• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.459-465
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• 2015

Energy absorption distribution according to lead shielding for 511 keV ${\gamma}$ ray was evaluated using a Monte Carlo simulation in PET/CT. Experimental method was performed about the depth of skin surface(0.07), lens(3) and the depth(10) was conducted by using ICRU Slab phantom. Difference of energy absorption distribution according to lead thickness and effect of air gap according to distance of lead and phantom. As a result, study showed that using a lead shielding makes high energy distribution by backscatter electron. As a distance between lead and phantom increased, energy absorption distribution gradually decreased. 9 cm or more air gap should exist to prevent effect of backscatter electron which reaches skin surface, when 0.25 mmPb shielding is used. Also 1 cm or more air gap was needed to prevent the effect in 0.5 mmPb. If air gap was not concerned, 0.75 mm or more lead thickness was necessary to prevent effect of backscatter electron.

• Progress in Medical Physics
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• v.21 no.2
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• pp.232-237
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• 2010

The shielding materials designed for replacement of lead equivalent materials for lighter apron than that of lead in diagnostic photon beams. The absorption characteristics of elements were applied to investigate the lead free material for design the shielding materials through the 50 kVp to 110 kVp x-ray energy in interval of 20 kVp respectively. The idea focused to the effect of K-edge absorption of variable elements excluding the lead material for weight reduction. The designed shielding materials composited of Tin 34.1%, Antimon 33.8% and Iodine 26.8% and Polyisoprene 5.3% gram weight account for 84 percent of weight of lead equivalent of 0.5 mm thickness. The size of lead-free shielder was $200{\times}200{\times}1.5\;mm^3$ and $3.2\;g/cm^3$ of density which is equivalent to 0.42 mm of Pb. The lead equivalent of 0.5 mm thickness generally used for shielding apron of diagnostic X rays which is transmitted 0.1% for 50 kVp, 0.9% for 70 kVp and 3.2% for 90 kVp and 4.8% for 110 kVp in experimental measurements. The experiment of transmittance for lead-free shielder has showed 0.3% for 50 kVp, 0.6% for 70 kVp, 2.0% for 90 kVp and 4.2% for 110 kVp within ${\pm}0.1%$. respectively. Using the attenuation coefficient of experiments for 0.5 mm Pb equivalent of lead-free materials showed 0.1%. 0.3%, 1.0% and 2.4%, respectively. Furthermore, the transmittance of lead-free shielder for scatter rays has showed the 2.4% in operation energy of 50 kVp and 5.9% in energy of 110 kVp against 2.4% and 5.1% for standard lead thickness within ${\pm}0.2%$ discrepancy, respectively. In this experiment shows the designed lead-free shielder is very effective for reduction the apron weight in diagnostic radiation fields.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.215-221
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• 2023

Among brain CT scan conditions including the lens, the tube voltage was changed to 80, 100, and 120 kVp and applied. The change in dose was analyzed using lead, lead goggles and barium sulfate silicon shielding materials, and the degree of influence of the shielding materials on image quality was compared and analyzed by applying the SNR, CNR, and SSIM index analysis methods. As a result, it was analyzed that although the dose was reduced by applying all shielding materials, the difference in dose reduction was not large (P > 0.05). In addition, as for the change in image quality due to the application of the shielding material, SNR and CNR were the highest when lead goggles were applied, and the structural similarity was measured to be the best as it was closest to the reference value of 1 in SSIM analysis. Therefore, based on the results of this study, it is thought that if more diverse shielding materials and clinical test results are derived and applied, it will be helpful for the clinical application criteria in the case of shielding utilization inspection.

• Journal of Advanced Technology Convergence
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• v.1 no.2
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• pp.19-25
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• 2022

It is intended to evaluate the performance of the shield after manufacturing a shield with cheap and eco-friendly iron oxide and alumina instead of lead, which is a radiation shielding material. After manufacturing the shield by mixing iron oxide and alumina with gypsum, the performance is evaluated by comparing it with gypsum board and lead apron using an X-ray tube. As a result of the experiment, the shielding performance of alumina was lower than that of the gypsum board, and when 50% of alumina was contained, the shielding performance was similar to that of the gypsum board. Iron oxide became similar to the shielding performance of lead apron when it contained about 75%. A shielding material using alumina shows shielding performance similar to that of gypsum, so it is not suitable as a substitute for lead. However, since iron oxide exhibits similar shielding performance to lead, it can be used as an X-ray shielding material to replace lead in the future, so further research is needed.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.687-695
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• 2022

To find a 3D printer material that can replace lead used as a shield for high-energy electron beam treatment, the shielding composites were simulated by using MCNP6 programs. The Percent Depth Dose (PDD), Flatness, and Symmetry of linear accelerators emitting high-energy electron beams were measured, and the linear accelerator was compared with MCNP6 after simulation, confirming that the source term between the actual measurement and simulation was consistent. By simulating the lead shield, the appropriate thickness of the lead shield capable of shielding 95% or more of the absorbed dose was selected. Based on the absorption dose data for lead shield with a thickness of 3 mm, the shielding performance was analyzed by simulating 1, 5, 10, and 15 mm thicknesses of ABS+W (10%), ABS+Bi (10%), and PLA+Fe (10%). Each prototype was manufactured with a 3D printer, measured and analyzed under the same conditions as in the simulation, and found that when ABS+W (10%) material was formed to have a thickness of at least 10mm, it had a shielding performance that could replace lead with a thickness of 3mm. The surface morphology and atomic composition of the ABS+W (10%) material were evaluated using a scanning electron microscope (SEM) and an energy dispersive X-ray spectrometer (EDS). From these results, it was confirmed that replacing the commercialized lead shield with ABS+W (10%) material not only produces a shielding effect such as lead, but also can be customized to patients using a 3D printer, which can be very useful for high-energy electron beam treatment.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.719-725
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• 2022

This study aimed to measure, quantitatively evaluate, and set the criteria for the minimum lead(Pb) shield thickness per level of clinically applied electron beam energy. The lead shield thickness per electron beam energy was measured using the primary field 95% reduction based on the open field at the depth of maximum dose (d_max) and depth from the surface as the reference depth of tissue dose(10 mm). The measured values were 1.906 mmPb and 1.992 mmPb at the d_max and 10 mm, respectively, regarding the lead shield thickness for 6 MeV electron beam; 2.746 mmPb and 3.743 mmPb for 9 MeV electron beam, 3.718 mmPb and 6.093 mmPb for 12 MeV electron beam, 7.300 mmPb and 15.270 mmPb for 16 MeV electron beam, and 16.825 mmPb and 25.090 mmPb for 20 MeV electron beam. Consequently, a thicker lead shield was required if the measurement was at 10 mm. The required lead shield thickness was also higher than that of the theoretical formula for electron beams of ≥ 16 MeV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.773-774
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• 2016

In this study, we perform the weight reduction and miniaturization of the shielding element that is applied for gamma-ray detectors for imaging of gamma-ray source. Through previous studies, we implemented a lead-based shielding element that represents the shielding effectiveness and performance of commercially available gamma-ray imaging apparatus similar to the shielding body. In this paper, we designed a tungsten-based shield for weight reduction and miniaturization than lead-based shield. We performed the MCNP simulation for shield design and then we obtained the results of reducing the weight of the 17% and 51% of the volume.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.419-425
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• 2022

In the medical field, lead aprons are used to protect the human body from radiation. However, lead is a heavy metal that is harmful to the human body and the environment, so various shield are being developed. In this study, bismuth, which has a similar atomic number to lead, was set as a new material and the absorption rate according to thickness in the same energy region was compared and evaluated through Monte Carlo simulation. The same tendency was confirmed when the thickness of the lead shield was 0.25 mm, the thickness of the bismuth was 0.3 mm, when the lead was 0.50 mm, the bismuth was 0.60 mm, and when the lead was 0.75 mm, the bismuth was 0.90 mm. Therefore, it is reasonable to replace lead with bismuth in the shield material.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.693-698
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• 2018

Currently, shields for shielding medical radiation during medical examinations in the medical environment are lead robe and lead glass. Lead, the main component of this shielding, has limitations in lead poisoning and light weight, and high price. Iodine, which is used as contrast medium instead of lead shield, is expected to be effective as a shield because it has radiation absorbing properties. The purpose of this study was to evaluate the effectiveness of shielding by using acrylic plate filled with CT contrast agent for clinical use instead of conventional lead glass. As a result, it was found that the acrylic plate filled with the CT contrast agent showed a shielding effect of 7 times or more when the scattering ray dose was not shielded. Therefore, CT contrast agent composed of iodine is expected to be used as a shield instead of conventional lead glass.

• Journal of radiological science and technology
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• v.37 no.2
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• pp.143-150
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• 2014

This study was designated to investigate the bremsstrahlung and radiation dose by beta rays. Radiation attenuation from I-131 treatment ward was analyzed using radio protective apron. Shielding materials which is included lead or water were simulated in Monte Carlo Simulation then the spectrum on interaction was analyzed. The shielding materials were categorized according to the thickness. 0.25mm and 0.5mm thick lead and 0.1mm and 0.2mm thick water shielding materials were configured in Monte Carlo Simulation for this study. Only lead shielding method and water plus lead shielding method were carried. As a results, when 0.5mm thick lead shielding method was performed, the radiation dose was similar to the results with water plus lead shielding method. In case of using 0.25mm thick lead shielding, the shielding effect was somewhat less. However, that shielding method cause dose reduction of about 60% compare with non-shielding material.