Re: reported side effects from CT scan of head

[John Jacobus <crispy_bird@YAHOO.COM>]

Sorry for the late response to this, but I was away

from my office last week and could access the data we

have been working with.



We have made some dose measurements outside of the

primary irradiation field for various CT scans using

an RANDO phantom http://www.phantomlab.com/rando.htm

and a electronic dosimeter with a remote detector

http://www.unfors.com/rp_edd.php.



The study being considered below was for an evaluation

of the patient's sinuses.  I have included results for

the a Head and Inner ear/temporal bone as well as for

a Sinus/Orbits exam.  We are using a multislice CT

scanner, so the results will be lower for a single

slice unit





Head CT Exam

Female Gonad	0.007 micro Gy

Male Gonad	0.000 micro Gy

Lens	77.82 micro Gy

Thyroid	176.7 micro Gy

L Breast	1.253 micro Gy

R Breast	1.699 micro Gy

	

Inner Ear/Temporal Bone CT Exam

Female Gonad	0.041 micro Gy

Male Gonad	0.040 micro Gy

Lens	87.80 micro Gy

Thyroid	238.2 micro Gy

L Breast	2.070 micro Gy

R Breast	2.784 micro Gy

	

	Sinuses/Orbits

Female Gonad	0.007 micro Gy

Male Gonad	0.000 micro Gy

Lens	100.5 micro Gy

Thyroid	180.3 micro Gy

L Breast	1.844 micro Gy

R Breast	2.562 micro Gy













--- JGinniver@AOL.COM wrote:

> A relative recently went to an Ear Nose and Throat

> Specialist due to sinus 

> problems.   Unfortunately the specialist was unable

> to identify the cause.   The 

> next step, which the specialist was reluctant to

> take was a CT Scan, 

> presumably of the head.   The specialist stated that

> unless the symptoms became more 

> severe that s/he wouldn't authorise the CT scan due

> to the high levels of 

> radiation involved.   The specialist then went on to

> state that some individuals 

> who had recived CT scan (again presumably of the

> head) had experienced thyroid 

> problems.

> 

> I don't wish to debate the merits or not of

> prescribing the CT examination.   

> The Doctors decision not to do this is consistent

> with guidance in the UK 

> that they shouldn;t not prescribe a radiation

> examination unless they believe it 

> is justified and that the benefits outweigh the

> risk, albeit small, of the 

> radiation exposure.

> 

> What I would like assistance with is the validity of

> the statement that a 

> proportion of patients who have recieved CT scans

> have then experienced thyroid 

> problems.   Based on current evidence I don't

> believe that this is possible, 

> but Medical Physics is   not my field and I would be

> grateful if others with 

> knowledge and experience in this area could help.  

> Has there every been any 

> published study that has managed to identify a

> statistical link between CT scans 

> and Thyroid problems.   I intend to write to the

> Doctor to establish the reason 

> for this statement, but would like some more

> information, if it's available, 

> before I do so.

> 

> Thanks for any help you can all provide.

> Regards,

>      Julian

> 





=====

+++++++++++++++++++

"Style is knowing who you are, what you want to say, and not giving a damn"

Gore Vidal



-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com



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