Bad Cat Scan Math

Ted

Ted

The pilot formerly known as Twin Engine Ted
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I had to have a Cat scan yesterday. I didn't drive the RV or the bulldozer, and I also didn't bring my pet cat. But they let me in anyway.

That got me thinking, so I did some quick Google searching. This led me to the following on cat scan radiation:

25 cat scans = 10,000 chest x-rays
3.6 roentgen (reported initial radiation at Chernobyl because the meters only went up to 3.6) = 400 chest x-rays
1 cat scan = 3.6 roentgen

Therefore, I was exposed to Chernobyl yesterday.

And my scan was "not great, not terrible" (hernia), so this math makes sense and makes me laugh.

I have no idea what type of x-ray either of the above references referred to, since my understanding is new digital x-rays have far, far less radiation than x-rays of old.
 
Ted said:
I had to have a Cat scan yesterday. I didn't drive the RV or the bulldozer, and I also didn't bring my pet cat. But they let me in anyway.

That got me thinking, so I did some quick Google searching. This led me to the following on cat scan radiation:

25 cat scans = 10,000 chest x-rays
3.6 roentgen (reported initial radiation at Chernobyl because the meters only went up to 3.6) = 400 chest x-rays
1 cat scan = 3.6 roentgen

Therefore, I was exposed to Chernobyl yesterday.

And my scan was "not great, not terrible" (hernia), so this math makes sense and makes me laugh.

I have no idea what type of x-ray either of the above references referred to, since my understanding is new digital x-rays have far, far less radiation than x-rays of old.
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What happened to just "turn your head and cough"?
 
What about dental x-rays? Seems like they give at least 6 or 8 at a time (for me, every year). :D
 
PaulS said:
What happened to just "turn your head and cough"?
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Funny enough, docs haven't asked to do that to me for some time. Not sure why. But, that didn't find this anyway.

I had the feeling that there was one, as certain things (sneezing, coughing, turning really tight bolts, yelling at kids for extended periods of time, etc.) were aggravating what felt like a hernia/bulge in that area. Nothing severe, but bothersome. Doc didn't feel anything readily apparent and then an ultrasound didn't find it, so that moved to a cat scan, which apparently it popped right up on. In between the last doc visit and the scan yesterday (this has been a few months - life's been busy) it progressed to where I could feel it, so they might've been able to find it better now. But what's done is done.

So I guess the next thread is "Thinking about hiring a surgeon"
 
Everskyward said:
What about dental x-rays? Seems like they give at least 6 or 8 at a time (for me, every year). :D
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If you get enough dental x-rays to be exposed to Chernobyl you'll probably be able to use your teeth as flashlights, just smile. ;)
 
Ted said:
25 cat scans = 10,000 chest x-rays
Click to expand...

I don't think that's right. Google tells me it is 1:70 rather than 25:10,000 (which is 1:400).
 
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dmspilot said:
I don't think that's right. Google tells me it is 1:70 rather than 25:10,000 (which is 1:1750).
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The 25 -> 10,000 works out to 1 cat scan = 400 chest x-rays, not 1:1750.

But like I said, this was bad math. Using 3.6 roentgen as an actual number for Chernobyl is exceedingly bad math, as shown by @Morgan3820 's chart above.

Edit: Per that referenced chart, CT scan = 5.8 mSv and chest x-ray = 20uSv, which would mean 290 chest x-rays = 1 cat scan.
 
According to the discharge paperwork (and the bill...) I got 8 CT scans ~4 weeks ago. The colorized/contrast ones sure are uncomfortable.
 
Ted said:
The 25 -> 10,000 works out to 1 cat scan = 400 chest x-rays, not 1:1750.
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Correct, my mistake. Had a bunch of numbers in my calculator and copy-pasted the wrong one.
 
jrcox19 said:
According to the discharge paperwork (and the bill...) I got 8 CT scans ~4 weeks ago. The colorized/contrast ones sure are uncomfortable.
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Yeah, I got to both drink and get shot up with the contrast. They really could've made that consumed contrast taste better by adding something like rum. "Uncomfortable" is a good way of putting that for the IV ones. Not a fan of needles ever, but banging myself up while wrenching is just fine.

But that's an interesting point/question. I considered it a single scan since it was one shop visit, but I think they passed me through the machine 3 or 4 times total. I'm not sure what that ends up being considered as from the perspective of both exposure and billing.
 
Matthew said:
Probably there are enough YouTube videos that you can learn how to DIY.
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I have a welder, saw zall, and superglue. I should be good for DIY.
 
Ted said:
Yeah, I got to both drink and get shot up with the contrast. They really could've made that consumed contrast taste better by adding something like rum. "Uncomfortable" is a good way of putting that for the IV ones. Not a fan of needles ever, but banging myself up while wrenching is just fine.

But that's an interesting point/question. I considered it a single scan since it was one shop visit, but I think they passed me through the machine 3 or 4 times total. I'm not sure what that ends up being considered as from the perspective of both exposure and billing.
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I was in the machine for an hour or so, from what I was told. Don't really remember it much thanks to the pain meds.
 
jrcox19 said:
I was in the machine for an hour or so, from what I was told. Don't really remember it much thanks to the pain meds.
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Ouch. That sounds extremely not fun. So yeah, if that was 8 and close to an hour, then mine probably does get counted as 1. Just a few passes through in one position.
 
When Chernobyl blew up (dramatized in a simply awesome HBO miniseries) there was constant radiation everywhere (way more than 3.6 Roentgens). When you get X-rays the duration of the radiation is usually fairly brief. A normal CAT (computer assisted tomography) exposes you to between 1 to 4 years of background radiation. This level of exposure isn't very likely to harm you. Have you ever noticed that the folks who administer the X-rays wear lots of shielding? Do it every day of the week and yes, it can harm you.

Airline pilots receive many many times the dose of radiation than the rest of us, because they spend a significant time in the Stratosphere. There's less atmosphere up there to block radiation coming from the sun, so they're exposed to more.
 
Okay so I actually know some about this topic. It's not quite as simple as you put it!

For one, the unit of measure you mentioned, the roentgen, is an legacy measurement of ionizing radiation (the kind a CT scan uses). The more appropriate form of radiation exposure is a Sievert, which can equate either the equivalent or effective dose of radiation. A chest CT scan exposure is between 7 and 16 mSv (milli Sieverts) which is roughly the same as 2 years of background radiation exposure (the radiation exposure you experience by being alive on Earth). The most common measurement for radiation levels in a given area is measured in Sv/hr (Sieverts per hour).

In Chernobyl, the radiation levels shortly after the explosion in the vicinity of the reactor core were about 300 Sv/hr or 300,000 mSv/hr. That means that the equivalent radiation dose you would experience EVERY SECOND in the vicinity of Chernobyl's reactor after the explosion would be equal to 7-8 chest CT scans. The lethal dose of ionizing radiation is debatable, but a dose of 10,000 mSv will kill you within weeks. The typical dosage of the Chernobyl workers who died within a month of the explosion was about 6,000 mSv. A dose of 1,000 mSv can cause radiation sickness but is not immediately fatal, but can be fatal due to cancer many years later. You would have to get over 60 CT scans back-to-back to receive that amount of radiation.

Now, the radiation output of a CT scan machine may be pretty damn high. It could potentially be as high or higher than that of the Chernobyl reactor, but a CT scan machine only projects radiation momentarily, so the effective dose you receive is very low. So you may wonder "well if CT scans and X-rays are safe, then why do the hospital staff hide behind a lead wall?" That's because radiation exposure, in a way, "adds up". Sure a handful of X-rays or CT scans aren't harmful to the patient, but being exposed to that level of radiation dozens of times every day, 5 days per week for years on end can mean dangerously high levels of radiation exposure for the operator of the equipment.
 
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Oh and as a fun fact, you are actually exposed to increased levels of radiation based on your altitude and global position. If you're an airline pilot, you will be exposed to significantly more radiation each year than someone who works on the ground. It's not enough to be concerning; it's just interesting!
 
Nick C said:
Oh and as a fun fact, you are actually exposed to increased levels of radiation based on your altitude and global position. If you're an airline pilot, you will be exposed to significantly more radiation each year than someone who works on the ground.
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So you're saying that I should be a J-3 Cub? :)
 
Medical X-ray imaging (X-ray, fluoroscopy, and computed tomography) has changed so much in the last 10 years, you really have to be careful which data you read and believe. Radiation safety and radiation biology are topics way above the scope of this forum. But, even in simplistic terms, such as equating 1 CT to 1 chest x-ray, the "math" is very fuzzy at best. For example, a CT of your pelvis (I can assume you're talking about an inguinal hernia) is a whole lot different than getting a CT of your head and neck. We used to have a chart that equated chest x-rays to number of years of exposure of natural background radiation. It was something like 1 chest xray is equal to 10 days exposure to natural background radiation. And, 1 abdomen/pelvis CT is equal to 2.5 years of natural background radiation. As far as I know, thats really about as far as you can carry that type of analogy. But, like I said, that's data we quoted when I was still working. With newer machines and protocols, I expect exposures to be even lower.
 
It's easier to just convert everything to Bananas (BED) and go from there.
BananaEquivalentDose-1024x673.jpeg
 
Just to make sure everyone is clear with the intent of my post:

tenor.png


At no point was it intended to be serious. And yes, I know that roentgen is a legacy disused measurement. But:

61RXD91jxFL._AC_SX466_.jpg


Again, joke.

Now that we've established that.

@Nick C good info. I'd read some of that before (Chernobyl fascinates me). Radiation in general is a very interesting phenomenon along with its effects, dosage/exposure, etc. etc.

Also to be clear, I wasn't concerned with the dosage of radiation I may have gotten from the scan (having to drink and get injected with the contrast material was significantly less fun). It was just an interesting use of Google.
 
Ted said:
I have a welder, saw zall, and superglue. I should be good for DIY.
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Let me know when to come over. I used to be pretty good at tying sutures. Might take me a bit to remember how, so the scar is going to look funny.
 
Matthew said:
Let me know when to come over. I used to be pretty good at tying sutures. Might take me a bit to remember how, so the scar is going to look funny.
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That’ll match the rest of me. I got referred to some surgeon who’ll actually do a good job. Doesn’t seem my style.
 
Ted said:
I had to have a Cat scan yesterday. I didn't drive the RV or the bulldozer, and I also didn't bring my pet cat. But they let me in anyway.

That got me thinking, so I did some quick Google searching. This led me to the following on cat scan radiation:

25 cat scans = 10,000 chest x-rays
3.6 roentgen (reported initial radiation at Chernobyl because the meters only went up to 3.6) = 400 chest x-rays
1 cat scan = 3.6 roentgen

Therefore, I was exposed to Chernobyl yesterday.

And my scan was "not great, not terrible" (hernia), so this math makes sense and makes me laugh.

I have no idea what type of x-ray either of the above references referred to, since my understanding is new digital x-rays have far, far less radiation than x-rays of old.
Click to expand...

Interestingly, there's not much data linking modern medical radiation to increased cancer risks. That doesn't mean the data doesn't exist, just that cancer biology is so complex, isolating the role of one factor is very challenging. If your CT scanner was produced in the last 5-10 years and properly set up by the hospital physicist, the dose was probably much lower than even the most recent figures. Dose reduction software and reconstruction algorithms have brought doses down substantially.

The radiation exposure from flying is actually pretty high, but what that translates into in terms of risk isn't really clear.
 

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Ted said:
That’ll match the rest of me. I got referred to some surgeon who’ll actually do a good job. Doesn’t seem my style.
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The real story is what mods you'll want to make later.
 
Everskyward said:
What about dental x-rays? Seems like they give at least 6 or 8 at a time (for me, every year). :D
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I've installed digital radiograph machines; they use a tiny fraction of what they used to. Unless your doc is old-school, and uses film ...
 
Everskyward said:
What about dental x-rays? Seems like they give at least 6 or 8 at a time (for me, every year). :D
Click to expand...
There is so little ionized radiation from dental xrays as to almost not be an issue.

When I built our veterinary practice we had digital xray (the first in the South East in a general practice companion animal hospital). We were required to either lead-line the walls, or use a double layer of drywall and ensure that no normally occupied room was on the other side of the room. One side was a bathroom, one side was a hallway and one side was a storage closet. For those walls we used double layer drywall. The other side was adjacent to the treatment area and was lead-lined. And anyone in the room had to wear lead lined aprons, gloves and thyroid protectors and an exposure badge.

As for our digital dental x-ray, we had to post a sign that everyone had to move 6 feet away from the beam source when radiographs were taken.
 
jrcox19 said:
According to the discharge paperwork (and the bill...) I got 8 CT scans ~4 weeks ago. The colorized/contrast ones sure are uncomfortable.
Click to expand...
Is that the one where they inject the stuff that makes it feel like you peed your pants?
 
Lindberg said:
Is that the one where they inject the stuff that makes it feel like you peed your pants?
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Contrast is a transient vasodilator. Makes people feel warm, flushed, and like you are going to urinate. No one actually does though.
 
Funny to be reading this thread now... I just met with my new RadOnc yesterday, for a long talk about the Radiation (with a capital "R") I'm going to be zapped with later this summer. (much more than a CT...)
He said that radiotherapy when given to children can be linked to increased rates of cancer later in life in a measurable way, but not really at all when given to adults.
He also said that in the world of cancer, people are trying to not do as many CT's unless it's really necessary, not because of the radiation but because of the rate of false positives.
All in all, an interesting convo...

*whoa!* We just had an earthquake!
OK, done now.
 
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