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23 Cards in this Set
- Front
- Back
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What are the goals of radiation therapy?
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- is considered a local treatment because only cells in the area being treated are affected.
- may be used before surgery to shrink the tumor or following surgery to prevent the cancer from coming back. - may be used in combination with surgery and/or chemotherapy. - may be used in early stage cancers in an attempt to cure or control the disease. |
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What is combined modality?
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using local therapy and systemic therapy
combining: radiation, chemotherapy and surgery |
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What is the most common type of radiation therapy?
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linear accelerator
(this is the standard - been here for 30-40 years) |
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Linear accelerator
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machine that uses high-energy photons from radioactive sources such as cobalt, cesium
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What types of radiation are used to treat cancer?
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Electromagnetic radiation, (x-rays and gamma rays). Particulate radiation (electrons, protons, neutrons, alpha particles, and beta particles) are all forms of ionizing radiation
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How does radiation work?
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works by damaging the DNA in cells
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Radiation attacks ...
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reproducing cells, it does not distinguish between cancer cells and normal tissues
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Radiation therapy involves a balance between:
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destroying the cancer cells (in order to cure or control the disease) and sparing the normal cells (to minimize undesirable side effects).
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What percentage of people with CA receive radiation during cancer treatment?
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50-60%
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TREATMENT PLANNING
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- is complex may take several days to complete, but it is one of the most important parts of radiation therapy.
- Simulation is the first part of treatment planning. - Determine radiation dose |
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Simulation
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- marking session
- the size or volume of the tumor is determined (Use CT/PET/MR overlay to determine target.) - Potential route of spread and normal tissues in the treatment area are assessed. |
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How do you determine radiation dose?
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- decided based on a number of factors and by the ability of the normal tissue to tolerate the radiation
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Radiation dosages
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- expressed in rads (radiation absorbed dose)
- total dose of radiation is divided into several smaller doses or fractions that are given over several weeks. This allows the optimal dose to kill the cancer to be administered with less damage to normal tissues |
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rad
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a measurement of the amount of radiation absorbed by the body
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Gray
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- a newer international term
- 1 gray = 100 rads - 1 cGray (cGy) = 1 rad |
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Can abdomen handle radiation?
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No
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Curative Dosages
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60-70 Gray
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Palliative Symptoms
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30 Gray
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Altered fractionation
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(hyperfractionated or accelerated radiation)
- sometimes seems to enhance the effect of the radiation by increasing the damage to the DNA of the cancer cells. |
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What are the disadvantages of altered fractionation?
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- side effects are seen earlier and may be more severe.
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External beam radiation
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- radiation is focused from a source outside the body onto the area affected by the cancer.
- this type of radiation may be given by machines called linear accelerators |
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Brachytherapy
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- a.k.a. internal radiation therapy
- short-distance therapy. two main types of brachytherapy: - interstitial radiation -intracavitary radiation. |
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Stereotactic surgery or stereotactic radiation therapy
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- terms used to describe several techniques used to deliver a large precise radiation dose to a small tumor volume
- No incision is actually made - The most common site being treated with this technique is the brain. (Gamma Knife) - Three-dimensional conformal radiation |
