ABSTRACT
Objective To investigate the effect of the correction of the position error of the abdominal tumor by cone beam scanning. Methods Six patients with abdominal tumor were selected with double-blind method, and electronical portal imaing device was used to collect the information of the patient dosimetry during radiotherapy.EDOSE tool was applied to 3D dose reconstruction so as to execute real-time 3D dose verification of the treatment plan. Each patient had 5 sets of data acquired when image guidance existed and another 5 sets when image guidance was absent. The treatment effects with or without image guidance were compared.Results The overall γ passing rate with cone beam CT image guidance gained no advantages over that without image guidance, though the setup error was corrected to some extent. Image guidance contributed nothing to increasing target area coverage while decreasing exposure dose to normal tissue. Conclusion Setup error correction by the image guidance based on bone marker has no significant effect on improving 3D dose verification and dose accuracy during the radiotherapy of the abdominal tumor patient.
ABSTRACT
Objective: To compare the efficacy of conventional radiotherapy and three dimensional conformal radiotherapy (3D-CRT) for malignant glioma retrospectively. Methods: From January 1997 to May 2007, 152 patients with malignant glioma received postoperative radiotherapy at our hospital. Patients were classified into two groups according to the radiotherapy techniques. Group A (n=85) received conventional whole brain or subtotal brain irradiation at 36.40 Gy followed by a boost of 20 Gy to the tumor bed. Group B (3 D-CRT group, n = 67) were given 50-54 Gy of irradiation in the clinical target volume (CTV) and 60 Gy of irradita-tion in the gross tumor volume (GTV). GTV was defined as the high signal area on T2 weighted FLAIR MRI image, and CTV was defined as GTV plus a 2-cm margin. The fraction dose for both conventional chemotherapy and 3D-CRT was 2.0 Gy/fx, once a day, five times per week. The efficacies of both ratiotherapy were compared and the failure mode was analyzed. Results: The 3-year overall survival rates were 22.9% and 31.9% in group A and group B, respectively (χ2 = 1.01, P = 0.31). Incidence of increased intracra-nial pressure were 47.1% and 31.3% in group A and group B, respectively(χ2 = 3.95, P = 0.04). All the tumor recurrence was detected within the range of GTV and CTV in 45 patients in group B. Conclusion: 3D-CRT reduces the incidence of radiation-induced high intracranial pressure of malignant glioma patients compared with conventional radiotherapy. The irradiation volume including the high signal area on T2 FLAIR MR imaging plus a 2-cm margin is feasible in 3D-CRT.