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Wondering about radiation and damage

Steve1961
Posts: 250
Joined: Dec 2017

I have a quick question since a lot seem to be so knowledgeable what is one gray of external beam radiation equal to it just a regular chest x-ray from what I read the normal human in can have 10,000 x-rays a lifetime I’m just wondering how many x-rays I have had I had a 45Greys And two CT scans and one bone scan I am so afraid to even have any x-ray done now

 

Steve1961
Posts: 250
Joined: Dec 2017
ascodaGama Sep 21 

It is good to be careful and attentive to radiation but you shouldn't be so worry to the extent of avoiding CT scans. We humans may get more damage in our life time from the sun's and other background radiation than from health exams. "The average person in the U.S. receives an effective dose of about 3 mSv per year from natural radiation". "The amount of radiation from one adult chest x-ray (0.1 mSv) is about the same as 10 days of natural background radiation that we are all exposed to as part of our daily living". Please read this;

https://www.radiologyinfo.org/en/info.cfm?pg=safety-xray

Regarding equivalences one can approximate it to 1 gray = 1 Joule/kilogram which equals 100 rad or 1,000 mSv. Grays represent the absorbed energy by body tissues and mSv (millisievert) quantifies the risk of applied energy at one spot. A value superior to 4,000 mSv signifies a 50% probability of death (the double 8,000 mSv equals to 100% death). In 1,000 mSv there is a 0.5% risk of contracting fatal cancer or a 1.2 % of non-fatal cancer.

In other words, 1 mSv is the dose produced by exposure to 1 milligray (mGy) of radiation, therefore, 1 Gray (approximately 1,000mSv) has 0. 5% chance of initiating a newer cancer at the affected tissues. This is rare but it is a fact. We PCa IMRT survivors have received at some tissues a maximum dose of 1.8 Gy (1,800 mSv). The total applied dose (45 grays in your case) is divided into fractions of 1.8 Gy and distributed over the several tissues/area of the treatment. None of us receive 45 Gy (the total dose) in one spot.

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VascodaGama
Posts: 3045
Joined: Nov 2010

Steve,

It is nice of you for posting our exchanged emails to those interested in the subject matter. Radiation is a matter of concern to us PCa patients but physicians uses it under evident control and follow the guidelines that were decided from studies over the years. We will experience the RT side effects because the doses are higher than what we experience in daily routines but RT treatments do not reach dangerous levels for death. After RT we need to be careful and care for the symptoms, if any, to avoid additional health issues. RT in all forms hare risks as much as surgery do in treatments for cancer.

Regarding the above contents, I would like to add that the equivalencies in radiation units and values (absorbed and doses) depend on the type of radiation (the source delivering it). Typically Grays are used to quantify absorbed radiation, the dose is expressed in Sievert (Sv) or millisievert (mSv), and the exposure to ionizing radiation (harmful radiation from all types of energy source, Chernobyl residents had 39 R), named radiation sickness is measured in Roentgen (R) or milliroentgen (mR).

In such regard the typical daily of absorbed dose of 1.8 Gy in IMRT treatments (ionizing radiation) was equivalent to a dose of 1,800 mSv and an exposure of 205 R. The numbers are high but it regards one spot in our body. Environmental radiation involves the whole body. Fukushima residents were exposed to 45R (0.4 Gy or 400 mSv) which risks are much higher than the radiation we received in our PCa treatment.

https://www.theguardian.com/news/datablog/2011/mar/15/radiation-exposure-levels-guide

Best,

VG

Georges Calvez
Posts: 307
Joined: Sep 2018

Hi Steve,

People seem to respond to radiation in very different ways.
I had 66 Gy in 33 fractions to the prostate bed over just over seven weeks to allow for the odd holiday and a machine shut down and update.
By the end I felt tired and it was like peeing warm water and doing a post curry bowel movement. I lost some ground on my incontinence and the pad was slightly pink.
Most of that disappeared within a few weeks of stopping and it has not returned.
Some people had awful burns to the skin, their urine turned red with blood, etc so I count myself very lucky.
I hope that any cancer cells in my prostate bed have been a lot less lucky!

Best wishes,

Georges

Clevelandguy
Posts: 471
Joined: Jun 2015

Hi All,

Whether radiation or surgery just about all of us are walking wounded with some side effects.  It’s just really sad when your hear about the really severe ones.  You have to wonder if its just their  physicality, doctors, or facilities that is the variable. I consider myself very lucky, after almost 5 yrs. undetectable PSA, about 85% on the dicktor scale, and a slight drip from time to time. Living a year at a time between PSA tests. I try my best to lead a normal life and don’t let my drips get in the way. Keep on keepin on.

Dave 3+4

Steve1961
Posts: 250
Joined: Dec 2017

 How many like let’s say chest x-rays is equal to 45 grays an external beam radiation 

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VascodaGama
Posts: 3045
Joined: Nov 2010

Steve,

You cannot analyze or estimate risks comparing your treatment dose to a number of chest x-rays. The treatment is done localized to the tumor which spot receives the full blow. A chest x-ray covers the full area being photographed. Apart from that, the absorbed radiation depends on the dose used which is different at each part of the body. The link in my initial post can give you details on that.

You are a worrier and it becomes difficult to me to give you a straight answer as you may interpret it erroneously. You need to understand radiation and the role of it in the treatment, instead of think it as the evil creature in the story.
It is also impossible to evaluate the risks (danger in organs failure or death) from cumulative radiation because this does not accumulate over the years striking us later with a bigger blow. In RT treatments what accumulates (therapy after therapy) are the dead tissue spots acquired in each intervention.

Radiation treatment works by destroying only the portion where it is directed. As Georges comments above the aimed spots in the RT fall within the area of the tumor (cancerous cells) which are expected to be killed. Neighboring organs and systems get negligible doses so that are not much affected and continue functioning naturally; recuperating fully once the dead cells are replaced by newer ones in their life cycle.

Chest X-rays use low ionizing radiation (0.1 mSv) with a very low possibility in damaging the DNA of cells causing scars. PCa treatment uses high ionizing doses of 1,800 to 2,500 mSv (1.8 to 2.5 Gy) assuring the killing of cancerous cells. In treatments for prostate cancer tissues in the bladder wall and colon are affected too. Not all dead tissues are disposed naturally by the body and these become sort of scars for life (cystitis and proctitis). Adding more radiation in these areas could cause fistulas so that one needs to avoid rads over rads of high intensity.

I do not know your age but in my lay opinion you can have as many chest X-rays as you need for the rest of your life. I doubt that any one person would have ever 10,000 x-rays in his whole life (your comment above). You shouldn’t be worried when a physician demands such an exam because they only do it if the benefits outweigh the risks. Even radiation treatment for cancer is done under such principles. A PCa patient with extensive advanced cancer (mets in bone etc) is never recommended to radiotherapy because it wouldn’t treat the issue. The radiotherapist would reserve it to other purposes such as pain control at affected spots.

Best wishes,

VGama

 

Georges Calvez
Posts: 307
Joined: Sep 2018

Hi Steve,

You can not make a direct comparison between x rays and radiotherapy.
The radiation used in chest x rays is diffuse and low energy, it has sufficient power to pass through soft tissues but is stopped or almost stopped entirely by bone.
The radiation used in radiotherapy is diffuse at the skin surface but focissed so that at the site of the power the target gest the full force of the radiation.
It is possible for low intensity radiation to cause DNA breaks, this is the reason why radon gas which is found in some areas, a lot of high altitude flying, etc has a slightly increased cancer risk.
High intensity radiation on the other hand causes massive DNA breaks including double breaks where both strands are broken. This normally results in cell death or when the cell tries to divide, it is impossible to copy the shattered DNA and the two daughter cells die.
Cancer cells are much more vulnerable to this than normal cells so they start out with a disadvantage, there are also hopefully less of them as well, thus at the end of the treatment it is hoped that the cancer cells are either dead or will die, the normal tissue will be damaged as well but hopefully less so.

Best wishes,

Georges

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