Effective Radiation Dose Research Articles

Ultra-low Dose Coronary Computed Tomography Angiography Using Photon-counting Detector Computed Tomography

Abstract Background Photon-counting detector computed tomography (PCD-CT), which allows exclusion of electronic noise, shows promise for significant dose reduction in coronary computed tomography angiography (CCTA). This study aimed to assess the radiation dose and image quality of CCTA using PCD-CT, combined with high-pitch helical scanning and an ultra-low tube potential of 70 kVp and investigate the effect of a sharp kernel on image quality and stenosis assessment in such an ultra-low dose CCTA setting. Methods Forty patients (65% male) with stable heart rates and no prior coronary interventions were included. Data on CT dose index volume (CTDIvol) and dose length product (DLP) were collected, with effective radiation dose estimated using a conversion factor of 0.014. Images were reconstructed using kernels of Bv64 and Bv40 for image quality and stenosis assessment. Results The mean CTDIvol, DLP, and effective dose of CCTA were 1.72±0.38 mGy, 29.1±6.8 mGy·cm, and 0.41±0.09 mSv, respectively. Image quality was similar (p=0.75) between the two kernels, with over 95% of segments achieving a rating of good image quality for both kernels. Additionally, 42% of non-calcified plaques showed an increased stenosis severity from Bv40 to Bv64 (p<0.001), while 25% of calcified plaques exhibited a decreased severity (p<0.001). Conclusion PCD-CT technology with high-pitch helical scanning and the tube potential of 70kVp can provide CCTA with ultra-low radiation exposure (DLP, 29 mGy·cm). The noise reduction capability of PCD-CT allows the use of a sharp kernel even in this low-dose CCTA setting without compromising image quality, potentially improving the evaluation of coronary artery stenosis.

Low-dose lung CT: Optimizing diagnostic radiation dose – A phantom study

Background/purposeTo investigate a quantitative method for assessing image quality of low dose lung computed tomography (CT) and find the lowest exposure dose providing diagnostic images. MethodsAxial volumetric lung CT acquisitions (256 slice scanner) were performed on three different sized anthropomorphic phantoms at different dose levels. The maximum steepness of sigmoid curves fitted to line density profiles was measured at lung-to-pleura interfaces. For each phantom, image sharpness was calculated as the median of 468 measurements from 39 different locations. Diagnostic image quality for the adult and paediatric phantom was rated by three radiologists using 4-point Likert scales. The image sharpness cut-off for obtaining adequate image quality was determined from qualitative ratings. ResultsAdequate diagnostic image quality was reached at a median steepness of 713 HU/mm in the adult phantom with a corresponding CTDIvol of 0.14 mGy and an effective dose of 0.13 mSv at a dose level of 100 kVp and 10 mA. In the paediatric phantom diagnostic image quality was reached at a median steepness of 1139 HU/mm with a corresponding CTDIvol of 0.13 mGy and an effective dose of 0.08 mSv at a dose level of 100 kVp and 10 mA. ConclusionsDetermination of image sharpness on line density profiles can be used as quantitative measure for image quality of lung CT. Sufficient-quality lung CT can be achieved at effective radiation doses of 0.13 mSv (adult phantom) and 0.08 mSv (paediatric phantom). These findings suggest that substantial dose reduction is feasible without compromising diagnostic accuracy.

Monte Carlo Simulation of Organ Absorbed Dose of Worker's Radiation Exposure in Bone Scintigraphy

Objectives: This study examines individual organ doses and the impact of ionizing radiation sources on effective radiation doses. Methods: In the research, the ICRP-defined adult standing phantom was used as the phantom material in the Visual Monte Carlo Dose Calculation Program (VMC). Subsequently, the incurred doses were calculated by defining different doses, distances, and durations for the 99mTc radioactive source. Results: Exposure times were set at 5 minutes and 20 minutes in comparison. The results indicated that for 5 minutes and 20 minutes at 360 cm, doses remained below the ICRP recommended annual dose limit of 5.7 µSv/h for occupational exposure. Conclusion: Organ absorbed and effective doses varied with exposure time and source-phantom distance. To optimize radiation exposure, people working in radiation fields must make an increased effort to reduce radiation doses following the ALARA principles. Keywords: Effective dose, absorbed dose, VMC software, Monte Carlo

Social aspects of rehabilitation of the Bryansk region settlements affected by the Chernobyl NPP accident

Relevance. Currently, in the south-west of the Bryansk region, the settlements most affected by the Chernobyl NPP accident show the radiation exposure of about 30 % of the natural level without causing any negative impact on health. However, the settlements are still facing severe social challenges. Throughout the timespan after the Chernobyl accident, significant population decline has been observed in these settlements. Over the past 20 years, the number of residential settlements in the south-west districts of the Bryansk region has decreased by 22 % and the number of residents by 16%. Considering the long-lasting consequences of the Chernobyl disaster, social protection of the accident affected population and the development of radioactively contaminated areas remains relevant so far.The objective is to assess the current demographic situation in the Bryansk region southwestern settlements, most affected by the Chernobyl NPP accident, as well as to justify the shortage of social infrastructure required to ensure the settlements return back to normal conditions.Methods. The study analyses current social problems, including demographics and infrastructure in the five southwestern districts of the Bryansk region, most affected by the Chernobyl NPP accident.Results and discussion. In 2023, the southwestern districts of the Bryansk region included 72 residential settlements (71 rural and the town of Novozybkov) with an average annual effective radiation dose of population exposure above 1 mSv. The total registered population of the settlements is 63,869 people. The share of rural and urban population is 39 and 61 %, respectively. A difficult demographic situation was noted in the populated areas of the Chernobyl accident zone. Thus, the share of persons under working age (0–15 years) does not exceed 17 % of the total population. Social infrastructure demands were assessed to ensure wellbeing of the population in the Bryansk region districts, most affected by the Chernobyl NPP accident.Conclusion. In the rural settlements where the population is exposed to an average annual effective radiation dose above 1 mS, assessment and audit of the existing social infrastructure is required with follow-up efforts to eliminate the shortages, if any, to comply with modern norms and standards.

Feasibility of new thresholds for coronary artery calcium score using low-tube voltage protocols in postmortem computed tomography1

ObjectiveTo validate whether low tube voltage scans of 100 kilovolt-peak (kVp) and 80 kVp for measuring coronary artery calcium score (CACS) using computed tomography (CT) yield comparable results to the standard protocol of 120 kVp using postmortem CT (PMCT). Materials and MethodsWe obtained scans for cadavers where CAC was observed on PMCT scans. In addition to the standard protocol, tube voltage scans were also obtained under conditions of 100 kVp and 80 kVp. We obtained a newly adapted threshold under low tube voltage and compared them with the standard protocol. ResultsThe CACS was 851±1421 (p=0.99) and 861±1433 (p=0.99) for the 120-kVp and 100-kVp scans, respectively, and 845±1390 (p=0.99) for the 80-kVp scan using the newly adapted threshold. The 120-kVp and 100-kVp scans demonstrated an almost perfect correlation (r=0.99996, p<0.0001). In the Bland–Altman analysis, the 9 5% limits of agreement ranged from -44 to 25. Similarly, the CACS obtained using the adapted threshold for the 80-kVp scan also demonstrated an excellent correlation with the standard 120-kVp scan (r=0.99993, p<0.0001). In the Bland–Altman analysis, the 95 % limits of agreement ranged from -62 to 75. The effective radiation dose was 2.21±0.064 mSv (p<0.0001) for the 120-kVp scan, 1.35±0.070 mSv (p<0.0001) for the 100-kVp scan, and 0.72±0.48 mSv (p<0.0001) for the 80-kVp scan. ConclusionThis study suggests that PMCT can be used to measure CACS at low tube voltages and that significant dose reductions in patients can be expected in clinical practice.

Assessing radiation doses and proposing DRLs for nuclear medicine procedures for pediatric and adult patients in Madinah, Saudi Arabia

BackgroundNuclear medicine diagnostic and treatment procedures represent significant sources of ionizing radiation exposure for both staff and patients. Consequently, assessing and optimizing radiation doses are crucial to minimize potential side effects. AimThis study seeks to evaluate the effective radiation doses associated with common diagnostic and treatment procedures, as well as propose diagnostic reference levels (DRLs), within two nuclear medicine centers in Madinah, Saudi Arabia. MethodologyData from 445 patients were gathered from two nuclear medicine centers in the Madinah region of Saudi Arabia. The data were categorized based on the type of nuclear medicine (NM) procedure, the chemical composition of the administered radiopharmaceutical, as well as patient age and weight. Effective radiation doses for prevalent NM procedures were computed, and suggested DRLs were formulated. ResultsEffective radiation doses were analyzed for 16 adult and 2 pediatric NM procedures (divided into 8 groups). The effective radiation doses for adult diagnostic nuclear medicine procedures range from 0.05 mSv (Nanocoloid) to 29 mSv (67Ga-citrate). For pediatric procedures, the doses range from 0.80 mSv (5-year-old undergoing renal DTPA) to 1.6 mSv (1-year-old undergoing renal DMSA). Furthermore, DRL values were determined for both adult and pediatric NM procedures. The study's findings demonstrated a high degree of concordance between effective radiation doses and DRL values, aligning well with previously published research. ConclusionWhile the effective radiation doses outlined in this study were generally within acceptable limits and consistent with prior research findings, optimizing radiation doses remains imperative, particularly for pediatric NM procedures.

Светодиодное ультрафиолетовое облучение семян декоративных растений

The article presents studies on determining the effective dose of ultraviolet irradiation when processing seeds of ornamental plants in a compact unit. A promising branch of plant grow-ing is ornamental gardening, since ornamental plants are widely used in landscaping of populated areas. In ornamental gardening, western thuja and prickly spruce are used, which reproduce by seeds. Among all the methods of seed treatment before sowing, we give preference to LED ul-traviolet irradiation (UVR), as the simplest, energy-saving, energy-efficient, environmentally friendly method. The purpose of the study is to determine the effective dose of UV irradiation of seeds of ornamental plants prickly spruce (Picea pungens Engelm) and western thuja (Thuja occi-dentalis L) to increase the germination energy and seed viability. The experiment on UFO of seeds was carried out on a compact UV LED setup with an irradiance of 17.16 W/m2 and only in the UFO-A zone (315...400 nm). The experiment was repeated four times. Each experiment in-cluded 100 seeds. The highest germination energy and maximum seed germination of prickly spruce are observed at a UFO dose of 9.9 kJ/m2 (tfact.=4.71&gt; ttable.=2.57 at P = 0.05). The highest values of germination energy and germination in western thuja occur at a UFO dose of 2.2 kJ/m2. UFO is a good stimulator of growth processes. This method is economically advanta-geous compared to traditional chemical stimulation of seeds, energy-efficient, and environmen-tally friendly because it does not pollute the soil. Keywords: LED IRRADIATION OF SEEDS, ORNAMENTAL GARDENING, THUJA OCCIDENTAL-IS, PRICKLY SPRUCE, ENERGY SAVING, ULTRAVIOLET, PRE-SOWING SEED TREATMENT

Diagnostic performance of digital tomosynthesis for postoperative assessment of acetabular fractures and pelvic ring injuries.

Digital tomosynthesis (DTS) has broad non-orthopaedic applications and has seen limited use within orthopaedics for imaging of the wrist. The utility of DTS for assessing reduction and hardware placement following operative treatment of pelvic ring injuries and acetabular fractures has not previously been investigated. All operatively treated acetabular fractures and pelvic ring injuries that underwent surgical fixation within a one-year time span received both a computed tomography (CT) scan and a DTS scan as part of their routine postoperative imaging workup. Three orthopaedic traumatologists independently reviewed the images for face-value clinical utility. Radimetrics and PCXMC software were utilized on a subset of the study population's DTS and CT studies to calculate the effective and organ radiation doses delivered. 52 patients (22 acetabular fractures, 22 pelvic ring injuries, 7 pelvic ring and acetabular fractures, 2 femoral head & acetabular fractures) were included. DTS was considered adequate to assess reduction 83% of the time, hardware position 83% of the time, and sufficient to replace the CT scan 67% of the time. DTS was associated with an 8.3 times lower effective radiation dose than CT. All organ doses were lower for DTS than CT. DTS appears to have face-value clinical utility for assessing reduction and hardware position following surgical treatment of acetabular fractures and pelvic ring injuries. Given that DTS is associated with significantly lower radiation doses to patients, further study utilizing more objective criteria is warranted.

Theranostic Potential of the iPSMA-Bombesin Radioligand in Patients with Metastatic Prostate Cancer: A Pilot Study.

Background/Objectives: Prostate cancer (PC) represents the second most diagnosed form of cancer in men on a global scale. Despite the theranostic efficacy of prostate-specific membrane antigen (PSMA) radioligands, there is a spectrum of PC disease in which PSMA expression is low or absent. The gastrin-releasing peptide receptor (GRPR), also known as the bombesin type 2 receptor, has been identified as a target in both the early and advanced stages of PC. The objective of this study was to prepare and preclinically evaluate [99mTc]Tc-iPSMA-Bombesin ([99mTc]Tc-iPSMA-BN), estimate dosimetry in healthy subjects, and assess the diagnostic efficacy of the radiotracer in patients with metastatic PC, with the hypothesis of non-inferiority to one of the gold standards, [18F]-PSMA-1007. Moreover, the potential of [99mTc]Tc-iPSMA-BN as a theranostic pair with [177Lu]Lu-iPSMA-BN was investigated. Methods: [99mTc]Tc-iPSMA-BN was prepared under GMP conditions with radiochemical purities > 95%, showing specific recognition by PSMA and GRP receptors in prostate cancer cells and mice bearing PC tumors. Six healthy volunteers were enrolled, and [99mTc]Tc-iPSMA-BN SPECT/CT imaging (740 MBq) was performed to estimate the dosimetry. The pilot clinical study included seven mCRPC and four mCSPC patients with prior androgen deprivation therapy. All patients had a recent [18F]-PSMA-PET/CT scan and were enrolled in this prospective study on their own signed behalf. Volumetric lesion target-to-background ratios (TBRs) were obtained from PET/CT and SPECT/CT images. Results: [99mTc]Tc-iPSMA-BN effective radiation dose was 1.94 ± 0.39 mSv/740 MBq. A total of 178 lesions were detected via CT, 162 via [18F]-PSMA-1007 PET, and 155 via [99mTc]Tc-iPSMA-BN SPECT. Three patients with mCRPC had higher TBR values on SPECT than on PET. [99mTc]Tc-iPSMA-BN appears to have better lesion detection in patients with aggressive histologic transformation. Two-way ANOVA analysis revealed a significant difference in TBR values between patients with mCRPC and mCSPC (p < 0.05) but no difference between [18F]-PSMA-1007 and [99mTc]Tc-iPSMA-BN (p > 0.05). In one patient, [177Lu]Lu-iPSMA-BN showed a high correlation with [99mTc]Tc-iPSMA-BN for lesions that concentrated radioactivity. Conclusions: [99mTc]Tc-iPSMA-BN SPECT/CT is a promising alternative not only for diagnostic purposes but also for broadening the spectrum of PC patients who may benefit from radionuclide theranostics. The results justify the development of a clinical trial involving a significant number of patients with PC.

Genetic variability increase by gamma irradiation of soybean seeds

The increase of genetic variability by the appearance of new genes of agronomic interest may be favored by the use of gamma radiation. The objective of this study was to evaluate different doses of gamma irradiation on dry seeds of VX04-5692 soybean line, aiming to increase the genetic variability and, with this, the identification of possible mutant plants. The doses of 0, 50, 150 and 250 Gy of gamma radiation were applied from a60Co source. The newly irradiated seeds were sown in the field, giving rise to the M1 cycle. Selected plants originated the M2 cycle. The number of seedlings was counted on the 21st day after sowing. Ten plants of each row were identified and evaluated for the various agronomic characteristics and for chemical composition. The data were submitted to analysis of variance. The F test was applied and the results were presented by boxplots and biplot (canonical variables). There was effect of gamma radiation doses at plant height at full bloom and maturity, number of nodes, pods with one seed and seeds per pod. The use of gamma radiation increases the variability in soybean, with consequent increase in the probabilities of identification of new mutants and gains in the chemical composition, useful for breeding programs that aim at better agronomic performance and gains in oil and protein contents. More satisfactory results in the generation of variability are obtained by the application of gamma radiation on soybean dry seeds between 50 and 150 Gy.

Estimation of the Effective Radiation Dose in Nuclear Medicine Workers from Dhaka by Measuring Radioactivity in Urine Sample Resulting from Internal Exposure

This study estimates the effective doses and activity concentration from 151 urine samples which are collected from 15 (Fifteen) occupational workers at National Institute of Nuclear Medicine and Allied Science (NINMAS) in Dhaka, Bangladesh. The radioactivity concentration in urine sample is due to intake of I-131, Tc-99m and F-18. The samples have been analyzed using High Purity Germanium (HPGe) detector. The radioactivity of I-131 and Tc-99m was found 0.91 ± 0.26 BqL-1 to 504.49 ± 6.03 BqL-1 and 0.15 ± 0.21 BqL-1 to 191.19 ± 6.98 BqL-1 respectively. Radioactivity of F-18 was found from 0.031 ± 0.022 BqL-1 to 0.282 ± 0.065 BqL-1. The effective doses of occupational workers have been also calculated using the radioactivity concentration and the dose coefficient according to ICRP publication 78. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 64−80

One pot gamma radiation mediated interfacial engineering of P-N synergistic flame retardant and antibacterial cellulose fabric: novel fabrics for future applications

The work describes an ionizing radiation mediated, toxic solvent free interfacial engineering of a novel Phosphorus-Nitrogen functionalized bifunctional cotton cellulose fabric (BCF) endowed with flame retardant (FR) and antibacterial properties. Monomers bis[2-(methacryloyloxy)ethyl] phosphate (B2MEP) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETC) in different proportions were co-grafted onto cellulose fabric via 60Co radiation mediated Simultaneous Irradiation Grafting Process (SIGP) to incorporate Phosphorus and Nitrogen functionalities. Effects of radiation dose, monomer concentration on the grafting yield (GY) were investigated and samples were characterized using TGA, ATR-FTIR, XRD, SEM–EDX, EDXRF, CHN Elemental Analysis and XPS analytical techniques. Limiting oxygen index (IS:13501/ASTM D 2863) and vertical flammability tests (IS11871-1986) were conducted to establish the halogen free, P-N synergistic FR properties of the fabric. All the co-grafted samples were observed to possess LOI values in excess of 30%, while BCF (1:2) (GY = ~ 44%) demonstrated LOI of 32% with the least char length of 74 mm in the vertical flammability tests. Tear strength studies were carried out as per ASTMD 1424-09. Antibacterial assay revealed that the fabric possessed activity against both gram positive (S. aureus) and gram negative (E. coli) organisms, with BCF (1:4) (GY = ~ 48%) demonstrating complete killing of ~ 5 log cycles for both microorganisms in 24 h. BCF retained its FR and antibacterial properties even after multiple washing cycles. With its bonafide green credentials, durability and unique properties, multifunctional BCF fabric prepared under optimized conditions of P/N ratio > 1.7 and GY ~ 45% can be a potential candidate for future applications.

Importance of Ultraviolet-C (UV-C) Emitter Configuration for the Attenuation of Staphylococcus aureus and Candida auris Pathogens.

The relative importance of different ultraviolet-C (UV-C) emitter configurations on the attenuation of vegetative bacterial and fungal pathogens has not been assessed. We hypothesized that emitter configuration would impact the efficacy of UV-C attenuation of Staphylococcus aureus ( S. aureus) and Candida auris (C. auris) pathogens. American Type Culture Collection (ATCC) S. aureus (ATCC 6538) and C. auris (ATCC MYA-5001) carriers (ReadyNowTM Test Carriers, Stratix Labs Corporation, Saint Paul, MN) were mounted on an aluminum stand along with three calibrated radiometers (International Light Technologies model ILT1270, Peabody, MA). Five UV-C emitter configurations were assessed, including three emitters with a triangular configuration about the stand and each rotating 360° (1), one emitter facing the stand and rotating 360° (2), three emitters facing the stand in a linear configuration and each rotating 5° (3), one emitter facing the stand and rotating 5° (4), and one emitter facing the stand and rotating 90° (5). Three serial experiments were conducted. The first experiment involved the establishment of the minimally effective irradiation dose (mean and standard deviation mJ/cm2) required to achieve no growth (6-log reduction (LR)) with direct exposure to pathogen carriers positioned at the center of the lamp. We then assessed the relative efficacy of delivery of the minimally effective dose via the five emitter configurations in attenuating polycarbonate and textured pathogen carriers. Polycarbonate carriers were positioned at 25.5 and 69.5 inches from the floor and oriented vertically to the emitters. Textured plastic pathogen carriers were positioned at 47.5 or 58.5 inches from the floor and with a 45° or horizontal orientation to the emitters. Standard carriers (1"x0.9") were used for both pathogens and large carriers (1"x3") for C. auris,the latter to address the potential for cell clustering. With standard carriers, the minimally effective dose was 27.01± 0.15 mJ/cm2 for S. aureus but was not achieved for C. auris. The minimally effective dose for large C. auris carriers was 596.62 ± 27.98 mJ/cm2. With standard carriers, all configurations achieved a >6 log reduction for S. aureus, and none achieved a >6 log reduction for C. auris.All configurations achieved a > 6 log reduction when 596.62 ± 27.98 mJ/cm2 was delivered to large C. auris carriers. Changing to textured plastic carriers (standard for S. aureus and large for C. auris) and varying height (47.5-69.5 inches) from the floor and orientation to the emitters (45° and horizontal), the mean ± standard deviation for S. aureus and C. auris log reductions with delivery of the minimally effective dose was 4.44 ± 2.02, 2.58 ± 2.37, 3.55 ± 2.67, 2.33 ± 2.47, and 3.00 ± 2.64 for configurations one through five, respectively. Configuration one achieved a significantly greater LR than configurations two (adjusted P = 0.0018) and four (adjusted P = 0.023). There were 22% (6/27) of sites ≥ 100 colony-forming units (CFU) following cleaning but before UV-C vs. 0% (0/27) of sites ≥ 100 CFU after surface disinfection cleaning and nine minutes of configuration three UV-C treatment (P = 0.023). The choice of UV-C emitter configuration can impact S. aureus and C. auris attenuation when there is indirect exposure to the pathogen. Emitter configuration should be considered as an important parameter for future UV-C technological assessments.

Importance of Ultraviolet-C (UV-C) Emitter Configuration for Clostridioides difficile Attenuation.

The impact of ultraviolet-C (UV-C) emitter configuration on pathogen attenuation has not been assessed. We hypothesized that emitter configuration would impact UV-C efficacy forClostridioides difficile(C. difficile) attenuation. C. difficilecarriers(ReadyNowTM Test Carriers, Stratix Labs Corporation, Saint Paul, MN) inoculated with > 108 C. difficile American Type Culture Collection (ATCC) 43593 (according to American Society for Testing and Materials (ASTM) 3135 standards) were obtained, and the following experiments were conducted from April to August of 2023. Each of the three carriers along with three calibrated radiometers (ILT1270, International Light Technologies, Peabody, MA) were mounted on an aluminum stand at positions A (left of center of stand), B (center of stand), and C (right of center of stand). The stand was positioned at 9 feet (2.74 m) from and directly ahead of UV-C emitters utilizing low-pressure mercury gas UV-C lamps (Surfacide, Waukesha, WI). Five UV-C emitter configurations were assessed; (1) three emitters with a triangular configuration about the stand and each rotating 360 degrees, (2) one emitter facing the stand and rotating 360 degrees, (3) three emitters facing the stand in a linear configuration and each rotating 5 degrees, (4) one emitter facing the stand and rotating 5 degrees, and (5) one emitter facing the stand and rotating 90 degrees. Three serial experiments were conducted. The first experiment used a dose titration curve to identify the minimally effective irradiation dose (mean and standard deviation mJ/cm2) to achieve no growth (6-log reduction) in C. difficile counts with direct irradiation exposure. The second experiment involved assessing the relative efficacy of the five emitter configurations with the use of the minimally effective dose in attenuating polycarbonate C. difficile carrierspositionedat 25.5 and 69.5 inches (64.77 to 176.53 cm) from the floor and oriented vertically to the emitters. The third experiment evaluated the relative efficacy of the five configurations for polycarbonate and textured plastic C. difficile carriers positioned at 25.5 or 58.5 inches (64.77 to 148.59 cm) from the floor and with a 45-degree or horizontal orientation to the emitters. We assessed residual anaerobic bacterial contamination for three intensive care unit (ICU) rooms to ascertain clinical applications of study results. The minimally effective dose for polycarbonate C. difficile carriers with direct exposurewas 432.28 ± 2.12 mJ/cm2. Configurations one through five achieveda > 4-log reduction when the minimally effective dose was delivered to polycarbonate C. difficile carriers that were positioned at 9 feet from the emitters, 25.5 or 69.5 inches from the floor, and with vertical orientation to the emitters. When C. difficile carriers were changed to textured plastic, orientation to the emitters was changed to horizontal or 45 degrees, and height from the floor was changed to 25.5 and 58.5 inches, the log reductions achieved by configuration one through five were 1.61, 0.61, 0.79, 1.15, and 0.98, respectively, with configuration one achieving a greater log reduction than two (P = 0.0137).In each of the three ICU rooms,at least one of nine sampled locations returned ≥ 500 anaerobic CFU, indicating the need for at least a 0.7-log reduction (500 to 99 CFU). UV-C emitter configuration impacts efficacy in attenuating C. difficile.

Analysis of forest fire dangers of the Bryansk region in the zones of radioactive contamination and beyond

The purpose of the study is to analyze the forest fire dangers of the Bryansk region forests, taking into account their radioactive contamination and potential risks for forestry workers involved in forest fires extinguishing. Significant areas of radioactive contamination of forests with a predominance of sites belonging to the classes of high and very high natural fire danger, restrictions on economic activity and a long fire-hazardous period contribute to the occurrence of radioactive forest fires. The analysis of the combined data on forest fires and radioactive contamination of forest areas showed that most forest fires occur outside the zones of radioactive contamination and are not radioactive. The largest number of fires occurs at the beginning of the fire season. Radioactive forest fires in most cases arise from the burning of dry grassy vegetation, as a result of the transition from lands of other categories and through the fault of the population. The average effective dose of additional radiation per a workday can be estimated at 1.96 μSv, and the maximum at ~ 15.4 μSv. Most fires are extinguished in the early stages and do not have time to cover large areas. It indicates the effective work of the forest fire service

8136 Using High-Resolution Peripheral Quantitative Computed Tomography to Assess Bone Microarchitecture and Guide Osteoporosis Treatment

Abstract Disclosure: S.V. Rupani: None. J. Sfeir: None. L. Graeff-Armas: None. Bone microarchitecture is an important factor that impacts bone strength. Unlike other factors that affect bone strength, such as bone mineral density and bone turnover, assessment of bone microarchitecture is not yet widely accessible in clinical practice. Computed tomography is the primary method of non-invasively assessing bone microarchitecture. High-resolution peripheral quantitative CT (HR-pQCT) is an emerging imaging modality that provides a three-dimensional assessment of bone densitometry, morphometry, and microarchitecture with a low effective radiation dose. It provides a quantitative and qualitative assessment of cortical and trabecular structural and mechanical properties. We present two similar cases of osteoporosis in males, where knowledge of bone microarchitecture through HR-pQCT helped formulate two distinct and targeted therapeutic approaches. The first case is of a 46-year-old male with a history of idiopathic osteoporosis with multiple nontraumatic vertebral fractures. Given his presentation and age, anabolic therapy such as teriparatide was being considered. He underwent HR-pQCT scanning, which showed average radial trabecular parameters, but his cortical porosity was significantly above average, with similar findings in his tibial parameters. Since teriparatide has been shown to increase cortical porosity, this would not be the best option for our patient, given the risk of further weakening of the microarchitecture of his cortical bone. Therefore, denosumab, which has been shown to decrease cortical porosity, was chosen. Our second patient is a 52-year-old male with idiopathic osteoporosis with multiple nontraumatic vertebral fractures, whose HR-pQCT showed average cortical parameters at both the radius and tibia but low trabecular number and increased trabecular separation at both sites. Since teriparatide increases trabecular thickness and mass, we could confidently choose teriparatide for this patient, with less concern for significant deleterious effects on his cortical bone parameters. These case reports highlight the impact that the assessment of qualitative properties of bone, such as microarchitecture, can have in the management of osteoporosis. Currently, the lack of sufficient validated normative data for HR-pQCT limits its widespread use in the diagnosis of osteoporosis and fracture prediction. However, given that HR-pQCT can characterize the properties of trabecular and cortical bone, it may have a role in helping guide osteoporosis treatment, especially in challenging and atypical cases. Presentation: 6/3/2024

Radiation dose to health care workers measured by thermoluminescent dosimetry

To evaluate radiation dose among physicians, nurses, nuclear medicine (NM) technicians, and radiographers at a single institution and to compare the difference in the measured dose during COVID-19 with other periods. A retrospective analysis of the occupational radiation doses received by all workers in diagnostic radiography and NM departments at a single institution during a 5-year period (2018-2022) was performed. Dose measurements were recorded for 94 radiology personnel: radiographers, NM technicians, physicians, and nurses. In addition to descriptive statistics, the Mann-Whitney U-test was used to compare the average annual effective dose between male and female workers and between the periods before and during COVID-19. Kruskal-Wallis test was used to compare effective radiation doses from different quadrants. The annual average effective doses were found to be between 0.58 and 0.72 mSv for males and 0.68 and 0.85 mSv for females. All radiographers, 86% of nurses, and 69% of physicians have received annual average effective doses below 0.99 mSv. The average annual effective doses for all radiation workers were similar in the period before COVID-19 when compared to the period during COVID-19 except for nurses who had significantly lower (P<0.05) doses before COVID-19. The average annual effective doses of radiation workers during 2018-2022 were well below the annual dose limit. A relatively higher average effective dose was received among NM technicians compared with other radiation occupational workers. While the caseload during the COVID-19 pandemic was lower due to government policies, the radiation dose to healthcare workers during the pandemic was similar to that before the pandemic.

Multimodal Photoacoustic/Elastography Imaging for the Detection of Acute Radiation Dermatitis in Breast Radiation Therapy

Purpose: This study evaluates whether photoacoustic (PA), sound touch elastography (STE), and viscoelasticity (VE) can distinguish between normal and abnormal post-radiotherapy breast skin and compare these methods with RTOG criteria at a 20 Gy threshold. Methods: Patients meeting inclusion and exclusion criteria underwent PA, STE, and VE on the same day. Collected data included radiation dose, molecular type, RTOG, Fitzpatrick skin type, pathology, neoadjuvant chemotherapy status, TNM classification, surgical procedures, primary breast cancer location, BMI, and age. A sample of 41 patients was determined using a two-sample t-test. Statistical tools like T-tests, variance analysis, rank sum tests, and chi-square tests, along with random forest analysis and ROC curves, were used to evaluate the radiation dose effects. Results: Data from 66 patients showed significant differences in parameters such as dermis and subcutaneous tissue oxygen saturation, dermal thickness, and skin elasticity (p-values < 0.05). However, minimum values of oxygen saturation and some photoacoustic measures were not significantly different. Notably, at a 20 Gy radiation threshold, significant variations in oxygen saturation, abnormal dermal thickness, and skin STE and VE were observed, proving more accurate than RTOG grading. Conclusion: The study confirms the effectiveness of PA and elastography imaging in differentiating normal from abnormal breast tissue and assessing radiation-induced changes, highlighting the potential of these imaging techniques.

Application value of individualized tube voltage, contrast injection, and adaptive statistical iterative reconstruction V algorithm based on body mass index in renal computed tomography angiography for radiation and iodinated contrast dose reduction.

To explore the application value of body mass index (BMI)-based kilovoltage peak (kVp) selection and contrast injection protocol combined with different adaptive statistical iterative reconstruction V (ASIR-V) strengths in renal computed tomography angiography (CTA) in reducing radiation and contrast medium (CM) doses. One-hundred renal CTA patients were prospectively enrolled and were divided into individualized kVp group (group A, n = 50) and conventional 100kVp group (group B, n = 50), both with automatic tube current modulation and CM of Iohexol at 350mgI/mL concentration. Group A: 70kVp, noise index (NI) of 18 and CM dose rate of 17mgI/kg/s for 10 s for BMI <25kg/m2 patients; 80kVp, NI = 17, and CM dose rate of 19mgI/kg/s for 10 s for 25 kg/m2≤BMI≤30kg/m2 patients. Group B: 100kVp, 50 mL of CM at the flow rate of 4.5 mL/s. The objective image quality, effective radiation dose, CM dose, injection rate, and image quality were compared between the 2 groups. There was no significant difference in patient characteristics between the 2 groups (P > .05). Compared to group B, group A significantly reduced effective radiation dose by 28.4%, CM dose by 27.2%, and injection rate by 22.7% (all P < .001). The 2 groups had similar SD values in erector spine (P > .05). Group A had significantly higher CT values, SNR, and CNR values of the renal arteries than group B (all P < .001). The 2 radiologists had excellent agreement (Kappa value > 0.8) in the subjective scores of renal CTA images and showed no statistically significant difference between the 2 groups (4.57 ± 0.42 vs 4.41 ± 0.49) (P > .05). BMI-based scan and reconstruction protocol in renal CTA significantly reduces radiation and contrast doses while maintaining diagnostic image quality. (i) BMI-based individualized tube voltage selection and contrast injection protocol in renal CTA reduces both radiation and contrast doses over conventional protocol. (ii) The combination of lower kVp and higher weight ASIR-V maybe used to improve image quality in terms of contrast enhancement and image noise under lower radiation and contrast dose conditions. (iii) Renal CTA of normal size (BMI ≤ 30kg/m2) patients acquired at low radiation dosage and low iodine contrast dose through the combination of low tube voltage and ASIR-V algorithm achieves excellent diagnostic image quality with a good inter-rater agreement.

Deep learning-based reconstruction improves the image quality of low-dose CT enterography in patients with inflammatory bowel disease.

Lifelong re-examination of CT enterography (CTE) in patients with inflammatory bowel disease (IBD) may be necessary, and reducing radiation exposure during CT examinations is crucial. We investigated the potential application of deep learning reconstruction (DLR) in CTE to reduce radiation dose and improve image quality in IBD. Thirty-six patients with known or suspected IBD were prospectively recruited to the low-dose CTE (LDCTE) group, while forty patients were retrospectively selected from previous clinical standard-dose CTE (STDCTE) scans as controls. STDCTE images were reconstructed with hybrid-IR (adaptive iterative dose reduction 3-dimensional [AIDR3D], standard setting); LDCTE images were reconstructed with AIDR3D and DLR (Advanced Intelligence ClearIQ Engine [AiCE], Body mild/standard/strong, Sharp Body mild/standard/strong setting). The effective radiation dose (ED), image noise, signal-to-noise ratio (SNR), overall image quality, subjective image noise, and diagnostic effectiveness were compared between the LDCTE and STDCTE groups. Compared with STDCTE, the ED of LDCTE was lower by 54.1% (p<0.001). Compared with STDCTE-AIDR3D, LDCTE-AIDR3D reconstruction objective image noise and SNR were greater (p<0.05), the subjective overall image quality was lower (p<0.05), and the diagnostic efficiency was lower (AUC=0.52, p<0.05). The SNRs of reconstructedimages of LDCTE-AiCE Body Strong and LDCTE-AiCE Body Sharp standard/strong groups were greater than that of STDCTE-AIDR3D group (all p<0.05), and the diagnostic performance was better than or comparable to that of STDCTE; the AUCs were 0.83, 0.76 and 0.76, respectively CONCLUSION: Compared with STDCTE with AIDR3D, LDCTE with DLR effectively reduced the radiation dose and improve image quality in IBD patients.