Masahiro Fukushi

Adaptation of DICOM 3.0 to jaw joint movement images

Kinetic MRI images has been developed and often applied to the diagnosis of soft tissues. The diagnosis of the temporomandibular joint seemed to be one of the typical application fields and has been already clinically performed in some hospitals. Kinetic MRI images cannot be dealt with by DICOM systems, since the information elements and transfer syntax has not been defined yet. We tried to define them and examined its performances. Several objects of temporomandibular joint kinetic MRI images in Quick TIME format were created using the newly defined information elements. The objects were transferred and stored to a DICOM image server using CTN software. The stored images were successfully reconstructed and replayed. The outline of the newly defined information elements, the procedures for making and reconstruction of the objects were discussed in this paper.

Comparison of SPECT images with four kinds of 99mTc collimators

Performance of SPECT imaging systems which use a rotating gamma camera, are affected by characteristics of the detector-collimator assembly, the data acquisition method, and the filter used in image reconstruction. The purpose of this study is to examine image qualities of SPECT with different types of low energy collimators. The SPECT imaging system in this study is a rotating gamma camera ZLC-7500 (Siemens) and a data processing unit Scintipac-700 (Shimadzu). The four types of collimators compared are UHR (ultra high resolution), HR (high resolution), AP (general all purpose), and HS (high sensitivity), with 0.27, 0.66, 1.00, and 2.06 relative sensitivity, respectively. In the case of the same collimator, the spatial resolutions measured in the slice plane showed a slight difference in the FWHM values (mean values of UHR, HR, AP, and HS were 11.3 mm, 13.6 mm, 15.8 mm, and 20.4 mm, respectively.) between the center and the circumference of the field of view, in the radial direction, but a large difference in the tangential direction, with lower FWHM values (values of UHR, HR, AP, and HS were 8.4 mm, 8.7 mm, 9.3 mm, and 10.8 mm at 12 cm from the center, respectively.). In comparison of SPECT images with the four types of collimators, except for the HS collimator, image qualities of UHR, HR, and AP collimators showed only a slight difference. From the pont of view of sensitivity and spatial resolution of the collimator, it is expected that the AP collimator would be suitable for SPeCT imaging with 99mTc.