Radiation Exposed

 From the American Cancer Association website:

What is radiation?

Radiation is the emission (sending out) of energy from any source. X-rays are an example of radiation, but so is the light that comes from the sun and the heat that is constantly coming off our bodies. There are different types of radiation, and many of them are not linked to cancer.

Types of radiation

Radiation exists across a spectrum from very high-energy (high-frequency) radiation to very low-energy (low-frequency) radiation. From highest to lowest energy, the main forms of radiation are:

·         Gamma rays

·         X-rays

·         Ultraviolet (UV) rays

·         Visible light

·         Infrared rays

·         Microwaves

·         Radiofrequency (radio) waves

·         Extremely low-frequency (ELF) radiation

An important distinction that affects the health risks from radiation is whether the energy is ionizing or non-ionizing.

Ionizing radiation

Ionizing radiation has enough energy to knock electrons off of atoms or molecules. This is called ionization. Ionized molecules are unstable and quickly undergo chemical changes.

If ionizing radiation passes through a cell in the body, it can lead to mutations (changes) in the cell's DNA, the part of the cell that contains its genes (blueprints). This could contribute to cancer, or to the death of the cell. The amount of damage in the cell is related to the dose of radiation it receives. The damage takes place in only a fraction of a second, but other changes such as the beginning of cancer may take years to develop.

Types of ionizing radiation include x-rays, mammograms, gamma rays, some high-energy UV rays, and particles given off by radioactive materials such as alpha particles and protons. These forms of radiation have different energy levels and can penetrate cells to different extents, but all are capable of causing ionization. The worst offenders seem to be CT scans and radiation therapy used for cancer patients.

Does ionizing radiation cause cancer?

Scientists and regulatory agencies agree that even small doses of ionizing radiation increase the risk of developing cancer, although by a very small amount. In general, the risk of cancer from radiation exposure increases as the dose of radiation increases. Likewise, the lower the exposure is, the smaller the increase in risk. But there is no threshold below which ionizing radiation is thought to be totally safe.

Sources of ionizing radiation

People may be exposed to ionizing radiation from 3 main sources:

·         Natural background radiation comes from cosmic rays from our solar system and radioactive elements normally present in the soil. This is the major contributor to worldwide radiation exposure.

·         Non-medical, man-made radiation can come from workplace and other sources, and is also a result of above ground nuclear weapons testing that took place before 1962.

·         Medical radiation comes in the form of diagnostic x-rays and other tests, as well as from radiation therapy. Radiation therapy is currently used to treat some types of cancer and involves dosages many thousand times higher than those used in diagnostic x-rays.

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Medical radiation

Ionizing radiation is used in the diagnosis and treatment of some medical conditions. This can be in the form of radiation that penetrates from outside the body, or radioactive particles that are swallowed or inserted into the body.

Imaging tests: Certain types of imaging tests, such as x-rays, CT scans, and nuclear medicine tests (such as PET scans and bone scans) expose people to low levels of radiation in order to create internal pictures of the body. (MRI and ultrasound exams do not use ionizing radiation.)

The increased risk of cancer from exposure to any single test is likely to be very small. Still, concerns have been raised in recent years as the average amount of radiation a person is exposed to from medical tests has risen. Children's growing bodies are especially sensitive to radiation.

Because of the very small but real risk, and the fact that radiation exposure from all sources can add up over one's lifetime, imaging tests that use radiation should only be done if there is a good medical reason to do so. The usefulness of the test must always be balanced against the possible risks from exposure to the radiation. In some cases, other imaging tests such as ultrasound or MRI may be an option. But if there is a reason to believe that an x-ray or CT scan is the best way to look for cancer or other diseases, the patient will most likely be helped more than the small dose of radiation can hurt.

Radiation therapy: Ionizing radiation is an effective way to treat certain kinds of cancer. During radiation therapy, high doses of ionizing radiation (much higher than those used for imaging tests) are directed at the cancer, resulting in the death of the cancer cells. However, this can lead to DNA mutations in other cells that survive the radiation, which may eventually lead to the development of a second cancer.

Overall, radiation therapy alone does not appear to be a very strong cause of second cancers. This is probably due to the fact that doctors try to focus the radiation on the cancer cells as much as possible, which means few normal cells are exposed to radiation. Still, some studies have linked radiation therapy with an increased risk of leukemia, thyroid cancer, early-onset breast cancer, and some other cancers. The amount of increased risk depends on a number of factors, include the dose of radiation, the location in the body, and the age of the person getting it (younger people are generally at greater risk later on).

If cancer does develop after radiation therapy, it does not happen right away. For leukemia, most cases develop within 5 to 9 years after exposure. In contrast, other cancers often take much longer to develop. Most of these cancers are not seen for 10 years after radiation therapy, and some are diagnosed even more than 15 years later.

When considering radiation exposure from radiation therapy treatment, the benefits generally outweigh the risks. However, some combinations of radiation therapy and chemotherapy are more risky than others. Doctors do their best to ensure the treatment that is given destroys the cancer while minimizing the risk that a secondary cancer will develop later on.

Try to be informed before you undergo any treatment or tests and weigh the benefits versus the possible risk.