Development of correction schemes for a small field of view gamma camera

Abstract

Purpose: The goal of this study is to develop data correction schemes for a small field of view (SFOV) high resolution gamma camera detector for a small organ dedicated system such as breast, thyroid and joints. Methods: The gamma camera contains PMTs coupled with single slap of NaI(TI) plate crystal. Correction schemes including energy, linearity and uniformity correction were developed. Energy and linearity correction was performed with 57Co sheet by utilizing same dot pattern phantom used for look up table (LUT) generation. Energy correction aligns the energy peaks of energy spectrum to reference energy by linear transformation. Linearity correction removes spatial distortions based on LUT of X, Y directions. Uniformity correction was executed with 99mTc flood source to redistribute counts in the image. This correction was based on pixel addition and subtraction for each event. Results: The results showed calibration measure for dot pattern image acquired with 57Co sheet and flood field image obtained with 99mTc. This system acquired with 99mTc provided 17. 54% FWHM energy resolution and 2. 5% integral uniformity within a useful field of view (UFOV). Conclusions: The correction schemes in this paper showed good results about linearity and uniformity. The measured energy resolution of the system is not as high as what we had expected due to the limitation of the current version of DAQ in the prototype system. In the future, we will revise the hardware so that we can maximize the performance of the proposed methods. © 2012 Korean Society of Medical and Biological Engineering and Springer.