PEDIATRIC CT SCAN WHERE ARE WE, DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW?

Transcription

1 PEDIATRIC CT SCAN WHERE ARE WE, DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? Carla Conceição, MD Neuroradiology Department Hospital D. Estefânia, CHLC Hospital da Luz

2 PEDIATRIC CT SCAN WHERE ARE WE CT numbers/sources of exposure, facts about CT numbers in children DO WE REALLY KNOW THE RISKS biological effects, risk in pediatric radiology, some studies AND WHICH WAY TO FOLLOW? reference levels TAKE HOME MESSAGES

3 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? MODERN MEDICINE ADVANCED TECHNOLOGIES DIAGNOSIS, TREATMENT AND FOLLOW- UP The development and of CT imaging led to an increase accuracy and in an growth in the number of carried out in children since the late 90s, especially since 2000.

4 3 Fevereiro º uso intencional do RX para fins médicos Dr. Gilman Frost Prof. Edwin Frost REVISTA SCIENCE On January 19, 1896, young Eddie McCarthy of Hanover fell while ska]ng on the Connec]cut River and fractured his le^ wrist.

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6 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW?

7 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? Sources of Radia]on Exposure Non Medical Medical Medical Non CT Medical Medical CT Non Medical 3.6 msv annual average dose 6.3 msv

8 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? FACTS ABOUT CT IN CHILDREN 7 million / year in children (USA, 10% of all CT) % in pediatric CT from % of children have 3 or more CT scans 33% are performed in children under age of 10 Up to 31% of pediatric body CT scans are mul]phase METTLER, F.A., et al., J. Radiol. Prot., 2000; 20 4:

9 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? FACTS ABOUT CT IN CHILDREN FACTS ABOUT CT IN CHILDREN 33% - 50% of the examina]ons have ques]onable indica]ons Many are conducted using inappropriate technical factors. The same CT protocol used for children and adults will result in a higher effec]ve dose to children. Head CT adult 1,5 msv children 6 msv Frush, RSNA, 2006 Berenner Pediatr. Radiol, 2002; 32: Oikarinen et al. Eur Radiol, 2009; 19: Huda et al. Radiology, 1997, 203:417-22

10 Exam type Head unadjusted (200 mas) Head adjusted (100 mas) Abdomen unadjusted (200 mas) Abdomen adjusted (50 mas) Relevant organ absorbed organ doses (mgy) effec]ve doses (msv) Brain Brain Stomach Stomach " NATIONAL CANCER INSTITUTE, RadiaRon Risks and Pediatric Computed Tomography (CT): A Guide for Health Care Providers (2008) risks- pediatric- CT

11 Male, 14 years Pediatric Hospital HDE Adult Hospital HSJ KVp 130 mas 54 / 70 KVp 120 mas

12 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? DETERMINISTIC BIOLOGICAL EFFECTS STOCHASTIC effects Threshold (1,20-3 Gy) Severity increases with dose Skin burns, cataract, hair fall and hereditary effects No threshold for Probability increases with dose Cancer, hereditary effects

13 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? BIOLOGICAL EFFECTS STOCHASTIC What are the risks from medical in children? What is the real CANCER risk? COMPLEX AND MUCH DEBATED SUBJECT Things we know well Things we don t know so well

14 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? Higher radia]on sensi]vity cells divide more rapidly organs may be less More suscep]ble to biological effects / radia]on damage + females and younger ages Dose is considered cumula]ve over the years Longer life expectancy to manifest the bioeffects Things we know well

15 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? How low level radia]on affects the risk of cancer below msv, especially below 10 msv The literature on low level radia]on is large and confusing data support increased or no risk of cancer only a few of these data are from imaging exposure Things we don t know so well

16 US Na]onal Academy of Science Biological Effects of Ionizing Radia]on Report VII A comprehensive review of the available biological and biophysical data supports a linear no threshold (LNT) risk model that the risk of cancer proceeds in a linear fashion at lower doses without a threshold and that the smallest dose has the poten@al to cause a small increase in risk to humans

17 US Na]onal Academy of Science Biological Effects of Ionizing Radia]on Report VII an excess life]me cancer risk of 1 case in 1000 popula@on for a standardized popula@on receiving 10- msv exposure. There is an inverse exponen]al rela]onship between es@mated risk and age of exposure. Age of exposure male Cases per 1000 female 10 y 1,4 2,6 5 y 1,8 3,3

18 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? The risk of developing cancer should be evaluated against the risk for developing cancer in the The overall risk of a cancer death over a person s life]me is es]mated to be 20% (200 per 1.000, without medical radia@on exposure) The addi]onal risk from a single CT scan is controversial, but es]mated to be a frac]on of this risk ( %) Frush D, et al, CT and RadiaRon Safety: Content for Community Radiologists

19 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? INDIVIDUAL RISKS COLLECTIVE/PUBLIC- HEALTH RISKS The INDIVIDUAL RISKS are small, so the benefit / risk ra@o for any child will generally be very large but the exposed popula@on is large Even a very small individual radia@on risk, when mul@plied by a large (and increasing) number of children, is likely to produce a significant long- term PUBLIC HEALTH CONCERN

20 Mark S Pearce et al; Lancet 2012; 380: OBJECTIVE: assess the excess risk of leukaemia and brain tumours ager CT scans in a cohort of children and young adults Retrospec@ve study Pa@ents younger than 22 years of age submihed to CT 1985 and hospitals from Na@onal Health Service (NHS) in Great Britain Data for cancer incidence, mortality and loss to follow- up from the NHS Central Registry from Jan 1, 1985, to Dec 31, Es]mated absorbed brain and red bone marrow doses per CT scan in mgy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson rela@ve risk models

21 Mark S Pearce et al; Lancet 2012; 380: RESULTS: During follow- up, 74 of pa@ents were diagnosed with leukaemia 135 of pa@ents were diagnosed with brain tumours Cumula@ve doses 50 mgy might almost triple the risk of leukaemia 60 mgy might triple the risk of brain cancer Cumula@ve absolute risks are small (because these cancers are rela@vely rare) in the 10 years ager the first scan for pa@ents younger than 10 years 1 excess case of leukaemia and 1 excess case of brain tumor per head CT scans is es@mated to occur.

22 John D Mathews et al: BMJ 2013;346:f2360 doi: /bmj.f2360 RESULTS: Among Australians exposed to a CT scan when aged 0-19 years, cancer incidence was increased by 24% compared with the incidence in over 10 million unexposed people. The propor@onal increase in risk was evident at short intervals ager exposure and was greater for persons exposed at younger ages. By 31 December 2007, with an average follow- up of 9.5 years ager exposure, the absolute excess cancer incidence rate was 9.38 per person years at risk. Incidence rates were increased for most individual types of solid cancer, and for leukaemias, myelodysplasias, and some other lymphoid cancers.

23 Ahmed BA et al; Pediatrics 2010;126;e851 OBJECTIVE: to the doses (CEDs) from radiologic procedures for a cohort of pediatric oncology pa@ents. retrospec@ve study 150 pediatric oncology pa@ents - 5 years ager diagnosis 30 / 5 subgroups - leukemia, lymphomas, brain tumors, neuroblastomas and assorted solid tumors radiography, CT, NM studies, fluoroscopy, and interven@onal procedures CED es@mates were calculated

24 Ahmed BA et al; Pediatrics 2010;126;e851 RESULTS: Individual CED - 1 msv to 642 msv Median 61 msv Mean 113 msv 41% > 100mSv 22% > 200 msv 1,3% > 500 msv There was considerable variability between tumor subgroups + neuroblastoma (median: 213 msv [range: msv]) + lymphoma (median: 191 msv [range: msv]) - leukemia group (median: 5 msv [range: msv]) + CT e NM

25 Ahmed BA et al; Pediatrics 2010;126;e851 The Biological Effects of Ionizing Radia]on VII report US Na]onal Academy of Science If we consider a mixedgender risk factor of 2 cases per 1000 popula@on per 10 msv, then exposure to the median CED of our study cohort (61 msv) at the age of 10 might result in an excess life@me cancer risk of 1.2%. Individuals receiving 100 msv (41% of our cohort) might have an excess risk of 2%, and those receiving 200 msv (22%) might have an excess risk of 4%.

26 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? JUSTIFICATION Dra Marta Conde OPTIMIZATION Dra Alexadra Ferreira A L A R A as low as reasonably achievable

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28 Low Dose Protocol 17

29 Female, 17 years Low Dose Protocol Normal Protocol KVp 110 mas mm thickness 24 slices DLP 288 KVp 130 mas 199/260 4 mm thickness 39 slices DLP 734

30 Low Dose Protocol Normal Protocol DLP 150 DLP 515

31 Eight paediatric hospitals Training and seminars on Dose greater than 50% Wallace, et al. Proceedings of IRPA 12, Buenos Aires, 2008, FP

32 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? DIAGNOSTIC REFERENCE LEVELS as a tool for op@mizing the radia@on dose delivered to pa@ents in the course of diagnos@c and/or therapeu@c procedures. It is a level of dose reference, for a typical radiological examina@on for standard- sized pa@ents. Interna@onal Commission on Radiological Protec@on (ICRP) American College of Radiology (ACR) United Kingdom Health Protec@on Agency Interna@onal Atomic Energy Agency (IAEA) European Commission (EC)

33 WHERE ARE WE DO WE REALLY KNOW THE RISKS AND WHICH WAY TO FOLLOW? DIAGNOSTIC REFERENCE LEVELS SAFETY REPORTS SERIES No. 71; RADIATION PROTECTION IN PAEDIATRIC RADIOLOGY; VIENNA, 2012

34 TAKE HOME MESSAGES Use of medical imaging to increase, namely CT scans Risks associated with ionizing are higher for children than for adults Although clinical benefits should outweigh the small absolute risks, doses from CT scans ought to be kept as low as possible, Trained staff in radiological and pediatric imaging / Be commihed to make a change in daily prac@ce by TEAM WORK between radiologists, technologists, referring healthcare providers and parents.

35 in Paediatric Radiology L06. RadiaRon protecron in 35