ABSTRACT
Objective To assess the feasibility and outcomes of fractionated stereotactice radiation therapy(FSRT) for brain metastases more than 3 cm in diameter. Methods From September 1996 to July 2006,47 patients(34 male and 13 female)with brain metastases larger than 3 cm were treated with FSRT. The median age was 58(range,31-87) years old. Pathologic diagnosis was adenocarcinoma in 19 patients, squamacarcinoma in 7, small cell carcinoma in 7, adeno-squamacarcinoma in 3, melanoma in 2, poor differen-tiated carcinoma, clear cell carcinoma, transitional cell carcinoma each in 1, and unknown in 6. FSRT was delivered as initial treatment for 26 patients, and as salvage therapy for 21. The largest diameter of brain me-tastases was 3.1-6.0 cm(median, 3.8 cm). Planning target volume were 2.5-33.8 cm3(median, 9.4 cm3). The median dose of FSRT was 30(range,16-57)Gy in 5(range,2 - 11) fractions. The treatment for primary tumor was surgery in 23 patients, radiotherapy and/or chemotherapy in 22, and none in 2. Results The last follow up was in April 2008. All patients were followed up and 33 had follow up more than 5 years. The 1-,2- and 5-year local control rate was 49%, 44% and 44%, respectively. The median survival time was 11 months(range,0.5-88.0 months, 95% CI=8.1-13.8 months). The corresponding overall survival rate was 40%, 17% and 6%, respectively. There were 46 patients died by the last follow up,including 21 died from brain metastases, 17 died from extracranial progression, and 8 died from other causes. Conclusion FSRT is safe and beneficial for selected patients with brain metastases larger than 3 cm.
ABSTRACT
Objective To study image-guided hypofractionated radiotherapy for thoracic and abdominal tumors,and to determine the margins extended from internal target volume(ITV) to planning target volume(PTV). Methods Twenty-four patients who received image-guided hypofractionated radiotherapy for thoracic and abdominal tumors were included in this study. X-ray cone beam CT was regularly performed before the treatment. The shift and Rotation in right-left ( R-L), superior-inferior(S-I) and anterior-posterior (A-P) directions were recorded and analyzed. The shift margin from ITV to PTV was calculated with the equation,margin =2'mean+0.7'standard deviation. Results Before online correction,the shift errors in R-L,S-I and A-P directions were [2.1±2.0] mm, [3.9±3.2] mm and [2.9±2.8] mm,and the corresponding margins were 5.6 mm, 10.2 mm and 7.7 mm. After the correction the shift errors were [0.8±0.7] mm, [0.9±0.7] mm and [0.9±0.7] mm, and the margins were 2.1 mm,2.3 mm and 2.3 mm. The set-up error was markedly decreased after the correction. There was no change in rotation after the correction. Conclusions The positioning error decreases after the correction in IGRT,and the precision of radiotherapy is improved. Measuring set-up error in radiotherapy can provide institution-specific margins for PTV designing.
ABSTRACT
Objective To evaluate the systematic and random set-up errors in patients immobilized with thermoplastic device during radiotherapy, and to determine the proper margins extended from clinical target volume ( CTV ) or internal target volume ( ITV ) to planning target volume ( PTV ). Methods From March 2007 to September 2007,120 patients were included in this study, including 13 receiving head and neck irradiation, 67 thoracic irradiation and 40 abdominal irradiation. All patients were immobilized with thermoplastic device and received CT simulation and intensity modulated radiation therapy(IMRT). X-ray cone beam CT was regularly performed before treatment and the images were compared with the simulation CT images. The shift and rotation in right-left( R-L), superior-inferior(S-I) and anterior-posterior(A-P) directions were recorded and analyzed. The shift margin from CTV or ITV to PTV was calculated with the equation, margin = 2'mean + 0.7'standard deviation. Results In head and neck region, the shift errors in R-L,S-I and A-P directions were(0.13 ±0.15) cm, (0.13 ±0.17) cm and(0.11 ±0.14) cm,and the corresponding rotation errors were 1.05°± 0.77°,0.87°± 1.13° and 0.68°±0.89°. The margins from CTV to PTV were 0.37 cm,0.38 cm and 0.31 cm,respectively. In thoraci region,the shift errors in R-L,S-I and AP directions were(0.20 ±0.27) cm, (0.34 ±0.44) cm and(0.25±0.31 ) cm,and the corresponding rotation errors were 1.06°±1.45° ,0.85°±1.23° and 0.78°±1.08°. The shift margins from ITV to PTV were 0.59 cm, 1.00 cm and 0.72 cm. In abdominal region, the shift errors in R-L, S-I and A-P directions were (0.23 ± 0.30) cm, (0.37 ±0.45 ) cm and ( 0.27 ±0.34 ) cm, and the corresponding rotation errors were 1.22°±1.56°, 1.05°± 1.44°and 0.98°± 1.24°. The shift margins from CTV or ITV to PTV were 0.66 cm, 1.05 cm and 0.78 cm. Conclusions Cone beam CT can be used in the precise measure of set-up errors,which can provide institution-specific margins for PTV designing in patients immobilized with thermoplastic device.