title: Precision control of eluted activity from a Sr/Rb generator for cardiac positron emission tomography.
abstract: A rubidium-82 (/sup 82/Rb) elution system is described for use with clinical positron emission tomography. The system is self-calibrating with 1.4% repeatability, independent of generator activity and elution flow rate. Saline flow is switched between a /sup 82/Sr//sup 82/Rb generator and a bypass line to achieve a constant activity elution of /sup 82/Rb. In the present study, pulse width modulation (PWM) of a solenoid valve is compared to simple threshold control as a means to simulate a proportional valve. A predictive-corrective control algorithm is developed which produces a constant activity elution within the constraints of long feedback delay and short elution time. Accurate constant-activity elutions of 10-70% of the total generator activity were demonstrated using the threshold comparison control. The adaptive-corrective control of the PWM valve provided a substantial improvement in precision of the steady-state output.
authors.affiliation: Nat. Cardiac PET Centre, Ottawa Univ. Heart Inst., Ont., Canada.
authors.forename: R
authors.initials: R
authors.lastname: Klein
authors.forename: A
authors.initials: A
authors.lastname: Adler
authors.forename: R S
authors.initials: RS
authors.lastname: Beanlands
authors.forename: R A
authors.initials: RA
authors.lastname: deKemp