Diagnostic Reference Levels (DRLs)

Section 7 Diagnostic Reference Levels (DRLs) Establishment and Use of Diagnostic Reference Levels (DRLs) The National Radiation Safety Committee (NRSC), established in November 2007, is a statutory committee appointed by the CEO, HSE to advise him on matters pertaining to medical exposure of patients to ionising radiation, in accordance with Statutory Instrument (SI) 478 (2002) (1) 22.6 The National Radiation Safety Committee shall monitor the population dosage for the health board functional area and will include their findings in an annual report. Since 2008 the HSE, on behalf of the National Radiation Safety Committee (NRSC), has been collecting and publishing statistics on population dose levels from the use of medical ionising radiation. This information is also useful for the purposes of establishing the national dose distribution for the modalities and examinations surveyed. The Population Dose and Optimisation Sub-Committee of the NRSC consider the data suitable for updating of National Diagnostic Reference Levels (NDRLs), previously set by the Medical Council in 2004 (2) DRLs are defined as dose levels in medical radio-diagnostic practices or, in the case of radiopharmaceuticals, levels of activity, for typical examinations for groups of standard-sized patients or standard phantoms for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. The standard-sized patient is defined in RP 109 (3) as one with a 20 cm AP trunk thickness and 70+-3kgweight. The APPM (4) states that the goal in medical imaging is to obtain image quality consistent with the medical imaging task.. The specific purpose of the diagnostic reference level is to provide a benchmark for comparison, not to define a maximum or minimum dose limit. A DRL is not applied to individual patients. DRLs should be applied with flexibility to allow higher doses when indicated and justified by the Radiologist. The Medical Council acknowledged that the 2004 NDRLs were established with considerable reliance on published data from U.K. and European sources due to a lack of local data. The National DRLs (2014) adopted by the NRSC are based on data from Irish hospitals (5) (6) (7) (8) both public and private. Additional sources of information for CT were taken from the literature (9) and from the National Integrated Medical Imaging System (10). National DRLs are a useful comparison tool to benchmark local practice. Local DRLs are recommended as the first step in optimisation of procedures, as they are most relevant to the patient cohort, examination type and equipment available locally. Review of DRLs Service providers are required to establish and use DRLs for each of their routine procedures. DRLs should be reviewed annually or when there is a significant change in protocol or where they are consistently exceeded. The review of DRLs should compare local with national or referenced DRLs and a note made of any significant variances to these DRLs, and the justification for it. The local DRLs can be higher or lower than the national DRLs depending on the imaging equipment available to them or the patient casemix of that location. This regular review provides opportunity to provide feedback to ensure good practice in medical exposures is maintained. A sample template to record and review CT DRLs for locations is under local documentation in this section. This template can be adapted to set DRLs for locations for all diagnostic procedures. 3

Definition of DRL Diagnostic reference levels means dose levels in medical radio-diagnostic practices or in the case of radio-pharmaceuticals, levels of activity, for typical examinations for groups of standardsized patients or standard phantoms for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. National, European and International DRLs The Medical Council is required to promote the establishment of DRLs and published a position paper on DRLs in 2004 outlining DRLs for use. Since then, national surveys have collated patient dose data and from these more recent DRLs have been established for adult patients, and are outlined below. These are the national benchmarks against which local DRLs can be compared. As new surveys are produced, these national DRLs will be reviewed. 4

Contents Adult Computed Tomography... 6 Adult General X ray... 7 Adult Nuclear Medicine... 8 Adult Interventional and Fluoroscopy... 9 Paediatric Computed Tomography... 10 Paediatric General X ray (2) (12)... 11 Paediatric Fluoroscopy (13)... 12 Information on Patient Radiation Doses, Ireland (14), (15)... 3 Band Classification of the Typical Doses of Ionising Radiation from Common Imaging Procedures (18)... 14 Bibliography... 15 5

Adult Computed Tomography The Dose Length Product (mgycm) was chosen as the parameter for NDRL in CT. The DRL is for specific procedures and should only be applied to those procedures, eg: CT Thorax is not a suitable DRL for CT Thorax&Liver. Examination Order Code NDRL DLP mgycm CT BRAIN 990 CT CERVICAL SPINE 600 CT KUB 370 CT PELVIS 570 CT THORAX 390 CT THORAX HIGH RESOLUTION 350 CT PA 430 CT THORAX + LIVER 460 CT THORAX AND ABDOMEN 660 CT ABDOMEN AND PELVIS 660 CT THORAX ABDOMEN AND PELVIS 850 PET WB (diagnostic quality) CT 800 PET Brain CT 290 6

Adult General X ray The Dose Area Product (DAP) Gycm2 was chosen as the parameter for the NDRL Examination Order Code NDRL DAP Gycm 2 Chest PA 0.16 Chest AP 0.18 Cervical Spine AP 0.22 Cervical Spine Lat 0.24 Thoracic Spine AP 0.97 Thoracic Spine Lat 2.03 Lumbar Spine AP 1.62 Lumbar Spine Lat 2.68 Full Spine (T+L) 6.6 Full Spine (C+T+L) 8.4 Abdominal AP 2.3 Pelvic AP 2.6 Single Hip AP 1.5 Both Hips 1.9 Femur AP 0.8 Femur Lat 1.0 Feet/Ankles/Wrist/Hand 0.07 Knees AP/Lateral 0.16 Mammography (2 views, single breast) 2.7 MGD (mgy) DAP dose units vary with manufacturer and local DAP values may need to be converted to Gycm 2 to compare with the NDRLs. Use this table to convert DAP Dose units to Gycm 2 Dose Units convert to Gycm 2 dgycm2 Divide by 10 cgycm2 Divide by 100 mgycm2 Divide by 1,000 μgym2 Divide by 100 7

Adult Nuclear Medicine The administered activity MBq was chosen as the parameter for NDRL. It is recommended that in setting Local DRLs consideration should also be given to the use of the Administration of Radioactive Substances Advisory Committee, UK (ARSAC) DRLs; levels not expected to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. Administrations above the ARSAC (11) DRLs would only be considered as good practice in particular circumstances. Examination Order Code NDRL MBq ARSAC DRL MBq 99mTc Bone Scan 660 800 99mTc Thyroid Scan 110 80 131 I Thyroid Uptake 2* 0.2 131 I Thyroid metastases 185 400 99mTc V/Q Perfusion Scan 125 200 99mTc DTPA Renogram Scan 250 300 99mTc MAG3 Renogram Scan 100 100 123 I DAT Scan 185 185 123 I MIBG Scan 385 400 111 In OctreoScan 200 220 99mTc Myocardial Scan 800 800 99mTc Cerebral blood flow 800 750 WB PET 380 400 Brain PET 290 250 * The reported administered activity for 131-I uptake in the Nuclear Medicine Population Dose Surve y (6) was considerably higher than the ARSAC recommended activity (11). MERU, HSE recommended a review with regard to justification and optimisation in the small number of organisations that carry out this examination, taking into account the ARSAC Guidelines. 8

Adult Interventional and Fluoroscopy The Dose Area Product (DAP) Gycm 2 was chosen as the parameter for the NDRL Examination Order Code NDRL DAP Gycm 2 Abdominal Barium Meal + follow through 11 Oesophageal& Stomach & small intestine 13 Colon 23 Biliary tract 16 Orthopaedics 0.7 Cerebral procedures (e.g.: embolization s) 62 Cardiac studies 55 PTCA 75 Pacemaker 12 All Peripheral procedures 30 All Thoracic procedures 8 All Pelvic/Abdominal procedures 70 All IV lines, e.g. Hickman 3 Arthrography 0.35 DAP dose units vary with manufacturer and local DAP values may need to be converted to Gycm 2 to compare with the NDRLs. Use this table to convert DAP Dose units to Gycm 2 Dose Units convert to Gycm 2 dgycm2 Divide by 10 cgycm2 Divide by 100 mgycm2 Divide by 1,000 μgym2 Divide by 100 9

Paediatric DRLs. Particular attention needs to be given to establish separate DRLs for paediatrics for different ages. Below are recommended DRLs for paediatric CT based on the 2009 survey (5). There are a number of published research articles on paediatric DRLs available in Ireland (12) or internationally (13) which should be taken in to account when setting a benchmark from which to compare local DRLs. As new radiation dose surveys are produced, these national DRLs will be reviewed. Paediatric Computed Tomography Examination Order Code Paediatric Age NDRL DLP mgycm Brain Newborn 340 1-4 years 470 5-9 years 620 10-15 years 850 Adult 950 Abdomen/Pelvis Newborn 130 1-4 years 160 5-9 years 230 10-15 years 400 Adult 640 10

Paediatric General X ray (2) (12) Examination Order Code Paediatric IRISH NDRL Entrance Age Surface Dose μgy Abdomen AP 1 years 330 UK NDRL Entrance Surface Dose μgy 5 years 752 700 10 years 2600 Chest AP/PA Newborn 70 1 year 57 90 5 years 53 150 10 years 66 15 years 88 100 Pelvis AP Newborn 210 1 year 265 5 years 475 10 years 807 15 years 892 1320 Skull AP 5 years 1370 Skull Lat 5 years 820 11

Paediatric Fluoroscopy (13) Examination Order Code Paediatric Age NDRL DAP mgycm 2 MCU newborn 400 1 year 900 5 years 1100 10 years 2100 15 years 4700 Barium Meal Newborn 700 1 year 2000 5 years 2000 10 years 4500 15 years 7200 Barium Swallow newborn 800 1 year 1600 5 years 1300 10 years 2700 15 years 4600 DAP dose units vary with manufacturer and local DAP values may need to be converted to Gycm 2 to compare with the NDRLs. Use this table to Convert DAP Dose units to Gycm 2 Dose Units convert to Gycm 2 dgycm2 Divide by 10 cgycm2 Divide by 100 mgycm2 Divide by 1,000 μgym2 Divide by 100 12

Information on Patient Radiation Doses, Ireland (14), (15) Typical effective doses, equivalent periods of natural background radiation and lifetime fatal cancer risks from most common diagnostic medical exposures. Ionising Radiation Typical Effective Dose* in millisieverts 2 Equivalent Period of Natural Background Radiation (15) Lifetime Additional Risk of Fatal Cancer per Single Examination (16)# Limbs and joints (excluding hip) <0.01mSv one hour <1 in 100 million Teeth, intra-oral 0.005mSv <1 day 1 in 4 million Teeth, panoramic 0.02mSv 2 days 1 in 1 million Chest PA x-ray 0.02mSv 2 days 1 in 1 million Return airplane flight Dublin Rome return 0.027mSv 2 days 1 in 750,000 Cervical spine AP& Lat. x-ray 0.07mSv 1 week 1 in 300,000 Hip x-ray 0.2mSv 3 weeks 1 in 100,000 Pelvis AP x-ray 0.3mSv 1 month 1 in 70,000 Thoracic Spine AP& Lat x-ray 0.4mSv 1.5 months 1 in 50,000 Abdomen AP x-ray 0.4mSv 1.5 months 1 in 50,000 Lumbar Spine AP& Lat x-ray 0.6mSv 2 months 1 in 35,000 Barium follow-through 1.2mSv 4 months 1 in 17,000 NM 99mTc Thyroid Scan 1.3mSv 5 months 1 in 15,000 NM 99mTc Renogram 1.3mSv 5 months 1 in 15,000 CT Brain / Head 1.7mSv 6 months 1 in 12,000 NM 99mTc Ventilation/Perfusion 3.22mSv 1 year 1 in 6,200 One year s natural background radiation Ireland 3.4mSv 1 year 1 in 5,900 NM 99mTc Bone Scan 3.5mSv 1 year 1 in 5,700 Barium enema 3.6mSv 1 years 1 in 5,500 PTCA 7mSv 2 years 1 in 3,000 CT of Chest / Thorax 7mSv 2 years 1 in 3,000 CT of Abdomen and Pelvis 8mSv 2.4 years 1 in 2,500 Interventional Radiology (abdominal) 8.5mSv 2.5 years 1 in 2,500 Interventional Cardiac 11mSv 3.2 years 1 in 2,000 CT of Chest, Abdomen and Pelvis 13mSv 3.8 years 1 in 1,500 NM 131-I Thyroid Uptake Scan 47mSv 14 years 1 in 425 Lifetime risk of cancer NOT caused by radiation (16) 1 in 3 13

* where Irish data is not available reference data from the UK (14) has been used #based on 5% per Sv within age group 18-64years Band Classification of the Typical Doses of Ionising Radiation from Common Imaging Procedures (18) Typical effective doses for radiological examinations and associated risks as presented in irefer Making the Best us of Clinical Radiology V 7.0.2. Royal College of Radiologists. Symbol Typical effective dose (msv) Examples Lifetime additional risk of fatal cancer/exam None 0 US: 0 MRI <1 CXR; XR limb, pelvis, lumbar spine; mammography 1-5 IVU; NM (e.g., bone); CT head and neck 5.1-10 CT chest or abdomen; NM (e.g., cardiac) >10 Extensive CT studies, some NM studies (e.g., some PET- CT) <1:20,000 1:20,000 1:4,000 1:4,000 1:2,000 >1:2,000 The average annual background dose in most parts of Europe falls within the 1-5mSv range ( ). Cancer risks from radiation vary considerable with age and sex, with higher risks from radiation vary considerably with age and sex, with higher risks in infants and females. Cancer risk indicated in this table is averaged for adults. This should be taken in the context of the considerably higher 1 in 3 average lifetime risk for cancer and must be balanced against the benefit of the investigation. [Key: US=ultrasound; MRI=magnetic resonance imaging; CXR=chest X-ray; XR=X-ray; IVU=intravenous urography; NM=nuclear medicine; CT=computed tomography; PET-CT=positron emission tomography coregistered with CT.] 14

Bibliography 1. European Communities (Medical Ionising Radiation Protection) Regulations 2002. EEC Directive 97/43/Euratom. Health Protection of Individuals against the danger of Ionising Radiation in relation to Medical Exposures. S.I. 478 (2002). 2. Medical Council. Diagnostic Reference Levels Position Paper. 2004. 3. European Commission. Guidance on Diagnostic Reference Levels for Medical Exposures. 1999. 4. American College of Radiology and American Association of Physicists in Medicine. ACR AAPM Practice Parameter for Diagnostic Referemce Levels and Achievable Doses in Medical X Ray Imaging. 2014. 5. Medical Exposure Radiation Unit, HSE. Population Dose from CT Scanning. 2009. 6. Medical Exposure Radiation Unit, HSE. Population Dose from General X ray and Nuclear Medicine. 2010. 7. Medical Exposure Radiation Unit, HSE. Population Dose from PET CT Scanning. 2013. 8. Radiological Protection Insitute of Ireland / Medical Exposure Radiation Unit, HSE. Radiation Doses Received by the Irish Population Chapter 2.7 Medical exposure of patients.. 2014. 9. Establishment of CT diagnostic reference levels in Ireland. Foley S, McEntee M, Rainford L.. : BJR, 2012, BJR, Vol. 85. 10. National Integrated Medical Imaging System. Private Communication, 75th percentile DLP values from CT examinations 2013. 11. Notes for Guidance on the Clinical Administration of Radiopharmaceuticals and Use of Sealed Radioactive Sources. Administration of Radioactive Substances Advisory Committee. 2014. 12. Paediatric reference levels. Byrne B, Kenny P. 2002, Private Communication. 13. Doses to patients from medical X ray examinations in the UK 2000 review. Hart D., Hillier M.C., Wall B F.: NRPB, 2000, Vol. W14. 14. Patient Dose Information (website). Public Health England. 15. Radiation Doses Received by the Irish Population Chapter. Radiological Protection Intitute of Ireland. 2008. 16. International Commission on Radiological Protection. The 2007 Recommendations of the ICRP. Annals of the ICRP. Publication 103, 2007, Vol. 37. 17. National Cancer Registry of Ireland (NCRI) (www.ncri.ie). 18. Royal College of Radiologists. irefer Making the best use of clinical radiology services 7.0.2. 2012. 15