Rectilinear scanner

In the early 1950s, Benedict Cassen (Figs. 5.4-5.6) at the University of California developed the first rectilinear scanner based on the use of radiotracers produced by a nuclear reactor. Later, Kuhl and Bender invented a method called photorecording of images on x-ray film. 

Fig. 5.4 Benedict Cassen, inventor of the rectilinear scanner In the early 1950s.

Fig. 5.6 Afused Image of a brain tumor obtained with a rectilinear scanner in the early 1960s. The scan was performed with 1-131 albumin and superimposed on a conventionai radiograph of the skuil.

Perfusion lung scanning was performed with a rectilinear scanner, built at Johns Hopkins and modeled on the scanner invented by Ben Cassen. 

Hal s greatest contribution was to replace the rectilinear scanners with the scintillation camera (Fig. 7.5.) invented in 1957, and perfected in the 1960s and 1970s. The invention of the Anger camera led to the birth of nuclear cardiology, which accounts for more than half of all nuclear medicine imaging studies in the US today. 

In 1951, Hal Anger read in the journal. Nucleonics, of the invention of the rectilinear scanner by Benedict Cassen at UCLA. He thought I can do better than that. He recognized that the mechanical movement of the crystal radiation detector over the patient s body as designed in the Cassen rectilinear scanner was a serious limitation, and set out to develop a gamma ray camera. 

The output of the single channel analyzer is a digital pulse or count of 5-10 volts in magnitude and indicates the acceptance of an x-ray photon of the appropriate energy. These digital pulses may be passed to a ratemeter to indicate count rate, to a scaler/timer to measure total counts, to the photoplotter on a rectilinear scanner to produce pictures, or to a computer to record digital information. 

Under optimal conditions, a cold nodule of 0.7 cm could be detected in a thyroid gland that was normal with respect to iodine content. When compared with other imaging instruments at a similar level of nodule-to-background activity (99mTc) the gamma camera resolution (pin-hole collimator) was superior, but the resolution of the rectilinear scanner was about equal to that obtained with the thyroid fluorescence unit. 

The PMT is faulty or has changed its characteristics. The dynodes may have changed position or shape. Especially in portable instruments, rectilinear scanners and other instruments of which the detector heads are moving or are exposed to mechanical shock. 

The alkaloids were extracted into ethanol and purified on a column chromatography of diatomaceous earth moistened with 2.5 H H2 SO. Non-alkaloidal materials were first eluted with ethylether, alkaloids were then eluted with CHCI3 saturated with aqueous ammonia. After evaporation of eluate, a solution of the residue in chloroform was submitted to TLC plates of silica gel 60 F-254 which developed in the solvent trichloroethane-diethylamine (9 1). After drying at 105 for 2 hours, the plates were sprayed with a solution of 4-dimethylaminobenzaldehyde in ethanol-4 M H2SO4 (1 1) and again dried at 105" for 60 minutes. Hyoscyamine and scopolamine spots were determined with the use of high-speed scanner at 495 nm. The calibration graph was rectilinear for 0.2 to 2.0 mg ml"1 of alkaloid, and the detection limit was 50 ng. The method was rapid and comparable with... 

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