[ RadSafe ] CT scans dangerous?

John Jacobus crispy_bird at yahoo.com
Thu Nov 8 07:03:51 CST 2007


Here is one example of CT doses from a 64-slice unit,
but it may not be typical of static imaging, such as a
head or abdoment CT scan, as in involves a cardiac
protocol.  Also, I think that erred in my previous
post.  I don't think that 126 slice CT scanners made
it into the market place.

Radiation Dose from Contemporary Cardiothoracic
Multidetector CT Protocols with an Anthropomorphic
Female Phantom: Implications for Cancer Induction.

Hurwitz LM, Reiman RE, Yoshizumi TT, Goodman PC,
Toncheva G, Nguyen G, Lowry C.
(Department of Radiology, Duke University Medical
Center, Box 3808, Durham, NC 27710.)

Radiology. 2007 Oct 8 [Epub ahead of print]

Purpose: To measure prospectively and directly both
organ dose and effective dose (ED) for adult cardiac
and pulmonary computed tomographic (CT) angiography by
using current clinical protocols for 64-detector CT in
an anthropomorphic female phantom and to estimate
lifetime attributable risk of breast and lung cancer
incidence on the basis of measured ED and organ dose.
Materials and Methods: Cardiac and pulmonary
64-detector CT angiography was performed by using
current clinical protocols to evaluate the pulmonary
veins (electrocardiographically [ECG] gated, 64
sections at 0.625-mm collimation, 120 kVp, 300 mA,
0.35-second tube rotation), native coronary arteries
(ECG gated; 64 sections at 0.625 mm; 120 kVp; maximum
current, 500-750 mA; minimum, 100-350 mA; 0.35-second
tube rotation) and pulmonary embolus (64 sections at
1.25 mm, 140 kVp, 645 mA, 0.5-second tube rotation).
Absorbed organ doses were measured by using an
anthropomorphic female phantom and metal oxide
semiconductor field effect transistor detectors. ED
was calculated from measured organ doses and the
dose-length product. Results: ED for current adult
cardiac and pulmonary 64-detector CT angiography
protocols were 12.4-31.8 mSv. Overall, skin, breast,
and esophagus and heart had the highest recorded
absorbed organ doses. Relative risk for breast cancer
incidence for girls and women was 1.004-1.042 for a
single examination. Relative risk for lung cancer
incidence for men and women was 1.005-1.076 from a
single examination. Conclusion: EDs and organ doses
from 64-detector CT are higher than those previously
reported for adult cardiac and pulmonary CT
angiography protocols. Risk for breast and lung cancer
induction from these studies is greatest for the
younger patient population. (c) RSNA, 2007.

--- John Jacobus <crispy_bird at yahoo.com> wrote:

> Roy,
> I will check.  For your information, the new
> scanners
> are 64 slice, with newer, developmental units hare
> 125
> and 256 slice.  There are also two orthogonal x-ray
> tube units.
> --- ROY HERREN <royherren2005 at yahoo.com> wrote:
> > Does anyone have a ballpark estimate for the
> > individual and combined exposures from a whole
> body
> > SPECT/CT from a new 16 slice CT scanner, or a
> whole
> > body PET/CT from a new 16 slice CT scanner?
> >    
> >   Roy Herren
> > 
> > "Brunkow, Ward" <ward.brunkow at wipp.ws> wrote: 
> >   
> > Good issue to bring up. I think the answer is as
> it
> > has been for
> > decades:
> > >ALARA principal is not observed well within the
> > medical community
> > >Dr.s aren't trained well in radiation safety and
> > therefore prescribe
> > diagnostic use freely
> > >I think the older CT scanners were giving 12 -20
> > Rem acute exposure at
> > times, especially upper and lower GI
> > >Not enough consideration given to rapidly
> dividing
> > cells, young people
> > >$$$$$$$$$$$$$$$$$$$$$$$$$$$, money driven yet,
> not
> > ethical to give
> > someone this exposure if there isn't significant
> > benefit, especially
> > younger person, but have to keep those bucks
> coming
> > in
> > >Too much "cook book" diagnosis in medical
> community
> > yet, diagnostic
> > (therapeutic for that matter also) radiation
> > exposure used too freely.
> > The Prescribe and move on to the next one....
> > premise....
> > 

"If you guard your toothbrushes and diamonds with equal zeal, you'll probably lose fewer toothbrushes and more diamonds."
- Former national security advised McGeorge Bundy
-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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