We have evaluated relationship between planning CT slice thickness and the accuracy of automatic target registration using cone-beam CT (CBCT). Planning CT images were acquired with reconstructed slice thickness of 1, 2, 3, 5, and 10 mm for three different phantoms: Penta-Guide phantom, acrylic ball phantom, and pelvic phantom. After correctly placing the phantom at the isocenter using an in-room laser, we purposely displaced it by moving the treatment couch and then obtained CBCT images. Registration between the planning CT and the CBCT was performed using automatic target registration software, and the registration errors were recorded for each planning CT data set with different slice thickness. The respective average and standard deviation of errors for 10 mm slice thickness CT in the lateral, longitudinal, and vertical directions (n=15 data sets) were: 0.7±0.2 mm, 0.8±0.2 mm, and 0.2±0.2 mm for the Penta-Guide phantom; 0.5±0.4 mm, 0.6±0.3 mm, and 0.4±0.3 mm for the acrylic ball phantom; and 0.6±0.2 mm, 0.9±0.2 mm, and 0.2±0.2 mm for the pelvic phantom. We found that the mean registration errors were always less than 1 mm regardless of the slice thickness tested. The results suggest that there is no obvious correlation between the planning CT slice thickness and the registration errors.

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Our purpose of study was to investigate the usefulness of treatment evaluation of severe heart failure by ECG-gated myocardial SPECT. We evaluated the cardiac function in the case of severe heart failure by gated SPECT and compared it with the cardiac function obtained by LVG, echocardiography, cardiac MRI, and BNP values. We investigated the correlation of EF, time lag of wall motion between the septal and lateral walls of the left ventricle for CRT and wall thickening (WT). We classified the LV into basal, middle and apical areas for comparison of WT. We investigated the effect of a perfusion defect score in these comparisons.
The gated SPECT results were correlated with comparative subjects in EF. The results were correlated with MRI on the middle area of the LV in the comparison of WT. We thought it was possible that there was an effect from a perfusion defect score in a time lag comparison of wall motion.
Treatment evaluation of severe heart failure by gated SPECT is useful, because it is able to obtain three-dimensional cardiac function analysis, and it offers objectivity and reproducible quantitative evaluation. At the same time, perfusion SPECT is helpful for CRT and LV-plasty.

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