•A new approach to denote patient size by T-shirt size is described.•Patient size was classified as T-shirt size using effective diameter from CT scan.•T-shirt size could provide a perception of dose ...differences in patients of different body-build.•Size based reference doses for 20 CT examination types of adults were determined.•The concept of expressing body size as T-shirt size is simple and intuitive.
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.
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.
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.
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.
Purpose: The concept of benefit-risk assessment has often been propagated for clinical professionals for deciding the radiological exam for the patient. A detailed look into how to use this concept ...leads to several unanswered questions. The purpose of this article is to bring forth questions which have remained unanswered for several decades. These questions pertain to our inability to provide needed information to physicians for making benefit-risk assessment for deciding a frequent imaging modality like the computed tomography (CT) such as non-applicability of risk estimates to an individual patient, the concept of cumulative risk at low doses, accounting for the time gap between series of CT scans, risk variation with age, gender and disease condition. In the absence of concrete information on these, it becomes essentially benefit assessment rather than benefit-risk. The article also provides a motivation to think that there are a large number of patients getting exposed every year to radiation doses over 100 mSv of effective dose and several tens of mGy of organ doses. This may provide a very large cohort for radiation effect studies. Further, a series of ideas are presented as a vision for future studies.
Conclusions: The article emphasizes the need to create a research agenda to deal with day-to-day questions faced in medical practice and provides a call-for-attention. Further, it provides some challenging ideas as outside of the box thinking points that may provide research direction for future years.
Abstract The article reviews the historical developments in radiation dose metrices in medical imaging. It identifies the good, the bad, and the ugly aspects of current-day metrices. The actions on ...shifting focus from International Commission on Radiological Protection (ICRP) Reference-Man–based population-average phantoms to patient-specific computational phantoms have been proposed and discussed. Technological developments in recent years involving AI-based automatic organ segmentation and ‘near real-time’ Monte Carlo dose calculations suggest the feasibility and advantage of obtaining patient-specific organ doses. It appears that the time for ICRP and other international organizations to embrace ‘patient-specific’ dose quantity representing risk may have finally come. While the existing dose metrices meet specific demands, emphasis needs to be also placed on making radiation units understandable to the medical community.
Objective
To identify a patient cohort who received ≥ 100 mSv during a single computed tomography (CT)-guided intervention and analyze clinical information.
Materials and methods
Using the ...dose-tracking platform Radimetrics that collects data from all CT scanners in a single hospital, a patient-level search was performed retrospectively by setting a threshold effective dose (E) of 100 mSv for the period from January 2013 to December 2017. Patients who received ≥ 100 mSv in a single day during a single CT-guided intervention were then identified. Procedure types were identified, and medical records were reviewed up to January 2020 to identify patients who developed short- and/or medium-term (up to 8 years) medical consequences.
Results
Of 8952 patients with 100 mSv+, there were 33 patients who underwent 37 CT-guided interventions each resulting in ≥ 100 mSv. Procedures included ablations (15), myelograms (8), drainages (7), biopsies (6), and other (1). The dose for individual procedures was 100.2 to 235.5 mSv with mean and median of 125.7 mSv and 111.8 mSv, respectively. Six patients (18 %) were less than 50 years of age. During the study period of 0.2 to 7 years, there were no deterministic or stochastic consequences identified in this study cohort.
Conclusions
While infrequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv. Awareness of the possibility of such high doses and potential for long-term deleterious effects, especially in younger patients, and consideration of alternative imaging guidance and/or further dose optimization should be strongly considered whenever feasible.
Key Points
• Although not so frequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv
• Procedures with potential for high dose includes ablations, myelograms, drainages, and biopsies
Objectives
To assess the magnitude and characterization of CT imaging protocols of patients receiving 50 or 100 mSv in a single day.
Methods
In this multicentric retrospective study covering up to ...279 hospitals from January 2015 to December 2019, the effective dose (E) as estimated by dose management system from dose length product of patients was filtered and grouped into per-day dose bands (≤ 20, > 20–50, > 50–70, > 70–100, > 100–200, > 200 mSv). Information on patient’s age and imaging protocol was noted. The data were analyzed to determine the frequency of occurrence in each dose band. Top 20 CT imaging protocols that led to patients with a dose of ≥ 50 mSv in a single acquisition were identified and their relative frequency was estimated.
Results
A total of approx. 4.3 million (4,283,738) CT exams were performed in approx. 3.9 million (3,880,524) patient-days indicating 9.41% had more than one CT exam in a single day. There were 31,058 (0.8%) patient-days with ≥ 50 mSv and 1191 (0.03%) with ≥ 100 mSv. Nearly 1/3
rd
patient-days reaching ≥ 50 mSv were of patients aged 50 years or younger. The top 20 CT imaging protocols that led to ≥ 50 mSv in a single day belonged to the body region (chest or abdomen and pelvis) and nearly one-third were angiographic studies.
Conclusions
In the first study of its kind, we report that patients with 50 mSv+ in a single day or a single exam are not rare. The information on imaging protocols leading to such doses and their frequency has been provided to help develop dose management strategies.
Key Points
• Our study of 4,283,738 CT exams performed in 3,880,524 patient-days indicates 0.8% with 50 mSv+ and 0.03% with 100 mSv+ in a single day.
• A total of 9.41% underwent more than one CT exam in a single day; nearly 1/3
rd
of those with 50 mSv+ were ≤ 50 years of age.
• Identified top 20 CT imaging protocols that led to 50 mSv+ doses in a single exam. All belong to chest or abdomen and pelvis and nearly 1/3
rd
were angiographic studies.
The benefits of cardiac imaging are immense, and modern medicine requires the extensive and versatile use of a variety of cardiac imaging techniques. Cardiologists are responsible for a large part of ...the radiation exposures every person gets per year from all medical sources. Therefore, they have a particular responsibility to avoid unjustified and non-optimized use of radiation, but sometimes are imperfectly aware of the radiological dose of the examination they prescribe or practice. This position paper aims to summarize the current knowledge on radiation effective doses (and risks) related to cardiac imaging procedures. We have reviewed the literature on radiation doses, which can range from the equivalent of 1-60 milliSievert (mSv) around a reference dose average of 15 mSv (corresponding to 750 chest X-rays) for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multidetector coronary angiography, or a myocardial perfusion imaging scintigraphy. We provide a European perspective on the best way to play an active role in implementing into clinical practice the key principle of radiation protection that: 'each patient should get the right imaging exam, at the right time, with the right radiation dose'.
The purpose of this article is to presage the upcoming challenges in the area of radiation protection of patients in imaging for different stakeholders, such as dosimetrists, radiation biologists, ...patients, referring physicians, radiologists, radiographers, medical physicists, and manufacturers.
Most of the challenges facing different stakeholders are actually based on the contribution required from industry; thus, manufacturers play the greatest role in making patients safer in this century.
•Effective dose (E) provides a measure of potential risk in terms of health detriment.•E is calculated as a risk-weighted average of organ doses.•E is applied to a reference person, but ...patient-specific calculations can be done.•E is useful as a guide in making everyday decisions about patient imaging.•E should be derived using the most up-to-date phantoms and weighting factors.
Effective dose (E) has been developed by the International Commission on Radiological Protection (ICRP) as a dose quantity with a link to risks of health detriment, mainly cancer. It is based on reference phantoms representing average individuals, but this is often forgotten in its application to medical exposures, for which its use sometimes goes beyond the intended purpose. There has been much debate about issues involved in the use of E in medicine and ICRP is preparing a publication with more information on this application. This article aims to describe the development of E and explain how it should be used in medicine. It discusses some of the issues that arise when E is applied to medical exposures and provides information on how its use might evolve in the future. The article concludes with responses to some frequently asked questions about uses of E that are in line with the forthcoming ICRP publication. The main use of E in medicine is in meaningful comparison of doses from different types of procedure not possible with measurable dose quantities. However, it can be used, with appropriate care, as a measure of possible cancer risks. When considering E to individual patients, it is important to note that the dose received will differ from that assessed for reference phantoms, and the risk per Sv is likely to be greater on average in children and less in older adults. Newer techniques allow the calculation of patient-specific E which should be distinguished from the reference quantity.
The lens of the eye is one of the most radiosensitive tissues in the body, and exposure of the lens to ionizing radiation can cause cataract. Cumulative X-ray doses to the lenses of interventional ...cardiologists and associated staff can be high. The International Commission on Radiological Protection recently noted considerable uncertainty concerning radiation risk to the lens. This study evaluated risk of radiation cataract after occupational exposure in interventional cardiology personnel. Comprehensive dilated slit-lamp examinations were performed in interventional cardiologists, associated workers and controls. Radiation exposures were estimated using experimental data from catheterization laboratories and answers to detailed questionnaires. A total of 116 exposed and 93 similarly aged nonexposed individuals were examined. The relative risk of posterior subcapsular opacities in interventional cardiologists compared to unexposed controls was 3.2 (38% compared to 12%; P < 0.005). A total of 21% of nurses and technicians had radiation-associated posterior lens changes typically associated with ionizing radiation exposure. Cumulative median values of lens doses were estimated at 6.0 Sv for cardiologists and 1.5 Sv for associated medical personnel. A significantly elevated incidence of radiation-associated lens changes in interventional cardiology workers indicates there is an urgent need to educate these professionals in radiation protection to reduce the likelihood of cataract.
To analyse the frequency, demographics, primary disease and cumulative effective dose of patients undergoing two or more
F-FDG PET/CT examinations in a year.
In a retrospective study performed at a ...tertiary-care hospital, patients who underwent ≥2
F-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.
10,714
F-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
F-FDG PET/CT examinations any patient underwent in a single year was seven. 20.9% patients had ≥2
F-FDG PET/CT exams in any single year. Thirty nine percent patients in the cohort were below 60 years age. The median dose for
F-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 25
percentile, 50
percentile and 75
percentile as well as the mean to be over 100 mSv, with the 25
percentile being 109 mSv. The dominant primary malignancies contributing to serial
F-FDG PET/CTs in decreasing frequency were melanoma, non-Hodgkin's lymphoma (NHL), gastrointestinal cancer, breast cancer and Hodgkin's lymphoma.
A sizeable number of patients undergo≥2
F-FDG PET/CT exams with one out of every eight patients receiving cumulative dose≥100 mSv and that includes patients with long-life expectancy.
The study found that one of five patients had≥2
F-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.
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