"Useful beam" means the radiation which passes through the tube housing port and the aperture of the beam-limiting device when the exposure switch or timer is activated.
Nev. Admin. Code § 459.528
NRS 459.201
"Useful beam" means the radiation which passes through the tube housing port and the aperture of the beam-limiting device when the exposure switch or timer is activated.
Nev. Admin. Code § 459.528
NRS 459.201