Multicrystal Gamma Camera Higher detection efficiency than Anger Cameras Uses a physical matrix of scintillation crystals separated by lead strips Collimator with holes corresponding to each crystal X/Y “lightpipe/PMT assembly replaces Anger positioning logic

Old Style (True) Multicrystal Gamma Camera 294 Crystals 294 Collimator Holes Each Crystal : Two Lucite Lightpipes One Lightpipe : X Axis One Lightpipe : Y Axis Bank of 35 PMTs Minimizes “Crosstalk” Pulses from more than one crystal Improves Efficiency Paul Early, D. Bruce Sodee, Principles and Practice of Nuclear Medicine, 2nd Ed., (St. Louis: Mosby 1995), pg. 254.

Scinticor-Type “Multicrystal” Camera Not really a multicrystal Camera Uses crystal kind of like “Starbright” – slotted Paul Christian, Donald Bernier, James Langan, Nuclear Medicine and Pet: Technology and Techniques, 5th Ed. (St. Louis: Mosby 2004) pg 69.

Multicrystal Gamma Camera Paul Early, D. Bruce Sodee, Principles and Practice of Nuclear Medicine, 2nd Ed., (St. Louis: Mosby 1995), pg X 20 Crystal Elements 115 PMTs Anger-like Positioning Logic

Multicrystal Primary Use: First Pass Bolus dose : Hi Concentration of Activity Quantifying Information Need Accurate Reading of Counts “Saturates” Anger Camera (Inaccurate Counts)

Solid State Gamma Camera Uses an array of many scintillation crystals (either Cadmium Zinc Telluride or Thallium Activated Cesium Iodide) Based on the formation of “electron- hole pairs” (has to do with an electron moving between valence band and conduction band) Each crystal has its own photodiode (instead of PMT) Creates a positioning matrix rather than the positioning logic of the Anger system.

Solid State Gamma Camera—Digirad System 4,096 CsI(Tl) Crystals and Photodiodes Good Efficiency Hi Noise Potential Very Good Resolution (2mm Intrinsic) “Pixelated” FOV property lends itself to digitization Consistent performance across entire FOV

Cadmium Zinc Telluride Crystals

Solid State Gamma Cameras Have a small FOV Useful for dedicated purposes such as heart, breast, and brain imaging Are portable—useful in ICU situations Watch these---may eventually become the basis for all gamma cameras

Images from Solid State System

Nuclear medicine techs and physician view cowardly lion scan