Exposure Dose Reduction Research Articles

CBCT-based online adaptive radiotherapy of the prostate bed: first clinical experience and comparison to nonadaptive conventional IGRT.

Conventional image-guided radiotherapy (IGRT) of the prostate bed is challenged by the varying anatomy due to dynamic changes of surrounding organs such as the bladder and rectum. This leads to changed dose coverage of target and surrounding tissue. The novel online adaptive radiotherapy (oART) aims to improve target coverage as well as reduce dose exposure to surrounding healthy tissues by daily reoptimization of treatment plans. Here we set out to quantify the resulting changes of this adaptation for patients and treatment team. Atotal of 198 fractions of radiotherapy of the prostate bed (6patients) were treated using oART with the Ethos accelerator (Varian Medical Systems, Palo Alto, CA, USA). For each fraction, volumes and several dose-volume parameters of target volumes and organs at risk were recorded for the scheduled plan (initial plan, recalculated based on daily cone beam computed tomography [CBCT]), the adapted plan, and the verification plan, which is the dose distribution of the applied plan recalculated on the closing CBCT after the adaptation process. Clinical acceptability for all plans was determined using given dose-volume parameters of target volumes. Additionally, the time needed for the adaptation process was registered and compared to the time required for the daily treatment of five conventional IGRT patients. Volumes of target and organs at risk (OAR) exhibited broad variation from day to day. The differences in dose coverage D98% of the clinical target volume (CTV) were significant through adaptation (p < 0.0001; median D98% 97.1-98.0%) and further after verification CBCT (p < 0.001; median D98% 98.1%). Similarly, differences in D98% of the planning target volume (PTV) were significant with adaptation (p < 0.0001; median D98% 91.8-96.5%) and after verification CBCT (p < 0.001; median D98% 96.4%) with decreasing interquartile ranges (IQR). Dose to OAR varied extensively and did not show aconsistent benefit from oART but decreased in IQR. Clinical acceptability increased significantly from 19.2% for scheduled plans to 76.8% for adapted plans and decreased to 70.7% for verification plans. The scheduled plan was never chosen for treatment. The median time needed for oART was 25 min compared to 8 min for IGRT. Target dose coverage was significantly improved using oART. IQR decreased for target coverage as well as OAR doses indicating higher repeatability of dose delivery using oART. Differences in doses after verification CBCT for targets as well as OAR were significant compared to adapted plans but did not offset the overall dosimetric gain of oART. The median time required is three times higher for oART compared to IGRT.

Outcomes of Radiation Dose Reduction Protocol in Electrophysiologic and Cardiac Device Procedures

Background: Exposure to radiation has been demonstrated to be associated with adverse short- and long-term health outcomes. Objective: To presented outcomes before and after the implementation of a radiation dose reduction protocol in electrophysiologic (EP) and cardiac device procedures. Materials and Methods: The present study was a retrospective comparative study, conducted at Chiang Mai University Hospital in Thailand using 2017 and 2019 data, including all patients who underwent EP and cardiac implantable electronic device (CIED) procedures. Exclusion criteria involved patients with incomplete radiation dose records. The authors compared fluoroscopic time, radiation exposure, and complication rates before and after the protocol. Results: Among the 458 cases, with 214 Eps and 244 devices, the mean age was 58 years. For device implantation procedures, there was no significant change in fluoroscopic time as median (P₂₅, P₇₅) before and after protocol implementation were 3.1 (0.4, 5.8) versus 4.4 (1.2,7.6) minutes, respectively (p=0.117). However, there was a decreasing trend in dose area product (DAP) at 242.0 (119.2, 766.0) versus 197.9 (71.5, 494.5) cGy.cm² (p=0.073). The reduction in DAP was more pronounced in cardiac resynchronization therapy (CRT) implantation when comparing 2017 to 2019 were 1,933.6 (1,039.4, 7,683.8) versus 1,074.6 (427.2, 2,890.7) cGy.cm² (p=0.020). In EP procedures, fluoroscopic time significantly decreased from 8.1 (3.0, 14.3) minutes in 2017 to 1.0 (0.0, 3.6) minute in 2019 (p&lt;0.001), accompanied by a significant reduction in exposure dose of 45.0 (10.8, 153.3) versus 1.7 (0.0, 31.6) mGy (p&lt;0.001) and DAP of 1,022.9 (247.2, 2,660.3) versus 38.5 (0.0, 566.9) cGy.cm² (p&lt;0.001). There was no difference in the complication rate between the two periods. Conclusion: The implementation of the radiation dose reduction protocol resulted in a significant decrease in radiation exposure during EP procedures and showed a trend towards reduction in CIED procedures.

Recommendation for reducing the crystalline lens exposure dose by reducing imaging field width in cone-beam computed tomography for image-guided radiation therapy: an anthropomorphic phantom study.

In cone-beam computed tomography (CBCT) for image-guided radiation therapy (IGRT) of the head, we evaluated the exposure dose reduction effect to the crystalline lens and position-matching accuracy by narrowing one side (X2) of the X-ray aperture (blade) in the X-direction. We defined the ocular surface dose of the head phantom as the crystalline lens exposure dose and measured using a radiophotoluminescence dosimeter (RPLD, GD-352M) in the preset field (13.6cm) and in each of the fields when blade X2 aperture was reduced in 0.5cm increments from 10.0 to 5.0cm. Auto-bone matching was performed on CBCT images acquired five times with blade X2 aperture set to 13.6cm and 5.0cm at each position when the head phantom was moved from -5.0 to + 5.0mm in 1.0mm increment. The maximum reduction rate in the crystalline lens exposure dose was -38.7% for the right lens and -13.2% for the left lens when blade X2 aperture was 5.0cm. The maximum difference in the amount of position correction between blade X2 aperture of 13.6cm and 5.0cm was 1mm, and the accuracy of auto-bone matching was similar. In CBCT of the head, reduced blade X2 aperture is a useful technique for reducing the crystalline lens exposure dose while ensuring the accuracy of position matching.

Patient radiation exposure dose reduction using stent-enhanced image processing in percutaneous coronary intervention.

We investigated the reduction in patient radiation exposure dose during percutaneous coronary intervention (PCI) by stent enhancement processing. We examined the effects of dose reduction based on the image quality of stent enhancement processing using a purpose-built dynamic phantom. We evaluated the image contrast (IC) of the stent in stent-enhanced images (SVref), digital angiography (DA), and stent-enhanced images with a 20%, 40%, and 60% lower imaging doses (SV20, SV40, and SV60). We visually evaluated graininess and stent shape using the mean opinion score (MOS) and retrospectively evaluated the acquisition duration of stent enhancement in PCI cases; finally, we estimated the decrease in patient radiation exposure due to stent enhancement. The image contrast of SVref at phantom thicknesses of 20cm was 51.25 ± 3.82, while the image contrast of DA was significantly reduced at 14.90 ± 1.57 (p < 0.05). We observed a significant decrease in the MOS of graininess in SV60 and MOS of stent shape in DA (p < 0.05). Furthermore, the average imaging duration for stent enhancement using PCI was 22.65 ± 7.43s, and the maximum imaging duration was 68.07s. We hypothesize that patient radiation exposure dose can be reduced by up to 60.17mGy by lowering the imaging dose during the stent enhancement process. Stent enhancement processing improves the visibility of stent images, and can reduce radiation exposure by approximately 40% during confirmation imaging of stents. Our study contributes to the reduction of radiation exposure dose for operators and patients in PCI.

Reducing image artifacts in sparse projection CT using conditional generative adversarial networks

Reducing the amount of projection data in computed tomography (CT), specifically sparse-view CT, can reduce exposure dose; however, image artifacts can occur. We quantitatively evaluated the effects of conditional generative adversarial networks (CGAN) on image quality restoration for sparse-view CT using simulated sparse projection images and compared them with autoencoder (AE) and U-Net models. The AE, U-Net, and CGAN models were trained using pairs of artifacts and original images; 90% of patient cases were used for training and the remaining for evaluation. Restoration of CT values was evaluated using mean error (ME) and mean absolute error (MAE). The image quality was evaluated using structural image similarity (SSIM) and peak signal-to-noise ratio (PSNR). Image quality improved in all sparse projection data; however, slight deformation in tumor and spine regions was observed, with a dispersed projection of over 5°. Some hallucination regions were observed in the CGAN results. Image resolution decreased, and blurring occurred in AE and U-Net; therefore, large deviations in ME and MAE were observed in lung and air regions, and the SSIM and PSNR results were degraded. The CGAN model achieved accurate CT value restoration and improved SSIM and PSNR compared to AE and U-Net models.

Radiation Exposure Dose Reduction according to ECG Window Acquisition Range Setting in Coronary Artery CT Angiography

This study was to reduce the radiation exposure dose of recipients by setting the ECG window acquisition range appropriately during Coronary artery CT Angiography (CCTA) examination. Group 1 (control group) opened ECG window acquisition range to 65% to 75% using the relative delay scan (RDS), which is divided by percentage (%) based on the R-R peak interval of recipient's Average HR, and tested by setting pitch to auto. Group 2 fixed the pitch according to the recipient's HR under the same conditions as Group 1. Group 3 used absolute delay scan (ADS), which is divided by milliseconds (ms) based on the R-R peak interval of recipient's Average HR and fixed the ECG window acquisition range by 60 ms intervals. Group 4 narrowed the scan range from 68% to 73% under the same conditions as Group 1. The values of the mean, minimum, maximum, the volume CT dose index (CTDIvol), and dose length product (DLP) were compared. The exposure dose was reduced by more than 10% when acquired with ADS, not RDS mainly obtained from CCTA. Also, compared to the existing RDS, when the scan range was reduced by half, it was reduced by more than 20%. In conclusion, In CCTA testing, setting the ECG window acquisition range to 5% or 60 ms can reduce radiation exposure without compromising the best phase image acquisition and image quality.

A window into the future: case study of long-term radiological risk modelling posed by unregulated mining waste repurposing activities.

The study aims to assess long-term radiological exposure risks and effects to both industrial workers and occupants living in the near vicinity of local tailing processing plants. The detrimental effects of licensing exemption were studied by comparing contaminated soil collected from 7 unlicensed-by the Atomic Energy Licensing Board-tailing processing plants with soil from control location. It was found that the average concentration of 226Ra, 232Th, and 40K for all seven processing plants fell between the range of 0.1 ± 0.0-7.21 ± 0.1 Bqg-1, 0.1 ± 0.0-16.34 ± 0.27 Bqg-1, and 0.18 ± 0.01-1.74 ± 0.01 Bqg-1, respectively, showing observable indication of soil contamination with Technologically Enhanced Naturally Occurring Radioactive (TENORM) material. The annual effective dose was calculated which showed that most samples exceeded the recommended value of the ICRP of 1 mSvy-1 for non-radiation workers. Assessment of radiological hazards in the environment was done by calculating the radium equivalent value; revealing the exposure risk posed by the contaminated soil is substantial. Using the relatable inputs, the RESRAD-ONSITE computed code revealed that the dose due to internal exposure via inhalation of radon gas contributes the most to the overall exposure. The covering of the contaminated soil with a clean layer is effective in reducing external dose but ineffective for radon inhalation. RESRAD-OFFSITE computer code also revealed that the contribution of exposure via contaminated soil in the neighbouring vicinity is below the recommended 1 mSvy-1 threshold but still contributes to a significant amount cumulatively when considering other exposure pathways as well. The study proposes the introduction of clean cover soil as a viable option in reducing external dose from contaminated soil as 1m of clean cover soil is able to reduce dose exposure by 23.8-30.5%.

A machine learning model for textured X-ray scattering and diffraction image denoising

With the advancements in instrumentations of next-generation synchrotron light sources, methodologies for small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) experiments have dramatically evolved. Such experiments have developed into dynamic and multiscale in situ characterizations, leaving prolonged exposure time as well as radiation-induced damage a serious concern. However, reduction on exposure time or dose may result in noisier images with a lower signal-to-noise ratio, requiring powerful denoising mechanisms for physical information retrieval. Here, we tackle the problem from an algorithmic perspective by proposing a small yet effective machine-learning model for experimental SAXS/WAXD image denoising, allowing more redundancy for exposure time or dose reduction. Compared with classic models developed for natural image scenarios, our model provides a bespoke denoising solution, demonstrating superior performance on highly textured SAXS/WAXD images. The model is versatile and can be applied to denoising in other synchrotron imaging experiments when data volume and image complexity is concerned.

Long-Term Analysis of Internal Exposure Dose-Reduction Effects by Food Regulation and Food Item Contribution to Dose after the Fukushima Daiichi Nuclear Power Plant Accident.

Over 10 years have passed since the Fukushima Daiichi Nuclear Power Plant accident. This study verifies the efficacy of longitudinal regulation on internal exposure doses and analyzes food group contributions to radiation doses using accumulated monitoring test results. The committed effective doses in 10,000 virtual persons from fiscal year (FY) 2012 to 2021, with and without regulation, were estimated as products of radioactivity concentrations randomly sampled from the test results, food intake, and dose coefficient. The distributed values of food intake rather than a mean value in dose estimation were assumed to reflect food intake variations and avoid underestimation of internal exposure doses for high-intake consumers. Furthermore, the ingestion of radioactive cesium from the calculation was analyzed per food group. The 95th percentile of the internal exposure dose (the dose of a "representative person") was less than 1 mSv/year in both FYs. The regulation effect was substantial in FY 2012, and no noticeable difference in radiation doses was found between the regulation and no regulation conditions after FY 2016. Internal exposure doses decreased until approximately FY 2016 and then remained constant. It was also shown that not only radioactivity concentration but also food intake is a major factor affecting cesium intake. In summary, it was confirmed that Japan had ensured food safety regarding radioactive materials.

ABSORBED DOSE AND IMAGE QUALITY ACCORDING TO THE SCAN MODE AND SHIELD POSITION IN PEDIATRIC BRAIN COMPUTED TOMOGRAPHY SCANS.

In this study, computed tomography dose index (CTDIvol), dose-length product (DLP), organ dose and signal-to-noise ratio (SNR) were measured in pediatric brain helical and volumetric CT scans using a pediatric phantom (equivalent to a 10-year-old) and optically stimulated luminescence dosemeters (OSLD) as the scan protocol used in Hospital A. Volumetric scans showed lower CTDIvol, DLP and organ dose than helical scans, and the SNR showed similar results. The organ doses were lower in the phantoms protected with front, rear or front and rear shielding than in those without shielding. However, no statistically significant differences were found among the different shield locations. In pediatric brain CT scans, to reduce exposure dose and patient discomfort while maintaining image quality, a volumetric scan rather than a helical scan was preferred, and a good shielding effect was observed with front or rear shielding.

Sex-Dependent Analysis of Temozolomide-Induced Myelosuppression and Effects on Survival in a Large Real-life Cohort of Patients With Glioma.

To investigate the association of radiochemotherapy-induced cytopenia with sex and its potential effect on survival in patients with glioma. We retrospectively analyzed cytopenia during temozolomide-based concomitant radiochemotherapy in 492 patients with glioma. Histologic grading, molecular pathology, surgical procedures, adjuvant chemotherapy subsequent to the radiochemotherapy phase, and overall survival (OS) were recorded. The extent of cytopenia was correlated with sex and outcome. Treatment-induced severe cytopenia (leukocytopenia, lymphocytopenia, neutropenia, and thrombocytopenia) was more frequent in women than men (44 vs 18%; p = 0.0002). In women with IDH-wt high-grade astrocytomas, there was a negative correlation of severe cytopenia in general and thrombocytopenia in particular during temozolomide radiochemotherapy with OS independent from other predictors (92 [77-111] vs 73 [21-127] weeks; p < 0.05). In men, there was also a trend for this unfavorable effect. In addition, severe cytopenia in all blood cell lineages correlated with reduced temozolomide dose exposure during radiochemotherapy (all p < 0.05 in the total cohort) and reduced dose exposure was independently associated with worse OS (hazard ratios for OS in complete vs reduced temozolomide dose in the total and female cohort 0.66 [0.47-0.92] and 0.4 [0.24-0.69], p < 0.05). Our analysis of treatment-induced cytopenia in a large cohort of patients with glioma confirms that women are at higher risk and demonstrates an association of cytopenia with shortened survival in women. This study provides Class II evidence that women with glioma treated with temozolomide-based concomitant radiochemotherapy have more frequent treatment-induced severe cytopenia than men and that severe myelosuppression correlates with worse OS in women.

Experimental study of X-ray dose reduction factor when using various size bismuth and lead particles

Low-energy X-rays are widely used during clinical examinations, therefore we need to reduce exposure dose to medical staff by using radiation shielding products. Current X-ray shielding materials are fabricated by embedding high-atomic-number metal particles into a base material. It is valuable to derive knowledge concerning metal particles and shielding ability from actual experimentation. This is necessary because it is unrealistic to mimic many particles in the Monte-Carlo simulation. Understanding the effect of the particle size on the dose reduction factor is important, but at this time this systematic clarification has not been achieved. In this study, we aim to investigate the effect of metal particle size on X-ray shielding ability. 28 investigational shielding products were prepared by embedding metal particles into clay. Lead, bismuth and bismuth oxide having particle diameters between 1.8 μm and 211.3 μm were used. The effective mass thicknesses related to the metals (lead or bismuth) were set at 2,400 g/m2, 1,200 g/m2 and 600 g/m2, resulting in the maximum dose reduction factors of 94.5%, 84.8% and 68.0%, respectively. The dose reduction factors of these investigational shielding products were measured using "International Standard Testing Geometry" with a tube voltage of 70 kV. As a result, we found that a high dose reduction factor can be obtained when the particle size is 40 μm or less. Furthermore, we found that the shielding ability decreased when the metal particles were embedded in various base materials such as polymer sheets, and that the loss was 2.4% or less. Our findings provide insight into the development of novel X-ray shielding products and guarantee the reliability of previous studies that used Monte-Carlo simulations.

Patient Exposure Dose Reduction in Coronary Angiography &amp; Intervention

Patient Exposure Dose Reduction in Coronary Angiography &amp; Intervention

JCS/JHRS 2021 guideline focused update on non-pharmacotherapy of cardiac arrhythmias.

JCS/JHRS 2021 guideline focused update on non-pharmacotherapy of cardiac arrhythmias.

Cone beam computed tomography (CBCT) guidance is helpful in reducing dose exposure to pediatric patients undergoing radiofrequency ablation of osteoid osteoma

PurposeTo assess efficacy and safety of cone beam computed tomography (CBCT) in the radiofrequency ablation (RFA) of osteoid osteoma (OO) in children and adolescents, and to compare technical success, clinical success, radiation dose and procedure duration time of CBCT guidance to conventional computed tomography (CT) guidance.Materials and methodsBetween 2015 and 2019, 53 consecutive percutaneous RFA were performed on pediatric patients with CBCT or conventional CT guidance, respectively, in 24 and 29 children and adolescents with 24-month follow-up. Dose area product (DAP) and dose length product (DLP) were recorded, respectively, for CBCT and conventional CT and converted to effective doses (ED).ResultsCBCT and conventional CT groups were similar in terms of patient age and weight, tumor size and tumor location. Technical success was achieved in all cases. Primary clinical success was 91.67% (22/24) for the CBCT group and 89.66% (26/29) for the conventional CT group. Mean DAP was 64.75Gycm2 (range 6.0–266.7). Mean DLP was 972.62mGycm (range 337–2344). ED was significantly lower in the CBCT group compared to the conventional CT group (0.34 mSv vs. 5.53 mSv, p = 0.0119). Procedure duration time was not significantly longer in the CBCT group (102.25 min vs. 92.34 min, p = 0.065). No major complication was registered. Minor complications were observed in 4 patients (2 in CBCT; 2 in conventional CT).ConclusionsCompared to conventional CT guidance, CBCT guidance for percutaneous OO ablation shows similar technical and clinical success rates, with reduced radiation dose and equivalent procedure duration time. This technique helps sparing dose exposure to pediatric patients.

Usefulness of an Image-Based Noise-Reduction Technique in Cone Beam Computed Tomography for Adaptive Radiotherapy

Cone-beam computed tomography (CBCT) plays an important role in adaptive radiation therapy and can be used to observe changes in body shape, tumor size, and organ position during the treatment period. This technique can also be used to generate an image for replanning. However, performing CBCT during every image guided radiotherapy (IGRT) process increases the radiation dose. Therefore, in this study, we investigated the reduction of the CBCT exposure dose using an image-based edge-preserving noise-reduction technique. A three-dimensional cross-directional bilateral filter (3D-CDBF) which was recently developed by one of the coauthors and reported to provide a noise reduction performance better than a mode-based iterative reconstruction.Catphan was used to evaluate the performance of 3D-CDBF in CBCT. The baseline scan parameters were 120 kV, 40 mA, 40 ms, and 660 frames/360° rotation. The tube current was changed to 32, 20, and 10 mA to reduce the exposure dose. The CBCT images were reconstructed with the filtered back projection (FBP). The 3D-CDBF images were obtained by processing the FBP images. Task-based spatial resolution (task-based transfer function: TTF) and noise power spectrum (NPS) were used to evaluate image quality. Visual evaluation of the image quality was also performed by two experienced radiation oncologists and five radiologists using clinical pelvic images of two patients undergoing radiotherapy for prostate cancer. Additionally, the accuracy of the dose calculation when replanning with 3D-CDBF images was evaluated.The 50%/10% TTFs were 0.364/0.646 mm-1 using FBP and 0.362/0.645 mm-1 using 3D-CDBF, suggesting the excellent edge preservation ability of 3D-CDBF. The noise power of 3D-CDBF compared to FBP were 25.4% at 0.2 mm-1 and 17.0% at 0.5 mm-1. 3D-CDBF notably reduced noise power over the entire frequency range. Therefore, the NPS level of 10 mA became similar to that of 40 mA. The visual evaluation allowed by the 3D-CDBF images was considerably higher than that realized with other images. Additionally, dose evaluation by gamma analysis showed that 3D-CDBF had no effect on the accuracy of the dose calculation.Compared with conventional FBP, the 3D-CDBF yielded significant improvements in quantitative and qualitative image qualities. The results indicated a possible 75% dose reduction of this method, while preserving the accuracy of the dose calculation.

P14.11 Severe treatment-induced myelosuppression is more frequent in female malignant glioma patients and associated with reduced overall survival

Abstract BACKGROUND An association of treatment-related myelotoxicity with female gender has been previously suggested. However, a systematic analysis of the prognostic relevance of radiochemotherapy-related cytopenia involving the different blood cell lineages is lacking. MATERIAL AND METHODS We retrospectively analyzed cytopenia during temozolomide-based concomitant radiochemotherapy (RCT) in 493 glioma patients. Histological grading, molecular pathology, surgical procedures and median overall survival (OS) were recorded. The extent of cytopenia was correlated with gender and outcome. RESULTS Treatment-induced severe cytopenia (leuko-, lympho-, neutro- and thrombocytopenia) occurred much more often in female than in male glioma patients (40.8 vs. 13.9%, p-value &amp;lt;0.0001). In female patients with IDH-wildtype high-grade astrocytomas there was a negative correlation of severe leuko-, lympho- and thrombocytopenia during temozolomide RCT with OS (36 vs. 54, 37 vs. 54 and 36 vs. 57 weeks, respectively; all p-values &amp;lt;0.05). In male patients there was also a trend for this unfavorable effect. Additionally, severe cytopenia correlated with reduced temozolomide dose exposure during RCT (all p-values &amp;lt;0.05 in total cohort) and reduced dose exposure was independently associated with worse OS (p-values &amp;lt;0.05 in the total and female cohort). CONCLUSION Our data confirm that women are at higher risk for treatment-induced cytopenia during RCT which is associated with a significant decrease in OS. From our data, it appears plausible that reduced temozolomide dose exposure during RCT is at least in part responsible for this finding. Immunosuppression of patients with severe cytopenia may be an independent contributor to adverse outcome.

On the use of flyash-lime-gypsum (FaLG) bricks in the storage facilities for low level nuclear waste

In the present study, radiation shielding and protection ability of prepared Flyash-lime-Gypsum (FaLG) bricks has been studied in terms of energy exposure build up factors and dose parameters. The energy exposure build up factors of Flyash-lime-Gypsum (FaLG) bricks have been calculated for the energy range of 0.015 MeV–15 MeV and for penetration depth upto 40 mfp directly using a new and simplified Piecewise Linear Spline Interpolation Method (PLSIM). In this new method, the calculations of G.P fitting parameters are not required. The verification and accuracy of this new method has been checked by comparing the results of exposure build up factor for NBS concrete calculated using present method with the results obtained by using G.P fitting method. Further, the relative dose distribution and reduced exposure dose rate for various radioactive isotopes without any shielding material and with Flyash-lime-Gypsum (FaLG) bricks have been calculated in the energy range of 59.59–1332 keV. On the basis of the obtained results, it has been reported that the prepared Flyash-lime-Gypsum (FaLG) bricks possess satisfactory radiation shielding properties and can be used as environmentally safe storage facilities for low level nuclear waste.

Performance estimation of lead-free dual-layered shielding in dismantling of steam generator: A Monte-Carlo simulation study

The Kori-1 nuclear power plant has been permanently shut down since 2017, and its major structures, systems, and components are currently planned to be dismantled according to the final decommissioning plan. To protect dismantling workers from external radiation exposure dose during decommissioning, we propose a dose reduction method involving dual-layered Pb-free shielding. Based on the Monte Carlo method, the performance of the abovementioned method and various types of materials are optimized and estimated in terms of the equivalent dose rate and radiation shielding rate. The results showed that Pb-free shielding with dual layers exhibited better performance than the conventional shield. In addition, the Pb-free material of WC-Co showed a relatively high performance for the reduction of the external radiation exposure dose in the dismantling process of the steam generator (S/G). In the dismantling process of the S/G, the results of our simulation will offer the choice of materials and flexibility in the design of Pb-free shielding with dual layers.

Effects of Exposure Dose Reduction by Optimization of Automatic Exposure Control Factors in Digital Radiographic Examination of Paranasal Sinus

Effects of Exposure Dose Reduction by Optimization of Automatic Exposure Control Factors in Digital Radiographic Examination of Paranasal Sinus