32.3 Therapeutic Uses of Ionizing Radiation

32.3 Therapeutic Uses of Ionizing Radiation

  • There are limits on the amount of radiation that can be used for medical purposes.
    • Diagnostic doses have been lowered with improved techniques and faster films.
    • With the exception of routine dental x-rays, radiation is only used for diagnostic purposes so that the low risk is justified.
    • Less than 5 percent of the x-rays scatter into tissues that are not directly imaged.
    • Other x-ray procedures range from about 10 mSv in a CT Scan to about 5 mSv per dental x-ray, which only affect the tissue imaged.
  • Medical images with radiopharmaceuticals can give up to 5 mSv.
    • The only exception is the Thyroid Scan.
    • Because of its long half-life, it exposes the Thyroid to 0.75 Sv.
    • The short half-life of the isotope limits exposure to 15 mSv.
  • The alpha particles escape from the polonium nucleus.
    • The half life is related to random decay times.
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    • radiotherapy is used for cancer therapy where it saves thousands of lives and improves the quality of life and longevity of many it cannot save.
    • Depending on the type of cancer and the response of the patient, radiotherapy may be used alone or in combination with surgery and chemotherapy.
    • Radiation therapy's benefits far outweigh its long-term risks according to a careful examination of all available data.
  • The earliest uses of ionizing radiation on humans were mostly harmful, with many at the level of snake oil as seen in adium-doped cosmetics that glowed in the dark being used around the time of World War I.
    • Those who were exposed but did not gain any benefits were promoted as healthful and rejuvenated in the 1950s.
  • For a long time radium salts were sold as health tonics.
    • The death of a wealthy industrialist who became psychologically addicted to the brew made the public aware of the dangers of radium salts.
    • The legislation ended most abuses.
  • The properties of radiation were once more important than they are today.
    • radium was advertised for a variety of uses.
  • Cancer cells are more sensitive to radiation than other cells, which is why it is effective against the disease.
    • There is a problem in making the dose for cancer cells as high as possible while limiting the dose for normal cells.
    • A number of techniques can be used to concentrate the radiation.
  • A narrow beam of radiation is passed through the patient from a variety of directions.
    • The dose is spread out over a large volume of normal tissue.
    • External radiation can be xrays, rays, or ionizing-particle beams.
    • Heavy ion beams such as nitrogen nuclei have been used to produce beams of neutrons.
    • The particles have larger QFs or RBEs and sometimes can be better located.
    • X-ray is more expensive and less frequently used than other forms.
  • The source of -radiation rotates around the patient so that the common crossing point is in the tumor, concentrating the dose there.
  • Radiation therapy uses radioactive implants.
    • There is one use for the disease.
    • The size of a grain of rice and the radioactivity of the seeds are placed in the region.
    • Six-month half life or three-month half life are how long the isotopes are used for.
    • A large QF and a small range are advantages of alpha emitters.
  • Radiopharmaceuticals can be used for cancer therapy if they are well located.
    • Thyroid cancer can be treated with radioactive iodine.
    • Cancerous thyroid cells are more aggressive in doing this.
    • Antibodies produced by a patient to combat his cancer are taken, cultured, loaded with a radioisotope, and then returned to the patient.
    • Localizing the radiation in abnormal tissue is achieved by the concentration of the antibodies in the tissue they developed to fight.
    • For short-range radiation, the therapeutic ratio can be high.
    • There is a significant amount of radiopharmaceuticals that can be removed from the body by organs.
    • The technique is limited by the amount of damage to the normal tissue.
  • Therapeutic doses of radiation are listed in the table.
    • The large doses are not fatal because they are spread out in time.
    • For a period of several weeks, three to five 200-rem treatments per week is typical.
    • The body can repair itself between treatments.
    • Damage is concentrated in the abnormal tissue and it is more sensitive to radiation.
    • Damage to normal tissue limits the doses.
    • The adult brain is a tissue that is not rapidly reproducing.
    • Lung cancer can't usually be cured with radiation because of its sensitivity to lung tissue and blood.
    • Radiotherapy for lung cancer can alleviate symptoms and prolong life in some cases.