67Ga planar imaging with a low-energy collimator and scatter correction using the triple energy window method

To improve the spatial resolution and contrast of 67Ga planar imaging, we used a low-energy collimator and two lower-energy windows with a triple-energy-window (TEW) scatter compensation method. The spatial resolution is better than with a medium-energy collimator, and the TEW method can correct for scattered photons and reduce the background counts. In a phantom study and a clinical study involving 44 patients, the images obtained by the proposed method were compared with the images obtained with a medium-energy collimator and three energy windows without scatter compensation (the conventional method). The spatial resolution and the counts were measured. Two nuclear medicine physicians interpreted the images and clinical usefulness was evaluated. The spatial resolution and contrast were improved by our proposed method. It enabled the detection of lesions in five locations in the clinical study. The counts were reduced but misreadings were not seen. We conclude that our proposed method shows a clinical advantage over the conventional method. It can be used easily and quickly with commercially available equipment and is useful in clinical practice.