Air Kerma Research Articles

Abstract 4140163: Initial Experience with Mini-Crush Versus Double Kissing Crush in Bifurcation Percutaneous Coronary Intervention: Insights from PROGRESS-BIFURCATION registry

Background: There is limited data on use of the mini-crush technique in two-stent bifurcation percutaneous coronary intervention (PCI). Methods: This retrospective, observational, cohort study was performed across 6 centers in the United States, Russia, and Turkey between 2013-2024, as part of the Prospective Global Registry of Percutaneous Coronary Intervention in Bifurcation Lesions (PROGRESS-BIFURCATION, NCT05100992). We evaluated procedural characteristics of patients who underwent bifurcation stenting using the mini-crush technique and compared it with those who were treated with double kissing (DK) crush. Results: Of 1,138 PCIs involving 1,499 lesions, 46 (4.04%) were performed using the mini-crush technique and 147 lesions (12.91%) using the DK crush technique. Baseline characteristics of the patients were similar in both groups. There was no difference between mini-crush versus DK-crush in technical success (100.0% versus 98.6%; p=0.99), procedural success (95.1% versus 97.1%, p=0.62), procedural complications (10.9% versus 14.7%, p=0.51), or in-hospital major adverse cardiovascular events (MACE) (6.5% versus 5.7%, p=0.73). In contrast, mini-crush technique was associated with shorter procedure time (79.00 vs 116.50 minutes; p<0.001; Figure 1A), fluoroscopy time (23.50 vs 30.35 minutes, p=0.002; Figure 1A), and lower contrast volume (150 versus 109 milliliters; p<0.001; Figure 1B), and air kerma radiation dose (1.11 vs 1.71 gray; p=0.024; Figure 1C). Conclusion: In patients undergoing PCI for bifurcation lesions, the mini-crush technique had similar rates of procedural complications and in-hospital MACE as compared with the DK crush technique but required less contrast volume, fluoroscopy time, radiation dose, and procedural time.

Abstract 4141480: Gender differences in bifurcation percutaneous coronary interventions: Update from the Prospective Global Registry for the Study of Bifurcation Lesion Interventions (PROGRESS-BIFURCATION)

Background: Gender differences on short and long-term outcomes following bifurcation percutaneous coronary intervention (PCI) have received limited study. Research Questions: To examine gender differences in outcomes of bifurcation PCI. Methods: We examined the angiographic, procedural characteristics, and outcomes of 1084 bifurcation PCIs (1076 patients) performed at five centers between 2013-2024 from the Prospective Global Registry for the Study of Bifurcation Lesion Interventions (PROGRESS-BIFURCATION). Results: Women represented 25.19% of the entire study population. They were older (68.37±12.34 vs 66.09±11.54; p=0.001), less likely to be currently smokers (13.7% vs 20.4%; p=0.014), with higher left ventricular ejection fraction (%) (55.46±13.27 vs 53.16±12.55; p<0.001) and lower baseline creatinine (0.85 vs 1.00; p<0.001). Lesion characteristics were mostly similar, with slightly lower proximal and distal main vessel diameter in women. Their proximal main vessel was more likely to be left anterior descending artery (46.5% vs 39.4%; p=0.030) and less likely to be right coronary artery (10.3% vs 16.1%; p=0.030), compared to men. Technical success was similar (94.5% vs 94.6%; p=0.952), while procedural success was lower (89.6% vs 94.1%; p=0.011). In-hospital major adverse cardiac events (MACE) were more common in women (8.5% vs 4.2%; p=0.007), which presented with increased in-hospital mortality (4.1% vs 0.6%; p<0.001), stroke (1.8% vs 0.1%; p=0.005) and bleeding (1.8% vs 0.2%; p=0.013). Their PCIs required equal procedure time, but lower fluoroscopy time, contrast volume and air kerma radiation dose. Female gender was independently associated with higher in-hospital major adverse cardiac events (MACE) (odds ratio (OR) 2.21; 95%CI 1.23-3.95; p=0.008) and lower procedural success (OR 0.56; 95%CI 0.32-1.00; p=0.044). Follow-up data were available for 733 patients (68.12%). The incidence of follow-up MACE was significantly higher in women (hazard ratio (HR) 1.36; 95%CI 1.02-1.81; p=0.038), while on adjusted mixed Cox proportional hazards analysis female gender was associated with higher follow-up MACE (HR 1.58; 95%CI 1.08-2.30; p=0.018). The incidence of follow-up mortality was similar between genders (HR 1.17; 95%CI 0.78-1.77; p=0.45). Conclusions: Bifurcation PCI can be accomplished with high technical success in women, but higher in-hospital and follow-up MACE, compared to men.

OPTIMIZATION OF EXPOSURE FACTORS WITH VARIATION OF FILTER THICKNESS ON DOSE VALUES AND RADIOGRAPHIC IMAGE QUALITY IN PELVIS EXAMINATION

This study examines the impact of varying X-ray tube voltage (kV) and filter thickness on patient radiation dose and image quality in radiographic procedures. It aims to optimize exposure factors to minimize patient dose while maintaining diagnostic image quality, contributing to safer and more efficient radiological practices. This quantitative experimental study investigates the impact of varying filter thickness and tube voltage on patient radiation dose. Using X-ray equipment, dosimeters, and phantoms, measurements of Incident Air Kerma (INAK) and Entrance Surface Air Kerma (ESAK) and effective dose are taken, followed by image quality assessments to optimize exposure factors while maintaining diagnostic efficacy. The study demonstrated that increasing filter thickness decreases both INAK and ESAK values, with the most significant dose reduction occurring at 2 mm thickness. Optimal image quality and effective dose reduction were observed with the 1 mm filter at 80 kV, reducing the dose by 14.3% to 20% while maintaining good spatial resolution and contrast. The study concludes that using a 1 mm aluminum filter with 80 kV significantly reduces the effective dose while maintaining image quality. It is recommended that hospitals adopt additional filters, conduct further research with different materials, and optimize exposure factors. Training for radiology technicians on these practices is essential to enhance patient safety and image quality. Keywords: X-ray Equipment, Entrance Surface Air Kerma, Effective Dose, Image Quality.

DETERMINATION OF DOSE REFERENCE LEVELS AT BENDAN PEKALONGAN REGIONAL HOSPITAL FOR INTERNAL DOSE AUDIT AS AN EFFORT TO OPTIMIZE RADIATION PROTECTION FOR PATIENTS

Unnecessary exposure is less of a concern because it is considered not to cause injury to patients. Radiation protection optimization is carried out for patients to reduce unnecessary exposure. Following BAPETEN Regulation No. 4 of 2020 Article 46, permit holders are required to implement radiation protection optimization [1]. This study aimed to obtain the local dose reference level (TPD) value through an internal dose audit to optimize patient radiation protection. This optimization is carried out in several steps, including conducting an internal dose audit, determining the local TPD, and evaluating the examination. This study is expected to motivate documentation of radiation parameters to obtain sufficient data for analysis. The method used in this study is a literature study through related references and X-ray radiation output data to calculate the dose in the form of incident air kerma (INAK) and entrance surface air kerma (ESAK). The results showed that the local INAK TPD value was 52% below the national TPD, and the local ESAK TPD value was 57% below the national TPD. The expected local TPD value is a TPD value that is lower than the national TPD value. This indicates that the imaging protocol at RSUD Bendan has been well-optimized. However, there are still several types of examinations where the local TPD value exceeds the national TPD, indicating the need to review further the imaging techniques and protocols used. The influence of body weight and radiological image diagnosis was analyzed as a basis for further optimization. Thus, the determination of this local TPD can be an essential reference in efforts to improve patient safety and optimize radiation protection in health facilities. Keywords: radiation protection optimization of patient, Dose Reference Level (DRL), patient dose.

Achieving reduced radiation exposure with maintained fluoroscopy effectiveness using ultralow‐dose settings in cryoballoon ablation

AbstractBackground and AimsOptimization of fluoroscopic image quality for reducing radiation exposure in cryoballoon pulmonary vein isolation (CB‐PVI) has not yet been fully investigated. Therefore, we tried to compare the radiation doses among three different X‐ray system settings.MethodsConsecutive 148 patients scheduled for their first CB‐PVI were prospectively enrolled: low dose with the use of an anti‐scatter grid for the first 51 patients (LD + G group), low dose without an anti‐scatter grid for the subsequent 46 patients (LD‐G group), and ultralow dose (ULD group) with an anti‐scatter grid for the remaining 51 patients. We compared the radiation doses required to complete CB‐PVI procedures among the groups. There were 27 patients for whom CB‐PVI was performed without cine acquisition, but with fluoroscopy only, and the radiation doses were also compared.ResultsThe median procedure time and fluoroscopy time were 119 and 35.5 min, respectively, with no significant differences among the groups. The median cumulative air Kerma (AK) decreased in both the LD‐G group (71.8 mGy, p < .001) and the ULD group (73.0 mGy, p < .001), compared to the LD + G group (145.0 mGy). Among 27 patients who underwent CB‐PVI without cine acquisition, the median cumulative AK further decreased in both the LD‐G group (31.4 mGy, p < .05) and the ULD group (22.7 mGy, p < .01), compared to the LD + G group (64.6 mGy).ConclusionUsing an ULD X‐ray setting and avoiding cine acquisition, we can reduce radiation exposure, while ensuring the necessary fluoroscopy time for the CB‐PVI procedure.

EFFECTIVE DOSE ANALYSIS IN ABDOMEN AP EXAMINATION PATIENTS WITH CALDOSE_X VERSION 5.0

This study evaluates radiation dose exposure during diagnostic radiology procedures using X-rays and their potential risks, including cancer, to optimize radiation safety through the CALDose_X software that calculates the absorbed organ dose, effective dose, and cancer risk, according to the lowest possible achievable (ALARA) principle. This study used a quantitative experimental design to evaluate the impact of filter thickness variations on Entrance Surface Air Kerma (ESAK) and effective dose by analyzing data from 54 patients undergoing AP Abdominal X-ray examinations. The results showed that the effective dose to the abdominal organs varied with exposure factors and Focus to Detector Distance (FDD), where the colon wall had the highest sensitivity with doses ranging from 0.030 mSv to 0.126 mSv, followed by the stomach and pancreas. Increasing kV, mAs, and FDD increased the effective dose, emphasizing the importance of careful dose management. This study concluded that exposure factors and FDD affect the effective dose received by the abdominal organs, with recommendations to monitor patient doses, revise national diagnostic reference levels, and establish standard protocols with health authorities. Keywords: CALDose_X, X-ray Exposure Factor, patient dose, ESAK, Effective Dose, Abdomen AP.

Dual-Fluoroscopy vs. Single-Fluoroscopy in Balloon Kyphoplasty: A Study of Efficiency and Safety.

Background: Vertebral compression fractures (VCFs) are the most prevalent type of osteoporotic fractures, often causing significant pain, morbidity, and mortality. Vertebral augmentation procedures like balloon kyphoplasty (BK) are effective in treating VCFs. These procedures are typically performed using a single fluoroscopy machine (SF) for anteroposterior (AP) and lateral views. We have implemented a dual-fluoroscopy (DF) technique to reduce procedure time and radiation exposure. The goal of this study was to determine whether dual-fluoroscopy could optimize surgical efficiency without compromising safety, offering a more effective alternative to traditional single-fluoroscopy methods. Methods: This retrospective study included 126 patients who underwent BK with either SF (n = 74, 58.7%) or DF (n = 52, 41.3%) between 2020 and 2024. We collected data on procedure duration per pedicle (PDPP), radiation exposure (reference air kerma and dose-area product [DAP]), and radiation duration. A sub-analysis of post-learning phase cases was performed. Results: A learning curve was identified for the first 24 cases and 15 cases using the SF technique and DF technique, respectively, which was followed by a stabilization in procedure duration per pedicle (Levene's statistic = 10.623, p = 0.002 for SD difference, p < 0.001 for mean PDPP difference). After the completion of the learning phase for both techniques, the DF group demonstrated a significantly shorter PDPP (11.83 ± 4.3 vs. 14.03 ± 5.57 min, p = 0.049). No significant differences were found in radiation exposure, including radiation duration (p = 0.577), reference air kerma, or DAP. Conclusions: Dual-fluoroscopy significantly reduces procedure time after the learning curve is overcome, improving efficiency without increasing radiation exposure. This technique holds promise for optimizing kyphoplasty workflow and safety, supporting broader clinical adoption.

Establishment of an absolute measurement of the reference air kerma rate for HDR 192Ir brachytherapy sources

Before this study, no institution in China had undertaken the calculation and official establishment of reference values for the reference air kerma rate associated with high-dose rate 192Ir sources used in brachytherapy. This research, carried out at the National Institute of Metrology (NIM) in China, has successfully established an 192Ir reference radiation facility. Consequently, it has achieved the absolute measurement of the reference air kerma rate for high-dose rate brachytherapy using 192Ir sources. For this study, a medical afterloader machine was acquired. The radiation source employed was a high-dose rate 192Ir source for brachytherapy, produced by HTA Co., Ltd. A reference graphite cavity ionization chamber with a volume of 100 cm3 was designed to serve as the ionization chamber for absolute measurements. The determination of various correction factors and physical constants was achieved through a method that combines Monte Carlo simulations with experimental techniques. The study successfully accomplished the absolute measurement of the reference air kerma rate for the high-dose rate brachytherapy 192Ir radiation source. The expanded uncertainty of the measurement results was 0.72% (k = 2). The relative standard deviation for the RAKR of the same 192Ir radiation source was 0.073%. This study marks a significant advancement in the field of radiation therapy in China, particularly in the accurate dosimetry for brachytherapy using high-dose rate 192Ir sources. The study will contribute to the BIPM.RI(I)-K8 international comparison, organized by the Bureau International des Poids et Mesures (BIPM), thus facilitating the international recognition of the measurement values.

Characterization of X-ray Beams: Determination of K\(_{a,e}\) for Comparison with DRLs

Aims: The aim of this experimental study was to quantify the entrance surface air kerma (Ka,e) of X-ray beams in radiographic examinations, and the obtained values were compared with national and international Diagnostic Reference Levels (DRLs). Place and Duration of Study: Sample: Department of Medical Physics and Radiology, Franciscan University (UFN), between June 2023 and August 2024. Methodology: Initially, the main quality control (QC) tests were applied to characterize the radiographic equipment. During the evaluation of the X-ray beam, a dosimetric set was used, and for the same QC geometry, Air Kerma Rate (KAIR) measurements were obtained to determine the output of the X-ray tube. Under the same conditions, a phantom without water and the same filled with water were used to determine the backscatter factor (BSF), which was then used to estimate the Ka,e for the main radiographic examinations. Results: The results of this study are consistent with other studies and identified the region/anatomy with the highest radiation exposure, highlighting the importance of its optimization and verifying that continued professional training should be integrated into best practices to ensure greater safety in procedures. The results obtained evidence the necessity for adjustments in image acquisition protocols, as the Ka,e values found in this study, although within the limits established by the national DRLs, exceed the reference values of countries such as the United Kingdom and Japan in the areas of the skull, abdomen, and lumbar spine. This discrepancy highlights the importance of the periodic review and update of DRLs, in accordance with international recommendations and the technological evolution of equipment. Dose optimization is an ongoing process that involves the evaluation of image quality, the appropriate selection of technical parameters, and the implementation of specific dose protocols. The continuous training of radiology professionals is essential to ensure the correct application of imaging techniques and the minimization of patient exposure to ionizing radiation. Conclusion: This study shows the importance of evaluating radiation dose in diagnostic imaging and the need for a multidisciplinary approach to dose optimization. Implementing quality assurance programs, updating DRLs, and providing ongoing training for professionals are essential to ensure patient safety and high-quality diagnostic imaging. The methodology adopted in this study can contribute to the ongoing education of radiology professionals, promoting the correct application of imaging techniques and reducing patient exposure to ionizing radiation.

Intravascular Lithotripsy Versus Rotational Atherectomy in Coronary Chronic Total Occlusions: Analysis from the Prospective Global Registry for the Study of Chronic Total Occlusion Intervention Registry

There are limited comparative data on the use of plaque modification devices during chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We compared intravascular lithotripsy (IVL) with rotational atherectomy (RA) for lesion preparation in patients who underwent CTO PCI across 50 US and non-US centers from 2019 to 2024. Of 15,690 patients who underwent CTO PCI during the study period, 436 (2.78%) underwent IVL and 381 (2.45%) RA. Patients treated with IVL had more co-morbidities and more complex CTO lesions. Anterograde wiring was the most used initial and successful crossing strategy for lesions treated with both IVL and RA, although the retrograde approach was more frequently used in IVL cases. Procedure and fluoroscopy times, and air kerma radiation doses and contrast volumes, were greater in patients treated with RA than in those with IVL. There were no significant differences between the groups in technical success (97.2% vs 95.3%, p = 0.20), procedural success (94.7% vs 91.8%, p = 0.14), and in-hospital major adverse cardiac events (MACEs) (3.0% vs 4.2%, p = 0.47). However, coronary artery perforations were more frequent in patients who underwent RA (9.5% vs 3.2%, p <0.001). Multivariable logistic regression analysis revealed that IVL compared with RA was not independently associated with technical success, procedural success, or in-hospital MACE. In patients who undergo CTO PCI, IVL is associated with similar in-hospital MACE, technical success, and procedural success to that of RA but smaller incidence of coronary artery perforation.

Measurement of average mass attenuation coefficient of air for 137Cs gamma-ray irradiation beam

Abstract The average mass attenuation coefficient of air for the KRISS 137Cs gamma-ray irradiation beam was measured using a 30 cm-long vacuum-sealable cylindrical column. Six different models of ionization chambers were employed for the measurement. Under ambient room conditions, the average mass attenuation coefficient was found to be (0.0778 ± 0.0012) cm2 g−1 across the six chambers. This coefficient will be used to adjust the variation in air kerma with air density for the 137Cs gamma-ray irradiation beam.

Comparative Analysis of Transradial and Transfemoral Approaches in Transarterial Radioembolization for Liver Tumors: A Systematic Review and Meta-Analysis.

Transarterial radioembolization (TARE) is a minimally invasive therapy combining embolization and radiation for cancer treatment. This meta-analysis compares radiation exposure, quality of life, and safety of the transradial (TRA) versus transfemoral (TFA) approaches in TARE for liver tumors. We searched PubMed, SCOPUS, Cochrane, EMBASE, and Web of Science for studies comparing TRA versus TFA in TARE for liver tumors. Our primary outcomes focused on various measures of patient radiation exposure, including procedure time, fluoroscopy time, air kerma, and dose-area product (DAP). For secondary outcomes, we evaluated safety parameters, such as overall pain experienced during the procedure, pain in the recovery room post-procedure, the incidence of adverse events, and the impact on quality of life. Study quality was assessed using Cochrane's ROB 2 tool for RCTs and the Newcastle-Ottawa scale for observational studies. Data analysis was conducted with REVMAN 5.4.1 software. Six studies, comprising one RCT and five cohort studies with 1,209 patients, underwent comprehensive analysis. The aggregated findings revealed a significant reduction in procedure duration associated with TRA (MD =- 6.30, 95% CI [- 9.88, - 2.73], P = 0.005). However, no statistically significant differences were found between TRA and TFA groups concerning fluoroscopy time, recovery time, air kerma, DAP, pain in the recovery room, overall pain during the procedure, quality of life measuring mental health and physical function or adverse events. TRA and TFA showed comparable results in TARE for liver tumors, but TRA offered a shorter procedure time. Further RCTs with larger samples are needed to confirm these findings. Future studies should assess long-term efficacy for a more complete evaluation.

Establishment of typical values in cerebral thrombectomy according to the stroke anatomical region and procedure clinical outcome.

The aim of the study is to establish local diagnostic reference levels (DRLs) in cerebral thrombectomy, according to the anatomical region of ischemic stroke. This is a retrospective study from a single center involving 255 examinations. The proposed median values (P50) for thrombectomy are: 123Gy.cm2 for air kerma-area product (PKA) and 915mGy for air kerma (Ka,r). For middle cerebral artery (MCA) thrombectomies, the proposed DRLs are 118Gy.cm2 for PKA and 112Gy.cm2 for internal carotid artery (ICA). The Ka,r values for MCA and ICA are 849 and 775mGy, respectively. It was observed that 94.9% of patients presented grade 0 on the initial modified treatment in cerebral infarction (mTICI) scale, and after thrombectomy, 63.1% of patients reached a final mTICI grade of 3. Stents were implanted in 37 patients (14.5% of cases). It was concluded that 16.1% of patients exceeded one trigger value of the Safety in Radiological Procedures' recommended parameters. Establishing DRLs is an important tool for optimizing practices and is considered a standard for quality control.

Radiation Exposure with Self-Expandable Metallic Stent versus Transanal Decompression Tube for Malignant Colorectal Obstruction: A Post Hoc Propensity Score Matched Analysis.

Background: Although several reports have compared the outcomes of self-expandable metallic stent (SEMSs) and transanal decompression tube (TDT) placement for malignant colorectal obstruction (MCO), few studies have compared the radiation exposure (RE) associated with these two procedures. Consequently, we aimed to compare the RE of SEMS and TDT placements for MCO using propensity score matching (PSM) in a multi-center, prospective observational study. Methods: This study investigated the clinical data of 236 patients who underwent SEMS or TDT placement. The air kerma at the patient entrance reference point (Ka,r: mGy) and air kerma-area product (PKA; Gycm2) were measured and compared between SEMS and TDT groups after PSM. Results: After PSM, 61 patients were identified in each group. The median Ka,r in the SEMS group was significantly greater than that in the TDT group (77.4 vs. 55.6 mGy; p = 0.025) across the entire cohort. With respect to subgroup analyses by location, in the rectum, the median Ka, r and PKA were significantly greater in the SEMS group than in the TDT group (172.9 vs. 34.6 mGy; p = 0.001; and 46.0 vs. 18.1 Gycm2; p = 0.006, respectively). However, in the colon, the RE parameters did not significantly differ between the two groups. Conclusions: TDT might be a more suitable option for decompression in patients with malignant rectal obstruction due to its lower RE and technical advantages. Conversely, SEMS placement is recommended as the first decompression method to treat malignant colonic obstruction, in line with the current guidelines.

Institutional Variation in Patient Radiation Doses During Transcatheter Valve Interventions: A Statewide Experience

BackgroundLittle is known about institutional radiation doses during transcatheter valve interventions. ObjectivesThe authors sought to evaluate institutional variability in radiation doses during transcatheter valve interventions. MethodsUsing a large statewide registry, transcatheter edge-to-edge mitral valve repair, transcatheter mitral valve replacement, and transcatheter aortic valve replacement procedures between January 1, 2020, and December 31, 2022, with an air kerma (AK) recorded were analyzed. Patient and procedural characteristics were compared between cases with AK ≥2 and <2 Gy. Associations of variables with AK ≥2 Gy were investigated using Bayesian random effects modeling and median ORs for the performing hospital. ResultsAmong 9,446 procedures across 30 hospitals, median (Q1-Q3) procedural AK was 0.592 Gy (0.348-0.989 Gy) with AK ≥2 Gy in 533 cases (5.6%). Wide variation in procedural AK was observed, with an institutional frequency of AK ≥2 Gy ranging from 0.0% to 29.5%. Bayesian modeling identified the performing hospital as more strongly associated with the odds of a procedural AK ≥2 Gy than any patient or procedural factors (hospital median OR: 3.54 [95% credible interval: 2.52-16.66]). ConclusionsIn a large, multicenter state-wide registry, there is wide institutional variability in patient-level radiation doses during transcatheter valve interventions, with the performing hospital having a higher odds of an AK ≥2 Gy than any patient or procedural factors. Future interventions are warranted to reduce procedural-related variation in radiation exposure.

Development and international multicentre pilot testing of a postal dosimetry audit methodology for high dose rate brachytherapy

Background and PurposeDosimetry audits are essential for reducing errors in brachytherapy. A postal dosimetry audit methodology was developed and tested in an international multicentre pilot, to assess the accuracy of the Reference Air Kerma Rate of 192Ir and 60Co brachytherapy sources Materials and MethodsA compact phantom made of polymethyl methacrylate was developed to accommodate two catheters, a radiophotoluminescence dosimeter (RPLD) for dose measurements and a Gafchromic (RTQA2) film strip for source position verification. Deviations of the audit setup from TG-43 conditions were quantified experimentally and compared to previous Monte Carlo (MC) simulations. A measurement uncertainty budget was estimated for the RPLD analysis. The methodology was tested in an international pilot study consisting of 59 dosimeter sets among 48 centres from 11 countries. ResultsThe experimental correction factors showed good agreement with previous MC simulations, and the total correction factor accounting for non-water equivalence, lack of scatter and beam quality was found to be 1.029 ± 0.009 for 192Ir and 1.059 ± 0.007 for 60Co sources, to be employed in audit measurement. The total uncertainty budget was estimated to be 2.24 % (k = 1). In the multicentre study, the ratio between measured and reported user dose ranged from 0.968 to 1.049, with all irradiated dosimeter sets within ± 5 %, and 54 out of 59 within ± 3 %. ConclusionsThe methodology was tested in an international multicentre pilot study and has shown good performance validating the uncertainty budget.

Measuring Spatial Radiation Dose Distribution During Abdominal Computed Tomography Scanning with Optically Stimulated Luminescence Dosimeters

PurposeAs the proportion of medical radiation exposure increases, the exposure dose has received increasing attention. When performing interventional radiological diagnosis, examiners are often exposed to radiation. Therefore, patients and medical personnel are exposed to higher amounts of radiation dose. Accordingly, we used optically stimulated luminescence dosimeters (OSLDs) to measure the ambient air kerma during abdominal CT scanning to observe the spatial distribution of the doses.MethodsAn abdominal CT scan under a voltage of 120 kVp was performed, and OSLDs were used for the measurement. The measurement range extended from the examination couch that serves as the center point to the walls and was divided into four areas. The OSLD measurements were undertaken at three different heights (i.e., 85, 140, and 150 cm from the floor) for spatial dose detection. The OSLDs were fixed up to lines at the three height levels. Each dosimetry point was 50 cm apart. In addition, the surface incident doses of the prosthesis's mammary gland, liver, and gonad were estimated.ResultsAccording to the spatial dose distribution at the three different heights, the maximum dose and minimum dose in front of the bore were 0.194 ± 0.008 and 0.006 ± 0.001 mGy, respectively; 2 m away from the bore, the dose reduced to 9% of the maximum dose. The surface incident doses of the mammary gland, liver, and gonad were 1.321 ± 0.121, 13.083 ± 0.642, and 13.441 ± 0.658 mGy, respectively.ConclusionThe spatial dose distribution revealed that the dose was the highest at the height of 140 cm and in front of the bore. The dose on the left side was higher than that on the right side. In addition, the dose was inversely proportional to the square of the distance. If the examiners must perform interventional radiological diagnosis during CT scanning, they should put on radiation protection equipment and stand behind the bore to minimize the radiation exposure.

Implementing a Phase II Quality Control Protocol for a High Precision 137Cs Dosimetry Calibration Irradiator.

In medical physics, rigorous quality assurance and quality control protocols are vital for precise dose delivery applications. In many health physics applications, the allowable uncertainty for various processes is often greater than that of medical physics due to looser safety ties. This results in less demand for quality control and uncertainty analyses, since these may not be needed. However, certain applications can benefit from a comprehensive quality control program, as it may yield important insights, such as air kerma monitoring in dosimetry calibrations for environmental and low-dose applications. By implementing a thorough quality control program tailored to specific contexts and needs, uncertainties associated with dose measurements can be quantified with greater accuracy and reliability. This proactive approach not only ensures the integrity of data collected but also enhances understanding of the measured doses. For these reasons, a comprehensive quality control initiative was implemented following documented failures in a 137Cs dosimetry calibration irradiator. This involved systematic charge collection using NIST-traceable ion chambers to observe long-term changes. A Phase I quality control protocol was previously implemented, which employed Shewhart control charts and Nelson's rules to analyze various datasets subgrouped under different conditions. This study addresses the development of a Phase II protocol, which focuses more on uncertainty quantification of systematic errors and irradiator changes, and air kerma precision for dosimetry calibrations. A designed experiment was performed to identify how much systematic errors influence the air kerma. Emphasis was placed on stricter quality assurance protocols, continuous data collection, and additional control charts to monitor short-term changes, such as exponentially weighted moving average control charts. A pre-irradiation control process was implemented to verify that the total air kerma met the measurement quality objective and to show how various uncertainties were applied before calibration. This study indicates how uncertainty is applied given observed air kerma measurements from the irradiator. Ongoing efforts aim to streamline the quality control procedure, ensure consistent data collection, and assess its impact on dosimetry applications.

Simulation of gamma reference field at Institute for Nuclear Science and Technology using Monte Carlo method

This paper presents the characterization of two gamma reference fields of 137Cs and 60Co sources at the Institute for Nuclear Science and Technology. The characterization of the fields in terms of gamma fluence Φ, mean energy, EΦ, kerma weighted mean energies, Eₖ, air kerma, Eair, were determined at various distances from the source center by Monte Carlo simulation using MCNP6. The air kerma results were compared with the measurements obtained by using a calibrated ionization chamber. The discrepancy between the simulated and measured air kerma was less than 4.5%. The scatterred component was also simulated and calculated. The results of both methods showed that the contribution of the scattered components to the gamma reference field is less than 3%. This contribution comply with the international standard criteria of ISO 4037 (&lt;5%). The results confirmed that the characterization of the gamma reference field could be determined using the simulation code.

Methodology study for determining the half-value layer using the Monte Carlo code PHITS

For most purposes, the quality of a beam can be specified in terms of the half-value layer (HVL), which is the thickness of material required to reduce the air kerma to half, at one meter from the source, from a unidirectional beam of infinitesimal width. Just like many other radiological quantities of interest, the HVL can be estimated via simulations employing the Monte Carlo Method (MCM). Among the variety of MCM based codes available, the Particles and Heavy Ions Transport Code System (PHITS) was the one adopted in this study. Primarily, simulations were conducted to determine the X-ray spectra resulting from the interaction of electron beams with different energies with a tungsten anode. Each of these spectra was then defined as a probability distribution for the photon source energies in a second round of simulations, where it was possible to estimate the X-ray beam qualities as specified by the reference literature. At this stage, it was possible to estimate the mean energy of the beam and the conversion coefficient for air kerma per unit fluence for each of the qualities. The results obtained in this phase were used to define the sources for other groups of simulations, where the air kerma was quantified for each source configuration, for different thicknesses of an aluminum metallic attenuator, which was also done with spectra for the same X-ray beam qualities obtained from a reference catalog. Curve fitting on the scatter of kerma points as a function of attenuation allowed the estimation of the HVL. The results obtained are consistent with the values described in the literature and demonstrate the efficiency of the developed methodology, as well as the use of the code in the evaluated energy range for X-rays.