[Evaluation of efficiency of a multi-crystal scintillation camera Digirad 2020tc Imager using a solid-state detectors].

Digirad 2020tc Imager is the movable scintillation camera, consisting of combining multi-crystal scintillators (CsI(Tl)) and photo-diodes. Total numbers of element are 4096, which are further divided into 16 x 16 modules. Each module contains 4 x 4 elements. We have examined Digirad 2020tc according to NEMA (National Electrical Manufactures Association), and the following results are obtained; the maximum count rate; 221 kcps, total system uniformity; 1.3% (integral uniformity), 0.9% (differential uniformity), system spatial resolution; 6.97 +/- 0.72 mm (the LEHR collimator to 99mTc source at 10 cm), intrinsic energy resolution; 12.8%, total system sensitivity; 3270.8 cpm/MBq (with LEHR collimator using 99mTc source at 10 cm). Further more, we determined the contrast of an imaging using the pin-hole (100 microns phi) 99mTc source in order to know the signal per noise (S/N) ratio among the pixels (S/N; 93.4 +/- 46.2 (first pixels)). Although the physical dimension of the camera has a smaller field of view, comparing with the standard camera, Digirad 2020tc has the equivalent characteristics as well as that of the standard camera and its field view is enough to measure the adult lung perfusion using a diverging collimator. We will further examine Digirad 2020tc with its movable portability and expect applications in nuclear medicine.

[Development of the chromatography analysis of liquid trapping 99mTc-Technegas using Jikei impinger].

We developed the equipment which collected 99mTc-Technegas into liquid (saline) and named this equipment an impinger of Jikei University Style. We further developed a technique using this impinger to evaluate its formation qualitatively by paper chromatography. Utilizing this technique we investigated various factors that caused environmental contamination by 99mTc-Technegas, including changes over time in a Technegas generator. It was demonstrated that upon getting mixed with oxygen gas to the argon gas, the Technegas generator induced contamination of 99mTc-Pertechnegas easily, leading to changes in its formation. The change of formation quality of the Technegas generator with the lapse of time was also revealed. These findings indicated that the maintenance and inspection of the equipment were important. This method is a simple and easy technique for the evaluation of 99mTc-Technegas formation, making it possible to perform the quality control of examination agent and the Technegas generator.

Use of digirad 2020tc Imager, a multi-crystal scintillation camera with solid-state detectors in one case for the imaging of autografts of parathyroid glands.

99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) scintigraphy with Digirad 2020tc ImagerTM (2020tc), which was a multi-crystal scintillation camera with solid-state detectors was performed for patients with secondary hyperparathyroidism having autografts of parathyroid glands in the right arm. With the 2020tc camera, three abnormal accumulations were found in the right arm. The images obtained with this camera were superior in resolution to those obtained with a conventional NaI crystal gamma camera (ZLC7500, Siemens, Germany). The next day, resection of autografts of parathyroid glands was done. Four hyperplastic parathyroid glands were resected and all were hyperplastic in pathological findings.

[Imaging of strontium-89 uptake with bremsstrahlung using NaI scintillation camera].

Strontium-89 chloride is widely available in the U.S. and Europe for patients afflicted by bone metastasis associated with pain. 89Sr is a pure beta-emitter and it is thought to be difficult to estimate its distribution externally. We tried to image the distribution of 89Sr uptake with bremsstrahlung from beta-minus decay of 89Sr by using Nal scintillation camera. Pronounced 89Sr depositions in the bone metastatic sites were imaged in the energy windows from 50 keV to 150 keV bremsstrahlung. The distribution of these depositions corresponded to 99mTc-HMDP image may be suspected to the effectiveness of this therapy. The identification of 89Sr distribution might be useful in evaluating the bone marrow radiation dose too.