Trends in examination frequency and population doses in Norway,

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1 Workshop on European Populaltion Doses from Medical Exposure, April 2012, Athens, Greece Trends in examination frequency and population doses in Norway, OLERUD H.M. 1,2, FRIBERG E.G. 1, WIDMARK A. 1,3 & ALMÉN A. 4 1 Norwegian Radiation Protection Authority, P.O.box 55, NO-1332 Østerås, Norway 2 University of Oslo, Department of Physics, P. O. Box 1048 Blindern, NO-0316 Oslo, Norway 3 Gjøvik University College, P.O Box 191, 2802 Gjøvik, Norway 4 Swedish Radiation Safety Authority, SE Stockholm, Sweden

Radiology in Norway 4,81 mill inhabitants 26 public Hospital Trusts/ 72 hospitals 8 private hospitals; 5 private trusts/ 24 institutes 600 radiologists, 2700 radiographers 30 diagnostic physicists

2 Radiology in Norway 4,81 mill inhabitants 26 public Hospital Trusts/ 72 hospitals 8 private hospitals; 5 private trusts/ 24 institutes 600 radiologists, 2700 radiographers 30 diagnostic physicists X-ray units ~ 850 (all digital) Mammography units ~ 100 (all digital) CT units ~ 130; MR units ~ 105 Interventional radiology/angiography: ~ NM centers ~ 52 gamma camera, 6 PET/CT 10 RT centers ~ 40 Linear accelerators, 5 brachy Norwegian Radiation Protection Authority Since 1939 (1993) Staff: ~ 100 Totally 40 enterprises and 104 clinics licensed to do X-ray (advanced Xray, NM, RT) Dentists, chiropractics, bone densitometry, veterinarian, X-ray in primary health care only object to notification

3 European Commission RADIATION PROTECTION No 154 DD Report 2 European Guidance on Estimating Population Doses from Medical X-ray procedures have been published as an EC Report in the RADIATION PROTECTION series. The document is available as a pdf files on the EC DGTREN Radiation Protection website Annex 1 DD Report 1 Review of recent national surveys of population exposure from medical X-rays in Europe Annex 2 DD Report 1 (a) Review of national surveys of population exposure from nuclear medicine examinations in eight European countries

4 Exam type or category % of total frequency* % of total S* The Top 20 Exams Plain film radiography 1. Chest/thorax Cervical spine Thoracic spine Lumbar spine (inc. LSJ) Mammography Abdomen Pelvis & hip Radiography/Fluoroscopy 8. Ba meal Ba enema Ba follow IVU Cardiac angiography All angiography CT 13. CT head CT neck CT chest CT spine CT abdomen CT pelvis CT trunk All CT Interventional 20. PTCA All interventional TOTAL

5 How to estimate examination frequency EC RP report 154: An x-ray examination or interventional procedure is defined as one or a series of x-ray exposures of one anatomical region/organ/ organ system, using a single imaging modality (radiography/fluoroscopy or CT), needed to answer a specific diagnostic problem or clinical question, during one visit to the radiology department, hospital or clinic. Annual numbers of examinations obtained directly by questionnaires sent to all Norwegian hospitals, clinics and practices No scaling necessary to cover the whole country. The code system developed by the Norwegian College of Radiology used both for activity analysis and reimbursement. The number of codes was gathered from the RIS systems in the departments The codes had to be interpreted into actual numbers of examinations double-counting, particularly for examinations of double-sided organs had to be adjusted for examinations which consisted of several contrast series that would create more than one radiological code in the system.

6 The Norwegian radiological code system The examination/procedure part Consists of five elements: Modality Location Procedure Side Additional Modality Location Procedure Side Additional Modality: Location: Procedure: Side: Additional: C T A B I V Modality Location Procedure Side Additional R G G E S X-rays, US, CT, MRI The examined organ, anatomical location, organ system or region Specifies the examination Left, rigth, bilateral Information for local use Modality, location and procedure are mandatory We also survey non-ionising medical applications

Dosimetric approach Radiography and fluoroscopy Mammography CT P KA = K a ( A)dA 1 50mm ( )dz

quantities are a source for establishing national average dose figures, and for revising the

stored in the DICOM header, and are transferred to the PACS dose collection will be easier in

7 Dosimetric approach Radiography and fluoroscopy Mammography CT P KA = K a ( A)dA 1 50mm ( )dz A C K = + K a z N T 50mm ESD DAP CTDI w CTDI vol DLP i i D air MGD These practical dose quantities are a source for establishing national average dose figures, and for revising the Diagnostic Reference Levels for selected examinations These are according to IEC standards stored in the DICOM header, and are transferred to the PACS dose collection will be easier in the future Conversion coefficients E/ESD, E/DAP, E/DLP are published for estimates of the effective dose

Collection of local DRL s in Norway 2006-2009 Local DRL=representative dose for a: Given type of X-ray/CT examination In a certain X-ray/CT room in a certain hospital For a common clinical indication

8 Collection of local DRL s in Norway Local DRL=representative dose for a: Given type of X-ray/CT examination In a certain X-ray/CT room in a certain hospital For a common clinical indication Based on the mean value of the dose to 20 normal weight patients EU: 70 ± 5 kg Norway: kg Totally 825 representative doses were collected Radiography and fluoroscopy: 442 CT: 383 In order to establish national dose figures to be used in collective effective dose estimates we try to at least have measurements in >10 rooms Focus on the RP154 TOP20, in addition some new CT procedures such as CT colonoscopy, CT urography, CT angiography

9 The radiological examination frequency 2008 Modality Total number of examination Exams per 1000 inhabitant Xray CT Ultrasound MR Total mill radiological examinations (900 per 1000 inhabitant) CT constitute 21% of all radiological examinations

10 Trends in the examination frequency Procentage of total number, % The total frequency has been unchanged since 2002: 900 per 1000 inhabitants (dental examinations excluded) RG CT US MR RG decreases, CT and MR are doubled, US stable

11 Trends in doses in conventional 2D exams TOP20 Examination type Effective dose (msv) 2002 Effective dose (msv) Chest/Thorax 0,1 0,07-0,03 2 Cervical spine 0,2 0,07-0,13 3 Thoracic spine 0,7 0,49-0,21 4 Lumbar spine (inc. LSJ) 1,4 1,4 5 Mammography 0,1 0,15 +0,05 6 Abdomen 3,6 1,2-2,4 7 Pelvis&hip 0,6 0,4-0,2 Changes (msv) Barium meal 5,1 5,2 +0,1 9 Barium enema 12,5 7,3-5,2 10 Barium follow-trhough 2,2 4,8 +2,6 11 Intravenious Urography 3,8 2,4-1,4 12 Cardiac angiography 9,4 7,6-1,8 Many radiography/fluoroscopy procedures involves lower doses today

12 Trends in patient doses in CT and PTCA TOP20 Examination type Effective dose (msv) 2002 Effective dose (msv) CT Head 1,8 1,5-0,3 14 CT neck 3,4 2,6-0,8 15 CT Chest 11,5 4,7-6,8 Changes (msv) CT spine 4,3 5,6 +1,3 17 CT Abdomen 12,6 10-2,6 18 CT Pelvis 9,3 7, PTCA 9, ,1 Most CT procedures involves lower doses today

13 Explainations for the trends in CT doses CT doses should increase because: Overbeaming High spatial resolution claims more dose if the noise level in images are to be maintained Larger scan volume per CT serie More fast CT series to follow different contrast phases CT doses should decrease because: More sensitive detectors Use of pitch>1 Technical development standardisation Tube current modulation/aec Focus on quality control and optimisation Development of new CT protocols is a multidisciplinary task The use of diagnostic reference levels (DRL s) Regulations: authorization, inspection and audits QA regulations

14 TOP20 Examination type Number of exams in NORWAY CED, S E (mansv) Uncertainty % 1 Chest/Thorax Cervical spine , Thoracic spine Lumbar spine (inc. LSJ) Mammography Abdomen Pelvis&hip Barium meal Barium enema Barium follow-trhough Intravenious Urography Cardiac angiography CT Head CT neck CT Chest CT spine CT Abdomen CT Pelvis PTCA Total

15 Trends in frequency and collective effective dose in Norway Collective effective dose (CED): 4475 mansv (1.1 msv/inhabitant) - CT contributed to 79% of CED in 2008 down x 2 -steady x 2 RG CT Examination frequency CED, mansv

16 Examination type Examination frequency in Norway in European perspective Relative to European mean value CT Pelvis 4,9 CT Abdomen 1,5 CT Chest 1,3 Cardiac angiography 1,3 PTCA 1,3 Mammography 1,2 CT Head 1,1 Pelvis&hip 1,1 CT neck 1 Barium meal 0,9 Chest/Thorax 0,8 Cervicalcolumna 0,6 Lumbar spine (inc. LSJ) 0,6 IVU 0,6 Barium followtrhough 0,6 Thoracic spine 0,6 Barium enema 0,6 CT spine 0,5 Notice the relative frequency of some radiological examinations in Norway compared with twelve other European countries: We do more CT s and less conventional 2D examinations Some of the deviations may be explained by differences in interpretation of the examination definition For example CT pelvis

17 The contribution to collective effective dose from Xray and CT to the total in some European counties (%) CT RG Iceland Norw ay Belgium Netherland Sw eden Denmark UK France Germany Finland Lithuania Sw itzerland As reported at IRPA 12 in Helsinki; watch

18 The distribution of medical exposures in Norway anno % 3 % 5 % 80 % 10 % Dental X-ray X-ray Rad and Fluor Nuclear medicine Angiography CT Visit our two poster presentations from NORWAY: Olerud&Almen. Trends in the choice of Xray, CT and MR over 20 years in Norwegian radiology for examinations of head and spine (P3) Unhjem&Friberg. Examination frequency and population dose from nuclear medicine (NM) in Norway 2008 (P23)

19 Organ specific trends in examination frequency example SPINE It may happen that the examination frequency decreases as well! To understand the trends survey all modalities!

20 Greetings from Norway in springtime

Introduction to RP154 methology for population dose estimates

Introduction to RP154 methology for population dose estimates Hilde M. Olerud (NRPA, NO) DDM 1 & DDM2 WP 3 Contract ENER/2010/NUCL/SI2.581237 Study on European Population Doses from Medical Exposure (Dose