ABSTRACT
PURPOSE: To analyze our quality assurance (QA) data for intensity modulated radiation therapy (IMRT) according to treatment site and to possibly improve QA for IMRT in Hospital. MATERIALS AND METHODS: We performed QA on 50 patients (head and neck, 28 patients; Breast, 14 patients; Pelvis, 8 patients) for IMRT. The calculated dose from RTP was compared with the measured value film, gamma index, and ionization chamber for dose measurement in each case. RESULTS: The point dose measurement results in 45 of 50 patients showed good agreement with the calculation dose (+/-3%). The largest error measured thus far has been 3.60%, with a mean of only -0.17% (SD, 2.25%). Each treatment site showed an error rate of -0.13% (SD, 1.93%) for head and neck cases, -0.26% (SD, 2.79%) for breast cases, and -0.24% (SD, 2.44%) for pelvis cases. The gamma index verified with the error rate of head and neck cases (6%), breast (10%), and pelvis (6%), which corresponded to a tolerance of 3 mm (3% for the head and neck, 2%, for the breast 1% for the pelvis, and 0% in the region where the isodose curve was greater than 90%. CONCLUSION: We recognize the cause of errors for each treatment site of IMRT QA and so we maximize our efforts to reduce error and increase accuracy.
Subject(s)
Humans , Breast , Head , Neck , PelvisABSTRACT
PURPOSE: The goal of this study was to determine the role of postoperative radiation therapy in extrahepatic bile duct cancers. MATERIALS AND METHODS: Between 1997 and 2001, 41 patients with extrahepatic bile duct cancer having undergone surgical resection were retrospectively analyzed. Of the 41 patients, 22 were treated by surgery alone (Group I) with remaining 19 treated by surgery and postoperative radiation therapy (Group II). A gross total surgical resection with pathologically negative margins was performed in 11 of the patients (50%) in Group I, and in 7 of the patients (36.8%) in Group II. There were no significant differences in the disease stage, surgical procedure or pathological characteristics of the two groups. The patients in group II received 45~54 Gy (median: 50.4 Gy) of external beam radiation therapy to the tumor bed and draining nodal area. RESULTS: The local failure rate was significantly higher in group I (54.5%) than in group II (15.8%)(p=0.010). Of the 12 failed patients in Group I and the 3 failed patients in group II, 7 and 3 had a positive resection margin. The overall 3-year survival rates were 38.3 and 38.9% and the 3-year disease free survival rates were 18.8 and 26.3% in groups I and II, respectively. However, the patients with positive resection margins who received adjuvant radiation therapy had higher 3-year overall survival rates than those with surgery alone (36.4% vs. 24.2%, p=0.06), and 3-year disease free survival rate was significantly higher in the group II patients who had positive margins compared with those in group I (25.0% vs. 18.2%, p=0.04). CONCLUSION: Postoperative adjuvant radiation therapy appeared to reduce the incidence of local failure in patients with extrahepatic bile duct cancer, and might improve the survival rate in the patients with positive resection margins.