ABSTRACT
Proton therapy can deliver highly conformal dose distribution to the targeted organs or tissues while minimizing radiation exposure to surrounding normal tissues. These characteristics of proton therapy have great significance for reducing patients′ radiation injuries. Proton therapy has to be performed based on accurate calculation of the dose distributions inside the patients′ body and the proton treatment planning system is thus an indispensable part of proton therapy. The paper intends to provide a review on recent progress in dose algorithm research for proton therapy planning system.
ABSTRACT
Objective@#To study the lumber spine imaging process of dual-energy X-ray absorptiometry (DXA) and parameters used to optimize the image quality.@*Methods@#A computational voxel phantom was constructed from patient computed tomography (CT) data. Using the Monte Carlo radiation transport method, a dual energy x-ray beam was simulated to scan the phantom of lumbar spine to generate a bone density image. The Figure of Merit (FOM) of each image was claculated. Parameters including the combination of the high and low energy tube voltage, the thickness of Cu filter, and the ratio of two beam energy incident photon number were optimized, which based on FOM.@*Results@#FOM reaches a minimum of 1.59 × 10-2 with the tube voltage combination of 75 and 200 kVp. With the thickness of the Cu filter from 0 mm to 3 mm, FOM decreases from 6.30×10-2 to 1.87×10-2, showing a gradually slow-down trend. With the incident photon number ratio (low energy/high energy) increasing from 1∶3 to 19∶1, FOM decreases firstly and then increases, reaching a minimum of 1.40×10-2 at 3∶1.@*Conclusions@#According to the simulation results, the combinations of low tube voltage from 70 kVp to 85 kVp and high tube voltage from 160 kVp to 200 kVp, 0.3 mm Cu filter and beam incident photon number ratio from 1 to 5 can yield the best lumbar spine image quality with the lowest patient dose.
ABSTRACT
Objective To develop an online organ doses reporting software VirtualDose-IR, which can compute the radiation doses and provide an easy access to evaluation and control of patients ′radiation doses.Methods Monte Carlo method was applied to simulating various interventional radiology ( IR) processes , which included various parameters such as different patient models at different ages and with different weights , different projection angles and regions of interest , and other parameters .All of the dose data was acquired and then integrated into a database , and displayed with hyper text markup language (HTML), so only a web browser was necessary for users .Results A web-based software that reports organ doses for patients under IR progress was developed .The organ doses assessed with VirtualDose-IR were compared with other experiment and simulation data , and the results were basically consistent with each other .Conclusions VirtualDose-IR is a easy and efficient method to assess patients′radiation doses of IR.