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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. [ABSTRACT FROM AUTHOR]

This technical report provides useful information on the current status and issues of quality control in 125 I seed source strength measurement for Permanent Prostate Brachytherapy in Japan.With the spread of 125 I seed brachytherapy, the traceability of source strength measurements with the single-seed assay was established in Japan. This allows medical facilities to measure reference air kerma rate of 125 I seeds with their own well-type of ionization chamber. However, it is difficult to maintain the traceability chain because the 125 I reference air kerma rate standards have been hardly utilized by medical facilities so far. Meanwhile, some serious incidents of contamination of the different source strengths and dead seeds were reported in Japan.To address the specific issues in Japan, JASTRO Brachytherapy Subcommittee established a working group (WG) in 2021. The goal of this WG is to investigate the management methods of source strength measurement used in medical facilities, and to discuss the ideal and practicable methods of source management such as verifying the number of seeds and source strength. Initially, a questionnaire survey was conducted to facilities offering 125 I seed brachytherapy in Japan. Sixty-seven out of 95 facilities responded (response rate 70.5%). This survey revealed that 41% of facilities did not perform either confirmation of the number of seeds or measurement of source strength. There are several reasons why the source strength was not measured in those facilities. For example, 125 I seeds are provided under the sterilized conditions; quality assurance by source suppliers is reliable; and there is not sufficient staff.The single-seed assay is regarded as an internationally standardized and the most reliable measurement method. Therefore, it is an essential measurement technique to ensure traceability of source strength measurements. However, our survey found that most Japanese facilities do not perform single-seed assays. Meanwhile, some facilities have performed batch assay as an alternative method, in which all of the multiple sources in a batch are measured while loaded into sterilized cartridges. Although the measurement by the batch assay is less accurate than the one by the single-seeded assay, the batch assay does not require re-sterilization of the source and can be performed quickly. It might be useful to detect unexpected errors such as differences in the number of sources and abnormalities in source strength.In this report, we will introduce several methods of source strength measurement that have been implemented in medical facilities. The quality assurance of 125 I seed sources in prostate interstitial brachytherapy should be provided not only by the source suppliers but also by the medical facilities that use sources to treat patients. We hope that medical facilities will refer to this technical report and use it as an aid to quality assurance in their own facilities.

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.

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.

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.