A Tcl/Tk Data Acquisition System for [C-11] Nicotine Time Course Studies R. Fox [1], Stephen Lokitz [2] It is widely believed that the addictive effects of cigarette smoking derive largely from the rapid absorption of nicotine from the pulmonary system. The immediate effects of an inhaled bolus of nicotine on brain function are thought to provide potent reinforcement for smoking behavior and maintain dependence on tobacco. A greater understanding of the initial time course of nicotine in arterial blood may be useful in achieving a greater understanding of smoking behavior. The Duke University Medical Center is developing a system to non-invasively measure the initial time course of [C-11] nicotine. This apparatus observes the inhalation of [C-11] nicotine inserted into a cigarette and the arrival of [C-11] nicotine at four locations in the body: the throat, lungs, brain, and wrist. The counting rates in the array of detectors placed around each subject will determine the arrival times of [C-11] nicotine with 0.5s precision. This paper will describe the data acquisition system developed for this detector array. The system is based on a minimal Tcl extension that supports access to arbitrary VME bus addresses. Using this extension a pure Tcl/Tk data acquisition system has been written to acquire, record, and display in real-time the data from the detector array. Tcl/Tk technologies used include Tcl loadable extension modules, Tk and BLT based graphical user interfaces, and the ability of Tcl/Tk to serve as a vehicle for delivering rapid prototypical solutions. [1] National Superconducting Cyclotron Lab, Michigan State University, East Lansing, MI [2] Duke University Medical Center, Durham, NC