Introduction of a Novel Technique in Density-Adjusted 3D Printing for the Manufacture of Soft-Tissue-Equivalent Radiological Phantoms

The aim of this study is to introduce a new filament and novel 3D printing technique toadjust the density of a printing job in order to mimic the radiological properties of different tissues. Weused a special filament, LightWeight PLA (LW-PLA), which utilizes foaming technology triggered bytemperature. Cylindrical samples were printed at various temperatures, flow rates, print speeds, anddiameters. A computed tomography (CT) scan was performed to identify their radiological propertiesin terms of the mean Hounsfield Unit (HU). The densities of the samples ranged from 0.36 g/cm3to 1.21 g/cm3, corresponding to mean HU values between −702.7 ± 13.9 HU and +141.4 ± 7.1 HU.Strong linear correlations were observed between the flow rate and density as well as the flow rateand mean HU. The axial homogeneity of the samples was reported as being comparable to that ofdistilled water. A reduction in the mean HU was observed at a lower print speed and it changedslightly with respect to the sample size. Reproducibility assessments confirmed consistent results foridentical printing jobs. Comparisons with regular PLA samples revealed a superior homogeneityin the LW-PLA samples. The findings of this study suggest a practical and accessible solution formimicking all of the soft tissues, including the lungs, by using a single filament.</p

The Software with a Graphical User Interface for GAMOS: Basic Training and an Educational Tool for Medical Physicists

Introduction: It is necessary to have special experience to perform the Monte Carlo calculation, commonly used in medical physics and accepted as the gold standard. In this study, we developed software to teach basic steps to medical physicists who were inexperienced in the medical linear accelerator Monte Carlo simulation.Material and methods: For the design interface, a software called GamosLinacGUI was developed using Gnome Builder, Python, and GTK. The user, who wants to learn the basics of GAMOS and simulate a linear accelerator, can enter the values in the software, select some options and quickly create geometry and physics files.Results: For proof that the software generates the correct inputs for GAMOS simulation in the same conditions for the measurements and calculations. Required files for GAMOS have been created and tested and run the simulation accordingly. This software was tested with Centos Linux.Conclusions: GamosLinacGUI has been successfully developed, which creates the geometry and physics files required for the simulation with GAMOS as a training and learning tool

Size specific dose estimates in pediatric chest, abdomen and pelvis CT examinations

IntroductionVolume&nbsp;computed tomography dose index&nbsp;(CTDIvol) does not contain any dose information regarding the patient size. Size specific dose estimates (SSDE) give more reliable results accounting for the patient size as well. This parameter uses CTDIvol and size dependent conversion factors (fDw) which are calculated by means of water equivalent diameter (Dw) of the patient cross section in every slice of image.PurposeTo develop software to automatically calculate SSDE and to assess the impact of variations in Dw along the z axis on SSDE for CT examinations of the torso in pediatric patients.Materials and methods55 consecutive CT exams of the combined chest, abdomen and pelvis (CAP) have been examined. SSDE has been calculated for 6 hypothetical scan ranges: chest alone, abdomen alone, pelvis alone, chest and abdomen, abdomen and pelvis, and CAP. Two methods were used in mean SSDE approach: (1) mean SSDE over each scan range; (2) SSDE value at the middle of the scan range.ResultsFor scan ranges 1 to 6, the average of the difference in maximal and minimal Dw accross patients was 3.7, 3.8, 2.6, 4.1, 4.4 and 4.5 cm. The mean SSDE values calculated using methods (1) and (2) were highly compatible, with root mean square differences of 0.4, 0.5, 0.3, 1.0, 1.5 and 0.7&nbsp;mGy or 3%, 4%, 2%, 7%, 10%, 5%.ConclusionUsing the mean CTDIvol and the water equivalent diameter at the middle of the scan range provides a reasonable estimation of patient dose in pediatric exams.</div

Radiological Evaluation of the Effects of Printing Parameters on 3D Printed Cylindrical LW-PLA Samples: Preliminary Results

Purpose: In this study, it is aimed to evaluate the radiological tissue equivalency of different 3D printed samples obtained at different printing temperatures, flow rates and infill rates. Materials and Methods: Ultimaker 3 Extended 3D printer and LW-PLA filament were used witin the scope of this study. A total of 18 cylinders were printed by using 3 different printing temperatures of 195°C, 200oC and 205oC, 3 different flow rates of 60%, 80% and 100%, and 2 different infilling rates of 90% and 100%. Each sample is obtained 1 cm in diameter and 3 cm in height. After calculating the densities of the samples, they were imaged by a Philips Brilliance 128-slice computed tomography scanner. In the images, the average Hounsfield Unit values and the standard deviations of these values were recorded at 5 different axial positions for each sample. The mean HU and standard deviation values recorded over 5 slices were evaluated according to the printing parameters. Results: Density of the samples are obtained between 0.63 g/cm3 and 1.19 g/cm3. It was observed that the density of the samples were directly proportional to the flow rate and the infill rate. In addition, the average Hounsfield Unit values of the samples varied between -450 and +73. On the other hand, the standard deviation values were recorded between ±6 and ±25. It was observed that the mean Hounsfield Unit values increased with increasing temperature, flow rate and infill rate. The standard deviation values decreased with increasing printing temperatures. Conclusion: Considering the mean Hounsfield Unit values of different tissues imaged in routine computed tomography examinations, it is concluded that the samples obtained at different printing parameters using LW-PLA filament may have radiological properties that can represent many soft tissues.</p

A Pilot Study to Establish DRLs in Interventional Radiology Procedures

Purpose: ICRP recommends the use of diagnostic reference levels(DRLs) as an important tool for the management and optimizationof radiation dose to patients who undergo radiologic examinations.In Turkey, there is no recent study or report considering DRLsfor interventional procedures. This study aims to present thepreliminary results for DRLs based on common interventionalprocedures carried out at the Department of Radiology, Dokuz EylülUniversity Hospital located in İzmir, Turkey.Materials and Method: Retrospective data collection have beenbased on four most frequent therapeutic or diagnostic interventionalprocedures which are carried out between August 2018 - June 2020and identified as cerebral angiography (CA), cerebral embolization(CE), biliary drainage (BD) and hepatic chemoembolization (HC). Allof the procedures were performed with Phillips Allura Xper 20/10biplane x-ray imaging system. Instructions of ICRP were followed forthe collection and statistical analysis of the data. Datasets involveddose area product (DAP), cumulative air Kerma at the reference point(Ka,r) and fluoroscopy time (FT). Median values of each dataset wererecorded as typical DRLs representing the institutional practice.Results: 169 patients have been included in this study. 54.4% of thepatients were male and 45.6% were female, with a mean age of 56.1(±15.8). Median DAP values were found to be 205, 75, 26 and 224Gy.cm2 for CE, CA, BD and HC, respectively. Median Ka,r values werefound to be 2023, 550, 144 and 719 mGy for CE, CA, BD and HC,respectively. Median FT values were found to be 18.55, 4.25, 4.0 and5.33 min for CE, CA, BD and HC, respectively.Conclusions: Findings of our study agree well with the findingsreported by various international studies. This indicates that theinterventional procedures in Dokuz Eylül University Departmentof Radiology are carried out under consideration of radiationprotection measures. This pilot study is part of an institutionalproject which is supported by Dokuz Eylül University and aims toreach a more extensive database to cover local and national DRLs inthe near future.</p