Advanced Physics for Brachytherapy 2018

Type B uncertainty … random number generator

Pseudo random number generators are used, e.g. Lehmer type, multiplicative- congruential of the form: r n+1 =Br n mod2 M

with B,M and r 0

(the “seed” of the sequence) appropriately selected.

• These generators are generally robust in benchmarked and extensively used codes

• These generators are periodic with a period of 2 M . Exceeding this period might underestimate result variance

• If you are using different simulations to estimate Var(k) make sure the seed is different