Radiotherapy physics is a cross subject that studies and solves the scientific problem referring to medicine treatment based on physics.Ceaseless progresses of Radiotherapy equipments such as Cobait-60 treatment machine,Linear Accelerator,Gama Knife,Tomotherapy have provided comprehensive treatment measures for malignant tumor.Therapies including conformal Radiotherapy,Intensity Modulation Radiotherapy and Gama Knife are progressing and being perfected.Further research should be done on dose fraction.Boron Neutron Capture Therapy and Proton Therapy are being studied.Treatment Plan System and Target Delimitation need perfecting.

Objective To evaluate the efficacy and side effects of whole body γ/-knife in patients with limited pancreatic carcinoma. Methods 111 patients with limited pancreatic carcinoma treated with the Stereotactie Gamma Ray Whole-Body Therapeutic System (Whole Body T-knife) were retrospectively an-alyzed. Patients were supine, fixed with a stereotactic body frame and vacuum bag, and then simulated by low-speed computed tomography. GTV, CTV and PTV were defined on the contrast-enhanced CT scans. It was required that 50% isedose line covered 100% of PTV and 70% isedose line covered more than 80% of GTV. The prescription dose was defined as 50% isodose. All patients were treated 5 fractions per week. The fractionated dose was 3-4 Gy for pancreatic head carcinoma, and 4-5 Gy for pancreatic body/tail carcino-ma. Irradiation of 40-51 Gy and 60-70 Gy were delivered to PTV and GTV margins, respectively. Re-suits The complete response rate, partial response rate and overall response rate of the primary tumors were 29.7%, 42.3% and 72.1%, respectively. The follow-up rate was 95.5%. The number of patients fol-lowed-up at 1-,2- and 3-year was 105,89 and 60. The 1-, 2- and 3-year overall survival rates were 49.3%,24.5% and 18.1%. For patients with stage Ⅰ/Ⅱ disease,the number of patients followed-up at 1-,2-,3-,4-and 5-year was 55,44,29,16 and 11 ;The 1-, 2-, 3-,4- and 5-year overall survival rates were 68%,34%, 30%, 21% and 17%, respectively. For patients with stage Ⅲ disease,the number of patients fol-lowed-up at 1-,2- and 3-year was 50,45 and 31 ;The 1-, 2- and 3-year overall survival rates were 28%,14% and 4%, respectively (χ~2=16.67, P=0.000). The acute side effects including nausea, vomiting and diarrhea were 71.2% of RTOG grade 1 -2 and 3.6% of RTOG grade 3. No treatment delay occurred.Conclusions With fractionated dose of 3-5 Gy,5 fractions per week and 40-51 Gy as total dose to PTV,whole body γ-knife is safe and effective to treat limited pancreatic carcinoma. The local control and overall survival could be improved.