Bentel Ch Questions
Terms
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- Year in which Roentgen was internationally accepted as unit for x-rays
- 1928
- Year rad was recommended by ICRU as a unit of absorbed dose
- 1953
- Primary reason betatrons were unpopular for use in rad therapy
- Low dose rate and limited field size
- Radiation therapy units operating from 50 - 120 kVp
- superficial units
- Orthovoltage x-ray units operate in this range of energy
- 150 - 500 kVp
- SSD for othovoltage units
- 50 - 70 cm
- HVT for superficial units.
- 1 - 8 mm Al
- Treatment distances for superficial units
- 15 - 20 cm
- The dose rate is high for orthovoltage units for this reason.
- Short treatment distances
- Depth to maximum dose for orthovoltage machines and depth to 90%
- Close to skin surface, depth to 90% is 2 cm
- the dose monitoring system in the beam path of a linac monitors these three things.
- Dose rate, integrated dose, beam symmetry
- Year in which Co-60 unit invented
- 1951
- What determines the sharpness of the beam edges in a linac?
- secondary collimator
- How does the depth to maximum dose depend on field size, SSD, and oblique incidence?
- Decreases with increasing field size and oblique incidence, is independent of SSD
- neuroblastoma origination
- sympathetic nervous system
- Define the abdomen
- lies between thorax and pelvis, contains peritoneal cavity
- dose under a 5-HVT kidney block vs. middepth on central axis is...
- 10-20% depending on energy and FS