Eliseo Vano

Guidelines for Patient Radiation Dose Management

Michael S. Stecker, MD, Stephen Balter, PhD, Richard B. Towbin, MD, Donald L. Miller, MD, Eliseo Vano, PhD,Gabriel Bartal, MD, J. Fritz Angle, MD, Christine P. Chao, MD, Alan M. Cohen, MD, Robert G. Dixon, MD,Kathleen Gross, MSN, RN-BC, CRN, George G. Hartnell, MD, Beth Schueler, PhD, John D. Statler, MD,Thierry de Baere, MD, and John F. Cardella, MD, for the SIR Safety and Health Committee and the CIRSEStandards of Practice Committee

Risk for radiation-induced cataract for staff in interventional cardiology: Is there reason for concern?†‡

Objectives: To examine the prevalence of radiation‐associated lens opacities among interventional cardiologists and nurses and correlate with occupational radiation exposure. Background: Interventional cardiology personnel are exposed to relatively high levels of X‐rays and based on recent findings of radiation‐associated lens opacities in other cohorts, they may be at risk for cataract without use of ocular radiation protection. Methods: Eyes of interventional cardiologists, nurses, and age‐ and sex‐matched unexposed controls were screened by dilated slit lamp examination and posterior lens changes graded using a modified Merriam‐Focht technique. Individual cumulative lens X‐ray exposure was calculated from responses to a questionnaire and personal interview. Results: The prevalence of radiation‐associated posterior lens opacities was 52% (29/56, 95% CI: 35–73) for interventional cardiologists, 45% (5/11, 95% CI: 15–100) for nurses, and 9% (2/22, 95% CI: 1–33) for controls. Relative risks of lens opacity was 5.7 (95% CI: 1.5–22) for interventional cardiologists and 5.0 (95% CI: 1.2–21) for nurses. Estimated cumulative ocular doses ranged from 0.01 to 43 Gy with mean and median values of 3.4 and 1.0 Gy, respectively. A strong dose–response relationship was found between occupational exposure and the prevalence of radiation‐associated posterior lens changes. Conclusions: These findings demonstrate a dose dependent increased risk of posterior lens opacities for interventional cardiologists and nurses when radiation protection tools are not used. While study of a larger cohort is needed to confirm these findings, the results suggest ocular radio‐protection should be utilized.

Eye lens exposure to radiation in interventional suites: caution is warranted.

PURPOSE To report estimated radiation doses to the eye lens of the interventionalist from procedures performed with and without use of radiation protection measures. MATERIALS AND METHODS Scattered radiation doses for seven interventional radiology fluoroscopic systems were measured by using phantoms simulating patients 16-28 cm in thickness undergoing low-, medium-, and high-mode fluoroscopy, cine cardiac imaging, and digital subtraction angiography (DSA). The radiation doses to the eye lens in low- and high-dose scenarios were estimated. Beam angulation, biplanar equipment, working distance, procedure complexity, imaging collimation, and use of eyeglasses and/or protective suspended screens were taken into account. The doses to the lens in several procedures were assessed. RESULTS Mean scattered radiation doses to the lens during fluoroscopy were 6.0 and 34.5 microSv/min in the low- and high-dose scenarios, respectively. For DSA, typical doses to the lens ranged from 0.77 to 3.33 microSv per image. Operation modes involving increasing or decreasing radiation doses were quantified. For hepatic chemoembolization, iliac angioplasty, pelvic embolization, and transjugular intrahepatic portosystemic shunt creation, lens doses ranged from 0.25 to 3.72 mSv per procedure when protection was not used. Lens doses in the neuroembolization procedures could exceed 10 mSv per procedure. CONCLUSION With typical reported workloads, radiation doses to eye lenses may exceed the threshold for deterministic effects (ie, lens opacities or cataracts) after several years of work if radiation protection tools are not used.

Radiation Cataract Risk in Interventional Cardiology Personnel

Abstract 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.

Cancer risk from professional exposure in staff working in cardiac catheterization laboratory: Insights from the National Research Council's Biological Effects of Ionizing Radiation VII Report

BACKGROUND Occupational doses from fluoroscopy-guided interventional procedures are the highest ones registered among medical staff using x-rays. The aim of the present study was to evaluate the order of magnitude of cancer risk caused by professional radiation exposure in modern invasive cardiology practice. METHODS From the dosimetric Tuscany Health Physics data bank of 2006, we selected dosimetric data of the 26 (7 women, 19 men; age 46 +/- 9 years) workers of the cardiovascular catheterization laboratory with effective dose >2 mSv. Effective dose (E) was expressed in milliSievert, calculated from personal dose equivalent registered by the thermoluminescent dosimeter, at waist or chest, under the apron, according to the recommendations of National Council of Radiation Protection. Lifetime attributable risk of cancer was estimated using the approach of Biological Effects of Ionizing Radiation 2006 report VII. RESULTS Cardiac catheterization laboratory staff represented 67% of the 6 workers with yearly exposure >6 mSv. Of the 26 workers with 2006 exposure >2 mSv, 15 of them had complete records of at least 10 (up to 25) consecutive years. For these 15 subjects having a more complete lifetime dosimetric history, the median individual effective dose was 46 mSv (interquartile range = 24-64). The median risk of (fatal and nonfatal) cancer (Biological Effects of Ionizing Radiation 2006) was 1 in 192 (interquartile range = 1 in 137-1 in 370). CONCLUSIONS Cumulative professional radiological exposure is associated with a non-negligible Lifetime attributable risk of cancer for the most exposed contemporary cardiac catheterization laboratory staff.

Patient dose values in interventional radiology

Large exposures incurred in interventional radiology procedures make it advisable to establish reference dose values. These dose values should be quoted in quantities representative of the radiological risk to the patient. In Spain, measurement methods were developed to comply with the European Directive on Patient Protection. Dose-area product and, when feasible, surface dose using thermoluminescent dosimetry chips were measured. Both approaches are discussed, as well as their potential use in patient protection programmes. Initial results are presented for a sample of 680 patients in 10 hospital centres in Spain. Mean, median and range are reported for some specific procedures. Mean values of 8750, 6651, 6663, 9292 and 6816 cGy cm2 are reported for percutaneous transluminal coronary angioplasty, coronary angiography, low extremity, renal and cerebral arteriographies, respectively.

Cumulative Patient Effective Dose and Acute Radiation-Induced Chromosomal DNA Damage in Children with Congenital Heart Disease

Background The seventh Committee on “Biological Effects of Ionizing Radiation” (BEIR VII, 2006) underlines “the need of studies of infants who are exposed to diagnostic radiation because catheters have been placed in their hearts”. Objective To determine the lifetime attributable risk (LAR) of cancer associated with the estimated cumulative radiological dose in 59 children (42 male, age 2.8±3.2 years) with complex congenital heart disease, and to assess chromosomal DNA damage after cardiac catheterisation procedures. Methods In all patients, the cumulative exposure was estimated as effective dose in milliSievert (mSv), and LAR cancer was determined from the BEIR VII report. In a subset of 18 patients (13 male, age 5.2±5.7 years) micronucleus as a biomarker of DNA damage and long-term risk predictor of cancer was assayed before and 2 h after catheterisation procedures. Dose–area product (Gy cm2) was assessed as a measure of patient dose. Results The median life time cumulative effective dose was 7.7 mSv per patient (range 4.6–41.2). Cardiac catheterisation procedures and CT were responsible for 95% of the total effective dose. For a 1-year-old child, the LAR cancer was 1 in 382 (25th to 75th centiles: 1 in 531 to 1 in 187) and 1 in 156 (25th to 75th centiles: 1 in 239 to 1 in 83) for male and female patients, respectively. Median micronucleus values increased significantly after the procedure in comparison with baseline (before 6‰ vs after 9‰, p=0.02). The median dose–area product value was 20 Gy cm2 (range 1–277). Conclusion Children with congenital heart disease are exposed to a significant cumulative dose. Indirect cancer risk estimations and direct DNA data both emphasise the need for strict radiation dose optimisation in children.

ICRP Publication 120: Radiological Protection in Cardiology

Cardiac nuclear medicine, cardiac computed tomography (CT), interventional cardiology procedures, and electrophysiology procedures are increasing in number and account for an important share of patient radiation exposure in medicine. Complex percutaneous coronary interventions and cardiac electrophysiology procedures are associated with high radiation doses. These procedures can result in patient skin doses that are high enough to cause radiation injury and an increased risk of cancer. Treatment of congenital heart disease in children is of particular concern. Additionally, staff(1) in cardiac catheterisation laboratories may receive high doses of radiation if radiological protection tools are not used properly. The Commission provided recommendations for radiological protection during fluoroscopically guided interventions in Publication 85, for radiological protection in CT in Publications 87 and 102, and for training in radiological protection in Publication 113 (ICRP, 2000b,c, 2007a, 2009). This report is focused specifically on cardiology, and brings together information relevant to cardiology from the Commissions published documents. There is emphasis on those imaging procedures and interventions specific to cardiology. The material and recommendations in the current document have been updated to reflect the most recent recommendations of the Commission. This report provides guidance to assist the cardiologist with justification procedures and optimisation of protection in cardiac CT studies, cardiac nuclear medicine studies, and fluoroscopically guided cardiac interventions. It includes discussions of the biological effects of radiation, principles of radiological protection, protection of staff during fluoroscopically guided interventions, radiological protection training, and establishment of a quality assurance programme for cardiac imaging and intervention. As tissue injury, principally skin injury, is a risk for fluoroscopically guided interventions, particular attention is devoted to clinical examples of radiation-related skin injuries from cardiac interventions, methods to reduce patient radiation dose, training recommendations, and quality assurance programmes for interventional fluoroscopy.

Radiation-associated Lens Opacities in Catheterization Personnel: Results of a Survey and Direct Assessments

PURPOSE To estimate ocular radiation doses and prevalence of lens opacities in a group of interventional catheterization professionals and offer practical recommendations based on these findings to avoid future lens damage. MATERIALS AND METHODS Subjects included 58 physicians and 69 nurses and technicians attending an interventional cardiology congress and appropriate unexposed age-matched controls. Lens dose estimates were derived from combining experimental measurements in catheterization laboratories with questionnaire responses regarding workload, types of procedures, and use of eye protection. Lens opacities were observed by dilated slit lamp examination using indirect illumination and retroillumination. The frequency and severity of posterior lens changes were compared between the exposed and unexposed groups. The severity of posterior lens changes was correlated with cumulative eye dose. RESULTS Posterior subcapsular lens changes characteristic of ionizing radiation exposure were found in 50% of interventional cardiologists and 41% of nurses and technicians compared with findings of similar lens changes in<10% of controls. Estimated cumulative eye doses ranged from 0.1-18.9 Sv. Most lens injuries result after several years of work without eye protection. CONCLUSIONS A high prevalence of lens changes likely induced by radiation exposure in the study population suggests an urgent need for improved radiation safety and training, use of eye protection during catheterization procedures, and improved occupational dosimetry.

Clinical radiation management for fluoroscopically guided interventional procedures.

The primary goal of radiation management in interventional radiology is to minimize the unnecessary use of radiation. Clinical radiation management minimizes radiation risk to the patient without increasing other risks, such as procedural risks. A number of factors are considered when estimating the likelihood and severity of patient radiation effects. These include demographic factors, medical history factors, and procedure factors. Important aspects of the patients medical history include coexisting diseases and genetic factors, medication use, radiation history, and pregnancy. As appropriate, these are evaluated as part of the preprocedure patient evaluation; radiation risk to the patient is considered along with other procedural risks. Dose optimization is possible through appropriate use of the basic features of interventional fluoroscopic equipment and intelligent use of dose-reducing technology. For all fluoroscopically guided interventional procedures, it is good practice to monitor radiation dose throughout the procedure and record it in the patients medical record. Patients who have received a clinically significant radiation dose should be followed up after the procedure for possible deterministic effects. The authors recommend including radiation management as part of the departmental quality assurance program.