Clinical implications of defining the gross tumor volume with combination of CT and 18FDG-positron emission tomography in non-small-cell lung cancer

PURPOSE: To compare the planning target volume (PTV) definitions for computed tomography (CT) vs. positron emission tomography (PET) in non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: A total of 21 patients with NSCLC underwent three-dimensional conformal radiotherapy planning. All underwent a staging F-18 fluorodeoxyglucose-position emission tomography (18FDG-PET) scan and underwent treatment simulation using CT plus a separate planning 18FDG-PET scan. Three sets of target volumes were defined: Set 1, CT volumes (CT tumor + staging PET nodal disease); Set 2, PET volumes (planning PET tumor {gross tumor volume (GTV) = [(0.3069 x mean standardized uptake value) + 0.5853])}; Set 3, composite CT-PET volumes (fused CT-PET tumor). Sets 1 and 2 were compared using a matching index. Three-dimensional conformal radiotherapy plans were created using the Set 1 (CT) volumes; and coverage of the Set 3 (composite) volumes was evaluated. Separate three-dimensional conformal radiotherapy plans were designed for the Set 3 volumes. RESULTS: For the primary tumor GTV, the Set 1 (CT) volume was larger than the Set 2 (PET) volume in 48%, smaller in 33%, and equal in 19%. The mean matching index was 0.65 (35% CT-PET mismatch). Although quantitatively similar, the volumes differed qualitatively. The Set 3 (composite) volume was larger than either CT or PET alone in 62%, smaller in 24%, and equal in 14%. The dose-volume histogram parameters did not differ among the plans for Set 1 (CT) vs. Set 3 (composite) volumes. Small portions of the Set 3 PTV were significantly underdosed in 40% of cases using the CT-only plan. CONCLUSION: Computed tomography and PET are complementary and should be obtained in the treatment position and fused to define the GTV for NSCLC. Although the quantitative absolute target volume is sometimes similar, the qualitative target locations can be substantially different, leading to underdosage of the target when planning is done using CT alone without PET fusion.     

CT灌注成像对非小细胞肺癌放疗靶区确定的临床意义

目的探讨CT灌注成像扫描对非小细胞肺癌（NSCLC）行三维适形放疗（3DCRT）时靶区确定的临床意义。方法对36例经病理组织学检查证实为NSCLC患者,先后行胸部常规CT扫描及CT灌注成像扫描。根据成像勾画原发病灶范围,分别称为CT-GTV和CTPI-CTV,由三维治疗计划系统得出GTV具体数值进行比较。结果所有患者均有不同程度差别。CT-GTV平均为133.00cm^3（90～194cm^3）,CTPI-CTV平均为106.60cm^3（67～152cm^3）;CTPI-CTV较CT-GTV缩小19.8%（26.4cm^3）（P=0.00）。GTV减少的主要原因是CT灌注成像能辨别肺不张和肿瘤,因而可以减少肿瘤靶体积并且避免正常组织不必要的勾画。结论CT灌注成像在确定非小细胞肺癌3DCRT靶区方面具有一定临床价值,并由此提高了靶区定位的精确性。     

Impact of computed tomography (CT) and 18F-deoxyglucose-coincidence detection emission tomography (FDG-CDET) image fusion for optimisation of conformal radiotherapy in non-small-cell lung cancers]

To report a retrospective study concerning the impact of fused 18F-fluorodeoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on three-dimensional conformal radiation therapy (3D-CRT) planning for patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: One hundred and one patients consecutively treated for stages I-III NSCLC were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define target volume. RESULTS: FDG-PET identified previously undetected distant metastatic disease in 8 patients making them ineligible for curative CRT (one patient presented some positive uptakes corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because fused CT/PET images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT/PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT/PET image fusion reduced pulmonary GTV in 6 patients (3 patients with atelectasis) and mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients due to an increase of the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Among 81 patients receiving a total dose > or = 60 Gy at ICRU point, after CT/PET image fusion, the percentage of total lung volume receiving more than 20 Gy (VL20) increased in 15 cases and decreased in 22 cases. The percentage of total heart volume receiving more than 36 Gy increased in 8 patients and decreased in 14 patients. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. After multivariate analysis, one single independent factor made significant effect of FDG/PET on the modification of the size of the GTV: tumor with atelectasis (P = 0.0001). Conclusion. - Our study confirms that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of patients with NSCLC. FDG images using dedicated PET scanners with modern image fusion techniques and respiration-gated acquisition protocols could improve CT/PET image coregistration. However, prospective studies with histological correlation are necessary and the impact on treatment outcome remains to be demonstrated.     

Radiotherapy treatment planning for patients with non-small cell lung cancer using positron emission tomography (PET).

PURPOSE: Many patients with non-small cell lung cancer (NSCLC) receive external beam radiation therapy as part of their treatment. Three-dimensional conformal radiation therapy (3DCRT) commonly uses computed tomography (CT) to accurately delineate the target lesion and normal tissues. Clinical studies, however, indicate that positron emission tomography (PET) has higher sensitivity than CT in detecting and staging of mediastinal metastases. Imaging with fluoro-2-deoxyglucose (FDG) PET in conjunction with CT, therefore, can improve the accuracy of lesion definition. In this pilot study, we investigated the potential benefits of incorporating PET data into the conventional treatment planning of NSCLC. Case-by-case, we prospectively analyzed planning target volume (PTV) and lung toxicity changes for a cohort of patients. MATERIALS AND METHODS: We have included 11 patients in this study. They were immobilized in the treatment position and CT simulation was performed. Following CT simulation, PET scanning was performed in the treatment position using the same body cast that was produced for CT simulation and treatment. The PTV, along with the gross target volume (GTV) and normal organs, was first delineated using the CT data set. The CT and PET transmission images were then registered in the treatment planning system using either manual or automated methods, leading to consequent registration of the CT and emission images. The PTV was then modified using the registered PET emission images. The modified PTV is seen simultaneously on both CT and PET images, allowing the physician to define the PTV utilizing the information from both data sets. Dose-volume histograms (DVHs) for lesion and normal organs were generated using both CT-based and PET+CT-based treatment plans. RESULTS: For all patients, there was a change in PTV outline based on CT images versus CT/PET fused images. In seven out of 11 cases, we found an increase in PTV volume (average increase of 19%) to incorporate distant nodal disease. Among these patients, the highest normal-tissue complication probability (NTCP) for lung was 22% with combined PET/CT plan and 21% with CT-only plan. In other four patients PTV was decreased an average of 18%. The reduction of PTV in two of these patients was due to excluding atelectasis and trimming the target volume to avoid delivering higher radiation doses to nearby spinal cord or heart. CONCLUSIONS: The incorporation of PET data improves definition of the primary lesion by including positive lymph nodes into the PTV. Thus, the PET data reduces the likelihood of geographic misses and hopefully improves the chance of achieving local control.     

Impact of computed tomography (CT) and 18F-deoxyglucose positron emission tomography (FDG-PET) image fusion for conformal radiotherapy in esophageal carcinoma]

PURPOSE: To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiation therapy (CRT) planning for patients with esophageal carcinoma. PATIENTS AND METHODS: Thirty-four patients with esophageal carcinoma were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. PET-images were coregistered using five fiducial markers. Target delineation was initially performed on CT images and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. RESULTS: FDG-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative CRT. The Gross Tumor Volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and was increased in 7 patients (20.5%). The GTV reduction was >or=25% in 4 patients due to reduction of the length of the esophageal tumor. The GTV increase was >or=25% with FDG-PET in 2 patients due to the detection of occult mediastinal lymph node involvement in one patient and an increased length of the esophageal tumor in the other patient. Modifications of the GTV affected the planning treatment volume (PTV) in 18 patients. Modifications of delineation of GTV and displacement of the isocenter of PTV by FDG-PET also affected the percentage of total lung volume receiving more than 20 Gy (VL20) in 25 patients (74%), with a dose reduction in 12 patients and a dose increase in 13 patients. CONCLUSION: In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of patients with esophageal carcinoma related to modifications of GTV. The impact on treatment outcome remains to be demonstrated.     

FDG PET对非小细胞肺癌合并肺不张三维适形放疗时靶区确定的临床意义

目的 探讨^18F-脱氧葡萄糖（FDG）PET对合并肺不张的非小细胞肺癌（NSCLC）行三维适形放疗时病变靶区确定的临床意义。方法 对14例经病理组织学证实为NSCLC且其影像学检查伴有不同程度肺不张者，先后行胸部增强明扫描及胸部或全身FDGP盯肿瘤显像。根据扫描及显像结果勾画原发病灶范围，分别称为CT-GTV和PET-GTV，并由CMS治疗计划系统给出GTV体积的具体数值加以比较。结果 全部患者的CT-GTV与PET-GTV均有不同程度差别，其中1例患者PET-GTV较CT-GTV增加16．9％（22cm^3），CT-GTV为130cm3，PET-G11V为152cm^3；13例患者PET-GTV较CT-GTV平均减少20．4％（27．2cm^3），CT-GTV平均为133cm^3（90-180cm^3），PET-GTV平均为106cm^3（60—153cm^3）（P=0．000）。GTV的减少主要原因是PET显像除外了因肿瘤原因造成的肺不张，从而引起靶区范围的缩小，进而避免对周围正常组织（主要是正常或不张的肺组织、脊髓及心血管）的不必要照射，最大限度地保护了正常组织。结论 FDG PET在确定肺不张与局部病变相互关系方面具有一定临床价值，并由此提高了靶区定位的精确性。     

The contribution of integrated PET/CT to the evolving definition of treatment volumes in radiation treatment planning in lung cancer

PURPOSE: Positron emission tomography (PET) with the glucose analog [18F]fluro-2-deoxy-D-glucose (FDG) has been accepted as a valuable tool for the staging of lung cancer, but the use of PET/CT in radiation treatment planning is still not yet clearly defined. By the use of (PET/computed tomography (CT) images in treatment planning, we were able to define a new gross treatment volume using anatomic biologic contour (ABC), delineated directly on PET/CT images. We prospectively addressed three issues in this study: (1) How to contour treatment volumes on PET/CT images, (2) Assessment of the degree of correlation between CT-based gross tumor volume/planning target volume (GTV/PTV) (GTV-CT and PTV-CT) and the corresponding PET/CT-based ABC treatment volumes (GTV-ABC and PTV-ABC), (3) Magnitude of interobserver (radiation oncologist planner) variability in the delineation of ABC treatment volumes (using our contouring method). METHODS AND MATERIALS: Nineteen patients with Stages II-IIIB non-small-cell lung cancer were planned for radiation treatments using a fully integrated PET/CT device. Median patient age was 74 years (range: 52-82 years), and median Karnofsky performance status was 70. Thermoplastic or vacuum-molded immobilization devices required for conformal radiation therapy were custom fabricated for the patient before the injection of [18]f-FDG. Integrated, coregistered PET/CT images were obtained and transferred to the radiation planning workstation (Xeleris). While the PET data remained obscured, a CT-based gross tumor volume (GTV-CT) was delineated by two independent observers. The PTV was obtained by adding a 1.5-cm margin around the GTV. The same volumes were recontoured using PET/CT data and termed GTV-ABC and PTV-ABC, correspondingly. RESULTS: We observed a distinct "halo" around areas of maximal standardized uptake value (SUV). The halo was identified by its distinct color at the periphery of all areas of maximal SUV uptake, independent of PET/CT gain ratio; the halo had an SUV of 2 +/- 0.4 and thickness of 2 mm +/- 0.5 mm. Whereas the center of our contoured treatment volume expressed the maximum SUV level, a steady decline of SUV was noted peripherally until SUV levels of 2 +/- 0.4 were reached at the peripheral edge of our contoured volume, coinciding with the observed halo region. This halo was always included in the contoured GTV-ABC. Because of the contribution of PET/CT to treatment planning, a clinically significant (> or =25%) treatment volume modification was observed between the GTV-CT and GTV-ABC in 10/19 (52%) cases, 5 of which resulted in an increase in GTV-ABC volume vs. GTV-CT. The modification of GTV between CT-based and PET/CT-based treatment planning resulted in an alteration of PTV exceeding 20% in 8 out of 19 patients (42%). Interobserver GTV variability decreased from a mean volume difference of 28.3 cm3 (in CT-based planning) to 9.12 cm3 (in PET/CT-based planning) with a respective decrease in standard deviation (SD) from 20.99 to 6.47. Interobserver PTV variability also decreased from 69.8 cm3 (SD +/- 82.76) in CT-based planning to 23.9 cm3 (SD +/- 15.31) with the use of PET/CT in planning. The concordance in treatment planning between observers was increased by the use of PET/CT; 16 (84%) had < or =10% difference from mean of GTVs using PET/CT compared to 7 cases (37%) using CT alone (p = 0.0035). Conclusion: Position emission tomography/CT-based radiation treatment planning is a useful tool resulting in modification of GTV in 52% and improvement of interobserver variability up to 84%. The use of PET/CT-based ABC can potentially replace the use of GTV. The anatomic biologic halo can be used for delineation of volumes.     

Initial experience of FDG-PET/CT guided IMRT of head-and-neck carcinoma

PURPOSE: The purpose of this study is to evaluate the impact of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) fused with planning computed tomography (CT) on tumor localization, which guided intensity-modulated radiotherapy (IMRT) of patients with head-and-neck carcinoma. METHODS AND MATERIALS: From October 2002 through April 2005, we performed FDG-PET/CT guided IMRT for 28 patients with head-and-neck carcinoma. Patients were immobilized with face masks that were attached with five fiducial markers. FDG-PET and planning CT scans were performed on the same flattop table in one session and were then fused. Target volumes and critical organs were contoured, and IMRT plans were generated based on the fused images. RESULTS: All 28 patients had abnormal increased uptake in FDG-PET/CT scans. PET/CT resulted in CT-based staging changes in 16 of 28 (57%) patients. PET/CT fusions were successfully performed and were found to be accurate with the use of the two commercial planning systems. Volume analysis revealed that the PET/CT-based gross target volumes (GTVs) were significantly different from those contoured from the CT scans alone in 14 of 16 patients. In addition, 16 of 28 patients who were followed for more than 6 months did not have any evidence of locoregional recurrence in the median time of 17 months. CONCLUSION: Fused images were found to be useful to delineate GTV required in IMRT planning. PET/CT should be considered for both initial staging and treatment planning in patients with head-and-neck carcinoma.     

术后复发性食管癌18^FDG PET/CT定位三维适形放疗的疗效分析

目的：对比研究18^FDG PET/CT定位三维适形常规分割放疗术后复发性食管癌的疗效、副反应及失败原因。方法：对58例术后复发性食管鳞癌患者用信封法随机分为18 FDG PET/CT定位三维适形放疗组（PET/CT组）和普通CT定位三维适形放疗组（普通CT组）。PET/CT组用PET/CT扫描定位,经PET/CT扫描后将扫描数据输入治疗计划系统,将PET图像和CT图像融合后进行靶区和重要脏器勾画、三维重建,制定治疗计划后进行常规分割三维适形放疗40Gy左右,然后适当缩野针对残存肿瘤病灶放疗至总剂量60Gy-70Gy;普通CT组用普通CT定位设野,三维适形放疗至相同剂量。结果：PET/CT组的平均GTV与PTV体积、左肺、右肺、心脏、胸胃、脊髓照射体积均比普通CT组小（P均〈0.05）;PET/CT组和普通CT组的1、2、3年生存率分别为93.0%、59.9%、20.4%和86.7%、54.6%、20.9%（P均〈0.01）;PET/CT组早期气管、食管、胃肠道、肺的1、2级副反应均低于普通CT组（P均〈0.05）;卡氏评分高、进食情况良好、病变长度≤5cm、标准摄入值低的病变预后较好。结论：PET/CT定位三维适形放疗术后复发性食管癌可以优化放疗计划,减轻正常组织的放射副反应,早期病变预后好。     

PET/CT对非小细胞肺癌三维适形放疗中治疗计划参数的影响

目的:观察PET/CT对非小细胞肺癌(NSCLC)三维适形放疗(3D-CRT)中治疗计划参数的影响.方法:对83例在PET/CT定位下拟行根治性3D-CRT的NSCLC患者,分别以CT图像和PET/CT融合图像勾画大体肿瘤靶区(GTVCT和GTVPET/CT),分别制定放疗计划,并对两者进行比较.结果:PET/CT明显改变44例(53.01％)患者GTV或PTV,31例PTV和(或)GTV减小,13例PTV和(或)GTV增加.根据PET/CT和CT分别制定的放疗计划在VGTV、VE50、SCM和ESM的差异有统计学意义,P值分别为0.001、0.001、0.000和0.002.结论:应用PET/CT制定NSCLC3D-CRT治疗计划可降低食管和脊髓的受照射剂量,从而有利于放疗剂量的提升.     

Impact of hybrid fluorodeoxyglucose positron-emission tomography/computed tomography on radiotherapy planning in esophageal and non-small-cell lung cancer

PURPOSE: The aim of this study was to investigate the impact of a hybrid fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) scanner in radiotherapy planning for esophageal and non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: A total of 30 patients (16 with esophageal cancer, 14 with NSCLC) underwent an FDG-PET/CT for radiotherapy planning purposes. Noncontrast total-body spiral CT scans were obtained first, followed immediately by FDG-PET imaging which was automatically co-registered to the CT scan. A physician not involved in the patients' original treatment planning designed a gross tumor volume (GTV) based first on the CT dataset alone, while blinded to the FDG-PET dataset. Afterward, the physician designed a GTV based on the fused PET/CT dataset. To standardize PET GTV margin definition, background liver PET activity was standardized in all images. The CT-based and PET/CT-based GTVs were then quantitatively compared by way of an index of conformality, which is the ratio of the intersection of the two GTVs to their union. RESULTS: The mean index of conformality was 0.44 (range, 0.00-0.70) for patients with NSCLC and 0.46 (range, 0.13-0.80) for patients with esophageal cancer. In 10 of the 16 (62.5%) esophageal cancer patients, and in 12 of the 14 (85.7%) NSCLC patients, the addition of the FDG-PET data led to the definition of a smaller GTV. CONCLUSION: The incorporation of a hybrid FDG-PET/CT scanner had an impact on the radiotherapy planning of esophageal cancer and NSCLC. In future studies, we recommend adoption of a conformality index for a more comprehensive comparison of newer treatment planning imaging modalities to conventional options.     

中晚期前列腺癌PET／CT定位三维适形放疗的疗效和预后分析

目的：探讨中晚期前列腺癌经18^FDGPET／CT定位适形放疗的疗效、副反应及失败原因。方法：对68例中晚期前列腺癌患者随机分为18^FDGPETYCT定位适形放疗组（PET／CT组）和普通CT定位适形放疗组（普通CT组）。PET／CT组用PET／CT扫描定位,将扫描数据输入三维治疗计划系统,将PET图像和CT图像融合后进行靶区（GTV与PrrV）和重要脏器勾画、三维重建,制定计划后常规分割适形放疗40Gy左右,然后缩野放疗至总剂量60Gy～70Gy;普通cT组用普通CT定位设野,三维适形放疗至相同剂量。结果：PET／CT组的平均刚体积、膀胱V40、直肠V40均小于普通cT组（P均〈0．01）;两组放疗后PSA均明显下降（P均〈0．01）;PET／CT组的中位复发时间12．1个月,普通CT组的中位复发时间9．2个月,两者差异有统计学意义（P〈0．01）;PET／CT组的胃肠道与膀胱放射性副反应低于普通CT组（P均〈0．05）;疗前GTV≤50cm^3者预后好。结论：PET／CT定位三维适形放疗中晚期前列腺癌可以优化放疗计划,减少放射副反应,分期早的病变预后好。     

Current status of PET/CT for tumour volume definition in radiotherapy treatment planning for non-small cell lung cancer (NSCLC)

Target volume delineation of lung cancer is well known to be prone to large inter-observer variability. The advent of PET/CT devices, with co-registered functional and anatomical data, has opened new exciting possibilities for target volume definition in radiation oncology. PET/CT imaging is rapidly being embraced by the radiation oncology community as a tool to improve the accuracy of target volume delineation for treatment optimization in NSCLC. Several studies have dealt with the feasibility of incorporating FDG-PET information into contour delineation with the aim to improve overall accuracy and to reduce inter-observer variation. A significant impact of PET-derived contours on treatment planning has been shown in 30-60% of the plans with respect to the CT-only target volume. The most prominent changes in the gross tumour volume (GTV) have been reported in cases with atelectasis and following the incorporation of PET-positive nodes in otherwise CT-insignificant nodal areas. Although inter-observer variability is still present following target volume delineation with PET/CT, it is greatly reduced compared to conventional CT-only contouring. PET/CT may also provide improved therapeutic ratio compared to conventional CT planning. Increased target coverage and often reduced target volumes may potentially result in PET/CT-based planning to yield better tumour control probability through dose escalation, while still complying with dose/volume constrains for normal tissues. Despite these exciting results, more clinical studies need to be performed to better define the role of combined PET/CT in treatment planning for NSCLC.     

PET／CT确定非小细胞肺癌三维适形放疗靶区的临床研究

目的探讨PET—CT检查对非小细胞肺癌（non—small—cell lung cancer,NSCLC）患者的分期与治疗方案的影响和PET／CT所确定的靶区（GTV）与病理学肿瘤大小的关系。方法2006年3月一2008年7月间37例接受手术或放疗的NSCLC患者,根据PET／CT检查结果,21例患者进入手术组（有手术指征）,16例患者进入放疗组（无手术指征）,手术组术前在PET／CT图像上确定肿瘤在冠状轴（x轴）、矢状轴（Y轴）、长轴（z轴）三维径线上的大小,术后病理检查,确定肿瘤在X、Y、Z轴上的大小;TNM分期分别用CT、PET／CT分期与病理学分期。放疗组分别在PET／CT和CT横断图像上勾画原发灶和纵隔淋巴结GTV,软件自动运算PET／CT和模拟定位增强CT所勾画靶区的体积。结果19例（51．4％）的TNM分期在PET／CT检查后发生改变;12例（37．8％）的治疗方案因而发生变化。CT、PET／CT、病理确定的原发灶大小在X、Y轴上无显著差异（P值〉0．05）,Z轴上有显著差异（P值〈0．05）;放疗组16例患者中,PET／CT所勾画的GTVPET〉GTVCT者共4例,因为PET／CT发现不符合CT诊断标准的纵隔淋巴结转移灶。GTVPET〈GTVCT者共7例,主要是因为PET／CT排除了阻塞性肺炎和肺不张。结论PET／CT检查对分期与治疗方案的影响较大,PET／CT与病理学的肿瘤大小基本一致,PET／CT所确定的肿瘤大小可以作为病理学的GTV,勾画非小细胞肺癌放疗靶区PET／CT优于CT。     

PET/CT对非小细胞肺癌临床分期及精确放疗计划的影响

目的 观察PET／CT对非小细胞肺癌（NSCLC）临床分期和靶区勾画的作用,探讨PET／CT对其精确放疗计划的影响。方法 对拟行根治性放疗或手术治疗的58例确诊的NSCLC患者进行PET／CT检查。参照1997年WHO肺癌分期标准,判定PET／CT对NSCLC临床分期的影响,再分别以CT图像、PET／CT融合图像勾画大体靶区（GTV）,以相同参数制定三维适形放疗（3D-CRT）计划。选择GTV体积（V GTV）、受照量≥20Gy的肺占全肺体积的比例（V20）、平均全肺受照剂量（MLD）、肿瘤控制概率（TCP）、正常组织并发症概率（NTCP）、脊髓受照剂量（Ds）等指标进行统计学对比研究,评价两个计划的优劣,分析PET／CT对NSCLC精确放疗计划的影响。结果 PET／CT使21例（36．2％）的临床分期发生改变,其中分期升高者14例,下降者7例,使16例（27．6％）的治疗计划因而发生改变,32例手术患者中,术后病理结果与PET／CT分期一致者29例,假阴性1例,假阳性2例;PET／CT分期的敏感性为96．9％,准确性为90．6％。由PET／CT与由CT制定的放疗计划的VGTV、V20和MLD之间的差异均有统计学意义（P均〈0．01）,前者小于后者,而Ds、TCP、NTCP（左肺、右肺、皮肤、脊髓）的差异无统计学意义（P〉0．05）。结论 PET／CT对NSCLCS临床分期与术后病理分期的符合率高。应用PET／CT勾画靶区,在伴有肺不张和阻塞性肺炎时可明显减小GTV,可更好地保护周围正常肺组织;PET／CT检测纵隔淋巴结敏感性较CT高,可避免靶区遗漏。PET／CT可明显减小V20和MLD,从而有效地减少放射性肺炎的发生。PET／CT可在保证Ds、TCP和NTCP符合临床要求的前提下,更精确地确定NSCLC放疗靶区和制定放疗计划。     

The impact of (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) lymph node staging on the radiation treatment volumes in patients with non-small cell lung cancer.

PURPOSE: (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) combined with computer tomography (PET-CT) is superior to CT alone in mediastinal lymph node (LN) staging in non-small cell lung cancer (NSCLC). We studied the potential impact of this non-invasive LN staging procedure on the radiation treatment plan of patients with NSCLC. PATIENTS AND METHODS: The imaging and surgical pathology data from 105 patients included in two previously published prospective LN staging protocols form the basis for the present analysis. For 73 of these patients, with positive LN's on CT and/or on PET, a theoretical study was performed in which for each patient the gross tumour volume (GTV) was defined based on CT and on PET-CT data. For each GTV, the completeness of tumour coverage was assessed, using the available surgical pathology data as gold standard. A more detailed analysis was done for the first ten consecutive patients in whom the PET-CT-GTV was smaller than the CT-GTV. Theoretical radiation treatment plans were constructed based on both CT-GTV and PET-CT-GTV. Dose-volume histograms for the planning target volume (PTV), for the total lung volume and the lung volume receiving more than 20 Gy (V(lung(20))), were calculated. RESULTS: Data from 988 assessed LN stations were available. In the subgroup of 73 patients with CT or PET positive LN's, tumour coverage improved from 75% when the CT-GTV was used to 89% with the PET-CT-GTV (P=0.005). In 45 patients (62%) the information obtained from PET would have led to a change of the treatment volumes. For the ten patients in the dosimetry study, the use of PET-CT to define the GTV, resulted in an average reduction of the PTV by 29+/-18% (+/-1 SD) (P=0.002) and of the V(lung(20)) of 27+/-18% (+/-1 SD) (P=0.001). CONCLUSION: In patients with NSCLC considered for curative radiation treatment, assessment of locoregional LN tumour extension by PET will improve tumour coverage, and in selected patients, will reduce the volume of normal tissues irradiated, and thus toxicity. This subgroup of patients could then become candidates for treatment intensification.     

Impact of computed tomography and F-deoxyglucose coincidence detection emission tomography image fusion for optimization of conformal radiotherapy in non–small-cell lung cancer

PURPOSE: To report a retrospective study concerning the impact of fused 18F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and CT images on three-dimensional conformal radiotherapy planning for patients with non-small-cell lung cancer. METHODS AND MATERIALS: A total of 101 patients consecutively treated for Stage I-III non-small-cell lung cancer were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images, and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define the target volume. RESULTS: 18F-fluoro-deoxy-D-glucose-PET identified previously undetected distant metastatic disease in 8 patients, making them ineligible for curative conformal radiotherapy (1 patient presented with some positive uptake corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because the fused PET-CT images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT-PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT-PET image fusion reduced the pulmonary GTV in 6 patients (3 patients with atelectasis) and the mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients owing to an increase in the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Of 81 patients receiving a total dose of > or = 60 Gy at the International Commission on Radiation Units and Measurements point, after CT-PET image fusion, the percentage of total lung volume receiving >20 Gy increased in 15 cases and decreased in 22. The percentage of total heart volume receiving >36 Gy increased in 8 patients and decreased in 14. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. Multivariate analysis showed that tumor with atelectasis was the single independent factor that resulted in a significant effect on the modification of the size of the GTV by FDG-PET: tumor with atelectasis (with vs. without atelectasis, p = 0.0001). CONCLUSION: The results of our study have confirmed that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of non-small-cell lung cancer. However, FDG images using dedicated PET scanners and respiration-gated acquisition protocols could improve the PET-CT image coregistration. Furthermore, the impact on treatment outcome remains to be demonstrated.     

贲门癌患者采用PET-CT定位三维适形放疗的疗效及预后分析

目的对比研究18FDG PET/CT定位三维适形常规分割放疗贲门癌的疗效、副反应及失败原因。方法对46例贲门癌患者采用信封法随机分为18FDG PET/CT定位三维适形放疗组(PET/CT组)和普通CT定位三维适形放疗组(普通CT组)。PET/CT组采用PET/CT扫描定位,经PET/CT扫描后将扫描数据输入治疗计划系统,将PET图像和CT图像融合后进行靶区和重要脏器勾画、三维重建,制定治疗计划后进行常规分割三维适形放疗40 Gy,然后适当缩野针对残存肿瘤病灶放疗至总剂量60～70 Gy。普通CT组采用普通CT定位设野,三维适形放疗至相同剂量。结果PET/CT组的平均大体肿瘤靶区(GTV)和计划治疗靶区(PTV)体积、左肺、右肺、左肾与右肾V20、胃、心脏、食管与脊髓V40均比普通CT组小(均P<0.05);PET/CT组的局部控制率和1、2、3年生存率均比普通CT组高(均P<0.01);PET/CT组早期气管、食管、胃肠道、肺的1、2级不良反应均低于普通CT组(均P<0.05)。多因素分析表明,年轻、病变长度≤5 cm、病变T分期早是影响预后的主要因素(均P<0.01)。结论 PET/CT定位三维适形放疗贲门癌可以优化放疗计划,减轻正常组织的早期放射不良反应,年轻、病变分期早的患者预后较好。     

食管癌常规及两种适形照射方法剂量分布的比较

 目的 采用三维治疗计划系统比较食管癌常规三野照射和两种三维适形放疗（3DCRT）计划中肿瘤和正常组织的剂量分布。方法 随机选择食管癌患者10例， CT扫描定位。勾画肿瘤体积（GTV）、临床靶体积（CTV）和计划靶体积（PTV）。设计常规三野、三野适形、五野适形3种设野。结果（1）三野适形与常规三野比较：三野适形中GTV均在90 %剂量线以内，而在常规三野计划中有50 %（5／10）部分GTV在90 %等剂量线以外；PTV的最小剂量、平均剂量差异均有统计学意义；脊髓剂量分布差异有统计学意义。（2）五野适形与三野适形比较：PTV最小剂量差异有统计学意义。五野适形中20、30 Gy包绕的百分体积变小，10 Gy包绕的百分体积增大，差异有统计学意义；脊髓最大剂量差异有统计学意义，但在安全范围内。结论 （1）三野适形计划的肿瘤和脊髓剂量分布优于常规三野放疗计划，尤其在病变较长时更有优势；（2）五野适形较三野适形肿瘤剂量分布更趋均匀，双肺和脊髓剂量都在安全范围内。     

Dosimetric implications of the addition of 18 fluorodeoxyglucose-positron emission tomography in CT-based radiotherapy planning for non-small-cell lung cancer

The aim of this study was to assess the impact of F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) CT on radiotherapy planning parameters for patients treated curatively with radiotherapy for non-small-cell lung cancer (NSCLC). Five patients with stages I–III NSCLC underwent a diagnostic FDG-PET CT (dPET CT), planning FDG-PET CT (pPET CT) and a simulation CT (RTP CT). For each patient, three radiation oncologists delineated a gross tumour volume based on RTP CT alone, and fused with dPET CT and pPET CT. Standard expansions were used to generate PTVs, and a 3D conformal plan was created. Normal tissue doses were compared between plans. Coverage of pPET CT PTV by the plans based on RTP CT and dPET CT was assessed, and tumour control probabilities were calculated. Mean PTV was similar between RTP CT, dPET CT and pPET CT, although there were significant inter-observer differences in four patients. The plans, however, showed no significant differences in doses to lung, oesophagus, heart or spinal cord. The RTP CT plan and dPET CT plan significantly underdosed the pPET PTV in two patients with minimum doses ranging from 12 to 63% of prescribed dose. Coverage by the 95% isodose was suboptimal in these patients, but this did not translate into poorer tumour control probability. The effect of fused FDG-PET varied between observers. The addition of dPET and pPET did not significantly change the radiotherapy planning parameters. Although FDG-PET is of benefit in tumour delineation, its effect on normal tissue complication probability and tumour control probability cannot be predicted.