Impact of equipment technology on reference levels in fluoroscopy-guided gastrointestinal procedures.

OBJECTIVES: To evaluate the effect of equipment technology on reference point air kerma (Ka,r), air kerma-area product (PKA), and fluoroscopic time for fluoroscopically-guided gastrointestinal endoscopic procedures and establish benchmark levels. METHODS: This retrospective study included the consecutive patients who underwent fluoroscopically-guided gastrointestinal endoscopic procedures from May 2016 to August 2023 at a tertiary care hospital in the U.S. Fluoroscopic systems included (a) Omega CS-50 e-View, (b) GE Precision 500D, and (c) Siemens Cios Alpha. Radiation dose was analyzed for four procedure types of endoscopic retrograde biliary, pancreas, biliary and pancreas combined, and other guidance. Median and 75th percentile values were computed using software package R (version 4.0.5, R Foundation). RESULTS: This large study analyzed 9,459 gastrointestinal endoscopic procedures. Among four procedure types, median Ka,r was 108.8-433.2 mGy (a), 70-272 mGy (b), and 22-55.1 mGy (c). Median PKA was 20.9-49.5 Gy∙cm2 (a), 13.4-39.7 Gy∙cm2 (b), and 8.91-20.9 Gy∙cm2 (c). Median fluoroscopic time was 2.8-8.1 min (a), 3.6-9.2 min (b), and 2.9-9.4 min (c). Their median value ratio (a:b:c) was 8.5:4.8:1 (Ka,r), 2.7:2.1:1 (PKA), and 1.0:1.1:1 (fluoroscopic time). Median value and 75th percentile are presented for Ka,r, PKA, and fluoroscopic time for each procedure type, which can function as benchmark for comparison for dose optimization studies. CONCLUSION: This study shows manifold variation in doses (Ka,r and PKA) among three fluoroscopic equipment types and provides local reference levels (50th and 75th percentiles) for four gastrointestinal endoscopic procedure types. Besides procedure type, imaging technology should be considered for establishing diagnostic reference level. SUMMARY: With manifold (2 to 12 times) variation in doses observed in this study among 3 machines, we recommend development of technology-based diagnostic reference levels for gastrointestinal endoscopic procedures.

Characterizing imaging radiation risk in a population of 8918 patients with recurrent imaging for a better effective dose.

An updated extension of effective dose was recently introduced, namely relative effective dose ( E r ), incorporating age and sex factors. In this study we extended E r application to a population of about 9000 patients who underwent multiple CT imaging exams, and we compared it with other commonly used radiation protection metrics in terms of their correlation with radiation risk. Using Monte Carlo methods, E r , dose-length-product based effective dose ( E DLP ), organ-dose based effective dose ( E OD ), and organ-dose based risk index ( RI ) were calculated for each patient. Each metric's dependency to RI was assessed in terms of its sensitivity and specificity. E r showed the best sensitivity, specificity, and agreement with RI (R2 = 0.97); while E DLP yielded the lowest specificity and, along with E OD , the lowest sensitivity. Compared to other metrics, E r provided a closer representation of patient and group risk also incorporating age and sex factors within the established framework of effective dose.

Is a one percent occurrence of high-dose patients significant?

Risk-free society is utopian. We come across risks in everyday life, and we use probabilities to get a feel of how risky a situation is. Risk probability numbers of around 1% are comforting, but an intercomparison of numbers among various low risks in popular situations can be enlightening. In this article, we compare risks of complications or death in several surgeries and risks in commercial air travel with risks for patients getting cumulative effective dose (CED) of 100 mSv or more, as the latter is a hot and controversial topic currently. The analysis shows that many common surgeries are a few tens or hundreds of times less risky than the risk from a 100 mSv dose, even though the former often frightens us more. Despite there being a much higher chance of developing cancer from radiation than being involved in a commercial plane accident, there is much less emphasis on patient radiation safety than aviation safety. Further, a look at the system of control on prescription drugs indicates that there is much to learn for policy planning. This analysis may help the International Commission on Radiological Protection (ICRP) in their review of recommendations.

Neurointerventions on two generations of angiography systems: Recent systems reduce radiation exposure by half.

PURPOSE: Fluoroscopically-guided neurointervention may be associated with prolonged procedure time and substantial radiation exposure to the patient and staff. This study sought to examine technological features affecting the potential radiation exposure reduction of new angiography systems, compared to older systems, for neurointerventional procedures. METHODS: Consecutive neurointerventional patients (2020-2022) were retrospectively analyzed. The air kerma at the reference point (Ka,r) and kerma-area product (KAP) were compared between Artis icono and Artis zee (Siemens) using statistical analyses (two-tailed t tests), where P < 0.05 is considered significant. X-ray tube potential and copper filtration were examined. Tests with an anthropomorphic phantom (Sun Nuclear) on Artis icono were conducted and entrance skin exposure and x-ray spectral half value layer were measured. Effective spectral filtration was characterized by x-ray spectral modeling. RESULTS: The number of procedures was 1158 [median (range) age, 59 (7-95) years] on Artis zee and 1087 [60 (1-95) years] on Artis icono, without significant difference in age (p = 0.059) between cohorts. Ka,r was 925.4 (890.6-960.1) mGy [mean (95 % CI)] and KAP was 119.8 (115-124.5) Gy∙cm2 on Artis zee. The measures were 48-50 % lower on Artis icono, 440.5 (411.7-469.4) mGy (Ka,r) and 59.5 (55.4-63.6) Gy∙cm2 (KAP); while the difference in fluoroscopic time between the two generations of angiography systems was insignificant (p = 0.55). CONCLUSIONS: The newer angiography system, with updated hardware and software, was found to result in half the radiation exposure compared to older technology of the same manufacturer, even though fluoroscopic time was similar.

Cumulative Effective Dose During Fluoroscopically Guided Interventions (FGI): Analysis of More Than 5000 FGIs in a Single European Center.

BACKGROUND: The number of fluoroscopically guided interventions (FGI) has increased significantly over time. However, little attention has been paid to possible stochastic radiation effects. The aim of this retrospective study was to investigate the number of patients who received cumulative effective doses over 100 mSv during FGI procedures. MATERIAL AND METHODS: Five thousand five hundred and fifty four classified FGI procedures were included. Radiation dose data, retrieved from an in-house-dose-management system, was analysed. Effective doses and cumulative effective doses (CED) were calculated. Patients who received a CED > 100 mSv were identified. Radiology reports, patient age, imaging and clinical data of these patients were used to identify reasons for CED ≥ 100 mSv. RESULTS: One Hundred and thirty two (41.1% female) of 3981 patients received a CED > 100 mSy, with a mean CED of 173.5 ± 84.5 mSv. Mean age at first intervention was 66.1 ± 11.7 years. 81 (61.4%) of 132 were older than 64 years, one patient was < 30 years. 110 patients received ≥ 100 mSv within one year (83.4%), through FGIs: EVAR, pelvic/mesenteric interventions (stent or embolization), hepatic interventions (chemoembolization, TIPSS), embolization of cerebral aneurysms or arterio-venous-malformations. CONCLUSIONS: Substantial CED may occur in a small but not ignorable fraction of patients (~ 3%) undergoing FGIs. Approximately 2/3rd of patients may most likely not encounter radiation-related stochastic effects due to life-threatening diseases and age at first treatment > 65 years but 1/3rd may. Patients undergoing more than one FGI (77%) carry a higher risk of accumulating effective doses > 100 mSv. Remarkably, 23% received a mean CED 162.2 ± 72.3 mSv in a single procedure.

Cumulative radiation exposure from multimodality recurrent imaging of CT, fluoroscopically guided intervention, and nuclear medicine.

OBJECTIVES: To assess cumulative effective dose (CED) over a 4-year period in patients undergoing multimodality recurrent imaging at a major hospital in the USA. METHODS: CED from CT, fluoroscopically guided intervention (FGI), and nuclear medicine was analyzed in consecutive exams in a tertiary care center in 2018-2021. Patients with CED ≥ 100 mSv were classified by age and body habitus (underweight, healthy weight, overweight, obese), as per body mass index percentiles < 5th, 5th to < 85th, 85th to < 95th, and ≥ 95th (age 2-19 years), and its ranges < 18.5, 18.5-24.9, 25-29.9, and ≥ 30 (≥ 20 years), respectively. RESULTS: Among a total of 205,425 patients, 5.7% received CED ≥ 100 mSv (mean 184 mSv, maximum 1165 mSv) and their ages were mostly 50-64 years (34.1%), followed by 65-74 years (29.8%), ≥ 75 years (19.5%), 20-49 years (16.3%), and ≤ 19 years (0.29%). Body habitus in decreasing occurrence was obese (38.6%), overweight (31.9%), healthy weight (27.5%), and underweight (2.1%). Classification by dose indicated 172 patients (≥ 500 mSv) and 3 (≥ 1000 mSv). In comparison, 5.3% of 189,030 CT patients, 1.6% of 18,963 FGI patients, and 0.19% of 41,401 nuclear-medicine patients received CED ≥ 100 mSv from a single modality. CONCLUSIONS: The study of total dose from CT, FGI, and nuclear medicine of patients with CED ≥ 100 mSv indicates major (89%) contribution of CT to CED with 70% of cohort being obese and overweight, and 64% of cohort aged 50-74 years. CLINICAL RELEVANCE STATEMENT: Multimodality recurrent exams are common and there is a lack of information on patient cumulative radiation exposure. This study attempts to address this lacuna and has the potential to motivate actions to improve the justification process for enhancing patient safety. KEY POINTS: • In total, 5.7% of patients undergoing multimodality recurrent imaging (CT, fluoroscopically guided intervention, nuclear medicine) incurred a dose of ≥ 100 mSv. • Mean dose was 184 mSv, with 15 to 18 times contribution from CT than that from fluoroscopically guided intervention or nuclear medicine. • In total, 70% of those who received ≥ 100mSv were either overweight or obese.

Global status of medical physics human resource - The IOMP survey report.

PURPOSE: Realizing the need for periodic surveys about global medical physics human resource, the International Organization for Medical Physics (IOMP) performed a third survey following the previous two (2015 and 2018). The objective was to collect information about the current numbers of medical physicists (MPs) in individual countries, about their MP training, and accreditation pathways. METHODS: The survey was designed using Google Forms. Forms were distributed to national MP associations around the world. The data was collected during May-Nov 2022. MS Excel and SPSS software were used to perform descriptive statistics. RESULTS: 64 valid responses were received covering all continents. The largest numbers of MPs are in high income countries of Europe, Australia and North America, while the lowest numbers of MPs are seen in middle and low-income countries of Asia, Latin America and Africa. Among the respondents, 73% reported MP shortages in their countries. 69% reported the existence of an official MP training program which comprises university courses and in-service training. Furthermore, 85% of the respondents indicated the availability of MP university courses, primarily at the Master's degree level. Participation in research was between 10 and 30% of allocated work time for 42% and below 10% for 33% respondents. CONCLUSIONS: There are new findings on number of MPs per million population in different countries, with some expressing adequacy in the total number of MPs, but the data breakdown indicates a shortage in diagnostic X-ray physicists. Future surveys should also investigate in more detail data on outsourcing, and involvement in research.

Losing the balance in risk-benefit analysis.

The idea of a benefit-risk analysis has been used for decades, but no one has probably bothered to see if there is a ratio or even questioned the concept because it does give an intuitive sense. There are situations where the tendency to lose the balance between the risk and benefit has been observed to move either towards benefit alone or risk alone. This may happen in medicine for benefit alone and in the nuclear industry for risk alone when public perceptions are involved. For example, in medicine, when the risk is uncertain and/or may happen in the long term as against the benefit, which may be immediate, the tendency to ignore risk has been observed. On the other hand, accidents in the nuclear industry shadow the benefits of nuclear power, resulting in authorities abandoning nuclear power in some countries. Similarly, tissue reactions to patients in fluoroscopic guided interventions have been highlighted despite the fact that the stochastic risks in the same procedure may be tens of times higher. Attention has been drawn to the analogy of risks in pharmaceuticals as against radiation and better-developed system for drugs for us to learn from. This article describes situations of losing balance and provides motivation for the International Commission on Radiological Protection to develop solutions for situations that entail immediate benefits with long-term radiation risk, commonly encountered in medical exposure.

Do patients with larger body sizes undergo more CT exams?

BACKGROUND: Overweight and obese patients are known to have more diseases than normal weight individuals, but it is currently unknown if there is higher utilization of computed tomography (CT) exams among those with larger body sizes. AIMS: To examine whether patients with larger body sizes undergo more CT exams and by how much more. METHODS: Using the recently described T-shirt size assessed from the lateral and transverse dimensions in CT localizer radiographs as a surrogate for body size, patients were classified into seven T-shirt sizes (XXS, XS, S, M, L, XL, XXL). This multi-center study analyzed over one million CT exams performed in 256 medical institutions in the USA to assess the frequency of CT use in patients of different body sizes. RESULTS: It was found that patients with larger body sizes (L, XL, XXL sizes) underwent 2.5-3.5 times more CT scans in the chest region and 7.8-17.7 times in the abdominopelvic region as compared to those with smaller body sizes (XXS, XS, S sizes). Further, the patients with extra-large body sizes (XL and XXL) underwent 4.6-9.9 times scans in the chest region and 39.2-187.8 times scans in the abdominopelvic region as compared to those with extra-small body sizes (XXS and XS). CONCLUSIONS: Our first-of-its-kind study demonstrating the manyfold use of CT in patients with large body sizes may be interesting for healthcare policy planning and developing guidelines for allocating resources for obese patients.

Patient follow-up for possible radiation injury from fluoroscopically-guided interventions: Need to consider high cumulative exposure from multiple procedures.

PURPOSE: Patient skin dose from interventional fluoroscopy procedures may exceed the threshold of tissue injuries and established guidelines recommend patient follow-up for air kerma at reference point (Ka,r) ≥ 5 Gy for individual procedures. Patients may undergo multiple procedures and skin injuries may be possible by cumulative exposure, even when individually insufficient to cause injury. This study sought to quantify the frequency of patients whose individual procedure doses are below 5 Gy but whose cumulative Ka,r is ≥ 5 Gy. METHODS: This retrospective study analyzed 37,917 consecutive procedures in interventional radiology and vascular surgery at a tertiary-care hospital between January 2016 and June 2021. Radiation dosage was retrieved from the fluoroscopy acquisition systems. For a patient receiving multiple procedures, but each with Ka,r < 5 Gy, cumulative Ka,r within 2, 7, 14, 30, 183, and 365 days was assessed. RESULTS: Nearly 1/3rd (37.4 %) patients underwent multiple procedures. With individual procedures of Ka,r < 5 Gy exclusively, 1.9, 4.4, and 5.6 in 1000 patients received cumulative Ka,r of 5-14.1 Gy from the procedures within 30, 183, and 365 days, respectively. From the procedures within 14 days, 1.3 in 1000 patients received cumulative Ka,r of 5-11.4 Gy; and from those within 7 days, 0.87 in 1000 patients received 5-9.1 Gy. In comparison, 4.3 in 1000 patients received Ka,r of 5-12 Gy from a single procedure. CONCLUSIONS: In the absence of guidelines on patient follow-up for multiple procedures, our study may provide good material for setting up such guidelines.

Accounting for radiation exposure from previous CT exams while deciding on the next exam: What do referring clinicians think?

PURPOSE: To obtain clinicians' views of the need to account for radiation exposure from previous CT scans and the advisability of a regulatory mechanism to control the number of CT scans for an individual patient. METHODS: A convenience survey was conducted by emailing a link to a three-question electronic survey to clinicians in many countries, mostly through radiology and radiation protection contacts. RESULTS: 505 responses were received from 24 countries. 293 respondents (58%) understand that current regulations do not limit the number of CT scans that can be prescribed for a single patient in a year. When asked whether there should be a regulation to limit the number of CT scans that can be prescribed for a single patient in one year, only a small fraction (143, 28%) answered 'No', 182 (36%) answered 'Maybe' and 166 (33%) answered 'Yes'. Most respondents (337; 67%) think that radiation risk should form part of the consideration when deciding whether to request a CT exam. A minority (138; 27%) think the decision should be based only on the medical indication for the CT exam. Comparison among the 4 countries (South Korea, Hungary, USA and Canada) with the largest number of respondents indicated wide variations in responses. CONCLUSIONS: A majority of the surveyed clinicians consider radiation risk, in addition to clinical factors, when prescribing CT exams. Most respondents are in favor of, or would consider, regulation to control the number of CT scans that could be performed on a patient annually.

The International Organization for Medical Physics - a driving force for the global development of medical physics.

The International Organization for Medical Physics (IOMP) is the world's largest professional organization in the field of medical physics and has official non-governmental organization status with the World Health Organization (WHO) and the International Atomic Energy Agency (IAEA). IOMP is charged with a mission to advance medical physics practice worldwide by disseminating scientific and technical information, fostering the educational and professional development of medical physics and promoting the highest quality medical services for patients. IOMP's activities are directed towards the promotion of medical physics globally, improving patient care, and contributing to the benefit of healthcare to the society. Major organizational activities include but are not limited to scientific events, international collaborations, dissemination of information, education, training, and research. For nearly 60 years of existence, IOMP turned into a key factor not only in the field of medical physics, but also healthcare, and other related disciplines. IOMP is looking forward to future perspectives in international collaboration and enhancement of the professional skills, all directed towards enhancing patient benefit.

T-shirt size as a classification for body habitus in computed tomography (CT) and development of size-based dose reference levels for different indications.

PURPOSE: To examine the impact of patient size on dose indices and develop size-based reference levels (50th and 75th percentiles) for 20 body CT exams for routine and organ-specific clinical indications. METHODS: Based on effective diameter estimated from adult body CT, each acquisition was classified into T-shirt size as XXS, XS, S, M, L, XL, and XXL. Radiation dose indices for each size and each exam type were correlated. RESULTS: About 0.93 million CT exams from 256 CT facilities in the United States were analysed. Taking T-shirt size M as a reference, the CTDIvol for other sizes were: XXS (∼60%), XS (∼65%), S (∼75%), L (∼130%), XL (∼165%), XXL (∼210%), or grossly small patients received about 60% of the dose as compared to M sized patients and XXL required doubling the dose. Taking ratio of the dose indices of the largest to smallest size, it was evident that SSDE variation was much less (about 50%) than that in CTDIvol, but there was still nearly 40 to 220% variation in SSDE across the range of t-shirt sizes. The 50th and 75th percentile values are presented for CTDIvol, SSDE and DLP for each of the 20 CT exams and for each of the seven T-shirt sizes. CONCLUSIONS: A novel approach expressing body habitus in terms of T-shirt size is not only simple and intuitive, but it also provides a tool to have a perception of differences in dose metrices among patients of different body build.

Patients undergoing multiple 18F-FDG PET/CT exams: Assessment of frequency, dose and disease classification.

OBJECTIVE: To analyse the frequency, demographics, primary disease and cumulative effective dose of patients undergoing two or more 18F-FDG PET/CT examinations in a year. METHODS: In a retrospective study performed at a tertiary-care hospital, patients who underwent ≥2 18F-FDG PET/CT scans in a calendar year were identified for two consecutive years. The CT radiation dose was calculated using dose-length-product and sex-specific conversion factors. The primary malignancy of patients was retrieved from electronic medical records. RESULTS: 10,714 18F-FDG PET/CT exams were performed for 6,831 unique patients in 2 years, yielding an average of 1.6 exams per patient. The maximum number of 18F-FDG PET/CT examinations any patient underwent in a single year was seven. 20.9% patients had ≥2 18F-FDG PET/CT exams in any single year. Thirty nine percent patients in the cohort were below 60 years age. The median dose for 18F-FDG PET/CT examination was 25.1 mSv and maximum value reaching 1.7 to 2.9 times the median value. Cumulative effective dose (CED) was≥100 mSv in 12-13% of the patients. The cumulative dose for both years combined demonstrated the 25th percentile, 50th percentile and 75th percentile as well as the mean to be over 100 mSv, with the 25th percentile being 109 mSv. The dominant primary malignancies contributing to serial 18F-FDG PET/CTs in decreasing frequency were melanoma, non-Hodgkin's lymphoma (NHL), gastrointestinal cancer, breast cancer and Hodgkin's lymphoma. CONCLUSIONS: A sizeable number of patients undergo≥2 18F-FDG PET/CT exams with one out of every eight patients receiving cumulative dose≥100 mSv and that includes patients with long-life expectancy. ADVANCES IN KNOWLEDGE: The study found that one of five patients had≥2 18F-FDG PET/CT exams in a calendar year, one of four patients in two years and one of eight patients received cumulative dose≥100 mSv. Top malignancies associated with serial imaging in decreasing order of frequency included melanoma, non-Hodgkin's lymphoma (NHL), gastrointestinal cancer, breast cancer and Hodgkin's lymphoma.

Comparison of Radiation Exposure between Endoscopic Ultrasound-Guided Hepaticogastrostomy and Hepaticogastrostomy with Antegrade Stenting.

Fluoroscopy forms an essential part of endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) and hepaticogastrostomy with antegrade stenting (EUS-HGAS). To date, no study has assessed and compared radiation exposure between EUS-HGS and EUS-HGAS. This study aimed to compare the radiation exposure parameters between EUS-HGS and EUS-HGAS. This retrospective single-center cohort study included consecutive patients who underwent EUS-HGS or EUS-HGAS from October 2017 to March 2019. The air kerma (AK: mGy), kerma-area product (KAP: Gycm2), fluoroscopy time (FT: min), and procedure time (PT: min) were assessed and compared between the two procedures. Altogether, 45 and 24 patients underwent EUS-HGS and EUS-HGAS, respectively. The median AK, KAP, FT, and PT were higher in the EUS-HGAS group than in the EUS-HGS group. A comparison revealed no difference in the technical success rate, complications rate, adverse event occurrence rate, and re-intervention rate between both procedures. This is the first report in which radiation exposure was used as a comparative parameter between EUS-HGS and EUS-HGAS. This study revealed that radiation exposure is significantly higher in EUS-HGAS than in EUS-HGS. Increased awareness on radiation exposure is warranted among gastroenterologists so that they choose the procedure with lower radiation exposure in cases where both procedures are indicated.

Communication of radiation risk from imaging studies: an IAEA-coordinated international survey.

The purpose of this IAEA-coordinated international study was to understand aspects related to the communication of radiation risk from imaging studies, such as how often imaging department personnel and referring physicians are asked about radiation risks in diagnostic imaging, who asks about these risks, how often professionals are able to provide satisfactory answers using qualitative metrics and how often quantitative risk estimates are needed. A web-based questionnaire with ten questions was completed by 386 healthcare professionals from 63 countries from all four continents, including clinicians/referring physicians (42.5%), radiologists or nuclear medicine physicians (26.7%), medical physicists (23.1%), radiographers/radiological technologists (6.2%) and others (1.6%). The results indicate that radiation risk-related questions are largely asked by patients (73.1%) and parents of child patients (38.6%), and 78% of the professionals believe they are able to answer those questions using qualitative metrics such as very small/minimal, small, medium rather than number of cancers likely occurring. The vast majority, with over three times higher frequency, indicated the purpose of knowing previous radiological exams as 'both clinical information and radiation exposure history' rather than 'only clinical information'. Nearly two-thirds of the clinicians/referring physicians indicated that knowing the radiation exposure history of the patient will affect their decision-making for the next exam, as against only about one-fifth who said 'no, it will not affect their decision-making'. The same question, when addressed to radiologists, resulted in a slightly larger fraction of about three-quarters who said 'yes', as opposed to a smaller fraction of about 12% who said 'no, it will not affect their decision-making'. Mapping the present situation of communication of benefits and risks for patients is important and may be the basis of further analysis, regular monitoring and possibly a target for clinical audits. Further studies focused on specific professional groups might help in obtaining á deeper understanding of the need for practical communication tools.

Point-of-care ultrasound-first for the evaluation of small bowel obstruction: National cost savings, length of stay reduction, and preventable radiation exposure.

OBJECTIVES: Computed tomography (CT) has long been the gold standard in diagnosing patients with suspected small bowel obstruction (SBO). Recently, point-of-care ultrasound (POCUS) has demonstrated comparable test characteristics to CT imaging for the diagnosis of SBO. Our primary objective was to estimate the annual national cost saving impact of a POCUS-first approach for the evaluation of SBO. Our secondary objectives were to estimate the reduction in radiation exposure and emergency department (ED) length of stay (LOS). METHODS: We created and ran 1000 trials of a Monte Carlo simulation. The study population included all patients presenting to the ED with abdominal pain who were diagnosed with SBO. Using this simulation, we modeled the national annual cost savings in averted advanced imaging from a POCUS-first approach for SBO. The model assumes that all patients who require surgery or have non-diagnostic POCUS exams undergo CT imaging. The model also conservatively assumes that a subset of patients with diagnostic POCUS exams undergo additional confirmatory CT imaging. We used the same Monte Carlo model to estimate the reduction in radiation exposure and total ED bed hours saved. RESULTS: A POCUS-first approach for diagnosing SBO was estimated to save a mean (±SD) of $30.1 million (±8.9 million) by avoiding 143,000 (±31,000) CT scans. This resulted in a national cumulative decrease of 507,000 bed hours (±268,000) in ED LOS. The reduction in radiation exposure to patients could potentially prevent 195 (±56) excess annual cancer cases and 98 (±28) excess annual cancer deaths. CONCLUSIONS: If adopted widely and used consistently, a POCUS-first algorithm for SBO could yield substantial national cost savings by averting advanced imaging, decreasing ED LOS, and reducing unnecessary radiation exposure in patients. Clinical decision tools are needed to better identify which patients would most benefit from CT imaging for SBO in the ED.

Organ doses and cancer risk assessment in patients exposed to high doses from recurrent CT exams.

PURPOSE: To estimate cumulative organ doses and age- and gender-stratified cancer mortality risks in patients undergoing recurrent computed tomography (CT) exams. METHODS: Cohorts of patients who received cumulative effective dose ≥ 100 mSv were stratified into age and gender groups. Organ doses of 27 organs using Monte Carlo methods were available, and the relative risk model from the Biological Effects of Ionizing Radiation VII (BEIR VII) was used to estimate lifetime attributable cancer mortality risks (LACMR). RESULTS: Out of the 8956 patients, 6.7% were 16-44 years of age, with median organ doses higher than 200 mGy for stomach and liver, whereas organ doses for nine organs, which included lungs, breasts, colon, red bone marrow, urinary bladder, esophagus, testicles, ovaries, and skin were between 100 and 200 mGy. Thyroid and salivary glands had smaller doses in the range of 45-69 mGy, but the mean dose for each organ was over 100 mGy. The age- and gender-specific median LACMR for the 16-44-years cohort was 0.6 to 0.7 deaths per 100 individuals for males, and 0.8 for females. The mortality estimated figures were highest for patients 16-54 years with slightly lower values for older age groups. Except for the highest age bracket of 75-84 years, the LACMR values for 55-74 years are not lower by orders of magnitude, and thus one cannot ignore risks in this age group. CONCLUSIONS: Organ doses over 100 mGy for most organs and for some organs ≥ 200 mGy with unignorable associated lifetime attributable cancer mortality rates were found.

Establishment of national diagnostic reference levels for percutaneous coronary interventions (PCIs) in Thailand.

PURPOSE: To establish national diagnostic reference levels (DRLs) for percutaneous coronary intervention (PCI) in Thailand for lesions of different complexity. METHODS: Radiation dose quantity as kerma-area-product (KAP) and cumulative air-kerma at reference point (CAK) from 76 catheterization labs in 38 hospitals in PCI registry of Thailand was transferred online to central data management. Sixteen months data (May 2018 to August 2019) was analyzed. We also investigated role of different factors that influence radiation dose the most. RESULTS: Analysis of 22,737 PCIs resulted in national DRLs for PCI of 91.3 Gy.cm2 (KAP) and 1360 mGy (CAK). The NDRLs for KAP for type C, B2, B1 and A lesions were 106.8, 82.6, 67.9, and 45.3 Gy.cm2 respectively and for CAK, 1705, 1247, 962, and 790 mGy respectively. Thus, as compared to lesion A, lesion C had more than double the dose and B2 had nearly 1.6 times and B1 had 1.2 times CAK. Our DRL values are lower than other Asian countries like Japan and Korea and are in the middle range of Western countries. University hospital had significantly higher dose than private or public hospital possibly because of higher load of complex procedures in university hospitals and trainees performing the procedures. Transradial approach showed lower doses than transfemoral approach. CONCLUSIONS: This large multi-centric study established DRLs for PCIs which can act as reference for future studies. A hallmark of our study is establishment of reference levels for coronary lesions classified as per ACC/AHA and thus for different complexities.