Rapid, rigorous computation of modulation transfer function on a pocket calculator.

This article describes a method for the rigorous calculation of modulation transfer function (MTF) of a collimated scintillation detector using a programmable pocket calculator. The calculation utilizes a normalized discrete Fourier transform (DFT) of the line spread function (LSF) including real and imaginary terms. A method is described for recording the LSF using an Anger camera and multichannel analyzer (MCA). The procedures for recording of the LSF and calculation of the MTF are therefore performed independently of a computer, allowing nuclear medicine laboratories without access to a computer, allowing nuclear medicine laboratories without access to incorporate MTF studies into their quality-assurance programs. The results obtained using the pocket calculator were compared with those using a PDP-12 minicomputer. The pocket calculator was slightly more accurate, since it does not suffer from the round-off errors of the PDP-12. The time required to plot an 11-point MTF curve using the pocket calculator was 5 min, using the PDP-12 0.5 min.