Radiation Protection of Patients Unit National DRL Programmes Regional Meeting on the Establishment and Utilization of Diagnostic Reference Levels Kampala, Uganda, 14-18 February, 2013 John Le Heron Radiation Protection of Patients Unit Radiation Safety and Monitoring Section Division for Radiation, Transport and Waste Safety

Outline Experiences and approaches of 2 countries UK Australia

UK approach – radiography & fluoroscopy Reference: HPA – CRCE – 034 Doses to patients from radiographic and fluoroscopic x-ray imaging procedures in the UK – 2010 review CT is handled separately

UK – Obtaining the data UK has a National Patient Dose Database – NPDD Set up in 1992 by NRPB (now HPA) A 5 year review cycle Data collection over a 5 year period Supplied from hospitals Medical physicists mainly Also radiographers and radiologists

UK – What data are collected? Standard forms used: Dose per radiograph Dose per examination Data on dose, patient, location, imaging equipment, and technique Some fields mandatory Many optional fields http://www.hpa.org.uk/Topics/Radiation/UnderstandingRadiation/UnderstandingRadiationTopics/MedicalRadiation/DiagnosticRadiology/diag_Npdd/

UK – More detail on data collected The submission of optional data was quite generally poor Factor % of dose measurements Patient height 44 Patient age 38 Patient gender 34 Radiographic kV 98 AEC used or not 2 Filtration 8 Image receptor used – FS, CR, DR 94

UK – Submitting the data Data were accepted in any format – paper and computer files Most were emailed Using a spreadsheet for the data

UK – Quality assurance of submitted data One person entered the data into NPDD A second person checked Statistical analysis for each set of data Key parameters – dose, age, patient weight, kVp, filtration, mAs Mean, standard deviation, sample size, and min and max were calculated Outliers were investigated

UK – Selection of data for analysis For a given room and procedure At least 10 patients Patient size Adults National protocol Sample mean weight in range 65 to 75 kg Patients in range 50 to 90 kg Children - UK paediatric data in NPDD about 3% Large variation in size between new born & 15 y Adjusting doses to 5 standard-sized children 0, 1, 5, 10 15 years Based on thickness of body part being x-rayed

UK – Deriving national DRLs Derived for those exams and procedures where dose measurements on adult patients are available from a sufficiently large sample size to be representative of national practice At least: 10 hospitals; 20 rooms; and 100 patients DRL values are based on rounded 3rd quartile values for the distributions of room mean doses for a given exam or procedure

UK – last cycle, Jan 2006 to Dec 2010 320 Hospitals ~ ¼ of hospitals and clinic with X-ray facilities Dose data For single radiographs 165 000 ESAK values 185 000 KAP values For complete examinations 221 000 KAP values 146 000 fluoroscopy times No. of radiograph data increased significantly over previous cycle About 96% of ESAK values were calculated, 4% using TLD

UK – numbers of data used in updating the DRLs ESD data per radiograph: Projection No. Hospitals No. Rooms No. Patients Abdomen AP 70 167 12 000 Chest PA 95 285 43 500 Lumbar Spine AP 80 192 5 300 Pelvis AP 84 204 9000 KAP data per radiograph: Projection No. Hospitals No. Rooms No. Patients Abdomen AP 78 188 17 800 Chest PA 162 433 110 500 Lumbar Spine AP 101 206 5 500 Pelvis AP 144 305 19 000

UK – national DRLs 38 diagnostic X-ray exams on adults 7 types of interventional procedures on adults 3 types of X-ray exams on children

Australia Very large country – long distances between hospitals Web based approach to establishing and using DRLs Started with CT only

Australia – Gathering the data – Who? ARPANSA (Federal Regulatory Body) But in consultation with: Royal Australian & New Zealand College of Radiology Australian Institute of Radiography Australasian College of Physical Scientists & Engineers in Medicine Australian & New Zealand Society of Nuclear Medicine Department of Health and Aging State and Territory radiation protection regulators

Australia – Gathering the data – How? Online survey Accessed via ARPANSA web page http://www.arpansa.gov.au Participants (CT practices) have to register online first Contact details CT scanner details Once registered, access to data entry sections

Australia – Gathering the data – What? 6 common CT examinations CT Head CT Neck CT Chest CT AbdoPelvis CT ChestAbdoPelvis CT Lumbar Spine 3 age groups Adults (15+ years) Children (5-14 years) Baby/infant (0-4 years)

But what about scan differences? ARPANSA defined the scan margins for each examination Facility scan had to fall within those margins to be included in the survey

E.g. AbdoPelvis Scan region is within the red lines Gives examples Above diaphragm to below symphysis pubis Gives examples Oncology, trauma, renal colic, abdominal pain, other pathology Volume based vs clinical purpose??

E.g. Chest Scan region is within the red lines Gives examples Lung apices to adrenal glands Gives examples Mediastinal, pleural, pulmonary pathology, oncology Volume based vs clinical purpose?? No HRCT

Australia – Examination data For each examination: Technical parameter data on protocol settings used on the CT scanner, including: kVp, starting mAs, pitch If contrast media was used If dose modulation was used Rotation time Number of phases Helical or axial acquisition Detector configuration Reconstruction slice width, Reconstruction algorithm/kernel Scan field of view, Beam shaping filter Noise index For all parameters, online help was given, and the entered value had to be within defined limits

Australia – Patient dose data Basic dose data from 20 patients on the same CT scanner Average CTDIvol for the examination Total Dose Length Product (DLP) for the exam Patient weight (kg) Dose metrics from the scanner console display – not measured Help given for exams with multiple runs – separate scans, multiple phases A survey is based on a calendar year Dose data are able to be input in several stages

Australia – Reporting back For each set of data submitted to the National DRL Database A Practice Reference Level was calculated (median), specific to: Examination Age group CT scanner used A comparison made with national DRL Recommendation back to the CT facility

Australia – DRLs – what has been achieved? ~ 800 CT scanners ~ 3 000 000 CT examinations per year At the end of 2011, there were: 80 registered practices in NDRLD 51 practices contributed 255 exam surveys of ≥ 10 patients 4700 patients At the end of 2012, there were: 173 registered practices in NDRLD 94 practices contributed 553 exam surveys of ≥ 10 patients 10 100 patients

Australia – growth in participation

Australia – DRLs CT national DRLs established in 2012 3 age groupings Volume based rather than exam purpose All patient weights used No selection on basis of weight

Summary Two approaches UK Australia Well established with good participation rate 4 review cycles completed Australia Early days, low participation CT only Pragmatic approach on some issues Dosimetry Age groups Patient weight