When using a gamma emitter, such as Technetium-99 or Indium-111, tomographic images can be collected using Siemens MicroCATTM II system which provides co-registered SPECT and x-ray computed tomography (CT) images without removing the animal from the imaging bed.
The SPECT system has 150 mm x 150 mm dual head detectors resulting in reduced acquisition time and increased sensitivity over single headed systems. In addition, different isotopes which emit different energies for each probe can be used for imaging different tissue compartments simultaneously, e.g., 99mTc (140 KeV) as well as 111In (247 KeV). Dual head detectors are equipped with interchangeable pinhole / parallel collimators ranging from 0.5 mm to 3 mm. The projection images may be ported to one of two Beowulf computer clusters for CT and SPECT tomography.
The CT system is a dual focus system allowing trabecular bone imaging as well as whole body imaging.