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

Tue Dec 15 13:49:52 CST 2009

"we estimated that approximately 29 000 (95% UL, 15 000-45 000) future cancers 

could be related to CT scans performed in the US in 2007" 

"We estimated" suggests that no cases were counted, only a rate extrapolation, LNT. 

This is as bad as the climate data fudging. Are all "scientific" data now subject to 

money source? 

Howard Long 

----- Original Message ----- 
From: blreider at aol.com 
To: "HOWARD LONG" <HOWARD.LONG at comcast.net>, eic at shaw.ca 
Cc: radsafe at radlab.nl 
Sent: Tuesday, December 15, 2009 11:40:50 AM GMT -08:00 Tijuana / Baja California 
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 
yearly from CTs"? 

Is that just assumption from discredited LNT ? 

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

Howard Long MD MPH 

----- Original Message ----- 
From: "Kai Kaletsch" < eic at shaw.ca > 
To: "Richard D. Urban Jr." < radmax at earthlink.net >, radsafe at radlab.nl Sent: 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 
4 or 5 years for every man woman and child. 

30 mSv in a few minutes is not a low dose rate. 

Kai 

----- Original Message ----- 
From: "Richard D. Urban Jr." < radmax at earthlink.net > 
To: < radsafe at radlab.nl > 
Sent: Tuesday, December 15, 2009 1:57 AM 
Subject: [ RadSafe ] Studies Quantify Cancer Risks From CT Scans (MSN 
article) http://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 
article link. 

Studies Quantify Cancer Risks From CT Scans 
Commonly performed CT scans are exposing patients to far more radiation than 
previously thought and in doses that could cause tens of thousands of 
cancers a year, two new studies claim... 

Based on the findings, reported in the Dec. 14/28 issue of the Archives of 
Internal Medicine, the study authors, joined by Archives editor Dr. Rita F. 
Redberg, 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 
lowered our threshold for using it—meaning we use it for patients who really 
are unlikely to have any underlying disease," said Dr. Rebecca 
Smith-Bindman, a professor in residence in the department of radiology at 
the University of California, San Francisco, and lead author of one of the 
studies. 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 
patients."... 

...In the United States, the total number of CT (or computed tomography) 
scans performed annually has swelled from 3 million in 1980 to nearly 70 
million 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 
than good... 

...Smith-Bindman's team collected data from 1,119 patients who received 11 
common types of CT scans performed at four San Francisco-area hospitals. For 
each type of CT scan, the dose of radiation varied widely within and across 
hospitals. There was a 13-fold variation, on average... 

...The dose of radiation for a multiphase abdomen-pelvis CT study ranged 
from 6 to 90 millisieverts, and the average dose was 31 millisieverts. 

Ninety millisieverts, depending on how you count it, is equivalent to "many 
thousands of chest X-rays," Einstein said. "That's like the background 
radiation you and I would receive over a 30-year period; it's just a 
tremendously high dose from one CT scan procedure."... 

...Overall, her team estimated that 29,000 future cancers could be related 
to scans performed in 2007, and that these cases would result in about 
14,500 deaths. The highest contributors to those numbers are the scans most 
frequently performed, including abdomen and pelvis, chest and head exams. 

It's estimated that two-thirds of the projected cancers will occur in women, 
primarily because of the higher frequency of use in women (60 percent) and 
because of higher breast and lung cancer risks from scans that expose the 
chest. 

While the numbers may be scary, Berrington de Gonzalez said people should 
realize "that CT scans provide great medical benefits and that, in general, 
individual risks are small and should be outweighed by the benefits if the 
CT scan is clinically justified."... 

...To ensure safe use, the authors' recommendations focus on reducing 
radiation dosages, eliminating unnecessary and repeat examinations, and 
creating searchable electronic medical records to collect and track CT 
studies over time... 

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