The hybrid pencil beam model (HPBM) is an effective algorithm for calculating electron dose distribution in radiotherapy. The mean energy distribution of incident electron beam in phantom is one of the factors that affect the calculation accuracy of HPBM, especially in field edge areas near the end of the electron range. A new fitted formula based on Monte Carlo (MC) simulation data for electron beams with energy range of 6-20 MeV in the homogeneous water phantom is proposed in this paper. The precision of the fitted formula within the scope of the energy was evaluated by comparing the electron dose distribution of ECWG measured data with that obtained from HPBM which took the mean electron energy that calculated by the fitted formula and the existed empirical formula, respectively. The results showed that the accuracy of dose distribution that obtained by the mean electron energy calculated with the fitted formula increased about 1%.
Algorithms ; Electrons ; Humans ; Monte Carlo Method ; Phantoms, Imaging ; Radiotherapy Planning, Computer-Assisted ; Water

OBJECTIVETo evaluate the effect of laparoscopic sleeve gastrectomy(LSG) on type 2 diabetes mellitus (T2DM) in patient with a body mass index(BMI) less than 40 kg/m.

METHODSTwenty four obese patients with T2DM and BMI less than 40 kg/mreceived LSG between 1 January 2011 and 1 September 2013 at the Department of General Surgery in Chinese PLA General Hospital. The clinical data and 3-year follow-up outcomes regarding weight loss and remission of diabetes were retrospectively analyzed.

RESULTSThere were 10 males and 14 females with a median age of 40.8(35 to 48) years. The preoperative body weight and BMI was(99.9±15.0) kg and (34.4±2.8) kg/m, respectively. The median duration of type 2 diabetes was 4.3(2 to 15) years. The preoperative fasting blood glucose and glycosylated hemoglobin(HbAlc) was (11.4±1.3) mmol/L and (8.7±0.8)%, respectively. All these patients were preoperatively diagnosed as T2DM by the multidisciplinary experts of the surgical treatment team for obesity and diabetes in our center. All these patients were eligible for surgical treatment through the screening and evaluation by the multidisciplinary joint outpatient service. All the procedures were successfully completed without conversion to laparotomy. There were no severe postoperative complications. The mean fasting blood glucose was (6.4±1.8) mmol/L, (6.1±1.7) mmol/L, (6.0±1.5) mmol/L, (5.9±1.4) mmol/L and (6.0±1.4) mmol/L, respectively, at 6, 9, 12, 24 and 36 months after operation. The mean HbA1c in the same observation intervals was (6.6±1.1)%, (6.2±1.2)%, (6.1±1.2)%, (6.0±1.3)% and (6.1±1.3)%, respectively. The body weight was (89.4±11.4) kg, (86.3±10.6) kg, (83.1±10.2) kg,(80.6±9.8) kg and (81.3±10.1) kg, respectively. The corresponding BMI was (30.8±1.6) kg/m, (29.8±1.5) kg/m, (28.7±1.5) kg/m, (27.8±1.8) kg/mand (28.1±1.8) kg/m, respectively. The %EWL was (36.7±8.7)%, (47.6±12.5)%, (58.8±16.4)%, (67.2±20.3)% and (64.8±21.5)%, respectively. The overall remission rate of diabetes at 6, 9, 12, 24 and 36 months was 50.0%(12/24), 79.2%(19/24), 70.8%(17/24), 66.7%(16/24) and 62.5%(15/24), respectively. The complete remission rate was 33.3%(8/24), 50.0%(12/24), 54.2%(13/24), 45.8%(11/24) and 50.0%(12/24), respectively. For patients with a duration of T2DM shorter than 5 years, the overall remission rate at 9, 12 and 24 months after operation was 10/10, 9/10 and 9/10, respectively, significantly higher than that of patients with a duration of 11-15 years (2/6, 2/6 and 2/6, Fisher's exact tests, P=0.008, 0.036 and 0.036, respectively).

CONCLUSIONThe present study confirms the efficacy of LSG in the treatment of T2DM patients with a BMI less than 40 kg/m.

Adult ; Bariatric Surgery ; methods ; Blood Glucose ; physiology ; Body Mass Index ; Diabetes Mellitus, Type 2 ; surgery ; Female ; Gastrectomy ; Glycated Hemoglobin A ; physiology ; Humans ; Laparoscopy ; Male ; Middle Aged ; Obesity ; surgery ; Postoperative Complications ; Remission Induction ; methods ; Retrospective Studies ; Treatment Outcome ; Weight Loss