Objective The beam data is compared with those obtained from Monte Carlo (MC)simulation and measurement to investigate their feasibility and reliability for X-ray small fields.MethodsThe beam data,including the total scatter factor (Scp),percentage depth dose (PDD) was acquired byneasurement and calculation with the field size ranging from 0.5 cm × 0.5 cm to 10 cm x 10 cm.The resultswere compared and analyzed.Results All the data is most consistent for the fields size of ≥3.5 cmx 3.5cm,but they are obvious different for the fields size of ≤ 3.0 cm × 3.0 cm.The measurements seem toreliable using the chambers of CC04 and CC13 for the fields size of ≥2.0 cm x 2.0 cm.Conclusions It isdemonstrated that the accurate measurements and calculations of Scp and PDD can be obtained for the fieldssize of ≥2.0 cm ×2.0 cm,but they needed morc rcscarchcs for thc smaller fields.

OBJECTIVETo simulate the multi-leaf collimator of Varian linear accelerator using Monte Carlo method.

METHODSThe multi-leaf collimator model was established using the DYNVMLC module of BEAMnrc and validated by comparison of Monte Carlo simulation and actual measurement results.

RESULTSThe simulation results were well consistent with the actual measurement results with a bias of less than 3%.

CONCLUSIONThe multi-leaf collimator of Varian linear accelerator can be successfully modeled using Monte Carlo method for analysis of the impact of the geometric properties of the multi-leaf collimator on the dose distribution.

Humans ; Models, Theoretical ; Monte Carlo Method ; Particle Accelerators ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted

Objective:To explore and validate the targets of Salvia miltiorrhiza in myopia using network pharmacology and molecular docking technology. Methods:The TCMSP database was used to extract the targets of Salvia miltiorrhiza.GeneCards, DisGeNET, Malacard and OMIM databases were used to extract the myopia-related targets.The target intersection was taken, and the intersecting targets were selected to extract the corresponding active ingredients of traditional Chinese medicine (TCM) and construct the pharmacological regulatory network of TCM using Cytoscape.The protein interaction network map for the key target genes was constructed using the String database, and the relevant proteins were selected to download the three-dimensional structures of the active ingredients from the PubChem database, and molecular docking was performed using AutoDockvina software.Twelve 3-week-old guinea pigs were induced with lens-induced myopia (LIM) in the right eye and randomly divided into normal saline group and sodium danshensu group, with 6 animals in each group.During the maintenance of LIM, periocular injection of 1 ml normal saline or sodium danshensu was performed daily.The contralateral eye was used as a negative control.On days 0, 14, and 28 of the experiment, the axial length of both eyes was measured by A-scan ultrasonography, and the refractive status was assessed with a streak retinoscope.To avoid individual differences, relative spherical equivalent (treated eye-contralateral eye) and relative axial length (treated eye-contralateral eye) were compared.On day 28, the relative expression levels of hypoxia-inducible factor-1α (HIF-1α) and transforming growth factor-β1 (TGF-β1) proteins were determined by Western blot.The feeding and use of laboratory animals followed the 3R principle, and the research program was approved by the Ethics Committee of Experimental Animal Center of Zhengzhou University (No.ZZU-LAC 202320405[02]). Results:Sixteen intersecting key targets were screened for myopia and TCM components derived from Salvia divinorum.A TCM network pharmacology map and protein interaction map were constructed with Salvia divinorum as a drug candidate, and the corresponding proteins of target genes, such as MMP2, TGFB1, and MMP9 were screened to perform molecular docking with the active ingredients, such as lignocellulosic acid, danshensu, tanshinone ⅡA, and so on.After 14 days of induction, the relative spherical equivalent and relative axial length were (-4.67±1.03)D and (0.67±0.26)mm in sodium danshensu group, and (-6.30±1.22)D and (1.08±0.34)mm normal saline group, indicating slower myopia progression and axial elongation in sodium danshensu group, and the differences were statistically significant ( t=2.412, P=0.039; t=2.750, P=0.049). The relative expression levels of HIF-1α protein were 0.20±0.01, 1.29±0.05 and 0.63±0.02, and the relative expression levels of TGF-β1 protein were 0.93±0.05, 0.25±0.01 and 0.74±0.05 in the negative control, normal saline and sodium danshensu groups, respectively.The expression of HIF-1α protein was higher in sodium danshensu group than in negative control group but lower than in the normal saline group, and the expression of TGF-β1 protein was lower in sodium danshensu group than in negative control group but higher than in the normal saline group, showing statistically significant differences (all at P<0.05). Conclusions:Natural compounds extracted from Salvia divinorum extracts may serve as potential drug candidates to combat scleral hypoxia and improve scleral extracellular matrix remodeling.