CLL Support Association

CT scan series part 14 – So, you are about to be CT scanned

Learning about CT scanning has been a work in progress. Doctors are not particularly knowledgeable about CT technology and large institutions employ many scanners of varying age and sophistication. CT manufacturers wouldn't talk so learning to ask the important questions has been a long process.

Initially I had focussed too much on the CT machines themselves; just listen to this description from a major CT manufacturer touting one of their models: “THE LEADING EDGE OF HIGH QUALITY CARE AT ULTRA-LOW DOSE You and your patients continue to demand lower dose, but not at the expense of diagnostic image quality. ASiR*, which comes standard on Revolution GSI, is the industry’s most-used iterative reconstruction technology with over 47 million patients benefiting from its use to date. Veo*, offered as an option, is the world’s first model-based iterative reconstruction product enabling imaging under 1 mSv with profound clarity.” No... I am not going to tell you which company or machine was being described when the critical component regarding radiation dosing is largely dependent in the software and your Cancer clinic may not have that machine but some other just as good.

Yes, there is much good info on the Internet such as an NIH published article “Strategies for Reducing Radiation Dose in CT” but how many of us will read, let alone understand the implications of this sampling sentence outlining the principle benefit behind lower kV (kilovolts) with some clinical applications?

“The attenuation coefficient of iodine increases as photon energy decreases toward the k-edge energy of 33 keV.” Yeah Doc, I'll take two of those;-) Link:

Is there an easier way to assure low dose and safety for your next scan? Stay tuned!

Here are several important perspectives regarding CT scanning that need to be considered in a personal context on your unique CLL journey. It has been a universal medical consensus that CT scanning has been over prescribed even though CTs are universally acknowledged as important diagnostic tools. The potential for CT scans increasing odds of contracting other cancers is real in a pediatric setting. The risk of secondary cancers in adults has many variables but is largely time dependent, generally thought to require about 20 years, generated from radiation damaged DNA that does not get properly repaired. If you are 70+ the odds of a secondary cancer from CT radiation is not the same as if you are in your 30s.

One way of assessing CT risk is to evaluate the research data on population exposure. One subset of the population, well studied were women undergoing annual mammography. A radiology physicist I recently spoke with said there was no statistically elevated risk of cancer from mammography on the radiation sensitive organ of the breast. Does this play equally well within the CLL population undergoing multiple CT scans every few months while on Clinical Trial? Since all cancer is in a sense a failure of immune function and CLL is fundamentally a cancer of immune function in which the 2nd greatest cause of death is secondary cancers, I would say the jury is out in the absence of a CLL frequently scanned population study.

The danger from ionizing radiation overdose was experienced by hundreds of unfortunate patients who were inadvertently overdosed due to operator error and lack of CT scan software safety features. The context of this type of error is much diminished in the CLL CT scan context because the patients who were overdosed were scanned for cerebral perfusion injury which requires around 10 times more radiation than the average CT scan for a CLL patient. The injured patients got 8 times over the radiation required for normal cerebral perfusion imaging. The newer software and regulation awareness greatly diminishes this unfortunate scenario for CLLers.

I was introduced to an interesting hypothesis going by the term “Hormesis”. I wrote in earlier essays about folks who spa in radon caves for their “health”. Here is the, as yet to be proved, hypothesis for the why of doing so. While this article might suggest a “Don't worry be happy” attitude, the unknowns are considerable and among them is; what can be expected from CLL patients whose immune repair capability is dysfunctional to begin with? The beneficial/harmful effects from UV radiation is another similar dilemma for the CLL patient and is referenced in the above Wiki article. Studies are not definitive and much needs to be learned. “A bit of the hair of the dog that bites you” is great for hangovers and a quandary for our situation regarding CT radiation and UV exposure.

CT scans are going to be a greater part of patient experience in a Clinical Trial setting due to exciting new drugs offering the promise of greater efficacy and less side effects. Avoiding these Clinical Trials because of fears over ionizing radiation exposure will become less if we patients help in the effort to usher in the use of newer scanning software that will guarantee minimal radiation exposure and host overdose warning features before we get “nuked”. We can only hope that what radiation we do receive will be of “hormetic” benefit;-).

In my CT scan series part 15, I will give you a simple generic way to assure you get the lowest dose and safest CT scan.


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Sorry everyone about this being out of step with #15. I tried to publish it yesterday but the cyber-Gremlins must have stolen it. It appears to have worked this time.

Happy scanning;-)



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