[Investigation of actual condition of management and disposal of medical radioactive waste in Korea].

In order to realize the rational management and disposal of radioactive waste like DIS or its clearance as performed in Europe, North America, and Japan, we investigated the situation of medical radioactive waste in Korea and its enforcement. We visited three major Korean facilities in May 2008 and confirmed details of the procedure being used by administering a questionnaire after our visit. From the results, we were able to verify that the governmental agency had established regulations for the clearance of radioactive waste as self-disposal based on the clearance level of IAEA in Korea and that the medical facilities performed suitable management and disposal of radioactive waste based on the regulations and superintendence of a radiation safety officer. The type of nuclear medicine was almost the same as that in Japan, and the half-life of all radiopharmaceuticals was 60 days or less. While performing regulatory adjustment concerning the rational management and disposal of radioactive waste in Korea for reference also in this country, it is important to provide an enforcement procedure with quality assurance in the regulations.

[Effectiveness of deep breath-hold SPECT in torso area: examination concerning improvement of resolution].

Because SPECT images are acquired under normal respiration, the respiratory motion induces artifacts and decreases resolution. In this study we developed a novel method of acquiring SPECT data during deep inhalation breath-hold (BrST) and assessed its efficacy in reducing motion artifacts and improving resolution. Reproducibility studies found that variations in SPECT image homogeneity were reduced using the BrST method to within a clinically non-problematic range. An experiment using a custom-built respiration phantom showed almost complete elimination of motion artifacts and significant improvement in resolution using the BrST method. Clinical assessment confirmed a significant reduction in motion artifacts along with the improvement in resolution. The BrST method enabled visualization of lesions that previously had been impossible to detect by standard acquisition under normal respiration. The BrST method is expected to both significantly reduce motion artifacts and improve resolution.

Evaluation of breath-hold 201Tl SPECT in the differential diagnosis of solitary pulmonary nodules.

UNLABELLED: The aim of this study was to evaluate the usefulness of deep inspiration breath-hold SPECT (BrST, a method for 201Tl SPECT) in the diagnosis of solitary pulmonary nodules (SPN). METHODS: Ten patients with malignant lesions and five with benign lesions were enrolled in this study. Early SPECT acquisition was performed 15 min after injection of 201Tl, while delayed SPECT images were acquired 3 h after injection. The first 15-sec acquisition was done using the BrST technique, and the second with the conventional free breathing (FB) method. We performed this technique alternately, and therefore, the odd data were from BrST and the even data were from FB. We referred to the T/N ratio of the early images as the ER and to the T/N ratio of the delayed images as the DR. To semi-quantitatively evaluate the degree of retention in the lesion, the retention index (RI) was calculated. RESULTS: The RI of BrST indicated greater accuracy than that of FB in the differential diagnosis of SPN. For the benign and malignant lesions, the RI of BrST was -3.07 +/- 31.51 and 29.86 +/- 25.01, respectively (p < 0.05). The sensitivity, specificity, and accuracy of BrST (80%, 80%, and 80%, respectively) were significantly higher than those of FB (p < 0.05). CONCLUSION: The BrST method is more accurate than that of the conventional FB method in the differential diagnosis of SPN.