dosimetry final Exam Questions and Answers radiation that penetrates material such as the human body is called - Correct Answers ✅ionizing the SI unit for radioactivity is - Correct Answers ✅Becquerel (Bq) the time it takes for activity to decay to 1/2 of its original value is called - Correct Answers ✅half life the thickness required of an absorber to reduce the intensity of a beam to half of its original value is - Correct Answers ✅half value layer
- Gy is equal to - Correct Answers ✅-100 rad
-10^2 cGy -1 J/kg the geometric point around which the gantry, collimator, and couch rotate is called - Correct Answers ✅isocenter the distance from a source of radiation to the patient's skin is called - Correct Answers ✅SSD (source to skin surface distance) 1 / 3
dosimetry final Exam Questions and Answers a field dimension at depth is (smaller, larger, the same) as the field size on the skin - Correct Answers ✅larger two circumstances for which it is advisable to treat a patient in the prone position - Correct Answers ✅-prone breast; moves breast away from lung/heart -prone belly board; moves small bowel out of field what type of imaging is required to create an ITV - Correct Answers ✅-4DCT simulation which beam arrangement would give the most circularly shaped isodose volume - Correct Answers ✅8-field equally spaced beams which beam arrangement would deliver the most integral dose to the patient - Correct Answers ✅360 degree arc in cranial spinal treatment, what needs to be rotated in order to deliver all the beams - Correct Answers ✅gantry, couch, and collimator what technique is not used in avoiding overdose in adjacent/abutting fields - Correct Answers ✅arc therapy 2 / 3
dosimetry final Exam Questions and Answers T/F roentgen is a unit to measure radioactivity - Correct Answers ✅false T/F ionizing radiation is used in radiotherapy treatment - Correct Answers ✅true T/F if a tumor in the liver needs to be treated using several beams around the patient, it is better to use the SSD set up - Correct Answers ✅false T/F supine position is the most commonly used treatment position - Correct Answers ✅true T/F the geometric point around which the gantry, collimator and couch rotate is called isocenter - Correct Answers ✅true T/F PTV is usually smaller than the CTV in contouring - Correct Answers ✅false T/F in percent depth dose curve, dmax has the highest value - Correct Answers ✅true T/F in SAD setup, the treatment depth plus the source to skin distance equals the source to isocenter distance - Correct Answers ✅true
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