Does Radiation from X-Rays/CT Stay in Body Forever (Risks)?

[kyphysics]

The units and conversations in this field is a maze. In the Radiation Biology class/lab I took at San Diego State white mice were irradiated with a Westinghouse x-ray. I forget all the data, ie how many Rads (100 ergs/g) they got. We moniteted the decreasing blood cell counts for as long as they lasted, a few weeks. So it would seem a proportional dose in humans would also be fatel.

The mouse LD₅₀ the dose needed to kill 50% of a population of mice is about 7 Gy (700 rads). The LD₅₀ for humans is only around 4 Gy (400 rads).

To check my understanding, are you saying a 4GY dose of radiation (all at once just a single time) would kill a human 50% of the time?

 

[kyphysics]

Radiation may be something I have to learn a lot about. Dad's PET/CT came back showing higher metabolic activity at the site of the nodule. Although never 100% a guarantee of cancer, the radiologist pointed out it's most statistically probable for it. Sometimes, we were told by the doctor, it's a false positive, b/c inflammation can produce the exact same result.

Only way to know for sure is biopsy.

 

[gleem]

To check my understanding, are you saying a 4GY dose of radiation (all at once just a single time) would kill a human 50% of the time?

About half of the humans receiving a 4 Gy dose all at once will die.

 

[hutchphd]

About half of the humans receiving a 4 Gy dose all at once will die.

I think this is better said that "About half of the humans receiving a full body 4 Gy dose all at once will die". Perhaps that is part of the confusion here. The nomenclature here is so very complicated because there are very many blind men looking at a many various elephants.
I had several full body CT scans a few years back and never figured it out completely. I am still healthy, wealthy and wise

 

[Rive]

4GY dose of radiation (all at once just a single time) would kill a human 50% of the time?

That's why it's important that not the whole body gets that dose but only the targeted piece of tissue

One can easily get a dose of 50 Gy in radiation therapy (per Google).

Nope. That's for a few grams of cancerous tissue, not for 'one'.

 

[pinball1970]

Radiation may be something I have to learn a lot about. Dad's PET/CT came back showing higher metabolic activity at the site of the nodule. Although never 100% a guarantee of cancer, the radiologist pointed out it's most statistically probable for it. Sometimes, we were told by the doctor, it's a false positive, b/c inflammation can produce the exact same result.

Only way to know for sure is biopsy.

This gives some comparisons of a couple of things you raised.
https://en.wikipedia.org/wiki/Chernobyl_disaster#/media/File:G_radiation-level_scale_01.png

 

[gleem]

Yes, LD₅₀ refers to the whole body receiving this dose. I should have been more clear.

While we're talking about lethal effects for humans, whole-body doses below about 2 Gy are usually not lethal but can still produce serious effects, especially in the GI tract as well as the bone marrow. At doses near 8 Gy death is almost certain. The GI tract and bone marrow are the critical organs from an acute whole-body radiation dose.

There is usually a time window specified for death to occur usually 30 days from the dose for animals and 60 days for humans.

 

[hutchphd]

Also makes you wonder if a cancer treatment can CAUSE more cancer down the line. 50 Gy is massive compared to 15 CT scans (at 10 mSv each).

The answer here is most certainly yes. But there are a host of chemotherapies that also do that, so treatment is a very complicated business (and I use the term business on purpose). You cannot possibly know enough, so need to find a doctor or other technical person upon whom you can rely. I have found the hospital staff "generalists" to be very useful (in the USA)
As an old person I can say this with certainty but no rancor: no one lives for ever. Best of luck with this.

 

[kyphysics]

The answer here is most certainly yes. But there are a host of chemotherapies that also do that, so treatment is a very complicated business (and I use the term business on purpose). You cannot possibly know enough, so need to find a doctor or other technical person upon whom you can rely. I have found the hospital staff "generalists" to be very useful (in the USA)
As an old person I can say this with certainty but no rancor: no one lives for ever. Best of luck with this.

Thank you for the thoughts.

If I'm allowed to press, could you elaborate on what you meant by "business" above? I think I get the general drift, but more specifics could be enlightening.

Were you at all suggesting that doctors might "steer" you towards a more monetarily profitable treatment program for them (and/or their affiliated medical org.)? If so and that comes at the expense of patient health, that's certainly something to be aware of.

As for cancer treatment causing more cancer in the future, does anyone have statistics on the odds?:

e.g., if you receive 50 Gy (total) to treat a targeted nodule in our stomach, are there statistics on how many such people get cancer later as a result of the first cancer radiation treatment? 10%? 20? . . .50? or more

I'm aware Google exists (and plan to search), but sometimes in life we just want a fast round of answers/opinions and may also feel the more information (in case we miss something) the better.

 

[kyphysics]

This gives some comparisons of a couple of things you raised.
https://en.wikipedia.org/wiki/Chernobyl_disaster#/media/File:G_radiation-level_scale_01.png

Thanks, pinball. Helpful, but scary too (given how much radiation my father has had in just a few months).

 

[kyphysics]

re: chart above

Although, it's unclear what the first top two levels mean. E.g., level too references 400 mSv (maximum) received per hour. But, there's no mention of how many hours people were exposed and what their health outcome was.

The top level of 6,000 mSv (6 Gy) is absolutely frightening. But, it doesn't say if it was received all at once...over the course of days...weeks (such as cancer radiation therapy). I'm guessing most of it was received in compressed time, as cancer patients obviously receive more (but spread out).

 

[gleem]

Thanks, pinball. Helpful, but scary too (given how much radiation my father has had in just a few months).

Scary, how so? By now I would have thought you had put the X-ray exam radiation dose concerns in perspective.

 

[pinball1970]

re: chart above

Although, it's unclear what the first top two levels mean. E.g., level too references 400 mSv (maximum) received per hour. But, there's no mention of how many hours people were exposed and what their health outcome was.

The top level of 6,000 mSv (6 Gy) is absolutely frightening. But, it doesn't say if it was received all at once...over the course of days...weeks (such as cancer radiation therapy). I'm guessing most of it was received in compressed time, as cancer patients obviously receive more (but spread out).

Really sorry mate, the chart was meant to put things into perspective for you a little bit.
There are risks associated with these treatments but giving you a risk that may manifest 10-20 years in the future, is a better option than leaving you with a disease that will make an impact much sooner.
I hope everything goes ok.

 

[hutchphd]

I'm aware Google exists (and plan to search), but sometimes in life we just want a fast round of answers/opinions and may also feel the more information (in case we miss something) the better.

First of all let me make it clear that I have no particular terminal diagnosis. But waking up in the morning in my 72nd year provides assurance to me that stuff will happen. This daily revelation is occasionally terrifying but mostly oddly reassuring.

With regard to the "business" of medicine in the US: I implicate mostly insurers and drug manufacturers. Doctors very much less so but they are in the thrall of insurers and somewhat swayed by the marginal PR practices of some drug companies. Mostly MD's remain agnostic to monetary costs to the degree possible, and consider only the medically optimal treatment path, and this view is occasionally narrow. Medical profesionals , in my exxperience, are almost always remarkably capable and caring people.
If I may offer advice, I think you might be better served directing your energies to talking with patient/disease organizations and perhaps hospital staff than worrying in excrutiating detail about treatment protocol. You need a few trusted experts on your side. Do check the bonafides of doctors (and the billing!).
The Docs and staff know more than you ever will about treating disease, but also they are very busy , and you know more about your dad. If he does not want a particular path of treatment then you need to be his advocate. It is not insulting to ask about price and coverage. But you must trust the professionals implicitly. Both they and you really deserve it. Keep PF posted

 

[Rive]

if you receive 50 Gy (total) to treat a targeted nodule in our stomach

Please. It's about that nodule receiving that (lethal) dose, and the patient (in general, as whole body) receives very little.
If calculated as an average, if 100g tissue gets 50 Gy, then for a 70kg patient that's 0.07 Gy.
But it's not calculated as average. The 'whole body' will be affected (by radiation) only very little.

are there statistics on how many such people get cancer later as a result of the first cancer radiation treatment?

Many cancer treatments are about survival chances and lengths.
The patient first needs to remain alive long enough to get any new cancer later on.
I don't know about exact statistics.

as cancer patients obviously receive more (but spread out).

One reason for spreading the dose is, that killing the cancer without actually removing its mass means that the rest of the body must clean up the dead cells. It's a very strenuous work, and better done over a longer time (less strain, less danger).
It's not about a dose being less lethal if strained for a few weeks or so.
Also, about that absurdly high dose: 6 Gy is about the whole body, as a system collapsing (death). But as the targeted cancer is hanging on the 'life support machine' of the whole body, it's harder to kill it to the last cell.

All this is not any expert opinion, but ... well, just very basic popsci.

 

[gleem]

One reason for spreading the dose is, that killing the cancer without actually removing its mass means that the rest of the body must clear up the dying cells.

The main reason the doses for radiation therapy are given in fractions typically 1.8 Gy per day is that cancer cells do not repair the radiation damage as much as the healthy tissue for each fraction. Over time the damage to the cancer cells accumulates considerably compared to the normal tissue so by the end of the course of treatment the cancer cells are either eliminated or sterilized while the surrounding healthy tissue has mostly repaired all the damage.

With regard to tumors caused by the therapy (radiogenic tumors), these tumors are very rare. The tumors that are identified as being caused by the radiation are soft tissue sarcomas. In a study of more than 2 million patients, only 359 were identified.

 

[Laroxe]

Just a few thoughts really as the issues involved in the original questions have broadened.
We are all unfortunately at risk from cancer and there are a whole range of things that can increase or decrease this risk. When we talk about radiation we are talking about one factor that is involved, we have to say its never the only factor. Time is always significant, cancer is overwhelmingly a disease of ageing, genetic damage tends to accumulate over time and the mechanisms of cellular repair become less effective. The effectiveness of our immune surveillance reduces as we age and can fail to identify abnormal cells, we also see increases in chronic inflammatory conditions another risk factor.

Radiation is pervasive in our environment and can potentially damage our DNA, cells have a range of methods that can mitigate and or repair this damage but over time some faults persist and new ones are added. Perhaps the main source of radiation exposure is that huge thermonuclear explosion in the sky, but our environment is full of sources.

When we expose people deliberately in medical diagnostics, the potential risk is an important consideration in the risk benefit analysis for carrying out the procedure. As the techniques are often non or minimally invasive, the risks are generally much lower than techniques used previously. There is a great deal of effort put into quantifying the risks but these always run parallel to continuous improvements in technique and technology. With this in mind and the generally low level of risk trying to get a reliable measure of the effect of one risk factor is extremely difficult. It is suggested that in children under 15 who were exposed to multiple CT scans in a short period of time it is possible to identify a measurable increase in cancer incidence in later life, but this is based on quite old data. The risks to people in later life appear to be very small.

Radiotherapy is a different matter, in this radiation is delivered in ways to cause irreparable damage to cancer tissue and there are a variety of ways of delivering the required dosages. However it remains very difficult to get accurate measures of risk as this is highly dependent on the tissues involved, the persons lifestyle and genetics. Because radiotherapy has become increasingly effective we are also seeing an increased incidence of new cancers in people who would have previously died. There are figures available around these radiotherapy induced cancers, which tend to arise in the therapy field but from different tissues after what might be a prolonged period of time. As before, these figures are based on old data as the follow up times are extended.

The treatment of cancer which now frequently involves very specific delivery methods in combination with drugs including drugs known as radio-sensitisers makes quantifying risks in a meaningful way almost impossible. It's worth considering that most of the fears associated with radiation are now primarily used by certain groups to promote political causes and collect money. Most people are aware of the incident at the Fukushima power station, often labelled as a disaster, which caused 16 injuries due to hydrogen explosions, 2 people treated as outpatients for burns and one possible cancer death attributed to radiation which allowed for government compensation.

 

[sophiecentaur]

That's why it's important that not the whole body gets that dose but only the targeted piece of tissue

Oncologists try to do their best but every dose of post surgical radiation has its effect and they are all hungry for success. RT (even these days) still leaves co-lateral damage.
I can speak from experience here. Patients are 'invited' to have Radiotherapy therapy and it often works fine at the time My PSA count is still undetectable after 15 years so you could say "it worked". However, radiotherapy is a very blunt instrument and mine caused a lot of scar tissue around the site. A year ago, I had more surgery (a different organ and different cancer) The poor old surgeon was wading through scar tissue for hours and did the best he could but the past RT has led to some annoying effects. I was warned before the earlier treatment that RT tends to make future surgery difficult but I accepted it and it certainly did.