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WHICH ONE DOESN’T FIT?
THAT’S MORE LIKE IT.
RADIATION DOSAGE
CXR= 1/100 Background Radiation
Background Radiation/yr
Sea level = 3 milli Sieverts
100 milli Rem = 1 milli Sievert
LARGEST STUDY GROUP
OF
RADIATION HEALTH EFFECTS IS THE HIROSHIMA
BOMB SURVIVORS
• There is an excess cancer risk seen in
large groups of Hiroshima survivors.
• Doses from 50 to 100 milli Sieverts can
produce cancer in humans.
TYPICAL EFFECTIVE DOSE VALUES
Imaging Examination
(mSv)
LINEAR – NO THRESHOLD RISK CURVE
CT DOSE IS IN RANGE OF
HIROSHIMA BOMB SURVIVORS DOSE
There is an excess cancer risk seen in
large groups of Hiroshima survivors.
Statistically CT scans WOULD increase risk of
cancer.
PERSPECTIVE
300/1000 die normally from cancer by age 80.
301/1000 of CT patients would die from cancer.
So out of our 1 million people 300,000 would
get cancer by normal risk.. and the 1 million
receiving a CT would produce a cancer group
of 301,000.
TAKE HOME MESSAGE
 Benefit of diagnostic information from CT Scan is far greater
that radiation risk, if there is an appropriate indication
 ALARA : Pediatric Radiology: Image Gently
 Be especially careful in children, pregnant patients, thoracic
imaging in young women, Repetitive scans
 Whole body CT screening is inappropriate
 Lung cancer screening –value ? Data being released