Radiology, Vol 144, 901-904, Copyright © 1982 by Radiological Society of North America
Spatial calibration of digital scintigraphic images: work in progress
PD Esser, DW Seldin, AB Nichols and PO Alderson
Accurate scintigraphic determination of organ dimensions is often difficult
because of the wide variety of camera-collimator combinations and display
formats used for imaging. An algorithm (SPACE-CAL) was developed for
digital spatial calibration of up to six large- or small- field gamma
cameras using various collimators and magnification factors. The algorithm
employs a master calibration file that can be used at multiple terminals.
An interactive subroutine permits the operator to measure distances and
areas directly from the images. Evaluation of three operators' measurements
of a pine-tree phantom acquired at various magnifications showed that
distances could be measured with a high degree of accuracy. Calculation of
ejection fraction from end-diastolic and end-systolic areas determined by
SPACE- CAL showed a high correlation with automatic count determinations (r
= 0.96) and angiographic calculations (r = 0.93) of ejection fraction in 12
patients. SPACE-CAL provides an easily implemented, reproducible, and rapid
method for accurate analysis of organ dimensions in digital images.
