Monte Carlo study of TG-43 dosimetry parameters of GammaMed Plus high dose rate 192 Ir brachytherapy source using TOPAS.

PURPOSE: To develop a simulation model for GammaMed Plus high dose rate 192 Ir brachytherapy source in TOPAS Monte Carlo software and validate it by calculating the TG-43 dosimetry parameters and comparing them with published data. METHODS: We built a model for GammaMed Plus high dose rate brachytherapy source in TOPAS. The TG-43 dosimetry parameters including air-kerma strength SK , dose-rate constant Λ, radial dose function gL (r), and 2D anisotropy function F(r,θ) were calculated using Monte Carlo simulation with Geant4 physics models and NNDC 192 Ir spectrum. Calculations using an old 192 Ir spectrum were also carried out to evaluate the impact of incident spectrum and cross sections. The results were compared with published data. RESULTS: For calculations using the NNDC spectrum, the air-kerma strength per unit source activity SK /A and Λ were 1.0139 × 10-7 U/Bq and 1.1101 cGy.h-1 .U-1 , which were 3.56% higher and 0.62% lower than the reference values, respectively. The gL (r) agreed with reference values within 1% for radial distances from 2 mm to 20 cm. For radial distances of 1, 3, 5, and 10 cm, the agreements between F(r,θ) from this work and the reference data were within 1.5% for 15° < Î¸ < 165°, and within 4% for all θ values. The discrepancies were attributed to the updated source spectrum and cross sections. They caused deviations of the SK /A of 2.90% and 0.64%, respectively. As for gL (r), they caused average deviations of -0.22% and 0.48%, respectively. Their impact on F(r,θ) was not quantified for the relatively high statistical uncertainties, but basically they did not result in significant discrepancies. CONCLUSION: A model for GammaMed Plus high dose rate 192 Ir brachytherapy source was developed in TOPAS and validated following TG-43 protocols, which can be used for future studies. The impact of updated incident spectrum and cross sections on the dosimetry parameters was quantified.

ETS Proto-Oncogene 1 Suppresses MicroRNA-128 Transcription to Promote Osteogenic Differentiation Through the HOXA13/ß-Catenin Axis.

ETS proto-oncogene 1 (ETS1) has been implicated in osteoporosis (OP), but the exact molecular mechanisms are complex. This work focuses on the impact of ETS1 on the osteogenic differentiation and the molecules involved. A mouse pre-osteoblast cell line MC3T3-E1 was used for in vitro experiments. ETS1 was upregulated during the process of osteogenic differentiation of MC3T3-E1 cells. Overexpression of ETS1 promoted expression of osteogenic markers, alkaline phosphate concentration, and calcareous accumulation in cells. ETS1 was found to specifically bind to miR-128 promoter to suppress its transcription, while miR-128 could target homeobox A13 (HOXA13). Therefore, ETS1 suppressed miR-128 transcription to upregulate HOXA13 expression. Overexpression of HOXA13 promoted the osteogenic differentiation ability of cells and increased the protein level of ß-catenin. Either overexpression of miR-128 or downregulation of ß-catenin by CWP232228, a ß-catenin-specific antagonist, blocked the promoting roles of ETS1 in cells. To conclude, this study provided evidence that ETS1 suppresses miR-128 transcription to activate the following HOXA13/ß-catenin axis, therefore promoting osteogenic differentiation ability of MC3T3-E1 cells. This finding may offer novel ideas for OP treatment.

1H-MR spectroscopy guided gamma knife radiosurgery for treatment of glioma.

AIM: To observe the outcomes of 1H- MR-spectroscopy (MRS) guided gamma knife surgery for treatment of glioma. MATERIAL AND METHODS: Twenty patients with glioma diagnosed pathologically were randomly divided into MRI group and MRI plus MRS group. The target volume was defined as the tumor enhanced area plus the surrounding area with a short T1 and a long T2 in the MRI group, while the tumor enhanced area plus the surrounding area with a short T1 and a long T2 and choline: N-acetyl aspartate index (CNI) ≥ 1.6 in the MRI plus MRS group.12 months after surgery were set as the endpoint. RESULTS: Thirteen (65%) patients were successfully treated, of whom 6 were in the MRI group and 7 in the MRI plus MRS group. Ten patients suffered from cerebral edema during treatment, including 8 in the MRI group and 2 in the other group. The cases of cerebral edema were significantly fewer in the MRI plus MRS group than the MRI group. The average maximum diameter of the target volume was smaller in the MRI plus MRS group. CONCLUSION: The MRS-guided gamma knife radiosurgery helps to identify and remove the lesion of glioma and reduce complications due to extended surgical scope.

[Study on the spiral CT reconstruction in the diagnosis and treatment of pelvic ring fractures].

OBJECTIVE: To investigate the clinical value of spiral CT with multi-planar reconstruction (MPR) and three diamensions reconstruction (3D) in the diagnosis and treatment of pelvic ring fractures. METHODS: Fifty-seven patients with pelvic ring fractures were examined with digital radiography and spiral CT in our hospital from April 2004 to April 2009. According to Tile classification, there were thirty-eight cases in type A, twelve in type B and seven in type C. Expectant treatment was used in type A, while surgery, open reduction internal fixation or percutaneous lag screw internal fixation technique for sacroiliac joint due to the displacement of fractures, for type B and C. Three days to twenty-seven months after operation, spiral CT examinations were used to evaluate the location of internal fixation. Cross-check analysis of images of digital radiography and spiral CT was performed before and after operation. RESULTS: Five posterior and three anterior pelvic ring fractures were diagnosed as suspected fractures. Nine posterior and three anterior pelvic ring fractures were missdiagnosed according to plain radiographs, which were corrected by spiral CT examination. According to the postoperative imageology evaluation, the results were excellent in 15, good in 3 and bad in 1. According to clinical evaluation, 16 cases were excellent, 3 good. CONCLUSION: Spiral CT with multi-planar reconstruction (MPR) and three diamensions reconstruction (3D) has clinical values for precise diagnosis and treatment for the complex pelvic ring fractures.