Physics Bucharest 2017

Example for primary beam

Waiting room adjacent to a linac bunker

Equipment type = linac, FAD = 1m, 6MV W = 40000Gy/year D = 2.5Gy U = 0.25 (lateral approach) d = 6m T = 0.25 (waiting room) E = 0.001Gy/year (limit value in the area to be shielded d 0 as the distance from source to reference point (e.g. isocentre)

E 0

= WUT (d ref

/d) 2 = 69.444

n= -log(E/E 0

)= 5

Need to know the TVL (tenth value layer or thickness required to attenuate the beam by a factor of 10) of concrete in a 6MV beam -> TVL ≈ 30cm

Required barrier thickness: t pri

= nTVL= ??? m