High spatial resolution and high sensitivity scintillation detector for PET, SPECT and CT systems using laser-induced optical barriers

Objectives Here we are reporting on the latest achievements in fabricating high performance scintillation detectors using laser processing technique that can be used for PET, SPECT and X-ray detectors. In many applications, high spatial resolution and high sensitivity scintillator arrays are necessary. However, achieving pixelated arrays with minimized inter-pixel gap and large pixel length to cross-section is very expensive or impossible. We have utilized a technique that is based on introducing optical barriers within scintillator crystals using laser pulses.

Methods In laser induced optical barriers (LIOB), laser beam is focused into the scintillation material bulk and by optimizing the laser parameters one can locally change the structure of the material and introduce optical barriers. We are now able to introduce these optical barriers at any depth and with different concentration. Using LIOB, we have fabricated multiple arrays of LYSO, CsI:Tl and GLuGAG with different thicknesses and pixel sizes. We are able to change the inter-pixel optical crosstalk by changing the laser parameters as well as number of laser passes. This has led to fabricating arrays suitable for clinical and pre-clinical PET and SPECT as well as arrays for X-ray detectors.

Results We have laser processed scintillator crystals ranging from 1 to 20 mm thick and with pixel size ranging from 0.25x0.25 to 1.5x1.5 mm^2 in cross section. Flood images of the arrays exposed to both X-rays and gamma-rays show excellent pixel separation. We have shown that the inter-pixel optical crosstalk can be controlled.

Conclusions Our method yields near-perfect, extremely high aspect ratio pixels. Our technique is automated and cost-effective, and is ideal for fabricating scintillator arrays for clinical/pre-clinical PET and SPECT systems as well as X-ray detectors.