Search

Objective: The purpose of this study was to differentiate between malignant tumors and benign tumors of the head and neck by means of thallium-201 chloride scintigraphy. Study Design: Thallium-201 chloride (Tl-201) scintigraphy and Ga-67 citrate (Ga-67) scintigraphy were performed in 10 patients with a benign tumor and in 90 patients with a malignant tumor. The blood flow index and the tumor retention index were obtained by means of Tl-201 scintigraphy. The blood flow index = the count of tumor/the count of control in the early dynamic scan from 30 to 120 seconds after injection, and the tumor retention index = (the count of tumor/the count of control in the delayed dynamic scan 2.5 hours after injection)/(the count of tumor/the count of control in the early dynamic scan from 4 to 5 minutes after injection). Results: The early and delayed scans with Tl-201 demonstrated a very high correlation with the blood flow index. The tumor retention index had a tendency to increase in malignant tumors, especially in the poorly differentiated tumors and the severely invasive tumors. Likewise, the tumor retention index decreased in benign tumors. These results proved to be statistically significant, and in turn Tl-201 scintigraphy was deemed superior to Ga-67 scintigraphy. Tl-201 scintigraphy was also useful in detecting small-size tumors. Conclusion: The tumor retention index of Tl-201 was useful for the differentiation of malignant tumors of the head and neck from benign tumors of the same areas. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:228-35)

To study the structure of an edge dislocation core in an ionic crystal, we measured the amplitude dependence of internal friction by the automated Marx's composite oscillator method and the vibrational current caused by charged dislocations in a hydrogen-absorbed NaCl single crystal. The change of the sign of dislocation charge at the strain amplitude of 10-6 disappeared with absorption of hydrogen, while it was preserved using helium. These findings suggest that hydrogen exists as a positive ion in the dislocation core.

Internal friction and Young's modulus were measured in a deuterium-absorbed titanium rod during the heating process from liquid nitrogen temperature, but no change was observed at 30 °C, the point at which neutrons were detected by a Los Alamos group. An internal friction peak was observed at -70 °C.

By automated Marx's composite oscillator method, changes of internal friction with the pressure of nitrogen, oxygen, and argon were measured. The range of the measurement was from a pressure of 103 mbar to 10-5 mbar. An application to a wide range vacuum gauge was discussed.