Kelps are very comprehensible educational tools for illustrating naturally existing radiation and radioisotopes due to natural potassium-40 that emits radiations. In the present study, a compression and formation method was applied to 18 varieties of commercially available dried kelps and 18 disk-shaped radiation sources were fabricated. Thus fabricated radiation sources were examined by comparing their dimensions(diameter and thickness), weights and radiation intensities(cpm) from the view point of raw materials of natural radiation sources. It was found that the dimensions of the fabricated radiation sources did not significantly vary by difference of kelp, but radiation intensity changed. The most intensive sources were three times larger than the weakest sources. To estimate the radiation intensity of natural radiation sources before fabricating them, a direct measurement of kelps in a bag was examined.
10336drams(50L dram) of granular active carbon, which were taken out from charcoal filters used in medical institutions, are stored at the Kaya Memorial Takizawa Laboratory. Samples were taken from 728 drams of them and radioactive concentration was measured. Measured results of gamma-emitting radionuclides in all the samples were below the minimum detection limit.
The review articles on the basic and application of Mössbauer spectrometry dealt with in a series were summarized. The changes on development of the equipments, the measuring systems and the analysis softwares for Mössbauer spectra were described. Attentions to the parameters in the velocity calibration were also remarked.
FDG-PET/CT plays various roles in diagnosis and treatment of malignancies. Currently, stereotactic body radiation therapy(SBRT) is considered as a treatment option for patients with medically inoperable early-stage non-small cell lung cancer. As it is relatively new treatment and is often used for inoperable, elder and/or frail patients, it has many controversial problems including diagnosis. Taking advantage of its non-invasiveness, FDG-PET/CT plays various roles in a process of SBRT as well. First, FDG-PET/CT assists diagnosis of solitary pulmonary nodules without pathological confirmation, along with clinical and tumor characteristics. Generally, the threshold SUVmax for malignancy is regarded as 2.5. SUVmax is used as one of the parameters to determine the probability of malignancy in solitary pulmonary nodule. Second, FDG-PET/CT is used for staging especially for hilar and mediastinal lymph node and distant metastasis. For treatment planning of SBRT, FDG-PET/CT provides useful information in differentiating a tumor from atelectasis. In follow-up, FDG-PET/CT can differentiate local recurrences from fibrotic opacities after SBRT more accurately than morphologic changes on CT images. Therefore, FDG-PET/CT is necessary in the entire process of SBRT.