APMP key comparison report of air kerma for 137Cs (APMP.RI(I)-K5)

Main text The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K5 key comparison of the air kerma for 137Cs in 2014. Five national metrology institutes (NMIs) took part in the comparison. Two commercial ionization chambers were used as transfer instruments and circulated among the participants. The results showed that the maximum difference between the participants and the Bureau International des Poids et Mesures, evaluated using the comparison data of the linking laboratories of the Korea Research Institute of Standards and Science and the National Metrology Institute of Japan, was less than 0.5% within the expanded uncertainty. This comparison supports the equivalence of the calibration capabilities of the participating laboratories. The results predate the publication of ICRU report 90, therefore, the revision of the data reflecting the effects of the ICRU report 90 on the degrees of equivalences of the participant laboratories is presented in Appendix C. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the NRC, Canada and the BIPM in 60Co gamma radiation

Main text A new key comparison of the standards for air kerma of the National Research Council of Canada (NRC), Canada and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in October 2020. The comparison result, based on the calibration coefficients for three transfer chambers and expressed as a ratio of the NRC and the BIPM standards for air kerma, is 1.0022 with a combined standard uncertainty of 2.2 parts in 103. The result agrees within the uncertainties with the indirect comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Radiation exposure in 101 non-coronary fluoroscopically guided interventional procedures: reference levels of air kerma at the reference point and air kerma-area product

Objectives: To present the median value and 75th percentile of air kerma at the reference point (Ka,r), air kerma-area product (KAP), and fluoroscopic time for a large number of fluoroscopically-guided interventional (FGI) procedures. Methods: This retrospective study included the consecutive non-coronary FGI procedures from a Radiology department between May 2016 and October 2018 at a large tertiary care hospital in the U.S. An in-house developed, semi-automated software, integrated with a dictation system, was used to record patient examination information, including Ka,r, KAP and fluoroscopic time. The included patient procedures were categorized into procedure types. A software package R (version 3.5.1, R Foundation) was used to calculate procedure-specific quartiles of radiation exposure. Results: Based on analysis of 24,911 FGI cases, median value and 75th percentile are presented for each of Ka,r, KAP and fluoroscopic time for 101 procedures that can act as benchmark for comparison for dose optimization studies. Conclusion: This study provides reference levels (50th and 75th percentiles) for a comprehensive list of FGI procedures, reflecting an overall picture of the latest FGI studies for diagnosis, targeted minimally invasive intervention, and therapeutic treatment. Advances in knowledge: This study provides reference levels (50th and 75th percentiles) for the largest number of fluoroscopically-guided interventional procedures reported to-date (101 procedures), in terms of air kerma at the reference point, air kerma-area product, and fluoroscopic time, among which these quartiles for ≥50 procedures are presented for the first time.

Effect of Collimator Elements on the Beam Spectrum and KERMA In Gamma Irradiator

In the development of low-medium energy photon calibration facilities we have simulated several types of gamma irradiator collimator materials with ISO 4037-1 design connected to the output beam spectrum and the resulting kerma. Four types of collimator material, namely Al, Fe, Pb, and WCu have been simulated with gamma radiation sources 241Am, 57Co, 137Cs, and 60Co. Simulations were carried out using the Monte Carlo method with the PHITS computer program. Based on the comparison of air kerma produced, collimators made from Al are suitable for gamma sources 241Am, Fe material for gamma sources 57Co, and Pb material for sources 137Cs and 60Co.

Mean Glandular Dose Measurement in Three Mammography Centers in Kashan: An approach to Provide a Local DRL

Purpose: Mammography is the most important diagnostic modality for early detection of breast cancer, however, concerns related to the side effects induced by ionizing radiation are still present. In the current study, the Mean Glandular Dose (MGD) values for mammography examinations as well as a local Diagnostic Reference Level (DRL) were obtained for mammography centers in Kashan, Iran. Materials and Methods: Three mammography devices from three radiology centers were selected to obtain the MGD values of mammography examinations. To assess the MGD values, the technical parameters for patients’ imaging at these three radiology centers were extracted. Then, the incident air kerma (in mGy) value received by each patient was measured by a UNIDOS E electrometer (PTW, Germany) along with a SFD mammography ionization chamber (PTW, Germany). Finally, the incident air kerma values were converted to the MGD values by specific conversion factors. Based on the obtained MGD values, a local DRL was also established for mammography examinations. Results: Mean MGD values per exposure were obtained 2.39 ± 1.46 mGy for Right Craniocaudal (RCC), 2.64 ± 1.67 mGy for Left Craniocaudal (LCC), 2.82 ± 1.89 mGy for Right Mediolateral Oblique (RMLO), and 3.09 ± 1.90 mGy for left mediolateral oblique views. Moreover, a local DRL obtained from mammography examinations, which was established as the overall median of MGD value, was 1.72 mGy (1.91 mGy for digital and 1.32 mGy for analog mammography). Conclusion: The MGD values for different views obtained in this study are in the range of previously reported values. Considering the European guidelines for quality assurance in breast cancer screening and diagnosis, it can be mentioned that the obtained DRL was less than the recommended dose level (2.0 mGy).

Radiation Protection Evaluations Following the Installations of Two Cardiovascular Digital X-ray Fluoroscopy Systems

Acceptance testing and commission are essential elements of the quality assurance program for imaging equipment. We present the results of a performance evaluation of Flat Panel-Based Cardiovascular Fluoroscopy X-ray Systems as a part of acceptance testing and commissioning. Measurements were obtained using a calibrated dose rate meter, patient equivalent phantoms, and Leeds image quality test tools. The results were compared with the manufacturer and European acceptability criteria. The entrance surface air kerma (ESAK) rate ranged from 8.0 to 12.0 mGy min−1 in the continuous mode and from 0.01 to 0.04 mGy fr−1 in the pulsed mode of operation. Detector-input air kerma rates ranged from 0.29 to 0.39 mGy min−1 in continuous mode and from 0.02 to 0.07 µGy fr−1 in pulsed mode. Fluoroscopy device half-value layer (HVL) ranged from 2.5 to 3.0 mm Al, and the low resolution ranged from 0.9 to 1.3%. The spatial resolution limit was double that of the image intensifier (2.4 to 3.6) lp/mm. Flat-panel fluoroscopy demonstrated superior image quality and dose performance as compared to conventional image intensifier-based fluoroscopy. The quality assurance measurements presented are essential in the rapid evaluation of the imaging system for acceptance testing and commissioning.

X-Rays through the Looking Glass: Mobile Imaging Dosimetry and Image Quality of Suspected COVID-19 Patients

Background: This paper aims to evaluate the clinical utility and radiation dosimetry, for the mobile X-ray imaging of patients with known or suspected infectious diseases, through the window of an isolation room. The suitability of this technique for imaging coronavirus disease 2019 (COVID-19) patients is of particular focus here, although it is expected to have equal relevance to many infectious respiratory disease outbreaks.Materials and Methods: Two exposure levels were examined, a “typical” mobile exposure of 100 kVp/1.6 mAs and a “high” exposure of 120 kVp/5 mAs. Exposures of an anthropomorphic phantom were made, with and without a glass window present in the beam. The resultant phantom images were provided to experienced radiographers for image quality evaluation, using a Likert scale to rate the anatomical structure visibility.Results and Discussion: The incident air kerma doubled using the high exposure technique, from 29.47 μGy to 67.82 μGy and scattered radiation inside and outside the room increased. Despite an increase in beam energy, high exposure technique images received higher image quality scores than images acquired using lower exposure settings.Conclusion: Increased scattered radiation was very low and can be further mitigated by ensuring surrounding staff are appropriately distanced from both the patient and X-ray tube. Although an increase in incident air kerma was observed, practical advantages in infection control and personal protective equipment conservation were identified. Sites are encouraged to consider the use of this technique where appropriate, following the completion of standard justification practices.