[ RadSafe ] Studies Quantify Cancer Risks From CT Scans (MSN article)

Wed Dec 16 09:14:57 CST 2009

Friends,

I do not support LNT as gospel truth. But in view of the uncertainties in the magnitude of the 'safe' dose, I would advocate ALARA when CT scan is clinically indicated. May be if there is a threshold, it may be different for different individuals because each individual carries in their cell genetically acquired insults besides those from environmental agents such as radiation, viruses etc.   I am unable to accept business as usual arguing that repair mechanisms will take care of the tiny cellular/tissue damage if any.

I found that some specialists who wanted  to carry out CT scans as a screening tool,advocate consumption of a special pill which contains a combination of anti-oxidants to prevent damage from free radicals released by radiation. 

In fact without much quantitative information, the company promotes two types of pills one for x-ray workers, air craft crew, frequent fliers etc and the other when undergoing nuclear medicine tests. A proponent of the pill argued that the pill is a BioShield just as lead apron or glove is a physical shield. Some radiologists are already prescribing it.

Regards
Parthasarathy

________________________________
From: "blreider at aol.com" <blreider at aol.com>
To: HOWARD.LONG at comcast.net; eic at shaw.ca
Cc: radsafe at radlab.nl
Sent: Wed, 16 December, 2009 1:10:50
Subject: Re: [ RadSafe ] Studies Quantify Cancer Risks From CT Scans (MSN article)

Howard, I was wondering that myself.  While it is known that photons can cause cancer - I believe the British did extensive testing with mammography in abut the 1970s - the article does not state what methods were used for extrapolation.  The astract (link below) says they used BEIR report age-related risk factors.  I believe BEIR uses LNT assumptions, but I have not read the latest BEIR report.   Here's the abstract:  http://archinte.ama-assn.org/cgi/content/abstract/169/22/2071

Kai, a spiral CT scan takes 8 seconds to give 3 to 5 rad, indeed a high dose rate.  The short time results in really good resolution too, reducing the effect of patient movement.

Mike, good point.  These tests are generally used for diagnostics for cancer patients, and used periodically to benchmark effectiveness of cancer treatment.   That group should be evaluated differently than healthy patients in a study.  A few years ago though, there were ads for elective CT scans for screening anyone.  Also I know someone who had one in the ER, when an MRI would probably have been a more effective test.  Perhaps overuse to pay for CT facilities is what initiated this study.

Barb Reider, CHP

-----Original Message-----
From: HOWARD.LONG at comcast.net
To: Kai Kaletsch <eic at shaw.ca>
Cc: radsafe at radlab.nl
Sent: Tue, Dec 15, 2009 1:54 pm
Subject: Re: [ RadSafe ] Studies Quantify Cancer Risks From CT Scans (MSN article)

Has anyone seen the data provoking the "26,000 cases of cancer and 9,000 deaths 
early from CTs"? 

Is that just assumption from discredited LNT ? 

A more scientific case could be made (from NSWS, bomb exposure, etc) that 9,000 
ives were saved (or X years of life) by the supplement of Vit R! 

Howard Long MD MPH 

---- Original Message ----- 
rom: "Kai Kaletsch" <eic at shaw.ca> 
o: "Richard D. Urban Jr." <radmax at earthlink.net>, radsafe at radlab.nl 
ent: Tuesday, December 15, 2009 3:24:25 AM GMT -08:00 Tijuana / Baja California 
Subject: Re: [ RadSafe ] Studies Quantify Cancer Risks From CT Scans 
MSN        article) 
Is that right: 70 million CT scans per year in the US? That's one scan every 
or 5 years for every man woman and child. 
30 mSv in a few minutes is not a low dose rate. 
Kai 
----- Original Message ----- 
rom: "Richard D. Urban Jr." <radmax at earthlink.net> 
o: <radsafe at radlab.nl> 
ent: Tuesday, December 15, 2009 1:57 AM 
ubject: [ RadSafe ] Studies Quantify Cancer Risks From CT Scans (MSN 
rticle) 

ttp://health.msn.com/health-topics/articlepage.aspx?cp-documentid=100251079&gt1=31036 
Those with more expertise than myself should weigh in on this at above 
rticle link. 
Studies Quantify Cancer Risks From CT Scans 
ommonly performed CT scans are exposing patients to far more radiation than 
reviously thought and in doses that could cause tens of thousands of 
ancers a year, two new studies claim... 
Based on the findings, reported in the Dec. 14/28 issue of the Archives of 
nternal Medicine, the study authors, joined by Archives editor Dr. Rita F. 
edberg, are calling on clinicians to limit radiation exposure to patients. 
"CT has become so quick that we are using it so commonly, and we have 
owered our threshold for using it—meaning we use it for patients who really 
re unlikely to have any underlying disease," said Dr. Rebecca 
mith-Bindman, a professor in residence in the department of radiology at 
he University of California, San Francisco, and lead author of one of the 
tudies. Although it's a "fabulous diagnostic tool," she said she believes 
we have lowered it to the point where there may be no benefit in some 
atients."... 
...In the United States, the total number of CT (or computed tomography) 
cans performed annually has swelled from 3 million in 1980 to nearly 70 
illion in 2007, according to data cited by Smith-Bindman's team... 
...In fact, the new data suggest that its overuse may be doing more harm 
han good... 
...Smith-Bindman's team collected data from 1,119 patients who received 11 
ommon types of CT scans performed at four San Francisco-area hospitals. For 
ach type of CT scan, the dose of radiation varied widely within and across 
ospitals. There was a 13-fold variation, on average... 
...The dose of radiation for a multiphase abdomen-pelvis CT study ranged 
rom 6 to 90 millisieverts, and the average dose was 31 millisieverts. 
Ninety millisieverts, depending on how you count it, is equivalent to "many 
housands of chest X-rays," Einstein said. "That's like the background 
adiation you and I would receive over a 30-year period; it's just a 
remendously high dose from one CT scan procedure."... 
...Overall, her team estimated that 29,000 future cancers could be related 
o scans performed in 2007, and that these cases would result in about 
4,500 deaths. The highest contributors to those numbers are the scans most 
requently performed, including abdomen and pelvis, chest and head exams. 
It's estimated that two-thirds of the projected cancers will occur in women, 
rimarily because of the higher frequency of use in women (60 percent) and 
ecause of higher breast and lung cancer risks from scans that expose the 
hest. 
While the numbers may be scary, Berrington de Gonzalez said people should 
ealize "that CT scans provide great medical benefits and that, in general, 
ndividual risks are small and should be outweighed by the benefits if the 
T scan is clinically justified."... 
...To ensure safe use, the authors' recommendations focus on reducing 
adiation dosages, eliminating unnecessary and repeat examinations, and 
reating searchable electronic medical records to collect and track CT 
tudies over time... 

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