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.     

氟脱氧葡萄糖正电子发射型体层摄影术在非小细胞肺癌适形放疗中的应用研究

目的探讨氟脱氧葡萄糖(FDG)正电子发射型体层摄影术(PET)在非小细胞肺癌(NSCLC)三维适形放疗定位中的辅助作用。方法13例非小细胞肺癌患者行FDG PET和CT检查，利用CT和FDG PET-CT图像融合软件分别勾画大体肿瘤体积(GTVCT和GTVPET-CT)，并对两者进行比较。结果13例患者除2例外，其他患者的GTVCT和GTVPET-CT均不同，其中5例GTVPET-CT大于GTVCT，平均增加29．2cm^3；6例GTVPET-CT小于GTVCT，平均减少41．6cm^3。结论与单纯CT图像相比，FDG PET-CT融合图像不仅能更好地分清肿瘤与正常组织，而且对纵隔淋巴结具有更高的敏感性和特异性。     

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.     

CT and F-deoxyglucose (FDG) image fusion for optimization of conformal radiotherapy of lung cancers

Purpose: To validate a computed tomography (CT) and ¹⁸F-deoxyglucose (FDG) image fusion procedure and to evaluate its usefulness to facilitate target definition and treatment planning in three-dimensional conformal radiation therapy (3D-CRT) for non–small-cell lung cancer.

Methods and Materials: Twelve patients were assessed by CT and FDG-coincidence mode dual-head gamma camera (CDET) before radiotherapy. The patients were placed in a similar position during CT and FDG-CDET. Matching was achieved by minimizing the cost function by 3D translation and rotation between four landmarks drawn on the patient’s skin. Virtual simulation was performed from image fusion and estimated dose–volume histograms (DVH) were calculated.

Results: Quantitative analysis indicated that the matching error was < 5 mm. Fusion of anatomic and metabolic data corrected staging of lymph nodes (N) for 4 patients and staging of metastases for 1 patient. In these 5 patients, DVH revealed that the lung volume irradiated at 20 Gy (Vl₂₀) was decreased by an average of 22.8%, and tumor volume irradiated at the 95% isodose (V₉₅) was increased by 22% and 8% for 2 patients, respectively, and was decreased by an average of 59% for 3 patients after fusion. No difference in terms of Vl₂₀ and V₉₅ was observed for the other 7 patients.

Conclusion: We have validated CT and FDG-CDET lung image fusion to facilitate determination of lung cancer volumes, which improved the accuracy of 3D-CRT.     

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.     

PET-CT在三维适形放射治疗晚期胰腺癌中的应用

目的：评价PET-CT在三维适形放射治疗晚期胰腺癌中靶区勾画的价值及放疗后评价疗效的意义。方法：对13例晚期胰腺癌患者,采用PET-CT检查并定位,分别勾画出大体肿瘤体积CT-GTV和PET-CT-GTV,并分别制定出三维适形放射治疗的GTV进行比较。放疗后3个月行PET-CT复查。结果：13例患者的PET-CT-GTV和CT-GTV均不同,其中5例患者PET-CT-GTV较CT-GTV平均减少10.9cm3（25.7%）。CT-GTV平均42.4 cm3,PET-CT-GTV平均为31.5cm3（P=0.0045）;8例患者的PET-CT-GTV较CT-GTV增加45.3%（27.4 cm3）,CT-GTV平均为60.4 cm3,PET-CT-GTV平均为87.8 cm3（P=0.0000）。治疗后3个月PET-CT复查示：7例胰腺病灶较前明显缩小,局部FDG代谢明显减低或消失。其余6例病灶略缩小,FDG不同程度减低。治疗后的SUVmax变化范围为1.6-6.0,SUVmean变化范围为1.4-2.2。结论：采用PET-CT融合图像能够更好地提高靶区确定的精度及不确定性,最大限度减少不同勾画者之间的差异性。治疗前后局部病灶代谢活性的不同程度改变,对评价放疗疗效具有一定的指导意义。     

PET-CT在三维适形放射治疗晚期胰腺癌中的应用

目的:评价PET-CT在三维适形放射治疗晚期胰腺癌中靶区勾画的价值及放疗后评价疗效的意义。方法:对13例晚期胰腺癌患者,采用PET-CT检查并定位,分别勾画出大体肿瘤体积CT-GTV和PET-CT-GTV,并分别制定出三维适形放射治疗的GTV进行比较。放疗后3个月行PET-CT复查。结果:13例患者的PET-CT-GTV和CT-GTV均不同,其中5例患者PET-CT-GTV较CT-GTV平均减少10.9cm3(25.7%)。CT-GTV平均42.4 cm3,PET-CT-GTV平均为31.5cm3(P=0.0045);8例患者的PET-CT-GTV较CT-GTV增加45.3%(27.4 cm3),CT-GTV平均为60.4 cm3,PET-CT-GTV平均为87.8 cm3(P=0.0000)。治疗后3个月PET-CT复查示:7例胰腺病灶较前明显缩小,局部FDG代谢明显减低或消失。其余6例病灶略缩小,FDG不同程度减低。治疗后的SUVmax变化范围为1.6-6.0,SUVmean变化范围为1.4-2.2。结论:采用PET-CT融合图像能够更好地提高靶区确定的精度及不确定性,最大限度减少不同勾画者之间的差异性。治疗前后局部病灶代谢活性的不同程度改变,对评价放疗疗效具有一定的指导意义。     

CT与MRI图像融合在颅内肿瘤三维适形放疗中的应用

目的采用CT与MRI图像融合技术,为颅脑肿瘤三维适形放疗提供更精确地靶区定义。方法对25例脑瘤患者分别使用CT和MRI进行三维适形放疗定位,比较2种图像采集方式确定靶区的不同。以MRI确定的靶区作为大体靶区(GTV),以CT图像提供的CT值进行剂量计算,制定放疗计划。结果25例患者均接受了CT和MRI定位,解剖结构及体表标记均基本重合。其中23例患者CT和MRI扫描后显示病灶数目相同,2例患者显示病灶数目不同。CT比MRI扫描GTV体积增大者10例,缩小者15例。放疗结束后复查颅脑MRI评价疗效,有效率为64.0%。结论CT与MRI融合技术进行三维立体适形放疗定位,提高了GTV确定的精确性,提高了适形放疗的精度。     

兔VX2鼻咽移植癌的PET-CT与病理结果对照研究

目的:观察VX2兔鼻咽癌生长特点,并与所获病理和MRI结果比较,探讨18F-FDGPET-CT在鼻咽肿物检测中的作用。方法:建立VX2兔鼻咽癌模型后,完成18F-FDGPET-CT和MRI扫描并解剖;在肉眼所见肿瘤周围不同的距离取标本并完整取出斜坡作病理诊断;测量鼻咽肿物最大标准摄取值(SUV),在PET-CT和MRI图像上勾画鼻咽肿物体积。结果:VX2兔鼻咽癌可向周围组织呈广泛浸润性生长;30只兔中经病理确诊有9只兔斜坡受癌细胞侵犯,PET-CT发现6例(66.7%),MRI发现5例(55.6%),CT发现1例(11.1%);兔VX2鼻咽癌的最大SUV值与鼻咽肿物的体积呈负相关,r=-0.426,P=0.03;30只兔在18F-FDGPET-CT图像上所勾画的鼻咽肿物体积较在MRI图像上勾画体积小,差异无统计学意义,P=0.17。结论:18F-FDGPET-CT能对鼻咽癌病灶范围的确定、放疗靶区的准确勾画提供有用的信息。     

Impact of positron emission tomography with computed tomography for image-guided radiotherapy

Therapeutic effectiveness in radiotherapy is partly related to correct staging of the disease and then precise therapeutic targeting. Positron emission tomography (PET) allows the stage of many cancers to be determined and therefore is essential before deciding on radiation treatment. The definition of the therapeutic target is essential to obtain correct tumour control and limit side effects. The part of adaptive radiotherapy remains to be defined, but PET by its functional nature makes it possible to define the prognosis of many cancers and to consider radiotherapy adapted to the initial response allowing an increase over the entire metabolic volume, or targeted at a subvolume at risk per dose painting, or with a decrease in the dose in case of good response at interim assessment.     

CT/CT图像融合技术评价食管癌二程放疗的可靠性研究

目的:探讨利用CT/CT图像融合技术来评价食管癌二程放疗的准确性和可靠性。方法:9例食管癌患者,接受调强放疗46Gy后,行二次CT定位,制定后程适形或调强计划,给予处方剂量20Gy。将两次CT图像融合得到全程融合计划,总处方剂量66Gy。比较两个疗程危及器官的体积变化,将首程计划移植到二次定位图像上,计算并比较危及器官受照剂量的差别;将一程计划和二程计划的危及器官评价结果直接相加,与融合计划进行比较。结果:两次定位肺与心脏的体积变化差异无统计学意义(P>0.05);CT/CT融合精度对肺和心脏的受量评价差异无统计学意义(P>0.05),而对于脊髓最大受照剂量差异具有统计学意义(P<0.05);分次计划评价指标相加与融合计划的比较结果是,双侧肺V20、心脏V30的差异有统计学意义(P<0.05),双侧肺平均受照剂量和脊髓的最大受照剂量差异无统计学意义(P>0.05)。结论:在食管癌分程放疗中,宜采用融合计划来评价肺和心脏的受照剂量,可以采用两次计划分别评价得出的脊髓最大受照剂量之和来作为全程脊髓最大受量的评价指标。     

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。     

术后复发性食管癌18FDG PET/CT定位三维适形放疗的疗效分析

目的:对比研究18FDG 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。     

CT/CT图像融合技术评价食管癌二程放疗的可靠性研究

目的：探讨利用CT/CT图像融合技术来评价食管癌二程放疗的准确性和可靠性。方法：9例食管癌患者,接受调强放疗46Gy后,行二次CT定位,制定后程适形或调强计划,给予处方剂量20Gy。将两次CT图像融合得到全程融合计划,总处方剂量66Gy。比较两个疗程危及器官的体积变化,将首程计划移植到二次定位图像上,计算并比较危及器官受照剂量的差别;将一程计划和二程计划的危及器官评价结果直接相加,与融合计划进行比较。结果：两次定位肺与心脏的体积变化差异无统计学意义（P〉0.05）;CT/CT融合精度对肺和心脏的受量评价差异无统计学意义（P〉0.05）,而对于脊髓最大受照剂量差异具有统计学意义（P〈0.05）;分次计划评价指标相加与融合计划的比较结果是,双侧肺V20、心脏V30的差异有统计学意义（P〈0.05）,双侧肺平均受照剂量和脊髓的最大受照剂量差异无统计学意义（P〉0.05）。结论：在食管癌分程放疗中,宜采用融合计划来评价肺和心脏的受照剂量,可以采用两次计划分别评价得出的脊髓最大受照剂量之和来作为全程脊髓最大受量的评价指标。     

CT/MRI图像融合精度对原发性肝癌三维适形放疗的剂量学影响

目的:研究原发性肝细胞癌(hepatocellular carcinoma,HCC)患者CT与MRI图像融合的精度,以及在三维适形放疗(three dimensional conformal radiotherapy,3DCRT)中对肿瘤靶区及周围重要器官的剂量学影响.方法:8例HCC患者行深吸气末屏气模拟CT扫描、呼气末MRIT2相扫描及深吸气末屏气快速MRIT2相(MRIT2F)扫描.采用互信息法进行图像融合,自动匹配后手动微调.分别在CT及MRI图像上勾画临床大体肿瘤体积(gross tumor volume,GTV)及肝脏,在CT图像上勾画周围重要器官.利用CT和MRI图像上骨性标志点在融合图像上2者之间的距离(DCT-MRIT2,DCT-MRIT2F)及肝脏交叠度P-LIVERCT-MRIT2 (CT-MRIT2F)评价图像融合精度.根据CT及MRI勾画的GTV,计算融合后形成的总体积V-GTVCT+MRIT2及V-GTVCT+MRIT2F.根据GTVCT+MRIT2及GTVCT+MRIT2F制定2组放疗计划,比较2组肿瘤95%计划靶体积的放疗受量(D95)及周围重要器官受量的差异.结果:DCT-MRIT2及DCT-MRIT2F分别为(2.3±0.9)及(2.0±1.0)mm,差异无统计学意义(P＞0.05),P-LIVERCT-MRIT2及P-LIVERCT-MRIT2F分别为(85.4±2.3)%和(93.0±1.4)%,差异有统计学意义(P＜0.05).V-GTVCT+MRIT2和V-GTVCT+MRIT2F分别为(642±561)和(547±474)cm3,差异有统计学意义(P＜0.05).2组放疗计划中的D95、十二直肠最大受量、胃最大受量及左肾平均受量差异无统计学意义(P＞0.05).2组脊髓最大受量、右肾平均受量、正常肝脏平均受量及正常肝脏接受5、10、15、20、25、30、35和40 Gy剂量的体积百分比差异有统计学意义(P＜0.05),CT+MRIT2组要大于CT+MRIT2F组.结论:将CT与MRI图像融合技术应用于HCC患者的3DCRT,在采集图像时应统一呼吸时相,可进一步减少周围重要器官的受量.     

PET-CT和MRI诊断兔鼻咽肿瘤颈淋巴结转移的比较研究

目的 探讨18FDG PET-CT在诊断兔鼻咽肿瘤颈部淋巴结性质上的作用.方法 建立兔鼻咽VX2肿瘤模型,对颈部淋巴结行PET-CT诊断并用病理诊断证实,同时与MRI诊断相比较.结果 30只鼻咽VX2肿瘤兔解剖检出颈部淋巴结共53个,病理证实转移淋巴结42个,且淋巴结是否转移与淋巴结体积、最短径显著相关(r=9.18,P=0.007;r=2.77,P:0.008).体积>0.5 cm3(25个)、≤0.5 cm3(17个)淋巴结的PET-T诊断敏感性分别为96%(24个)、29%(5个),最短径≥0.5cm(30个)、<0.5 cm(12个)淋巴结的PET-CT诊断敏感性分别为83%(25个)、33%(4个),PET-CT诊断的总敏感性为69%(29/42),特异性为100%(11/11),准确性为95%(40/42).MRI诊断敏感性为60%(25/42),特异性为9l%(10/11),准确性为83%(35/42).PET-CT图像所测淋巴结体积与实测体积相当(t=-1.23,P=0.233),MRI的则大于实测体积(t=-3.99,P=0.001).结论 18FDGPET-CT诊断颈部淋巴结转移的敏感性、特异性均高于MRI,特别对体积>0.5 cm3或最短径≥0.5 cm的颈部淋巴结转移的敏感性更高,对更小淋巴结的诊断仍有参考价值,仉假阴性较高.     

18F-deoxyglucose positron emission tomography (FDG-PET) for the planning of radiotherapy in lung cancer: high impact in patients with atelectasis.

PURPOSE: 18F-deoxyglucose positron emission tomography (FDG-PET) is increasingly applied in the staging of lung cancer (LC). This study analyzes the potential contribution of PET in radiotherapy planning for LC with special respect to tumor-associated atelectasis. METHODS AND MATERIALS: Thirty-four patients with histologically confirmed LC, who had been examined by PET during pretreatment staging, were included. All were irradiated after CT-based therapy planning with anterior/posterior (AP) portals encompassing the primary tumor and the mediastinum (CT portals, CP). The result of the PET examination was unknown in treatment planning. In retrospect, a PET portal (PP) was delineated and compared with the CP. RESULTS: In 12/34 cases, the shape and/or size of the portals were changed, primarily (n = 10) the size of the fields was reduced. The median area of CP was 182 cm2 versus 167 cm2 of PP. Seventeen of 34 patients had dys- or atelectasis caused by a central primary tumor. In these cases, differences between CP and PP were significantly more frequent than in the other patients (8/17 vs. 3/17, p = 0.03). CONCLUSION: In this retrospective analysis, the information provided by FDG-PET would have contributed to a substantial reduction of the size of radiotherapy portals. This applies particularly for patients with tumor-associated dys- or atelectasis.     

The impact of 18F-deoxyglucose positron emission tomography on tumor staging, treatment strategy and treatment planning for radiotherapy in a department of radiation oncology

AIMS AND BACKGROUND: The study analyzed the potential contribution of positron emission tomography (PET) in patient selection for radiotherapy and in radiation therapy planning. METHODS: Eighty-seven patients with a histological cancer diagnosis were accrued for the study from December 2000 to December 2001. Demographic characteristics included a median age of 54 years and male/female ratio of 51/36. All patients staged by conventional workup who were candidates for radiotherapy had PET imaging and were allocated to a conventional "pre/post-PET stage". The treatment protocol and the shape and/or size of the portals was directly related to PET results. We examined 26 lung cancers, 15 gastrointestinal tumors, 22 genitourinary cancers and 24 hematologic malignancies. RESULTS: In the lung cancer group, the stage was modified in 10/26 patients (38.5%) by PET, with a change in management in 13 (50%) and a change in radiotherapy planning in 6 (23.1%). In the hematological group, stage was modified by PET in 8/24 cases (33.3%), with a change in treatment strategy in 9 (37.5%) and a change in radiotherapy planning in 3 (12.5%). In the gastrointestinal group, the stage was modified by PET in 2/15 cases (13.4%), with a change inn treatment strategy in 4 (26.7%) and a change in the decision for radiotherapy in 8 (no radiotherapy in 53.3%). In the mixed group (genitourinary, breast and other), the stage was modified by PET in 6/22 cases (27.3%), with a change in treatment strategy in 11 (50%) and a very low rate of change in radiotherapy planning. CONCLUSIONS: PET contributed to a modification of stage in 26/87 patients (30%), to a changing in treatment strategy in 37/87 (42.5%), and to a substantial change of the shape and/or size of radiotherapy portals in 13/43 (30%) who underwent radiotherapy.