Search

Purpose: In recent years various international organisations including IAEA, ICRP, and EURATOM consider interventional radiology procedures to be special practice, involving high doses of radiation with considerable potential risk associated with these procedures. The objective of this study is to assess dose to patients undergoing interventional procedures in five diagnostic facilities, leading to the establishment and utilization of Diagnostic Reference Levels in interventional procedures in Ghana. Methods: A sample of 748 procedures performed in five hospitals in Ghana were collected. Hospitals were asked to complete a questionnaire giving information on procedure, equipment, and protocol, experience of operator graded in number of procedures performed, and complexity level of each procedure. The procedures type included percutaneous nephrostomy, Intraforaminal infiltration, catheter embolization, percutaneous liver drainage, intracranial circulation, intraoperative angiography, biopsy, abdominal aorta endoprosthesis, splenic angiography, biliary stenting. For each procedure, fluoroscopy time, incident air-kerma at the Interventional Reference Point (IRP), number of images (frame), kerma-area product (KAP) Fluoro and Total kerma-area product, together with total irradiation time were collected. The upper quartile of the median distribution for number of images, fluoroscopy time, total KAP, and KAP Fluoro were used as measure of DRL. Results: The study results shows that the proposed DRL dose metric ranged from a minimum of 1.8 Gy.cm and 5.51 Gy.cm for Percutaneous Liver Drainage to a maximum of 86.98 and 118.80 for Abdominal Aorta Endoprosthesis in terms of KAP Fluoro and Total KAP respectively. The study also observed that the abdominal aorta endoprosthesis procedures took a longer time with significant number of images to performed relative to other cases. Time for abdominal aorta endoprosthesis procedure could be as much as three-fold comparable to the period needed for Intraforaminal infiltration, with more images acquired in the same procedures. The effect of this longer length of time and more image acquired resulted in higher patients' radiation dose, in terms of KAP Fluoro and total KAP, as applied to abdominal aorta endoprosthesis than any other procedures. The DRLs were found to be strongly influenced by clinical circumstances like complexity of the procedure, the length of time, training and experience of the operator. Furthermore, it was also observed that, the quality of the images for each procedure had direct positive correlation with estimated patient dose values. Conclusion: The preliminary results of this study propose local DRLs for the selected procedures, setting a good basis for establishment of a national DRL for interventional procedures in Ghana. The proposed DRL values are comparable to international published data from Spain, US and Switzerland. [ABSTRACT FROM AUTHOR]

Characterizing radiation measurement systems, such as diagnostic radiology systems for RQR and RQA, is essential for ensuring reliable results in standardized instrument calibration laboratories. Quality control of dosimetry devices, such as patient dose calibrators (PDCs), a reference meter, is crucial for ensuring accurate measurements. This study demonstrates the use of spectrometry and ionization chambers to characterize a set of semi-automated 3D prototyping filter holder systems, developed in a previously project, designed for applications such as Kerma-Area Product (KAP) meter calibration. The set of 3D prototypes were adjusted to a filter wheel and characterized using an X-ray spectrometer, followed by an ionization chamber, according to international standards. The characterization of radiation qualities from 50 to 150 kV in diagnostic radiology was performed using the substitution method: first with an ionization chamber, then with a PDC. The PDC was calibrated for KAP and Air Kerma quantities, considering the conditions of the X-ray system and factors such as temperature, humidity, and pressure. Spectrometric analysis and the use of an ionization chamber were effective in determining these parameters. Spectral characterization allowed for accurate measurements to establish proper quality control, then it is possible to use the PDC calibrated for calibration procedures for KAP meters. Future studies intend to compare these results with computational simulations using the TOPAS Monte Carlo code to validate the calibration method. • Dosimetry in diagnostic radiology is crucial to ensure the accuracy standards. • The PDC calibration method is conducted using spectrometry and ionization chambers. • Spectral characterization ensures precise measurements for good quality control. • The calibrated system is used for PDCs in KAP meter calibration procedures. [ABSTRACT FROM AUTHOR]

The present study was conducted as part of a comprehensive work to establish National Diagnostic Reference Levels (NDRLs) in Sri Lanka for the first time. DRLs can be used as an effective optimization tool for identifying unusually high or low patient doses during X‐ray examinations. This study aims to propose institutional DRLs (IDRLs) by measuring the kerma‐area product (KAP) of adult patients undergoing routine projection X‐ray examinations. The median and the 75th percentile KAP values obtained were compared with that of the single institution KAP values reported from India and Greece. This descriptive cross‐sectional study was conducted in a public hospital in Uva province, Sri Lanka, with 400 adult patients aged 18–87 years and weighing 58 ± 20 kg. The patient‐specific information (age, sex, weight, and height) and corresponding exposure parameters (tube voltage and current‐exposure time product) were obtained. The KAP values were measured, and descriptive statistics were utilized for data analysis. The median KAP values obtained were proposed as IDRLs. The IDRLs in Gy.cm2 were 0.23 for cervical spine anterior–posterior (AP), 0.19 for cervical spine lateral (LAT), 0.10 for chest posterior–anterior (PA), 0.06 for knee joint AP, 0.05 for knee joint LAT, 1.47 for KUB AP, 0.85 for lumbar spine AP, 1.97 for lumbar spine LAT, 0.29 for shoulder joint AP, 0.61 for skull PA, and 0.60 for skull LAT examinations. The maximum to minimum ratio of KAP values ranged from 2.4 for KUB AP to 6.3 for the cervical spine AP examinations. The median and the 75th percentile of most of the examinations were comparable to corresponding KAP values reported by the countries mentioned above, except for the skull PA and LAT examinations. Accordingly, interquartile ranges of exposure parameters are recommended for skull examinations to improve the optimization of patient doses. [ABSTRACT FROM AUTHOR]

Kerma-area product and kerma-length product are important practical dosimetric quantities used in diagnostic radiology. These quantities are measured by special types of dosimeters which are calibrated in standard radiation qualities established in calibration laboratories. However, in clinical practice the dosimeters are used in different conditions, including the radiation quality and field size. In this paper, energy and field size dependence are studied for both types of dosimeters. One dosimeter of each type is tested. The KAP-meter has shown significant dependence on both radiation quality and field size, while the dependence of the CT-chamber is much less pronounced. Two different approaches can be used to correct for the difference between conditions during calibration and in clinical practice. When the clinical beam is well characterized and energy and field size dependence of the dosimeter are well known, the optimum solution is to apply the adequate correction factor to the measurements, keeping measurement uncertainty as low as possible. If this is not the case, the above limitations must be taken under consideration in the calculation of the expanded uncertainty budget.

In this study, we sought to estimate the patient radiation doses in the digital radiography X-ray examinations conducted in a large hospital. The patient exposure factors and kerma-area product (PKA) were retrospectively recorded via the Digital Imaging and Communications in Medicine (DICOM) header for 547 patients. The entrance surface air kerma (ESAK) was estimated from the measurements of the X-ray tube output and recorded exposure factors, as well as from the console that displayed PKA as an alternative method. Effective doses were estimated from ESAK and PKA values using the appropriate conversion coefficient. In the chest PA, chest LAT, cervical spine AP, cervical spine LAT, abdomen AP, pelvis AP, lumbar spine AP, and lumbar spine LAT, the median ESAK (mGy) was found to be 0.13, 0.27, 0.35, 0.52, 0.70, 1.06, 2.33, and 4.18 mGy, respectively. Median PKA values were 0.10, 0.26, 0.14, 0.17, 0.77, 0.68, 0.81, and 1.11 Gy cm2, respectively. The estimated effective dose from ESAK and PKA values yielded comparable results. The comparison revealed that the ESAK and PKA values fell far below the reported in the literature. The results showed that the information of the DICOM deader is valuable for dosimetry and optimization. [ABSTRACT FROM AUTHOR]

Aim: To find out whether obesity or injection level have an impact on the amount of radiation exposure during fluoroscopy-guided lumbosacral transforaminal epidural steroid injections (TFESIs). Material and Methods: Patients aged 19-65 years who underwent lumbosacral transforaminal epidural steroid injection were retrospectively reviewed. Eighty-three patients with a mean age of 42.7±13.2 (19-65) years with signs and symptoms of unilateral lumbar radicular pain due to single level disc herniation were included. Subjects were categorized as normal weighted (18.5≤body mass index (BMI) ≤ 24.9), overweighed (25≤BMI<30) and obese (BMI≥30) according to World Health Organization BMI criteria. All patients were given unilateral TFESIs, including39 (47%) L5, and 44 (53%) S1 level. Radiation exposure dose and procedure time was automatically measured by fluoroscope. Results: Radiation dosage increased significantly with increasing BMI (p=0.0001). No statistically significant differences were found when three groups' procedure durations and NRS scores were compared (>0.05). The radiation dosages and procedure durations between the two different injection levels (L5 and S1) were not found to be statistically significant (>0.05). Conclusion: Obesity is associated with increased radiation exposure independent of procedure duration and the injection level. [ABSTRACT FROM AUTHOR]

Contrast investigations of hysterosalpingography (HSG) and retrograde urethrography (RUG) fluoroscopy procedures remain the dominant diagnostic tools for the investigation of infertility in females and urethral strictures in males, respectively, owing to the scarcity and high cost of services of alternative diagnostic technologies. In light of the radiological risks associated with contrast based investigations of the genitourinary tract systems, there is a need to assess the magnitude of radiation burden imparted to patients undergoing HSG and RUG fluoroscopy procedures in Tanzania. The air kerma area product (KAP), fluoroscopy time, number of images, organ dose and effective dose to patients undergoing HSG and RUG procedures were obtained from four hospitals. The KAP was measured using a flat transmission ionization chamber, while the organ and effective doses were estimated using the knowledge of the patient characteristics, patient related exposure parameters, geometry of examination, KAP and Monte Carlo calculations (PCXMC). The median values of KAP for the HSG and RUG were 2.2 Gy cm 2 and 3.3 Gy cm 2 , respectively. The median organ doses in the present study for the ovaries, urinary bladder and uterus for the HSG procedures, were 1.0 mGy, 4.0 mGy and 1.6 mGy, respectively, while for urinary bladder and testes of the RUG were 3.4 mGy and 5.9 mGy, respectively. The median values of effective doses for the HSG and RUG procedures were 0.65 mSv and 0.59 mSv, respectively. The median values of effective dose per hospital for the HSG and RUG procedures had a range of 1.6–2.8 mSv and 1.9–5.6 mSv, respectively, while the overall differences between individual effective doses across the four hospitals varied by factors of up to 22.0 and 46.7, respectively for the HSG and RUG procedures. The proposed diagnostic reference levels (DRLs) for the HSG and RUG were for KAP 2.8 Gy cm 2 and 3.9 Gy cm 2 , for fluoroscopy time 0.8 min and 0.9 min, and for number of images 5 and 4, respectively. The suggested DRLs for the HSG and RUG procedures may be used by the radiology departments in Tanzania for management of attained dose levels until the national DRLs are established. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Cardiovascular Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective The worldwide prevalence of peripheral artery disease (PAD) has evolved to an intervention as the primary treatment option and therefore radiation is used with escalating incidence. Dose area product (DAP) correlates well with the total energy imparted to the patient during fluoroscopic interventions. This study aims to determine whether there are any associations among stage of disease, gender, age, and expertise on the radiation dose in single endovascular treatments of PAD. Methods This study was a prospective, mandatory, population based cross-sectional registry design. In total, 24,000 invasive percutaneous endovascular treatments of PAD conducted in the metropolitan area of Hamburg (Germany) were consecutively collected between January 2004 and December 2015. DAP was analysed by discipline conducting the procedure, Fontaine classification, patient gender, and age. Results Statistically significant differences in median DAP values were found. The lowest median DAP values were observed in surgical centres (7.1 vs. 18.0 Gy*cm 2 , p <.001) and in endovascular revascularisations (ER) following multidisciplinary consultation (11.6 vs. 23.4 Gy*cm 2 , p <.001). Considering the treatment of intermittent claudication, men had statistically significantly higher DAP values compared with women. Furthermore, lower median DAP values were observed in higher age groups, with lowest dosages in octogenarians. Conclusion This is the first large population based study on DAP during ER for PAD. Several significant differences in median DAP values were observed, although patient stratification was comparable. Pre-operative therapy strategy planning can lead to lower DAP values, emphasising the importance of further vascular research and quality improvement projects targeting this topic. To date, available evidence is limited and therefore there is no accepted range of DAP levels. However, the ever increasing use of fluoroscopic interventions means that further investigation into radiation exposure to patients and healthcare professionals is required in order to keep DAP levels low. [ABSTRACT FROM AUTHOR]

The purpose of this study was to define an optimal radiological procedure to evaluate the results of rehabilitation therapy for swallowing disorders and to calculate both the effective and organ dose to the patient to provide a measure of the radiation risk associated with the procedure. In order to define the optimal radiological procedure, kerma-area product (KAP) measurements and evaluations of image quality in fluoroscopy and fluorography mode were made using dedicated phantoms. Twenty-two patients were included in the study, and the values of KAP, screening time and average voltage selected were individually recorded. The recorded KAP values were used to estimate radiation risk with the use of dedicated calculation software. Median, first and third quartiles of the KAP distribution were, respectively, 2.1, 1.5 and 2.7 Gy cm2, with a corresponding effective dose of 0.35, 0.26 and 0.46 mSv. A good correlation between KAP and exposure time was also found (R2=0.85). Exposure of the thyroid, which is inside the radiation field, accounts for the greatest share to the effective dose, with a calculated median dose of 6 mGy. With the defined radiological procedure, the obtained KAP values are lower than recorded doses in interventional radiology, and the corresponding values of entrance skin dose are lower than the threshold dose for deterministic effects. Considering the effective dose at the median KAP value, the probability for stochastic effects is shown to be low, at approximately 1 in 39,000. [ABSTRACT FROM AUTHOR]

The aim of this study was to test the applicability of the guidance levels for patient doses cooperatively set by the radiation protection authorities in the five Nordic countries. The kerma-area product (KAP) for five conventional radiological examination types was obtained from several hospitals in each of the Nordic countries. The number of radiographic images and fluoroscopy time were also registered, and the mean values for each examination type and hospital were established based on a representative number of patients (40-100 kg). The results indicate that the situation is very similar in the five Nordic countries, even though some differences were identified. Most of the hospitals demonstrated lower doses than the proposed guidance levels for chest, probably explained by use of faster film/screen combinations during the past decade. An increased use of fluoroscopy for positioning was observed for radiographic examinations of lumbar spine and urography. Large variations in patient doses were found for barium enema depending on the use of fluorospot or 100-mm camera vs full-format film, the range in fluoroscopy times, dose rate, and field size. The guidance levels for lumbar spine (10 Gy x cm2), pelvis (4 Gy x cm2), urography (20 Gy x cm2), and barium enema (50 Gy x cm2) seem to reflect the present quality of X-ray equipment and examination techniques in the Nordic countries. The guidance levels for chest (1 Gy x cm2) should be lowered to 0.6 Gy x cm2. [ABSTRACT FROM AUTHOR]

The aim of this systematic review is to undertake a critical appraisal of the evidence in the published literature concerning the conversion factors between kerma-area product ( P KA ) and effective/organ dose (DC ED&#95;PKA , DC HT&#95;PKA ) for cardiac interventional fluoroscopy procedures performed in adults and paediatric patients and to propose reference conversion factors to help standardize dose calculations. A search strategy utilizing MeSH headings in three databases identified 59 (adult) and 37 (paediatric) papers deemed eligible for the review. Exclusion criteria were adopted to select data only from publications which established DC ED&#95;PKA in patients using the ICRP 103 tissue weighting factors. A time restriction from January 2007 was introduced in the search to capture the evolving trends of utilization of fluoroscopy-guided intervention technologies only in recent years. The suggested DC ED&#95;PKA and DC HT&#95;PKA were synthesized by calculating the weighted averages of the values reported by the authors with weights corresponding to the study sample size. Eighteen studies for both adult (9) and paediatric (9) patients matching the search terms fulfilled the inclusion criteria. The suggested value for DC ED&#95;PKA in adult patients amounts to 0.24 mSv Gy -1 cm -2 . The suggested values for DC HT&#95;PKA ranged from a minimum of 0.15 mSv Gy -1 cm -2 for the female breast to a maximum of 0.97 mSv Gy -1 cm -2 for the lungs. The suggested values for DC ED&#95;PKA in paediatric patients ranged from 3.45 mSv Gy -1 cm -2 for the new-born to 0.49 mSv Gy -1 cm -2 in the 15 years age class. The suggested values for DC HT&#95;PKA ranged from a minimum of 0.33 mSv Gy -1 cm -2 for bone marrow in the 15 years age class to a maximum of 11.49 mSv Gy -1 cm -2 for the heart in the new-born. To conclude, values of DC ED&#95;PKA /DC HT&#95;PKA were provided for calculating effective/organ doses in cardiac interventional procedures. They can be useful for standardizing dose calculations, hence for comparison of the radiation detriment from different imaging procedures and in the framework of epidemiologic studies., (© 2022 Institute of Physics and Engineering in Medicine.)

The kerma-area product (KAP) is a useful quantity to establish the reference levels of conventional X-ray examinations. It can be obtained by measurements carried out with a KAP meter on a plane parallel transmission ionization chamber mounted on the X-ray system. A KAP meter can be calibrated in laboratory or in situ, where it is used. It is important to use one reference KAP meter in order to obtain reliable quantity of doses on the patient. The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. It was manufactured following the IEC 60580 recommendations, an international standard for KAP meters. This study had the aim to calibrate KAP meters using the PDC in situ. Previous studies and the quality control program of the PDC have shown that it has good function in characterization tests of dosimeters with ionization chamber and it also has low energy dependence. Three types of KAP meters were calibrated in four different diagnostic X-ray equipments. The voltages used in the two first calibrations were 50 kV, 70 kV, 100 kV and 120 kV. The other two used 50 kV, 70 kV and 90 kV. This was related to the equipments limitations. The field sizes used for the calibration were 10 cm, 20 cm and 30 cm. The calibrations were done in three different cities with the purpose to analyze the reproducibility of the PDC. The results gave the calibration coefficient for each KAP meter and showed that the PDC can be used as a reference instrument to calibrate clinical KAP meters. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper was to evaluate the energy dependence of the kerma-area product meter Patient Dose Calibrator (PDC). The research was done using the calculation of the coefficient calibration of the air kerma values of different energies that are related to the radiation qualities provided on the International Standard of the International Electrotechnical Commission IEC 61267 for conventional X-rays, mammography and computerized tomography (CT), established at the Calibration Laboratory of IPEN. The calibration was made using reference ionization chambers with traceability to the Primary Laboratory Physikalisch-Technische Bundesanstalt (PTB), Germany. The energy dependence of the PDC was determined and the results showed that the PDC has small energy dependence, less than 6%, for the range of recommended energy while to the mammography range the values were 16% and for CT qualities the dependence was 1%. [Copyright &y& Elsevier]

The aim of the present study was to assess the patient-specific equivalent organ dose (H T) and effective dose (ED) delivered to individual patients from cardiovascular interventional radiology (CVIR) procedures and to compare these doses to those reported in the literature. The H T and EDs to 113 patients from two CVIR procedures: coronary angiography (CA) and percutaneous coronary interventions (PCI) were acquired from two major hospitals in Tanzania. The H T and EDs were estimated using the knowledge of the patient characteristics, patient related exposure parameters, geometry of examination, measurements of air kerma area product and Monte Carlo-based PCXMC software. The median H T in the present study for the lung, heart and oesophagus for the CA, were 47.1 mSv, 33.8 mSv, and 22.9 mSv, respectively, while for the PCI were 102.6 mSv, 77.5 mSv, and 51.9 mSv, respectively. The median values of ED as recommended by ICRP 103 for the CA and PCI procedures were 11.1 mSv and 24.7 mSv, respectively. The overall variations between individual EDs across the two hospitals differed by factors of up to 63.1 and 25.1, respectively for the CA and PCI procedures. The mean values of H T and EDs in the present study were, for the most part, higher than the reported values for India, Belgium and Italy, while comparable with those reported for Greece. The proposed diagnostic reference levels (DRLs) for the CA and PCI were for KAP 91.4 Gy cm2 and 129.4 Gy cm2, for fluoroscopy time 15.5 min and 28.4 min, for number of cine frames 791.5 and 1213.5, and ED 19.8 and 36.9 mSv, respectively. The observed wide range of exposure parameters and patient doses within and across the hospitals and the observed relatively high patient doses compared to those reported in the literature, call for the need to standardize examination protocols and optimise radiation dose to patients from CVIR procedures. • Wide range of patient dose (H T and ED) within and across the hospitals were observed. • Mean values of KAP, H T and EDs were higher than the values reported from literature. • Proposed DRLs for CA and PCI were higher than reported DRLs from USA and Europe. [ABSTRACT FROM AUTHOR]