The Gamma Camera. The thickness of the lead septa is chosen to ensure that only 5% of the -rays penetrate from one collimator hole to

The Gamma Camera. The thickness of the lead septa is chosen to ensure that only 5% of the γ-rays penetrate from one collimator hole to the adjacent one. The thickness is given by [60/µ/][L-3/ µ). Calculate the septal thickness required for γ-rays of 140 keV for lead collimators with a hole diameter of 0.1 cm and a length of 2.5 cm. The attenuation coefficient for lead is 30cm ^-1 . at 140keV.