SNM: Collimator combination clarifies small-tumor SPECT

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Combining high-resolution and high-sensitivity collimation provides better quality SPECT images, according to a study presented Monday at the 2009 SNM meeting in Toronto.

Collimators are used in SPECT because it is not yet possible to focus radiation with such short wavelengths into an image with the use of lenses. Researchers have established that SPECT image quality generally improves when using collimators with higher sensitivity than traditional low-energy high-resolution (LEHR) collimators. However, this is not the case when small tumors are being imaged. In these cases, the authors said that LEHR actually provides better images.

The new study combined a high-resolution collimator with a high-sensitivity collimator. A dual-head SPECT camera with three different collimator settings was simulated using the Gate Monte Carlo simulator. The results indicated that SPECT image quality was better with the mixed collimation than it was by using only high-resolution or only high-sensitivity collimation.

"SPECT is an important tool in molecular imaging because of its ability to provide accurate images of what is going on in the body without the need for invasive procedures such as surgery," said the study's lead author Roel Van Holen, MD, from the department of electronics and information systems at Ghent University in Ghent, Belgium. "However, researchers have had to make tradeoffs in SPECT image quality, especially in imaging very small tumors. Our research is exciting because it shows that combining high-resolution and high-energy collimators can improve SPECT's ability to image small tumors."