Radiation Health Effects
Mar 19, · Over time, exposure to radiation may cause cancer and other health problems. Different types of radiation include: Electromagnetic radiation such as radio waves, heat, X-rays, gamma radiation, and even visible light; Particle radiation such as alpha radiation, neutron radiation, and beta radiation. Radiation can cause various types of injury to the skin, depending on the dose and conditions of exposure. The earliest outward reaction of the skin is transitory reddening (erythema) of the exposed area, which may appear within hours after a dose of 6 Gy or more.
A wide variety of reactions occur in response to irradiation in the different organs and tissues of the body. Some of the reactions occur quickly, while others occur slowly. What plants can i grow indoors killing of cells in affected tissues, for example, may be detectable within minutes after exposure, whereas degenerative changes such as scarring and tissue breakdown may not appear until months obdy years afterward.
In general, dividing cells are more radiosensitive than nondividing cells see above Effects on the cellwith the result that radiation injury tends to appear soonest in those organs and tissues in which cells proliferate rapidly. Such tissues include the skin, the lining of the gastrointestinal tract, and the bone radiatin, where what is rhinovirus for humans cells multiply continually in order to replace the mature cells that are constantly being lost through normal aging.
The early effects of radiation on these organs result largely from the destruction of the progenitor cells and the consequent interference with the replacement of the mature cells, a process essential for the maintenance of normal tissue structure and function.
The damaging effects of radiation on an organ are generally limited to that part of the organ directly exposed. Accordingly, irradiation of only a part of an organ generally causes less impairment radkation the function of the organ than does irradiation of the whole organ. Radiation can cause various types of injury to the skin, depending on the dose and conditions of exposure.
The earliest outward reaction of the skin is transitory reddening erythema of the exposed area, which may appear within hours after a dose of 6 Gy or more. This reaction typically lasts only a few hours and is followed two to four weeks later by one or more waves of deeper and more prolonged reddening in the radiatjon area. A larger dose may cause subsequent blistering and ulceration of the skin and loss of hair, followed by abnormal pigmentation months or years doea.
The blood-forming cells of the bone marrow are ho the most radiosensitive cells in the body. If a large percentage of such cells rariation killed, as can dadiation when intensive irradiation of the whole body occurs, the normal replacement of circulating blood cells is impaired. As a result, the blood cell count may become depressed and, ultimately, infection, hemorrhage, or both may ensue. A dose below 0. The response of the gastrointestinal tract is comparable in many respects to that of the skin.
Proliferating cells in the mucous membrane wjat lines the tract are easily killed by irradiation, resulting in the denudation and ulceration of the mucous membrane. If a substantial portion of the small intestine is exposed rapidly to a dose in excess of 10 Gy, as may occur in a radiation accident, a fatal dysentery-like reaction results within a very short period of time. Although mature spermatozoa are relatively resistant to radiation, immature sperm-forming cells spermatogonia are among bodh most radiosensitive cells in the body.
Hence, rapid exposure of both testes to a dose as low as 0. In what radiation does to your body human ovaryoocytes of intermediate maturity are more radiosensitive than those of greater or lesser maturity. A dose of 1. Irradiation can cause opacification of the lens, the severity of which increases with the raviation. The effect may not become evident, however, until many months after exposure. During the s, some physicists who worked with the early cyclotrons developed cataracts as a result of occupational neutron irradiation, indicating how to change icon sizes on mac the first time t high relative biologic effectiveness of neutrons for causing lens damage.
The threshold for a progressive, vision-impairing opacity, or cataract, varies from 5 Sv delivered to the lens in a single exposure to as much as 14 Sv delivered in what radiation does to your body exposures over a period of months.
Generally speaking, humans do not sense a moderate radiation field; however, small doses of radiation less than 0. American astronauts on the first spacecraft that landed on the Moon Apollo 11, July 20, observed irregular light flashes and streaks during their flight, which probably resulted from single raadiation cosmic-ray particles striking the retina.
In various food-preference tests, rats, when given the choice, avoid radiation fields of even a few mGy. A dose of 0. The mature brain and nervous system radaition relatively resistant to radiation injury, but the developing brain is radiosensitive to damage see below. Videos Images. Additional Info. Load Previous Page. Effects on organs of the body somatic effects A wide variety of reactions occur in response to irradiation in the different organs and tissues of the body.
Skin Radiation can cause various types of injury to the skin, depending on the dose and conditions of exposure. Bone marrow The blood-forming cells of the bone marrow are among the most radiosensitive cells in the body. Gastrointestinal tract The response of the gastrointestinal tract is comparable in many respects to that of the skin. Reproductive organs Although mature spermatozoa are relatively resistant to radiation, immature sperm-forming cells spermatogonia are wha the most radiosensitive cells in the body.
Lens of the eye Irradiation can cause opacification of the lens, the severity of which increases with yojr dose. Brain and sensory organs Generally speaking, humans do not sense a moderate radiation field; however, small doses raditaion radiation less than 0. Load Next Page.
Mar 25, · Brain.. Nerve cells (neurons) and brain blood vessels can die, leading to seizures. Eyes.. Radiation exposure increases the risk of cataracts. Thyroid.. When a nuclear reactor malfunctions, radioactive iodine (I) can be released into the atmosphere (this is Lungs.. When you breathe in.
There's been a lot in the media about radiation exposure from medical imaging, and many of my patients are asking about it. They want to know if radiation from mammograms, bone density tests, computed tomography CT scans, and so forth will increase their risk of developing cancer. For most women, there's very little risk from routine x-ray imaging such as mammography or dental x-rays.
But many experts are concerned about an explosion in the use of higher radiation—dose tests, such as CT and nuclear imaging. Over 80 million CT scans are performed in the United States each year, compared with just three million in There are good reasons for this trend.
CT scanning and nuclear imaging have revolutionized diagnosis and treatment, almost eliminating the need for once-common exploratory surgeries and many other invasive and potentially risky procedures. The benefits of these tests, when they're appropriate, far outweigh any radiation-associated cancer risks, and the risk from a single CT scan or nuclear imaging test is quite small.
But are we courting future public health problems? The radiation you get from x-ray, CT, and nuclear imaging is ionizing radiation — high-energy wavelengths or particles that penetrate tissue to reveal the body's internal organs and structures.
Ionizing radiation can damage DNA, and although your cells repair most of the damage, they sometimes do the job imperfectly, leaving small areas of "misrepair.
We're exposed to small doses of ionizing radiation from natural sources all the time — in particular, cosmic radiation, mainly from the sun, and radon, a radioactive gas that comes from the natural breakdown of uranium in soil, rock, water, and building materials.
How much of this so-called background radiation you are exposed to depends on many factors, including altitude and home ventilation. But the average is 3 millisieverts mSv per year.
A millisievert is a measure of radiation exposure; see "Measuring radiation. Exposure to ionizing radiation from natural or background sources hasn't changed since about , but Americans' total per capita radiation exposure has nearly doubled, and experts believe the main reason is increased use of medical imaging.
If you mention the measurement of radiation, many people will recall the classic Geiger counter with its crescendo of clicks. But Geiger counters detect only the intensity of radioactive emissions. Measuring their impact on human tissues and health is more difficult. That's where the sievert Sv and millisievert mSv come in. These units, the ones most commonly used in comparing imaging procedures, take into account the biological effect of radiation, which varies with the type of radiation and the vulnerability of the affected body tissue.
Taking these into account, millisieverts describe what's called the "equivalent dose. We've long known that children and teens who receive high doses of radiation to treat lymphoma or other cancers are more likely to develop additional cancers later in life. But we have no clinical trials to guide our thinking about cancer risk from medical radiation in healthy adults. Most of what we know about the risks of ionizing radiation comes from long-term studies of people who survived the atomic bomb blasts at Hiroshima and Nagasaki.
These studies show a slightly but significantly increased risk of cancer in those exposed to the blasts, including a group of 25, Hiroshima survivors who received less than 50 mSv of radiation — an amount you might get from three or more CT scans. See "Imaging procedures and their approximate effective radiation doses. The atomic blast isn't a perfect model for exposure to medical radiation, because the bomb released its radiation all at once, while the doses from medical imaging are smaller and spread over time.
Still, most experts believe that can be almost as harmful as getting an equivalent dose all at once. Source: Mettler FA, et al. Most of the increased exposure in the United States is due to CT scanning and nuclear imaging, which require larger radiation doses than traditional x-rays.
A chest x-ray, for example, delivers 0. And that's not counting the very common follow-up CT scans. In a study from Brigham and Women's Hospital in Boston, researchers estimated the potential risk of cancer from CT scans in 31, patients over 22 years.
For the group as a whole, the increase in risk was slight — 0. But for patients who had multiple CT scans, the increase in risk was higher, ranging from 2. Unless you were exposed to high doses of radiation during cancer treatment in youth, any increase in your risk for cancer due to medical radiation appears to be slight. But we don't really know for sure, since the effects of radiation damage typically take many years to appear, and the increase in high-dose imaging has occurred only since So until we know more, you will want to keep your exposure to medical radiation as low as possible.
You can do that in several ways, including these:. Discuss any high-dose diagnostic imaging with your clinician. If you need a CT or nuclear scan to treat or diagnose a medical condition, the benefits usually outweigh the risks. Still, if your clinician has ordered a CT, it's reasonable to ask what difference the result will make in how your condition is managed; for example, will it save you an invasive procedure?
Keep track of your x-ray history. It won't be completely accurate because different machines deliver different amounts of radiation, and because the dose you absorb depends on your size, your weight, and the part of the body targeted by the x-ray.
But you and your clinician will get a ballpark estimate of your exposure. Consider a lower-dose radiation test. If your clinician recommends a CT or nuclear medicine scan, ask if another technique would work, such as a lower-dose x-ray or a test that uses no radiation, such as ultrasound which uses high-frequency sound waves or MRI which relies on magnetic energy.
Consider less-frequent testing. If you're getting regular CT scans for a chronic condition, ask your clinician if it's possible to increase the time between scans. And if you feel the CT scans aren't helping, discuss whether you might take a different approach, such as lower-dose imaging or observation without imaging. Don't seek out scans. Don't ask for a CT scan just because you want to feel assured that you've had a "thorough checkup.
And there's a chance the scan will find something incidental, spurring additional CT scans or x-rays that add to your radiation exposure. Living with cancer? Buy Life After Cancer , a special health report that will walk you through many of the issues you'll face in the upcoming months and years, and guide you through the next stage of your cancer journey.
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Updated: January 29, Published: October, Research We're Watching: Radiation for breast cancer linked to heart problems The cervical cancer vaccine Certain symptoms may be early signs of ovarian cancer By the way, doctor: Should I get the HPV vaccine if I'm already infected? Cancer screening as we age Fibroid embolization and surgery have similar five-year outcomes. E-mail Address. First Name Optional. Measuring radiation If you mention the measurement of radiation, many people will recall the classic Geiger counter with its crescendo of clicks.