With the terrible crisis in Japan unfolding, I have paid a minor notice to how radiation is being measured from the Dai Ichi nuclear plant in Fukushima. This is a topic where I am a bit weak. We measure our treatment dosages in Gray and the measurements in Japan are measured in Millisieverts. Rolph Sievert was a Swedich physicist who studied dosages in nuclear medicine. His goal was to balance the cancer causing possibilities with radiation, with treating patients with cancer. From my basic, and I mean very basic, understanding, one sievert requires 1 gray of beta or gamma radiation but only 0.05 gray of alpha radiation or 0.1 gray of neutron radiation. . The difference is that gray is a quantity of radiation, and the sievert is a human absorption rate. Here are some examples of absorption rates:
Living near a nuclear power station = less than 0.01 mSv/year
Chest x-ray = 0.04 mSv
Cosmic radiation (from sky) at sea level = 0.24 mSv/year
Terrestrial radiation (from ground) = 0.28 mSv/year
Mammogram = 0.30 mSv
Natural radiation in the human body = 0.40 mSv/year
Brain CT scan = 0.8–5 mSv
Typical individual's natural background radiation: 2 mSv/year; 1.5 mSv/year for Australians, 3 mSv/year for Americans
Radon in the average US home = 2 mSv/year
Chest CT scan = 6–18 mSv
Average American's total radiation exposure: 6.2 mSv/year
New York-Tokyo flights for airline crew: 9mSv/year
Smoking 1.5 packs/day = 13 mSv/year
Gastrointestinal series X-ray investigation = 14 mSv
Current average limit for nuclear workers: 20 mSv/year
Background radiation in parts of Iran, India and Europe: 50 mSv/year
Lowest clearly carcinogenic level: 100 mSv/year
Criterion for re
location after Chernobyl disaster: 350 mSv/lifetime
Clearly in our doses we receive more than the average nuclear worker in our doses. I linked a presentation below on imaging doses that we can receive. Interestingly this paints a different picture than our RO's paint. The presentation clearly shows that X-ray, CT Scans, and MRI in a single year increases risk of secondary cancers. A bit disturbing when you consider we guys who have indeed completed diagnosis, imaging, and in many cases radiation to treat our cancer. With our doses we may actually exceed the Chernobyl exposure rates for a single year. In fact this tidbit caught my attention in the presentation:
“The delivery of 1 rad (0.01Gy) … to a women younger than 35 is estimated to increase her lifetime risk of breast cancer by 13.6%." Great ~ a typical dose for our radiation therapy is around 75 gray over 45 treatments.
Here is that presentation...
tinyurl.com/6h6s955I can see where exposure even in prostate cancer delivery protocols are small. But I can also see where a younger man in his thirties has far greater secondary cancer risk than a man 50 and above. Is there enough to be concerned about
? I am not clear on that at all from the brief study I just did. The risks, however, are present. There is no clear way to measure how men are affected 30 years after therapy other than with theory. Today's radiation dosing is far safer than even ten years ago as precision has been the technological push. To what degree is safety for younger men? Not sure...
Tony