| 1. Study of Setup Errors in 3-Dimensional Conformal Radiotherapy (3D-CRT) and Intensity - Modulated Radiotherapy (IMRT) for Esophageal CarcinomaPurpose: The aim of 3D-CRT and IMRT is to eliminate the tumor and subclinical regions while sparing the important normal tissues. The border between clinical target volume (CTV) and planning target volume (PTV) remains unclear, especially in esophageal carcinoma. This study intends to investigate the status of radiotherapy and setup error in esophageal carcinoma of our cancer center, to get more detailed information of the proper border between CTV and PTV.Materials and Methods: Patients with primary esophageal carcinoma receiving naive 3D-CRT or IMRT were enrolled into this study. All of them were treated by Elekta Synergy 5954 linear accelerator with treatment planning from ADAC Pinnacle3 7.4b software. Orthogonal digital reconstructive radiographs (DRRs) were chosen from 2 directions before the according electronic portal images (EPIs) were taken and two radiation oncologists used the iView GT software to compare the EPIs with DRRs. Statistic analysis were performed by SPSS 11.5 software, 95% confidential interval were taken.Results: Fifty-three patients in our radiotherapy department entered this study between April to November, 2005. Among them, 44 were male and 9 were female patients with median age of 59 (range: 38-79). There were 17 (32%) cervical and upper thoracic esophageal patients, 33 (62%) with mid thoracic and 3 (6%) with lower thoracic esophageal lesions. Clinical stages ranged from IIA to IVB. There were 226 AP-PA field EPIs and 182 lateral EPIs taken. Medium setup motions of left/right (LR), anterior/posterior (AP), superior/inferior (SI) were 2.9±2.3mm, 3.1±2.8mm, 2.0±1.8mm, respectively. Systematic errors and random errors of LR, AP, SI were 0.6 ± 2.7mm, 2.4 ± 1.7mm; 0.8 ± 3.3mm, 2.4 ± 1.7mm; -0.4± 1.4mm, 2.2 ± 2.2mm, respectively. Correlations were showed between sex, age, location oftumor and immobilization devices between setup errors, respectively.Conclusions: The study investigated the setup errors on esophageal patients receiving 3D-CRT or IMRT. The results of setup motions and setup errors were similar with reports in acceptable regions. Setup errors were caused mainly by random errors. Female, elder, lower thoracic esophageal carcinoma patients or those who used the vacuum-locks might have the tendency of having more motions during the treatment.2. Impact of Tumor Regression on Doses to Target Volumes and Surrounding Normal Organs during the course of Intensity -Modulated Radiotherapy for Esophageal CarcinomaPurpose: The intensity-modulated radiotherapy (IMRT) for esophageal carcinoma is to conduct one plan for the whole course of treatment at present. This prospective study is to investigate the regression of tumor and variation of surrounding organs at 3 dose points during the course of IMRT, compare the dosimetric effects of repeat CT imaging and the need for IMRT replanning of esophageal carcinoma.Materials and Methods: Patients with primary esophageal carcinoma without distant metastasis of organs underwent IMRT. The prescribed dose to 95% volume of PTV was 66Gy/33Fx. Original IMRT plan for each patient was generated based on the CT before treatment (CT 0 Gy). During the course of IMRT, three times repeat CT were made with the same patient position and scanning method at the dose point of 20Gy /10Fx (CT 20 Gy), 40Gy/20Fx (CT 40 Gy) and 60Gy/30Fx (CT 60 Gy). After CT-CT fusion (CT 20 Gy, CT 40 Gy and CT 60 Gy fused with CT 0 Gy, respectively), new target volumes (GTV, PTV) and normal tissues (lung, heart, spinal cord, etc.) were delineated accordingly. By using a commercial inverse IMRT planning system, a hybrid IMRT plan was generated for each patient by applying the beam configurations of the original IMRT plan (including the intensity profile of each beam) to the anatomy of CT 20 Gy, CT 40 Gy, CT 60 Gy, respectively. The dose-volume histograms (DVH) of the original and hybrid IMRT plans were compared. Statistical analyses were performed by SPSS 11.5 software, 95% confidential interval were taken.Results: Twenty-one patients of stage IIA-IVA entered this study between April to Oct 2004. Eighteen (86%) were male and 3 (14%) were female patients with median age of 60 (range: 38-79). There were 4 (19%) cervical and upper thoracic esophageal patients, 15 (71%) with mid thoracic lesions and 2 (10%) with lower thoracic lesions. Weight changes were -0.8±2.2 Kg (-5～5Kg) for all the patientsduring treatment. Volume of GTV and PTV shrank apparently during the course of IMRT and the differences were significant (P = 0.045 and P=0.051). Conformity index (CI) declined and had significant difference among different CT imaging (P<0.001). No significant differences of DVH were observed between different imaging of lung, heart and spinal cord. However, the maximum dose (Dmax) to the spinal cord of CT 20Gy and CT 40Gy were both above 45Gy. Positive correlation was found between CI and the percentage of the new volume occupying the original volume of PTV (PTV%), while negative correlation was found between lung dose and Dmax to the spinal cord with PTV%, respectively. Which means CI might decline and dose to lung and spinal cord might be raised in those patients whose PTV shrank apparently during treatment. No apparent correlation was found between weight change and other parameters.Conclusions: Volume of GTV and PTV regression could be observed and CI declined obviously and progressively during the course of IMRT in esophageal carcinoma with significant difference among different CT imaging. PTV% correlated with CI, dose to lung and Dmax to the spinal cord. To identify dosimetric changes in target volumes and critical surrounding organs seems essential. Further studies with larger sample sizes and more lower and upper thoracic lesion patients will help to determine more detailed criteria for repeat CT imaging and the need of IMRT replanning for esophageal patients underwent curative radiotherapy.3. Dosimetric Comparison in Intensity - Modulated Radiotherapy (IMRT) and 3-Dimensional Conformal Radiotherapy (3D-CRT) for Esophageal CarcinomaPurpose: To demonstrate the use of intensity - modulated radiotherapy (IMRT) and 3-dimensional conformal radiotherapy (3D-CRT) in esophageal cancer patients, and evaluate their dosimetric results by comparison.Materials and Methods: Patients with primary esophageal carcinoma without surgeries or malformations of chest in our radiotherapy department were enrolled into this study. Radiation treatment plans were made by Pinnacle3 7.4b software. The aim of IMRT was as follows: prescribed dose of 66Gy/33Fx to 95% of PTV, 62.7Gy/33Fx to 99% of PTV. V20 of lung ≤25%, the mean dose (Dmean) of heart ≤30Gy, the maximum dose (Dmax) to the spinal cord<45Gy. 3D-CRT plans were made according to the same criteria as similar as possible. Inhomogeneity corrections were made. Four 3D-CRT plans were made for each patient with 3, 4, 5, 6 fields, while 5 IMRT plans were made with 4, 5, 7, 9, 11 fields and 9 plans altogether for each patient. Evaluation contents include: percentage of GTV covered by 95% isodose line (GTV V95), percentage of PTV covered by 95% isodose line (PTV V95), conformity index (CI), lung V20, V25, V30, mean lung dose (MLD), Dmean of heart and Dmax to the spinal cord. Statistic analysis were performed by SPSS 11.5 software, 95% confidential interval were taken.Results: Nine male patients with median age of 58 (range: 38-79) entered this study. Each portion of esophageal cancer consisted of 3 patients, one of them with relatively small lesion, one of them with relatively wide lesion and 1 with relatively long lesion. All plans were coplanar and total 81 plans were made.Significant differences of CI were obtained among the plans (P< 0.001), with the best IMRT 11 of CI=0.725, IMRT 7 of CI=0.722 and worst CRT3 of CI=0.520. There were also significant differences of lung V20, V25, V30 (all P< 0.001) with the lowest of IMRT 9 and IMRT 11, the highest of CRT3, CRT5. The lowest MLD wasin the plan of IMRT 4 and IMRT 7, while the highest was in CRT 5.Among the cervical and upper thoracic esophageal cancer,significant differences were found in CI (P<0.001), with the best of IMRT 5 (CI=0.719) and IMRT 9 (CI=0.718), the worst of CRT 3 (CI=0.524). No significant differences were found among the plans in PTV V95, GTV V95, lung V20, V25, Dmean of heart and Dmax to the spinal cord. But all the Dmax to the spinal cord were above 45Gy. Difference of CI was also significant in mid thoracic esophageal cancer patients (P< 0.001), the best were IMRT 11 (CI=0.772) and IMRT 9 (CI=0.762), CRT 3 (CI=0.540) was the worst. There were significant differences in lung V20 (P = 0.002) and lung V25 (P = 0.024), with the lowest in IMRT 11 and IMRT 9,the highest in CRT 5 and CRT 6. Dmax to the spinal cord was lowest in IMRT 11 and IMRT 9,while of all the 3D-CRT plans, Dmax to the spinal cord were not less than 45Gy except CRT 5. Lung V25 (P = 0.034) and V30 (P = 0.015) has significant differences among the plans of lower esophageal carcinoma, with the lowest of IMRT 9 and IMRT 11, the highest of CRT 5 and CRT 3. All the Dmean of heart were above 30Gy in 3D-CRT plans although P>0.05.Conclusions: IMRT plan has the advantage in the treatment of esophageal carcinoma of every portion with better conformity of target volume and sparing of normal tissues compared to 3D-CRT. Differences of CI were significant in every portion. Lung V20, V25 and Dmax to the spinal cord also had significant differences in plans of mid thoracic lesions. Among the plans of lower thoracic lesions, significant differences were found in both V25 and V30 of lung. IMRT 5 and IMRT 7 plan could be recommended considering dosimetric results and clinical practices.
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