The ICRP System of Protection Applied to Medical Exposures Results from UNSCEAR & ICRP Recommendations South Africa -- 2009 April 15-17 Chris Clement ICRP Scientific Secretary

Overview Why is radiological protection important in medical exposures? The ICRP system of radiological protection in medicine

Why is radiological protection in medical exposures important?

Medical Exposures The highest source of artificial exposure, by far Average and collective doses increasing rapidly, particularly due to increasing use of CT Source Global Average Dose (mSv per year) Occupational 0.005 Atmospheric Nuclear Testing Chernobyl Accident Medical Diagnosis 0.6 From UNSCEAR

US NCRP Report 160, Radiation Exposure to the US Population

US NCRP Report 160, Radiation Exposure to the US Population

Medical Overexposures Brain damage from radiotherapy overexposure Whole body of baby exposed instead of chest only Overheated X-ray tube stopped cardiac procedure 18 months after cardiac catheteri-sation and stent placement

The ICRP system of radiological protection in medicine

System of Protection in Medicine P 103: the complete system of protection P 105: Radiological Protection in Medicine (replaces P 73) P 80: Radiation Dose to Patients from Radiopharmaceuticals P 84: Pregnancy and Medical Radiation P 85: Avoidance of Radiation Injuries from Medical Interventional Procedures P 86: Prevention of accidental exposures to patients undergoing radiation therapy

System of Protection in Medicine P 87: Managing Patient Dose in Computed Tomography SG 2: Radiation and your patient: A guide for medical practitioners P 93: Managing patient dose in digital radiology P 97: Prevention of high-dose-rate brachytherapy accidents P 98: Radiation safety aspects of brachytherapy for prostate cancer using permanently implanted sources P 102: Managing Patient Dose in Multi-Detector Computed Tomography (MDCT)

System of Protection in Medicine P 106: Radiation Dose to Patients from Radiopharmaceuticals and in the works: Minimising unintended exposure in radiation therapy from new technologies Evaluation and management of secondary cancer risk in radiation therapy Protecting Children in Paediatric Radiology

System of Protection in Medicine Justification Benefit and most of the risk apply to the patient Optimization ALARA in medicine is management of the radiation dose to the patient commensurate with the medical purpose Diagnostic reference levels (not constraints) Dose Limitation Does not apply to medical exposures (of patients)

Three Levels of Justification Is the proper use of radiation in medicine doing more good than harm to society? A specified procedure with a specified objective e.g. chest x-ray for diagnostic purposes for patients showing relevant symptoms Application to a specific patient i.e. Do more good than harm to the patient (60) There are three levels of justification of a radiological practice in medicine. At the first and most general level, the proper use of radiation in medicine is accepted as doing more good than harm to society. This general level of justification is now taken for granted, and is not discussed here further. At the second level, a specified procedure with a specified objective is defined and justified (e.g. chest x rays for patients showing relevant symptoms, or a group of individuals at risk for a condition that can be detected and treated). The aim of the second level of justification is to judge whether the radiological procedure will improve the diagnosis or treatment, or will provide necessary information about the exposed individuals. At the third level, the application of the procedure to an individual patient should be justified (i.e. the particular application should be judged to do more good than harm to the individual patient). Hence all individual medical exposures should be justified in advance, taking into account the specific objectives of the exposure and the characteristics of the individual involved.

‘Buy Our CT, Earn $ 2,163,000 in 5 Years’ (58) Depending on the healthcare system in a country, there may be an influence of commercial interests on referral of patients to radiological examinations, since such examinations may be a major source of income to hospitals, academic medical institutions, and clinics with modern radiological departments. Such a situation may create referral incentives for frequent radiological examinations of patients that could exceed the needs of good medical practice. The Commission disapproves of such referrals that confer unjustifiable risk on patients, being inconsistent with medical ethics and principles of radiological protection. INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION ——————————————————————————————————————  

Gift Certificates for Radiation Exposure ???? (58) Depending on the healthcare system in a country, there may be an influence of commercial interests on referral of patients to radiological examinations, since such examinations may be a major source of income to hospitals, academic medical institutions, and clinics with modern radiological departments. Such a situation may create referral incentives for frequent radiological examinations of patients that could exceed the needs of good medical practice. The Commission disapproves of such referrals that confer unjustifiable risk on patients, being inconsistent with medical ethics and principles of radiological protection. INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION ——————————————————————————————————————  

Even in South Africa! Maybe not all that bad... “responsible ... low-dose screening” “targeted scans of vital organs” “does not perform unproven Full Body Scans” “If you have risk factors...”

Optimization Two levels of optimization: The design, selection and construction of equipment and installations The day-to-day methods of working Keeping doses ALARA, economic and societal factors being taken into account In medicine this is management of the radiation dose to the patient commensurate with the medical purpose (68) The optimisation of radiological protection for patients in medicine is usually applied at two levels: (1) the design, appropriate selection, and construction of equipment and installations; and (2) the day-to-day methods of working (i.e. the working procedures). The basic aim of this optimisation of protection is to adjust the protection measures for a source of radiation in such a way that the net benefit is maximised. (70) The optimisation of radiological protection means keeping the doses ‘as low as reasonably achievable, economic and societal factors being taken into account’, and is best described as management of the radiation dose to the patient to be commensurate with the medical purpose.

Optimization Doses can be too high Non-optimised diagnostic equipment or methods (e.g. QA problems, limited access to, short-lived radiopharmaceuticals) Non-optimised therapeutic equipment or methods (e.g. limited access to conformal therapy, inverse dose-planning) Inadequate or insufficient training (e.g. over-utilisation of ‘boost’ options in digital radiology) Doses can be too low The UK Computerised Treatment Planning accident, 1982-1991 1 045 patients affected, 5-30% under-dosage 492 patients had a recurrence, believed to be caused by the under-dosage

Diagnostic Reference Levels Detriments and benefits are received by the same individual, the patient Dose is determined principally by medical needs Dose constraints are therefore inappropriate Diagnostic Reference Levels help evaluate whether a patient dose is unusually high or low for a particular procedure (71) In protection of the patient, the detriments and benefits are received by the same individual, the patient, and the dose to the patient is determined principally by the medical needs. Dose constraints for patients are therefore inappropriate, in contrast to their importance in occupational and public exposure. Nevertheless, management of patient dose is important and can often be facilitated for diagnostic and interventional procedures by use of a diagnostic reference level, which is a method for evaluating whether the patient dose (with regard to stochastic effects) is unusually high or low for a particular medical imaging procedure (Section 10).

Diagnostic Reference Levels (SG-2) The concept: are my doses in line with those of my peers? If not: Do I have a good reason? DRLs should be set by regional / national / local bodies One size does not fit all! DRL numerical values are advisory Implementation of the concept may be a legal requirement DRLs should be easily measured ESD, DAP, DLP, administered activity… DRLs apply to groups, not to single patients

Paediatric Radiology Poster & Sticker

Image Gently Alliance for Radiation Safety in Pediatric Imaging (Society for Pediatric Radiology) www.imagegently.org US organization There's no question: CT helps us save kids' lives! But, when we image, radiation matters! Children are more sensitive to radiation. What we do now lasts their lifetimes. So, when we image, let's image gently: More is often not better. When CT is the right thing to do: Child size the kVp and mA One scan (single phase) is often enough Scan only the indicated area

Christopher Clement CHP Scientific Secretary International Commission on Radiological Protection PO Box 1046, Station B 280 Slater Street Ottawa, Ontario K1P 5S9 CANADA sci.sec@icrp.org www.icrp.org