1. Choose and write the correct answer: 1. (a) Beyond the depth of Dmax, PDD - (i) increases with depth (ii) decreases with depth (iii) remains same (iv) none of these 2. (b) Outpu... 1. Choose and write the correct answer: 1. (a) Beyond the depth of Dmax, PDD - (i) increases with depth (ii) decreases with depth (iii) remains same (iv) none of these 2. (b) Output of Co-60 source is higher - (i) with wedge filter (ii) without wedge filter (iii) same in both cases (iv) none of these 3. (c) Reference depth for measuring tissue maximum ratio is - (i) 5x5 cm field (ii) 5x5 mm field (iii) 10x10 cm field 4. (d) Primary radiation beam is measured to - (i) PDD (ii) SSD (iii) TAR (iv) none of these 5. (e) At the depth of Dmax, BSF equal to - (i) PDD (ii) SSD (iii) TAR (iv) none of these 6. (f) Flatness of electron beam changes significantly with depth due to - (i) high energy electron (ii) low energy electron (iii) medium energy electron (iv) 10MV electron 7. (g) Electron beam can be used to treat superficial tumor up to the depth - (i) 0.5 cm (ii) 5 cm (iii) 5 mm (iv) 2 cm 8. (h) Central axis depth dose for lower energy x-ray is maximum at - (i) 0.5 cm depth from the surface (ii) 5 cm from surface (iii) surface of the phantom (iv) none of these 9. (i) The most useful treatment considered as - (i) mono-energetic (ii) hetero-energetic (iii) low energetic (iv) none of these 10. (j) Electron beam can be considered as - (i) mono-energetic (ii) hetero-energetic (iii) low energetic (iv) none of these 11. (k) The range of 9MeV electron beam in water is approximately - (i) 4.5 cm (ii) 10 cm (iii) 5 cm (iv) none of these 12. (l) For ortho-voltage x-ray, the reference depth dose is at - (i) d=0 (ii) d=0.5 cm (iii) 5 cm (iv) 10 cm 13. (m) Which one is the most predominant mode of interaction for megavoltage photon beam in the clinical situation? (i) Photoelectric effect (ii) Pair production (iii) Augereffect Read more