RADIATION THERAPY PHYSICS QUESTIONS WITH 100% CORRECT ANSWERS

Half-life values of some nuclides


Give this one a try later!


99mTc 6h
99Mo 67h


198Au(Gold) 2.7d
222Rn(Radon) 3.8d
131Cs(Cesium) 9.69d
103Pd(Palladium) 17d
169Yb(Ytterbium) 32d
125I(Iodine) 59.6d
192Ir(Iridium) 73.8d
145Sm(Samarium) 340d

252Cf(Californium) 2.65y
60Co(Cobalt) 5.26y
90Sr(Strontium) 28.9y
90Y(Yttrium) 28.9y
137Cs(Cesium) 30y

, 241Am(Americium) 432y
226Ra(Radium) 1622y




MOSFET vs diodes


Give this one a try later!


(a) Improvements
- Even smaller
- Can be readout later or instantly
- Can be implanted
(b) Drawbacks
- Limited lifetime ~100 Gy
- Sensitivity falls with accumulated dose




Inherent filtration in conventional x-ray tube


Give this one a try later!


0.5- to 1.0-mm aluminum.




Ion chamber pros


Give this one a try later!


(a) In use for 120+ years
(b) Well known corrections
(c) Absolute or relative dosimetry
(d) Instant readout
(e) Easy use
(f) 1D & 2D measurements
(g) Accurate

, (h) High SNR
(i) Reusable & stable
( j) Flat energy response
(k) Direction independent (cylindrical chambers)




How much is the Bremsstahlung contamination in electron beam?


Give this one a try later!


about 5%




Bq (becquerel)


Give this one a try later!


(a) SI unit for activity
(b) 1 dps
(c) 2.7E-11 Ci




Radiographic film pros


Give this one a try later!


(a) The gold standard for spatial resolution
(b) Fast 2D planar measurements
(c) Field matching patient QA
(d) Fast and easy machine QA tests
(e) Personnel monitor