radiation in paediatric emergency medicine what is the risk? what are other options? what do we tell...

Radiation in Paediatric Radiation in Paediatric Emergency Medicine Emergency Medicine What is the risk?What are other options?What do we tell families?

Gavin Burgess, R5 PEM

Grand Rounds 25 September 2008

CT scan usage in Paediatric CT scan usage in Paediatric Emergency MedicineEmergency Medicine

CT has been around for 30 years Technology has progressed from

single slice scanning to the modern, multichannel scanner that produces very high-quality images in a short time (5-10s)

This generates more radiation exposure for patients

There is no “penalty” for too much radiation as with a plain film

Some terms…..Some terms…..

Roentgens the pure EXPOSURE level

Gray the ABSORBED radiation dose

Sievert the “EFFECTIVE” radiation takes into account the radiosensitivity of

tissue good measure of risk of developing cancer this dose is much higher in children, inversely

proportional to age background exposure ~ 3mSv/year

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Some terms.....Some terms..... Sieverts are higher in children:

less tissue to absorb radiation in front of organs

tissue with high turnover/more radiosensitive more time to develop cancer

Radiation a function of both mA and time, ie mAs (milliAmperes per second)

What are the risks?What are the risks? Follow up studies from Hiroshima and

Nagasaki…… >100mSv strong evidence for significant risk 50-100mSv good evidence for increased risk 10-50mSv reasonable evidence for increased risk

no level with no increased risk Risk of childhood cancer from fetal

irradiation. Doll, R, et al Br J Radiol 1997;70:130-139

In the fetus, 6% increased risk of cancer in childhood per Sv received in utero

What are the risks?What are the risks? Estimating risks of radiation-induced

fatal cancer from pediatric CT Brenner, D, et al Am J Roentgen 2001;176:289-

296 CTs of head and abdomen CTs on children still performed with adult settings

(400-500mAs) Helical CTs generate more energy Females more at risk (thyroid, bowel) 0.3 vs 0.15 M=F for brain tumours In 2001, 700 deaths due to CT head, 1800 due to

CT abdomen in US Paediatric scans = 4% of CTs, but 20% of deaths

due to radiation Reductions of 30-50% in mAs, would reduce

cancer by 30-50%

What are the risks?What are the risks?

What are the risks?What are the risks? Estimating risks of radiation-induced

fatal cancer from pediatric CT 600 000 abdo + head CTs in children < 15y, 500

deaths/PA But, of the 600 000 <15y getting CTs, 140 000

will die of cancer – 500 = 0.35% increase in risk CT will likely result in increased lifetime risk vs

adult CT due to increased dose per mAs AND increased lifetime risk per dose

Copyright © 2006 by the American Roentgen Ray Society

Brenner, D. J. et al. Am. J. Roentgenol. 2001;176:289-296

--Graph shows lifetime attributable cancer mortality risks per unit dose as a function of age at a single acute exposure as estimated by National Academy of Sciences BEIR V (Biological Effects of

lonizing Radiations) committee (solid line) [12] and in ICRP (International Commission on Radiological Protection) report 60 (dotted line) [13]



--Estimated age-dependent CT doses to various organs



--Breakdown by cancer type of estimated lifetime CT-attributable cancer mortality risks as a function of age

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What are the risks?What are the risks? Pediatric CT. Practical approach to

diminish radiation dose. Frush Pediatr Radiol 2002;32:714-17

“ALARA” concept - as low as reasonably achievable

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What are the risks?What are the risks? Cancer risks following diagnostic and

therapeutic radiation exposure in children

Kleinerman Pediatr Radiol 2006 36 (suppl 2):121-125

data derived from studies of children irradiated for benign disease

in order of risk: thyroid, breast, bone marrow, brain and skin

expressed as excess relative risk or excess absolute risk

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Thyroid EAR 4.4 strong linear dose-response up to 0.1 Gy persists up to 30 years females 3 times higher than males

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Breast ERR 1/7 thyroid linear response persists for 50 years

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Leukaemia ERR 5 in childhood

Brain tumours ERR 2.7 (benign and malignant) decreased with decreasing age remains elevated up to 30 years

Non-melanotic skin cancer ERR 0.7-1.6 UV radiation impact

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Diagnostic imaging few studies OR from 0.7-2

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What are the risks?What are the risks? Thyroid dose from common head and

neck CT examinations in children: is there an excess risk for thyroid cancer induction?

Mazonakis Eur Radiol (2007) 17: 1352-57CT examination Risk (×10−6) Brain, sequential 16–21 Brain, spiral 36–65 Sinuses, spiral 20–36 Inner ear, sequential 5–8 Inner ear, spiral 4–7 Neck, spiral 114–390

Lifetime risk for thyroid cancer induction from head and neck CT

If the thyroid is included in scanned area, the risk is 114-390, if not, the risk is 4-65

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Increasing utilization in the Increasing utilization in the Paediatric EmergencyPaediatric Emergency

Increasing utilisation of CT in the pediatric emergency department, 2000-2006

Broder, J. et al. Emerg Radiol (2007) 14: 227-232 6073 scans on 4138 patients 78932 patients in the ED Acuity unchanged 2% increase in visits Head 23%, cervical spine 366%, chest 435%,

abdominal 49%, misc. 96% Biggest jump: 13-17y group Does this lead to improved outcomes?


ACH: 1600 CT’s from the ED 2007 trauma stats 2007 (Dr Grant, ACH

trauma register) n=73

Radiology: yield on abdominal CT around 10% at ACH

42 abdominal, 41 pelvic,58 head scans

percentage of total patients


CT scan and the paediatric trauma - are we overdoing it?

Fenton J Pediatr Surg (2004) 39:1877-1881 1653 TTL activations 1999-2003 1422 (86%) CT’d for a total of 2361 scans At the level 1: 1068 scans,

605 head, normal in 62%, 437 (40%) abdominal 75% normal, 26 chest, 36% normal



Fenton J Pediatr Surg (2004) 39:1877-1881 transferred without scans: 835 total, 329

(39%) subsequently scanned 302 head (56%), normal 39%, 217 abdominal (40%), normal 72%, 21 chest, 52% normal



Fenton J Pediatr Surg (2004) 39:1877-1881 transferred with scans: 409 scanned (689

scans), head 401, 34% normal, abdominal 243, 50% normal, chest 45, 40% normal

9 patients (2%) with scans, taken to the OR at referring hospital



Fenton J Pediatr Surg (2004) 39:1877-1881 repeat scans in transferred patients: 9%

reimaged. Head most commonly repeated 53 (83%), with

89% showing abnormalities 10 repeat abdominal scans, 40% normal 63 were transferred and rescanned, 13 went to

OR How many undergo scans and aren’t

transferred?



Fenton J Pediatr Surg (2004) 39:1877-1881 897 had abdominal CT = 19 per month 33% had abnormality 5% went to OR (45) =1 per month

CT for evaluation of mild to moderate pediatric trauma: Are we overusing it?

Jindal 2002 World J Surg 26: 13-16 108 patientst, matched to adults. ISS mean 3.4 significantly more scans, no more injuries

identified


And then....... Whole body imaging in blunt

multisystem trauma patients without obvious signs of injury.

Salim Arch Surg 2006;141:468-475 significant mechanism, no visible evidence of

injury, haemodynamically stable, normal or abnormal neurological exam. n =1000

pan-scan 408 unevaluable, 592 scanned based on

mechanism alone


C-spine - 54 abnormalities, but no plain film comparisons

4 abnormal CT chest with normal CXR, 2 aorta injuries identified

83 abdominal injuries on CT, 22 underwent laparotomy

“mechanism” alone: 20% (of 592) had management adjustment based on panscan

discharge 16% 4% had further interventions (8 to OR - 1.3%)

CT false negative rate of 0.22% most literature quotes rates 13-15% conclusion: “we’ll continue to scan

everything”


Should helical CT scanning of the thoracic cavity replace the conventional CXR as a primary assessment tool in pediatric trauma? An efficacy and cost analysis

Renton J Ped Surg 2003 5:793-797 n = 45 thoracic injury, pathological findings on exam,

high force impact on chest wall 40% not identified on CXR 12 contusions, 6

haemothoraces, 4 pneumothoraces, 4 wide mediastinums, 2 rib fractures, 1 diapragm rupture, 1 aortic injury


8 had a change in management age, sex, ISS, mechanism and indication for

chest CT could not predict differences between CT and CXR (P<0.05)

increased costs $180 000 routine CXR provides good information, CT

should be reserved for selected cases

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C-spineC-spine

C-spinesC-spines NEXUS trial:

the five criteria - no posterior midline tenderness, no focal deficits, normal level of consciousness, no intoxication, no other painful, distracting injury.

paediatric subset review - small numbers, but no cases missed

cautious endorsement in paediatrics

C-spineC-spine the Canadian C-spine rule for

radiography in alert and stable trauma patients

Steill JAMA 2001 286;15:1841-48 >16y 3 questions:

high risk patients (age, mechanism, paraesthesias need Xrays)

low risk characteristics (simple rear end MVC, sitting in ED, ambulation at any time,delayed onset of neck pain, no midline tenderness

ability to rotate neck to 45% despite pain

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C-spinesC-spines dangerous mechanisms:

fall >1m or 5 stairs, axial load, high speed (>100km/h), ejection, rollover, bicycle

simple rear end does not include: pushed into oncoming traffic, hit by bus or truck,rollover, high speed vehicle

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C-spineC-spine The pediatric trauma C-spine: is the

odontoid view necessary? Buhs J Pediatr Surg 2000;35:994-7

n=51, none of the open mouth views provided diagnosis

potential problems in <8 year group (frightened, squirm, multiple shots, stenting mouth open impractical and dangerous

CT if tender or neurological deficit

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C-spineC-spine Is the open mouth odontoid view

necessary in children under 5 years? Swischuk Pediatr Radiol 2000; 30:186-89

surveyed 432 radiologists on missed C-spine injuries

missed fracture rate 0.007 per year per radiologist

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C-spineC-spine CT vs plain radiographs for evaluation

of c-spine injury in young children: do benefits outweigh the risks?

Jimenez Pediatr Radiol 2008 38:635-44 By NEXUS, the incident rate is 0.98% using phantoms, 1 year old received 200 times

and the 5 year old phantom received 90 times the radiation from CT vs conventional radiation (with 7 views)

the scattered radiation received by the thyroid during head CT was larger than 7 c-spine views

ERR 0.7 from c-spine CT

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C-spineC-spine Use of helical CT for imaging the

pediatric cervical spine. Adelgais Acad Emerg Med 2004 Mar 11(3): 228-

36 poor screening tool in blunt trauma increased radiation without a reduction in

sedation use or length of stay

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C-spineC-spine Cervical spine trauma in children

under 5 years: productivity of CT Hernandez, Swischuk Emergency Radiology

2004 10: 176-8 n=606 75% cleared clinically and with films 4 patients with fracture/dislocation, all seen

on lateral suggest: 1) normal lateral, don’t CT even if

poor odontoid view 2) if poor visualisation of lower c-spine and no

significant mechanism, no CT 3)otherwise CT (mechanism, LOC)

C-spinesC-spines

American Association of Neurological Surgeons and the Congress of Neurological Surgeons 2003

insufficient evidence for treatment or

diagnostic standards or guidelines

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C-spineC-spine But......

• if NEXUS criteria can be met AND the child is >9 years, discretion can be used

• <9 years, radiographs recommended (only AP and lateral)

• >9 years, not meeting NEXUS, radiographs recommended AP, lateral and odontoid

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C-spineC-spine There may be some evidence for

dynamic flex-ex views. There is no evidence for static radiographs AANS and CNS recommend neither static films nor fluoroscopy

CT has limited use for BONY anatomy, but not recommended to “clear the C-spine”. MRI may be need for the < 9 year age group

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C-spineC-spine

patients who are asymptomatic should be cleared clinically or with plain films

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Facial fracturesFacial fractures

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Facial fracturesFacial fractures Pediatric facial fractures: children are

not just small adults Alcala-Galiano Radiographics 2008

Mar;28(2):441-61 facial fractures need to be managed correctly fractures are difficult to detect on plain film fractures tend to occur in predictable places ultrasound can be used as a screen

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AbdomenAbdomen

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AbdomenAbdomen Pediatric multidetector CT using tube

current modulation and a patient image gallery

Honnef Acta Radiologica 2008 49 (4) 475-83 Reduced radiation with preserved image

quality

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AbdomenAbdomen A clinical decision tool to identify

children at low risk for appendicitis Kharbanda Pediatrics 2005;116:709-16

decision rule (logistic regression): nausea=2, RLQ pain=2, migration of pain=1,

difficulty walking=1, absolute neutrophil count >6.75=6

<5 points: sens 96.3%, NPR 95.65% decision rule (recursive partitioning) for low risk: ANC <6.75, no nausea (emesis/anorexia) no

maximal RLQ tenderness (sens 98.1, NPR 97.5%)

• don’t CT

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AbdomenAbdomen Peer assessment of pediatric

surgeons for potential risks of radiation exposure from CT scans

Rice J Pediatr Surg 2007 Jul;42(7)1157-64 estimated dose discrepancy for CT vs CXR risks not discussed with patients

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AbdomenAbdomen Outcomes of management in stable

children with intraabbdominal free fluid without solid organ injury after blunt trauma injury

Venkatesh J Trauma 2007 Jan; 62(1):216-220 normal exam and small amount of fluid, no

intervention necessary, increasing pain and moderate to large amounts of fluid need intervention

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Localised = limited to 2 or fewer quadrants

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AbdomenAbdomen Blunt bowel and mesenteric injuries

in children: do nonspecific CT findings reliably identify these injuries?

Peters Pediatr Crit Care Med 2006 Nov; 7(6):551-6

risk of BBMI increased with increased number of findings

32 had surgically proven BBMI, 12 had no findings on CT

n=2114 complications appeared to occur independent

of the time to surgical intervention

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AbdomenAbdomen Rate and prediction of traumatic

injuries detected by abdominal CT scan in intubated children

Flood J Trauma 2006 Aug;61(2):340-5 abnormal abdominal exam and abnormal

LFT’s predicted abnormal CT Common tasks and problems in

paediatric trauma radiology Partan Eur J Radiology 2003 Oct; 48(1):103-124

Europeans favour US and are confident in it’s use in trauma

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What are other options?What are other options?

What are other options?What are other options? Some strategies:

• limit the number is the CT necessary? what other modalities can I use? (US, plain

film etc)• technique

reduce the number (pre/post contrast) limit the area scanned breast shielding adjust the settings depending on the clinical

question, size of the child, area scanned new scanners that automatically adjust

settings

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What are other options?What are other options? Sonographic evaluation of the child

with lower abdominal or pelvic pain Strouse Radiol Clin N Am 2006 44:911-23

Appendix: experienced operator, graded compression try to visualise “normal” appendix, rare often not visualised, however patient’s reaction to

scanning is an important clue abnormal >7mm, not compressible CT remains more reliable, at the expense of

increased rates of CT for children with less convincing histories and physical exams

CT is better for perforated appendices

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What are other options?What are other options? Intussusception:

good for ileocolic disease usually right sided, however a full scan of the

abdomen is needed if not identified here reduction can be monitored with US

Duplication cysts: readily seen oesphagus or terminal ileum, may occur

anywhere Inflammatory bowel disease:

wall thickening, hyperaemia used longitudinally in Europe to monitor Crohns

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What are other options?What are other options? Meckel diverticulum and HSP:

can help identify inflamed tissue, intussusception, lead points and hyperaemia

Small bowel obstruction: visualise dilated loops and collapsed loops after

the obstruction Renal diseases

impacted calculi, dilated collecting system urachal cyst

Gynaecological diseases haematocolpos ruptured cyst ovarian neoplasia ectopic pregnancy and tubo-ovarian abscess torsion

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What are other options?What are other options? Ultrasonography of suspected

appendicitis in children: a new ultrasonographic classification

Wiersma Abstracts Radiological Society of North America 93th congress 2007

categorised into 4 groups normal appendix appendix not seen with no secondary signs of

appendicitis (inflamed fat or fluid) appendix not seen but secondary signs inflamed appendix seen sensitivity 99%, specificity 97%, PPV 93%, NPV

99%

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What do we tell families?What do we tell families?

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What do we tell families?What do we tell families? Informing parents about CT radiation

exposure in children: it’s OK to tell them

Larson AJR 2007 Mar;189:271-75 Non-emergent CT, n=100 66% believed radiation was used, 99% post

survey 13% believed CT increased cancer risk vs 86%

after 23% were more willing to observe if this was

as good an option as CT no-one refused CT handout took 5min to read

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Figure 1

In Summary....In Summary.... Although the risk is around 1 in 500,

this represents an increase of >0.5% over baseline lifetime cancer risk

This does not include non-fatal cancer there are other modalities, in some

instances the literature is sparse the parents should be informed it is worth asking the radiologist if the

scanner will be using paediatric settings

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In Summary....In Summary.... CXR dose: 0.02 mSv 3 hour plane flight: 0.015 mSv

radiation in paediatric emergency medicine what is the risk? what are other options? what do we tell...

Documents

risks of radiation

radiation exposure

increased risk of cancer

fatal cancer

ct head

j roentgen

ct abdomen

cts of head