自动勾画软件ABAS在鼻咽癌自适应放疗中的应用

目的:评估ABAS自动勾画软件勾画的危及器官准确度和效率,以此来评估它在鼻咽癌患者自适应放疗中的适用程度.方法:随机抽取15例在我院治疗的鼻咽癌患者.CT1为患者的计划CT,CT2为三分之二疗程重薪扫描的CT图像,CT3为患者放疗结束后扫描的CT图像.在ABAS软件中CT1图像设为模板,在CT2和CT3上自动勾画出所需的危及器官,并将自动勾画结果和手工勾画的结果进行对比分析.利用形状相似性指数(Dice similarity coefficient,DSC)和自动勾画时间评价软件自动勾画的精准性和效率性.结果:ABAS软件自动勾画的体积较大的危及器官的DSC指数均大于0.9,在CT1和CT2组中DSC指数的最高为脊髓(0.96±0.01),最低为晶体(0.43±0.19),在CT1和CT3组中DSC指数最高为下颌骨(0.93±0.45),最低为晶体(0.49 ±0.17).同时用ABAS自动勾画危及器官所需平均时间为十分钟左右.结论:在鼻咽癌自适应放疗过程中,自动勾画软件勾画的危器官可以达到很好的准确度同时又明显的节省时间.这样就可以快速评价危及器官受量,使得鼻咽癌自适应放疗成为可能.     

Locate: An application of computed tomography in radiation therapy treatment planning with emphasis on tumor localization

Computed tomography can provide precise information for radiation therapy treatment planning. However, inaccuracies in radiation field design may occur when the radiation oncologist attempts to transfer information about tumor location from the transverse plane of the CT scan to the longitudinal plane of the simulation film. This report describes a new computer program, LOCATE, which addresses this problem. The program uses operator generated information from the cross sectional CT images to draw an outline of tumor on AP and lateral longitudinal scanned projection radiographs. The resultant images are useful because they are in the same plane as radiographs obtained on a therapy simulator. The impact of LOCATE on radiation treatment planning for 26 patients is discussed along with several cases in which LOCATE was particularly helpful.     

Megavoltage computed tomography imaging: a potential tool to guide and improve the delivery of thoracic radiation therapy

Helical tomotherapy is an innovative means of delivering intensity-modulated radiation therapy (IMRT) using a device that merges features of a linear accelerator and a helical computed tomography (CT) scanner. The tomotherapy unit can generate CT images from the megavoltage radiation it uses for treatment as often as needed during a course of radiation therapy. These megavoltage CT (MVCT) images offer verification of patient position prior to and potentially during radiation therapy, and provide considerably more anatomical detail than the conventional radiation therapy port films used for patient set-up verification. Also, MVCT imaging may enable reconstruction of the radiation dose delivered, thereby providing unprecedented verification of the actual treatment. These key features of helical tomotherapy distinguish it from other IMRT approaches. We report results from a pilot feasibility trial of 10 patients with non-small-cell lung cancer (NSCLC) on whom we obtained MVCT images using a prototype helical tomotherapy system. All patients underwent conventional CT imaging for radiation therapy treatment planning. Specific aims were to subjectively compare MVCT and conventional CT images and then to objectively compare the 2 modalities by contouring tumors and performing a volumetric comparison. Seven patients had disease located primarily in the lung parenchyma, 2 primarily in the mediastinum, and 1 in both. When evaluated by location, all 7 patients with lesions primarily in the lung parenchyma had subjectively high-quality MVCT images. Objectively, the volumetric agreement between conventional and MVCT for parenchymal lesions was excellent in 5 of the 7 patients. Megavoltage CT imaging via the helical tomotherapy prototype provided adequate information for use in verification of patient position and dose reconstruction for lesions within the pulmonary parenchyma, but presently appears suboptimal for primarily mediastinal disease. Further studies are ongoing to optimize MVCT imaging and better define its utility in patients with NSCLC.     

CT/MRI影像融合对肺癌脑转移放射治疗靶区勾画的影响

背景与目的脑转移瘤靶区勾画的准确性一直是放射治疗的关键,CT/MRI融合技术提供了可行的方法 ,本研究旨在探讨CT/MRI图像融合技术在肺癌脑转移靶区勾画中的作用。方法将31例肺癌脑转移患者的增强CT和MRI图像传送至图像处理工作站,分别在CT和CT/MRI融合图像上勾画GTV,比较勾画后的GTV体积,分析最大平均误差及瘤周水肿对靶区勾画的影响。结果 CT/MRI融合图像上勾画的GTV明显小于CT图像上勾画的GTV;瘤周水肿对靶区勾画存在明显影响。结论 CT/MRI图像融合技术可以提高肺癌脑转移靶区勾画的准确性。     

磁共振弥散加权成像在食管癌调强放疗中的应用及影响

[目的]探讨在食管癌调强放疗(IMRT)中,应用磁共振弥散加权成像技术(DWI)与CT融合图像勾画靶区对靶体积及正常肺组织受照剂量的影响,以及应用DWI对于放疗近期疗效评价的影响.[方法]随机选择40例初治食管癌患者,分别依据单纯CT图像、DWI与CT融合图像以及PET-CT与CT融合图像勾画靶区及危及器官.比较三种影像资料下勾画的GTV、PTV体积的大小差异;以及在PTV的处方剂量达到64Gy/32次时,比较三组调强放疗计划中双肺V5、V20、MLD的差异.同时在放疗前、放疗中(放疗开始后的1个月)及放疗后(放疗结束后1个月)各行1次胸部DWI扫描,比较放疗不同阶段、不同b值下所测肿瘤病灶ADC值的差异.[结果] 92.5％(37/40)的病例在DWI融合组以及PET-CT融合组勾画的GTV比在单纯CT组勾画的GTV体积小,差异具有统计学意义(P＜0.05).而DWI融合组勾画的GTV与PET-CT融合组勾画的GTV体积比较,差异无统计学意义(P＞0.05).在GTV基础上外扩得到的PTV,92.5％的病例在DWI融合组以及PET-CT融合组中比在单纯CT组的体积小,差异具有统计学意义(P＜0.05).将三组计划中的双肺V5、V20、MLD进行比较,92.5％的病例在DWI融合组及PET-CT融合组的双肺V5、Va0、MLD均较单纯CT组小,差异有统计学意义(P＜0.05).不同b值条件下,随着放疗的进行,放疗前、中、后所测得的ADC值逐渐升高,前后比较,差异有统计学意义(P＜0.05).[结论]应用DWI定位及融合技术勾画食管癌靶区提高了靶区勾画的精确性,更有利于正常肺组织的保护,降低正常肺组织的照射剂量.同时DWI对于食管癌患者放疗的近期疗效评价具有可靠价值.     

宫颈癌放射治疗疗效的MRI评价

目的分析宫颈癌放射治疗中与后MRI表现,探讨MRI成像对宫颈癌放射治疗疗效评估的价值。方法23例经病理证实的宫颈癌患者在放射治疗前、中及后不同时间段行盆腔的轴位T1WI,轴位及矢状位T2WI,冠状位SPIR,以及GDDTPA增强后T1WI的轴位、冠状位、矢状位扫描。在MRI图像上观察肿瘤在放射治疗前、后的大小及信号改变。结果外照射结束时,9例肿瘤缩小率在85%以下,14例>85%。T1WI增强扫描7例见肿瘤内出现“无强化区”,其中6例放射治疗结束后有肿瘤残留;16例肿瘤未见“无强化区”,其中13例肿瘤缩小率>85%,仅2例放射治疗后有肿瘤残留。MRI图像上,肿瘤痊愈表现为T2WI、SPIR序列呈低信号,T1WI增强扫描轻微强化或无强化。结论MRI成像可反应肿瘤对射线的疗效。外照射结束时肿瘤容积缩小程度与T1WI增强肿瘤内有无“无强化区”是预测放射治疗效果的重要观测指标。     

Penile bulb imaging

PURPOSE: Because of the apparent relationship between potency loss and radiation doses to the erectile bodies, there is increasing rationale for incorporating penile bulb dosimetry into treatment planning and posttreatment evaluation. Because the location and shape of the penile bulb have not been described in detail on various imaging modalities, we herein describe the anatomic boundaries of the penile bulb on computed tomography (CT), magnetic resonance imaging (MR), and transrectal ultrasound (TRUS), before and after brachytherapy. METHODS AND MATERIALS: Nonenhanced axial CT images were taken on a CTi CT Scanner (General Electric Medical Systems, Milwaukee, WI) with the patient in the supine position. Settings were at 300 ma, 140 kvp, 4-s scan time per slice, and collimation of 3 mm with data obtained at 3-mm intervals. Nonenhanced MR images were obtained with a 1.5 Tesla Signa Horizon LX Scanner using fast spin-echo T1-weighted (TR/TE, 466/20) and T2-weighted (TR/TE, 8000/90) images, with a slice thickness of 2 mm and an interslice gap of 0.5 mm. TRUS images were obtained with a Siemens SONOLINE Prima ultrasound machine at 6.0 MHz and a Winston-Barzell stepper unit. RESULTS: The penile bulb is best visualized on T2-weighted MR images in the axial, sagittal, and coronal planes, appearing as an oval-shaped, hyperintense midline structure. On axial CT imaging, the bulb of the penis is typically readily identifiable, bounded by the paired crura laterally, the corpora spongiosum anteriorly, and the levator ani posteriorly. The penile bulb is typically well visualized on transverse TRUS, but usually only faintly seen on sagittal TRUS. The bulb is partially obscured on postimplant CT and MR images, presumably because of implant-related edema. Bulb volumes vary markedly from patient to patient, ranging from 5.6 to 12.4 cc (median: 8.1 cc). CONCLUSION: Closer attention to penile erectile tissue doses should lead to improved external beam radiation and brachytherapy delivery. It will benefit the radiation oncology community to become familiar with these imaging findings, so that penile bulb dosimetry can be incorporated into our daily practice.     

CT图像后处理技术在周围型肺癌诊断中的应用

目的：用螺旋CT轴位图像与后处理重建图像技术在周围型肺癌形态显示对比分析.方法：经手术病理证实的周围型肺癌,利用多种图像工作站后处理软件重建,分别观察肿块表面形态与周围的关系,并与轴位图像进行比较.结果：左肺上叶18例（舌段5例）,左肺下叶14例,右肺上叶16例,中叶9例,右肺下叶22例.HRCT显示周围型肺癌表面征象和内部结构优于SCT,处理重建图像的肿瘤表面征象与常规图像显示率无明显差异.结论：螺旋CT薄层轴位图像对肿瘤的边缘和内部细微改变显示佳,可为诊断提供更多依据;各种图像后处理重建技术能很好地显示周围型肺癌的形态特征,及与周围支气管、血管束的立体解剖关系,是CT轴位图像的重要补充.     

Assessment of residual error in liver position using kV cone-beam computed tomography for liver cancer high-precision radiation therapy

PURPOSE: To evaluate the residual error in liver position using breath-hold kilovoltage (kV) cone-beam computed tomography (CT) following on-line orthogonal megavoltage (MV) image-guided breath-hold liver cancer conformal radiotherapy. METHODS AND MATERIALS: Thirteen patients with liver cancer treated with 6-fraction breath-hold conformal radiotherapy were investigated. Before each fraction, orthogonal MV images were obtained during exhale breath-hold, with repositioning for offsets>3 mm, using the diaphragm for cranio-caudal (CC) alignment and vertebral bodies for medial-lateral (ML) and anterior posterior (AP) alignment. After repositioning, repeat orthogonal MV images, orthogonal kV fluoroscopic movies, and kV cone-beam CTs were obtained in exhale breath-hold. The cone-beam CT livers were registered to the planning CT liver to obtain the residual setup error in liver position. RESULTS: After repositioning, 78 orthogonal MV image pairs, 61 orthogonal kV image pairs, and 72 kV cone-beam CT scans were obtained. Population random setup errors (sigma) in liver position were 2.7 mm (CC), 2.3 mm (ML), and 3.0 mm (AP), and systematic errors (Sigma) were 1.1 mm, 1.9 mm, and 1.3 mm in the superior, medial, and posterior directions. Liver offsets>5 mm were observed in 33% of cases; offsets>10 mm and liver deformation>5 mm were observed in a minority of patients. CONCLUSIONS: Liver position after radiation therapy guided with MV orthogonal imaging was within 5 mm of planned position in the majority of patients. kV cone-beam CT image guidance should improve accuracy with reduced dose compared with orthogonal MV image guidance for liver cancer radiation therapy.     

Prostate seed implant quality assessment using MR and CT image fusion

Purpose: After a seed implant of the prostate, computerized tomography (CT) is ideal for determining seed distribution but soft tissue anatomy is frequently not well visualized. Magnetic resonance (MR) images soft tissue anatomy well but seed visualization is problematic. We describe a method of fusing CT and MR images to exploit the advantages of both of these modalities when assessing the quality of a prostate seed implant.Methods and Materials: Eleven consecutive prostate seed implant patients were imaged with axial MR and CT scans. MR and CT images were fused in three dimensions using the Pinnacle 3.0 version of the ADAC treatment planning system. The urethra and bladder base were used to “line up” MR and CT image sets during image fusion. Alignment was accomplished using translation and rotation in the three ortho-normal planes. Accuracy of image fusion was evaluated by calculating the maximum deviation in millimeters between the center of the urethra on axial MR versus CT images. Implant quality was determined by comparing dosimetric results to previously set parameters.Results: Image fusion was performed with a high degree of accuracy. When lining up the urethra and base of bladder, the maximum difference in axial position of the urethra between MR and CT averaged 2.5 mm (range 1.3–4.0 mm, SD 0.9 mm). By projecting CT-derived dose distributions over MR images of soft tissue structures, qualitative and quantitative evaluation of implant quality is straightforward.Conclusions: The image-fusion process we describe provides a sophisticated way of assessing the quality of a prostate seed implant. Commercial software makes the process time-efficient and available to any clinical practice with a high-quality treatment planning system. While we use MR to image soft tissue structures, the process could be used with any imaging modality that is able to visualize the prostatic urethra (e.g., ultrasound).     

螺旋CT在喉及下咽癌的临床应用价值

目的 探讨螺旋ＣＴ多平面重组（ＭＰＲ）、三维重建（3D）和领导 具喉镜（CTVL）在喉及下咽癌的临床应用价值。方法 24例喉及下咽癌患者进行轴位螺旋CT扫描。同时做MPR、3D和CTVL成像,并与纤维喉镜和手术所见进行对照分析。结果 螺旋CT轴位结合MPR图像对术前肿瘤分期和诊断颈部淋巴结转移的准确性均为96%;25%的患者MPR显示肿瘤侵犯的范围优于轴位,3D重建可立体显示肿瘤的侵犯范围及其与血管、气管的关系;头端CTVL显示的喉及下咽部腔内肿瘤的部位、大小及侵犯范围与纤维喉镜所见相似,4例从足侧观察肿瘤与声带和前联合的关系弥补了纤维喉镜的不足,结论 螺旋CT轴位结合MPR、3D和CTVL图像可以更完整地提高喉及下咽癌的全面资料。     

Flat-panel cone-beam computed tomography for image-guided radiation therapy

: Geometric uncertainties in the process of radiation planning and delivery constrain dose escalation and induce normal tissue complications. An imaging system has been developed to generate high-resolution, soft-tissue images of the patient at the time of treatment for the purpose of guiding therapy and reducing such uncertainties. The performance of the imaging system is evaluated and the application to image-guided radiation therapy is discussed.

: A kilovoltage imaging system capable of radiography, fluoroscopy, and cone-beam computed tomography (CT) has been integrated with a medical linear accelerator. Kilovoltage X-rays are generated by a conventional X-ray tube mounted on a retractable arm at 90° to the treatment source. A 41 × 41 cm² flat-panel X-ray detector is mounted opposite the kV tube. The entire imaging system operates under computer control, with a single application providing calibration, image acquisition, processing, and cone-beam CT reconstruction. Cone-beam CT imaging involves acquiring multiple kV radiographs as the gantry rotates through 360° of rotation. A filtered back-projection algorithm is employed to reconstruct the volumetric images. Geometric nonidealities in the rotation of the gantry system are measured and corrected during reconstruction. Qualitative evaluation of imaging performance is performed using an anthropomorphic head phantom and a coronal contrast phantom. The influence of geometric nonidealities is examined.

: Images of the head phantom were acquired and illustrate the submillimeter spatial resolution that is achieved with the cone-beam approach. High-resolution sagittal and coronal views demonstrate nearly isotropic spatial resolution. Flex corrections on the order of 0.2 cm were required to compensate gravity-induced flex in the support arms of the source and detector, as well as slight axial movements of the entire gantry structure. Images reconstructed without flex correction suffered from loss of detail, misregistration, and streak artifacts. Reconstructions of the contrast phantom demonstrate the soft-tissue imaging capability of the system. A contrast of 47 Hounsfield units was easily detected in a 0.1-cm-thick reconstruction for an imaging exposure of 1.2 R (in-air, in absence of phantom). The comparison with a conventional CT scan of the phantom further demonstrates the spatial resolution advantages of the cone-beam CT approach.

: A kV cone-beam CT imaging system based on a large-area, flat-panel detector has been successfully adapted to a medical linear accelerator. The system is capable of producing images of soft tissue with excellent spatial resolution at acceptable imaging doses. Integration of this technology with the medical accelerator will result in an ideal platform for high-precision, image-guided radiation therapy.     

Image Storage Requirements for Treatment Planning and Verification

Digital imaging techniques are becoming increasingly accepted in radiation therapy, and they bring significant advantages when compared with film, especially the ease of storage and retrieval. A simple model is proposed for the estimation of digital data storage requirements in a typical department of radiation therapy. The model assumes that 100 patients are undergoing treatment at any given time, and their computed tomography (CT) images, treatment plans, digitized simulator films, and portal images are to be available at short notice ("on-line"). Off-line archival image storage is required after the completion of treatment, for 1,000 patients per year. Reasonable assumptions are postulated regarding image sizes and acquisition rates, and on-line storage requirements are estimated to be up to 300 megabytes (MB) for CT data, 170 MB for treatment plans, 200 MB for digitized simulator films, and 500 MB for digitized port films. If electronic portal imaging is used instead of port films, the on-line requirement becomes about 2 gigabytes (GB) for verification images, and 20 GB if portal movies are to be archived. Off-line storage requirements are a factor of ten larger. It is suggested that data compression may reduce these requirements by up to a factor of 20.     

Defining the target volume for post-operative radiotherapy after D2 dissection in gastric cancer by CT-based vessel-guided delineation

Purpose

To determine the recurrent nodal gross tumor volume (rnGTV) based on CT-guided vascular structure to refine the clinical target volume (CTV) delineation in postoperative radiotherapy for advanced gastric cancer following radical gastrectomy with D2 dissection.

Materials and methods

We retrospectively reviewed follow-up images from 91 patients with their first regional recurrence after D2 dissection in stage III gastric cancer with N3 disease. We defined rnGTV as recurrent nodes shown in follow-up CT images, in which one diagnostic radiologist with specialty of gastrointestinal tract investigated. We drew rnGTVs at the equivalent location based on the same vessels of reference comparing CT images to recurrence CT images.

Results

We propose vessel-based locations of rnGTVs on CT images with axial and coronal views. We show different patterns of regional recurrence according to the location of primary gastric cancer using CT and digitally reconstructed radiograph (DRR) images. Frequently recurred sites, overlapped by more than five rnGTVs, are depicted in a DRR image.

Conclusions

This study suggests vessel-based delineations of rnGTVs on CT images depending on nodal recurrence sites from follow-up images after D2 lymphadenectomy. Our results could help reduce the inter-observer variation of CTV delineation after D2 dissection in gastric cancer.     

Magnetic resonance imaging in the radiation treatment planning of localized prostate cancer using intra-prostatic fiducial markers for computed tomography co-registration.

PURPOSE: To assess the feasibility, and potential implications, of using intra-prostatic fiducial markers, rather than bony landmarks, for the co-registration of computed tomography (CT) and magnetic resonance (MR) images in the radiation treatment planning of localized prostate cancer. METHODS: All men treated with conformal therapy for localized prostate cancer underwent routine pre-treatment insertion of prostatic fiducial markers to assist with gross target volume (GTV) delineation and to identify prostate positioning during therapy. Six of these men were selected for investigation. Phantom MRI measurements were obtained to quantify image distortion, to determine the most suitable gold alloy marker composition, and to identify the spin-echo sequences that optimized both marker identification and the contrast between the prostate and the surrounding tissues. The GTV for each patient was contoured independently by three radiation oncologists on axial planning CT slices, and on axial MRI slices fused to the CT slices by matching the implanted fiducial markers. From each set of contours the scan common volume (SCV), and the scan encompassing volume (SEV), were obtained. The ratio SEV/SCV for a given scan is a measure of inter-observer variation in contouring. For each of the 18 patient-observer combinations the observer common volume (OCV) and the observer encompassing volume (OEV) was obtained. The ratio OEV/OCV for a given patient-observer combination is a measure of the inter-modality variation in contouring. The distance from the treatment planning isocenter to the prostate contours was measured and the discrepancy between the CT- and the MR-defined contour recorded. The discrepancies between the CT- and MR-defined contours of the posterior prostate were recorded in the sagittal plane at 1-cm intervals above and below the isocenter. RESULTS: Phantom measurements demonstrated trivial image distortion within the required field of view, and an 18K Au/Cu alloy to be the marker composition most suitable for CT-MRI image fusion purposes. Inter-observer variation in prostate contouring was significantly less for MR compared to CT. The mean SEV/SCV ratio was 1.58 (confidence interval (CI): 1.47-1.69) for CT scans and 1.37 (CI: 1.33-1.41) for MR scans (paired t-test; P=0.036). The overall magnitude of contoured GTV was similar for MR and CT; however, there were spatial discrepancies in contouring between the two modalities. The greatest systematic discrepancy was at the posterior apical prostate border, which was defined 3.6 mm (SD 3.5 mm) more posterior on MR- than CT-defined contouring. CONCLUSIONS: Prostate contouring on MR is associated with less inter-observer variation than on CT. In addition, we have demonstrated the feasibility of using intra-prostatic fiducial markers, rather than bony landmarks, for the co-registration of CT and MR images in the radiation treatment planning of localized prostate cancer. This technique, together with on-line correction of treatment set-up according to the fiducial marker position on electronic portal imaging, may enable a reduction in the planning target volume (PTV) margin needed to account for inter-observer error in target delineation, and for prostate motion.     

Use of lymphoscintigraphy in radiation treatment of primary breast cancer in the context of lymphedema risk reduction

Purpose

The goal of this study was to determine the feasibility of SPECT/CT scintigraphic method for mapping lymphatic drainage for radiation therapy of breast cancer.

Materials and methods

Thirty-six patients were enrolled in a SPECT/CT lymphoscintigraphy study. ^99mTc sulfur colloid (1 mCi) was injected intradermally in the ipsilateral arm. After 5–8 h post-injection, the SPECT/CT scans were taken and analyzed on a GE eNTRGRA system. The SPECT/CT images were co-registered in the treatment planning system (TPS). The original treatment plan was recreated for nodal dosimetry. Intensity modulated radiation therapy (IMRT) planning was performed for reducing lymph node dose for reducing arm lymphedema.

Results

The number of lymph nodes varied from 0 to 10 with a mean value of 3.4 ± 5.4 nodes. The location of nodes varied in the axillary, supraclavicular, and breast regions depending upon the surgical procedure and the extent of the disease. The prescribed radiation dose to the breast varied from 45 to 50.4 Gy depending on the disease pattern in 32 evaluated patients having CT data. The dose to lymph nodes varied from 0 to 61.8 Gy depending upon the location and the radiation technique used. SPECT/CT study in conjunction with IMRT plan showed that it is possible to decrease nodal dose and thereby potentially reduce the risk of developing arm lymphedema.

Conclusions

The SPECT/CT device provides a novel method to map the lymph nodes in the radiation treatment fields that could be used to tailor the radiation dose.     

Characterisation of radiotherapy planning volumes using textural analysis

Computer-based artificial intelligence methods for classification and delineation of the gross tumour volume (GTV) on computerised tomography (CT) and magnetic resonance (MR) images do not, at present, provide the accuracy required for radiotherapy applications. This paper describes an image analysis method for classification of distinct regions within the GTV, and other clinically relevant regions, on CT images acquired on eight bladder cancer patients at the radiotherapy planning stage and thereafter at regular intervals during treatment. Statistical and fractal textural features (N=27) were calculated on the bladder, rectum and a control region identified on axial, coronal and sagittal CT images. Unsupervised classification results demonstrate that with a reduced feature set (N=3) the approach offers significant classification accuracy on axial, coronal and sagittal CT image planes and has the potential to be developed further for radiotherapy applications, particularly towards an automatic outlining approach.     

多层螺旋CT灌注成像对胃癌血管通透性评估的价值

目的:探讨多层螺旋CT(multi-slice spiral CT,MSCT)灌注成像对胃癌血管通透性评估的价值。方法:对30例活检证实的胃癌患者术前行多层螺旋CT灌注成像,扫描图像经ADW4.0工作站处理,计算得到胃癌组织的表面通透性(permeability surface,PS)值,并分析其与胃癌临床病理特征和CT征象(CT轴位图像上瘤周低密度带厚度、肿瘤最大径和厚度)的关系。结果:胃癌病灶的PS值与淋巴结转移、TNM分期、组织学类型和肿瘤最大径均密切相关(P均<0.05),而与浸润深度、远处转移、性别、患者年龄和肿瘤部位无关。同时,胃癌PS值与CT轴位图像上瘤周低密度带厚度(r=0.417,P<0.05)和肿瘤最大径(r=0.557,P<0.01)均呈线性相关,而与肿瘤厚度无关。受试者工作特征(ROC)分析显示,胃癌PS值对胃癌组织学类型(分化型/未分化型)和TNM分期(Ia~IIIa/IIIb~IV)判断的准确率均较高[ROC曲线下面积(Az)分别为0.79和0.78]。结论:多层螺旋CT灌注成像对胃癌血管通透性的评估具有较大的临床应用价值。     

CT图像影像组学特征参数变化与放射性肺炎的相关性研究

目的 应用影像组学技术分析发生放射性肺炎(RP)的肺癌患者定位及复位CT图像特征参数变化,筛选与RP发生密切相关的指标。方法 选取放疗后经过随访发生2级及以上RP的肺癌患者31例,获取其放疗前的定位CT图像和经过40 Gy放疗后的复位CT图像,将患侧肺和健侧肺设置为提取参数的ROI,在完成正常肺组织自动分割后,使用IBEX软件进行radiomics特征参数的提取,比较这些特征参数在定位和复位CT图像中的差异。结果 (1)每个时段的单侧肺分别提取了86个有效参数指标;(2)放疗前患侧肺和健侧肺差异有统计学意义的参数指标有22个;(3)复位CT中健侧肺和患侧肺差异有统计学意义的参数有12个;(4)患侧肺放疗前后差异有统计学意义的参数有28个;(5)健侧肺放疗前后差异有统计学意义的参数有28个。结论 在发生RP的肺癌患者中,部分CT影像组学特征在定位和复位CT间差异显著,对这些指标动态变化的追踪分析具有预测RP发生的潜在优势。     

Impact of FDG-PET on radiation therapy volume delineation in non-small-cell lung cancer

PURPOSE: Locoregional failure remains a significant problem for patients receiving definitive radiation therapy alone or combined with chemotherapy for non-small-cell lung cancer (NSCLC). Positron emission tomography (PET) with [(18)F]fluoro-2-deoxy-d-glucose (FDG) has proven to be a valuable diagnostic and staging tool for NSCLC. This prospective study was performed to determine the impact of treatment simulation with FDG-PET and CT on radiation therapy target volume definition and toxicity profiles by comparison to simulation with computed tomography (CT) scanning alone. METHODS: Twenty-six patients with Stages I-III NSCLC were studied. Each patient underwent sequential CT and FDG-PET simulation on the same day. Immobilization devices used for both simulations included an alpha cradle, a flat tabletop, 6 external fiducial markers, and a laser positioning system. A radiation therapist participated in both simulations to reproduce the treatment setup. Both the CT and fused PET/CT image data sets were transferred to the radiation treatment planning workstation for contouring. Each FDG-PET study was reviewed with the interpreting nuclear radiologist before tumor volumes were contoured. The fused PET/CT images were used to develop the three-dimensional conformal radiation therapy (3DCRT) plan. A second physician, blinded to the results of PET, contoured the gross tumor volumes (GTV) and planning target volumes (PTV) from the CT data sets, and these volumes were used to generate mock 3DCRT plans. The PTV was defined by a 10-mm margin around the GTV. The two 3DCRT plans for each patient were compared with respect to the GTV, PTV, mean lung dose, volume of normal lung receiving > or =20 Gy (V20), and mean esophageal dose. RESULTS: The FDG-PET findings altered the AJCC TNM stage in 8 of 26 (31%) patients; 2 patients were diagnosed with metastatic disease based on FDG-PET and received palliative radiation therapy. Of the 24 patients who were planned with 3DCRT, PET clearly altered the radiation therapy volume in 14 (58%), as follows. PET helped to distinguish tumor from atelectasis in all 3 patients with atelectasis. Unsuspected nodal disease was detected by PET in 10 patients, and 1 patient had a separate tumor focus detected within the same lobe of the lung. Increases in the target volumes led to increases in the mean lung dose, V20, and mean esophageal dose. Decreases in the target volumes in the patients with atelectasis led to decreases in these normal-tissue toxicity parameters. CONCLUSIONS: Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in over 50% of patients by comparison with CT targeting. The increasing availability of integrated PET/CT units will facilitate the use of this technology for radiation treatment planning. A confirmatory multicenter, cooperative group trial is planned within the Radiation Therapy Oncology Group.