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32 Cards in this Set
- Front
- Back
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what is the goal of radiation therapy?
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deliver an evenly distributed radiation dose to a target volume while minimizing dose to surrounding normal tissue
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what do radiation therapists do?
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play and advocate role for the patient in regards to their radiation treatment
deliver radiation therapy treatments operate radiation producing equipment maintain detailed treatment records |
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what is the isocenter?
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the axes of rotation of the center of the gantry, couch, and collimator
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what is the jobs of the quality assurance program?
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documentation, ensure accuracy in delivery of radiation treatment plan, ensure informed consent, weekly chart checks
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what 4 things are necessary for treatment?
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correct patient identification
correct signed prescription treatment planning data daily treatment record |
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what all is needed for a correct and signed prescription?
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1. site (breast)
2. total dose 3. daily dose or fraction 4. technique 5. physician signature |
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what are fiducial (reference) markers?
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natural anatomy
artificial marks placed internally in the patient artificial marks placed externally |
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what are permanent marks?
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most common are visible and palpable externally. tattoos. implanted seeds
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what is carfusion?
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dye like liquid that is magenta colored and may be used as a semi permanent form of localization
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how do we position the isocenter?
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align tattoos with lasers
verify SSD and ODI beam direction port films electronic portal imaging devices |
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what are the shielding blocks made of?
BLT w/ cheese |
bismuth
lead tin cadmium |
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how much of the original beam makes it through the blocks?
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5%
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what does MLC stand for?
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multileaf collimator
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what do MLC's do?
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customize field shapes with use of 'jaws' in treatment head
they are independent and move while beam is on |
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what is orthogonal imaging?
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2 images taken at a 90 degree angle from one another
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what are the 4 main beam modifiers?
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1. bolus
2. compensator 3. wedges 4. transmission filters |
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what is a bolus?
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materials whose interactions with radiation beam mimic those of tissue
brings dose closer to the skin surface *must conform without air gaps |
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what are some examples of a bolus?
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paraffin wax, vaseline gauze, wet gauze, wet towels
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when is a bolus used?
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when the loss of skin sparing is acceptable or desireable
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what are wedges?
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designed to change the angle of the isodose curve relative to the beam axis at a specified depth
reduce the dose in areas of overlap |
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what is the thick part of the wedge called? thin end?
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heel
toe |
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what part of the wedge always goes together?
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heel
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what are the isodose lines angled at?
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15, 30, 45, 60
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what is a dynamic jaw system?
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use of the Y jaws, moves during treatment to act as a wedge
the faster it moves- smaller angle slower it moves- larger angle |
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what is a transmission filter?
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used to allow transmission of predetermined % of treatment beam to a portion of the field. protect sensitive areas (kidneys)
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what are some examples of transmission filter?
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treating a whole abdomen with transmission filters placed over the kidneys
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what must you do when using transmission filters?
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record doses for each area
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all beam shaping and modification devices must be a minimum of how many centimeters aways from the patient?
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15cm
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where are low energy electrons absorbed?
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15 cm of air
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what are the different ways to turn off the machine?
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beam off button
turn key to off open door emergency off button |
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what is feathering?
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changing position of the jaws where the hot spot moves
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what is a non divergent beam?
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independent jaw, covers one side while treat part of the other side
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