。回顾性选取2023年8月至2024年5月解放军总医院第一医学中心收治的6例临床放疗患者,使用胸部扫描和腹部扫描获取6例患者的图像,分析基于CBCT和iCBCT图像形变配准所得sCT图像,并与定位CT图像进行对比,定量分析其绝对误差(MAE)和均方根误差(RMSE)。结果:iCBCT与CBCT相比,胸部图像NPS显著降低0.08,腹部图像降低0.06;iCBCT胸部、腹部图像UI分别为0.37和0.28,CBCT分别为0.65和0.39;iCBCT胸部、腹部图像LCV分别为0.67和0.56,CBCT分别为0.93和0.90;MTF50%除腹部iCBCT是0.29 lp/mm外,其余均为0.28 lp/mm,iCBCT和CBCT图像高对比度分辨率基本一致。基于CBCT和iCBCT生成的sCT与定位CT的相似度分析差异均无统计学意义(P>0.05)。结论:iCBCT图像质量优于传统CBCT,而基于CBCT和iCBCT生成的sCT,其CT值准确性皆符合要求,均可用于ART的剂量计算。

计算机模拟放疗计划临床应用中的若干技巧

针对放疗计划计算模拟过程中出现的若干常见问题,文章依据主流计划系统的原理分析并提出了解决方法,分别列举了食道癌和带淋巴结靶区的宫颈癌实例,通过对比说明了所提方法的应用效果。

4DCT联合呼吸管理对NSCLC SBRT治疗精度的影响

目的通过对比四维X线断层扫描(four dimension computed tomography,4DCT)联合呼吸门控、腹部加压以及自由呼吸模式下立体定向放射治疗(stereotactic body radiotherapy,SBRT)计划参数的对比,分析呼吸管理对肿瘤靶区体积、剂量精度的影响。方法选取2021年10月—2022年12月在山东第一医科大学附属中心医院肿瘤科就诊的12例早期非小细胞肺癌(non-small cell lung cancer,NSCLC)采用立体定向放射治疗的患者,分别设计3套图像计划,每套图像12例为一组。搜集4DCT扫描图像,按呼吸时相将CT数据重建,分层处理得到0%~90%图像(0%为吸气末,50%为呼气末),勾画各时相肿瘤靶区,利用最大密度投影融合成全时相图像,用来模拟自由呼吸模式下的普通CT图像(FB'组);将30%~70%时相图像用最大密度投影融合,因其与利用呼吸附件腹部加压后其呼吸时相相同,定义为腹部适度加压组图像(RA'组);将吸气末0%时相图像模拟主动呼吸控制状态图像(ABC'组)。在这3组图像上分别得到肿瘤靶区、肿瘤内靶区及计划靶区,比较3组治疗模式中肿瘤靶区及危机器官剂量学差异。结果(1)ABC'组、RA'组及FB'组肿瘤内靶区体积值差异有统计学意义(P<0.05)。计划靶区适形性指数、均匀性指数、5%计划靶区(planned target volume,PTV)体积的剂量及体积的剂量、及95%PTV体积的剂量差异均无统计学意义(P>0.05)。(2)ABC'组、RA'组及FB'组患者计划靶区双肺剂量5 Gy照射时的百分体积、双肺剂量20 Gy照射时的百分体积、平均肺剂量,差异有统计学意义(P<0.05)。心脏最大剂量、<15 cm^(3)体积的剂量示RA'组、ABC'组均略低于FB'组,但差异无统计学意义(P>0.05)。结论在非小细胞肺癌立体定向放射治疗中应用呼吸门控、适度腹部加压等呼吸管理方式联合4DCT,较自由呼吸模式下的FB'组有效地减小肿瘤内靶区体积、双肺剂量5 Gy的百分体积、双肺剂量20 Gy的百分体积、平均肺剂量等指标,减少呼吸动度对靶区的影响,提高定位、治疗的精度。腹部加压呼吸管理技术是对呼吸门控呼吸管理技术不适应者的一种有效补救措施。

基于区域判别生成对抗网络的宫颈癌放射治疗锥形束CT影像质量提升研究

目的:提出基于区域判别生成对抗网络(GAN)的改善宫颈癌放射治疗锥形束CT(CBCT)图像质量模型,以满足自适应放疗图像质量的需求。方法:采用基于区域判别的策略与生成对抗网络思想,构建一种能够关注宫颈癌放疗影像局部细节的CBCT图像质量提升模型,其判别器可提高图像局部细节的生成质量。将该图像质量模型应用于宫颈癌放疗中的CBCT图像,通过量化指标和可视化评价图像处理效果。结果:CBCT图像质量提升后其纹理清晰度与对比度皆得到明显提升。图像峰值信噪比提高47.2%,结构相似性指标提升至0.838以上。相对于其他模型,在可视化和指标角度皆表现出更好的模型效能,结构相似性与U-Net网络和CycleGAN网络比较分别提高11.88%和19.54%;峰值信噪比分别提高19.75%和25.99%。结论:基于区域判别的GAN可有效提升宫颈癌放疗CBCT图像整体与细节上的生成质量,能够为提升低剂量CBCT图像质量提供新的技术路径,为提高放疗安全性和有效性发挥重要作用,并对制定和执行放疗计划具有重要临床价值。

Significant value of 18F-FDG-PET/CT in diagnosing small cervical lymph node metastases in patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

Background: Little is known about the nature of metaistasis to small cervical lymph nodes(SCLNS) in the patients with nasopharyngeal carcinoma(NPC)examined by using 18-fluoro-2-deoxy-glucose(^(18)F-FDG) positron emission tomography/computed tomography(PET/CT).The present study aimed to evaluate the diagnostic values of PET/CT in identifying metastasis in SCLNs in NPC patients.Methods: Magnetic resonance images(MRI) and PET/CT scans for 470 patients with newly diagnosed, non-distant metastatic NPC were analyzed. Metastatic rates of SCLNs were defined by the positive number of SCLNs on PET/CT scans and total number of SCLNs on MRI scans. Receiver operating characteristic curve was applied to compare PET/CT-determined stage with MRI-determined stage.Results: In total, 2082 SCLNs were identified, with 808(38.8%) ≥ 5 and < 6 mm in diameter(group A), 526(25.3%)≥ 6 and < 7 mm in diameter(group B),374(18.0%)≥ 7 and < 8 mm in diameter(group C), 237(11.4%) ≥8 and<9 mm in diameter(group D),and 137(6.5%) ≥ 9 and <10 mm in diameter(group E).The overall metastatic rates examined by using PET/CT for groups A, B,C,D, and E were 3.5%, 8.0%, 31.3%, 60.0%, and 83.9%, respectively(P< 0.001). In level IV/Vb, the metastatic rate for nodes ≥ 8 mm was 84.6%. PET/CT examination resulted in modification of N category and overall stage for 135(28.7%) and 46(9.8%) patients, respectively. The areas under curve of MRIdetermined and PET/CT-determined overall stage were 0.659 and 0.704 for predicting overall survival, 0.661 and 0.711 for predicting distant metastasis-free survival, and 0.636 and 0.663 for predicting disease-free survival.Conclusions: PET/CT was more effective than MRI in identifying metastatic SCLNs, and the radiologic diagnostic criteria for metastatic lymph nodes in level IV/Vb should be re-defined.

Clinical usefulness of ^(18) F-FDG PET/CT in the restaging of esophageal cancer after surgical resection and radiotherapy

AIM： To evaluate the clinical usefulness of lSF-fluorodeoxyglucose positron emission and computed tomography QSF-FDG PET/CT） in restaging of esophageal cancer after surgical resection and radiotherapy. METHODS： Between January 2007 and Aug 2008, twenty histopathologically diagnosed esophageal cancer patients underwent 25 PET/CT scans （three patients had two scans and one patient had three scans） for restaging after surgical resection and radiotherapy. The standard reference for tumor recurrence was histopathologic confirmation or clinical follow-up for at least ten months after ^18F-FDG PET/CT examinations. RESULTS： Tumor recurrence was confirmed histopathologically in seven of the 20 patients （35%） and by clinical and radiological follow-up in 13 （65%）. ^18F-FDG PET/CT was positive in 14 patients （68.4%） and negative in six （31.6%）. ^18F-FDG PET/CT was true positive in 11 patients, false positive in three and true negative in six. Overall, the accuracy of ^18F-FDG PET/CT was 85%, negative predictive value （NPV） was 100%, and positive predictive value （PPV） was 78.6%.The three false positive PET/CT findings comprised chronic inflammation of mediastinal lymph nodes （n = 2） and anastomosis inflammation （n = 1）. PET/ CT demonstrated distant metastasis in 10 patients. ^18F-FDG PET/CT imaging-guided salvage treatment in nine patients was performed. Treatment regimens were changed in 12 （60%） patients after introducing ^18F-FDG PET/CT into their conventional post-treatment follow-up program. CONCLUSION： Whole body ^18F-FDG PET/CT is effective in detecting relapse of esophageal cancer after surgical resection and radiotherapy. It could also have important clinical impact on the management of esophageal cancer, influencing both clinical restaging and salvage treatment of patients.