Monte carlo dose calculation in dental amalgam phantom

Abstract

It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

The application of metal artifact reduction methods on computed tomography scans for radiotherapy applications: A literature review

“…The density correction methods which are available in the TPSs can also be used to reduce the metal artifacts on CT scans for RT applications, see | 13 based on image inpainting or sinogram inpainting [72][73][74][75] ; some others require the acquisition of additional tilted CT scans, 76 propose novel image acquisition, and reconstruction methods 77,78 ; or require the use of magnetic resonance imaging (MRI) 79,80 or megavoltage CT (MVCT). 81,82 For the metal deletion technique (MDT) 75 (Fig.…”

Effects of density from various hip prosthesis materials on 6 MV photon beam: a Monte Carlo study

“…uncertainties originating from streak artefacts in CT images. 3,4 Streak artefact reduction techniques have been discussed comprehensively in the literature 3,5,6 by using the dual step adaptive thresholding technique, the sinogram correction method, and filtering methods to remove the artefacts from affected CT images.…”

“…Figure 6 shows that the magnitude of dose perturbation was directly proportional to the density of the material struck by photons. Bone with density of 2•08 g/cm 3 was the least perturbed material followed by titanium (4•48 g/cm 3 ) and stainless steel (6•45 g/cm 3 ), with 32 and 41% dose difference relative to water, respectively. For CoCrMo, the dose difference was 49%.…”

“…Notes: Drastic perturbation of doses were observed at depths of 4-9 cm (first femoral head position) and 19-24 cm (second femoral head position). Water ρ, 1 g/cm 3 ; bone ρ, 2•08 g/cm 3 ; Ti ρ, 4•48 g/cm 3 ; SST ρ, 6•45 g/cm3 ; and CoCrMo ρ, 8•20 g/cm 3 .…”

Monte Carlo simulation of X-ray room shielding in diagnostic radiology using PHITS code

“…Nowadays, simulation is used in all fields including medical physics because simulation can assist us in understanding the underlying processes since all the details are accessible (Aziz et al, 2015, Tajuddin et al, 2019. Simulation studies generally have several advantages over experimental study.…”