Ultrasonographic measurement of tumor regression in radiation therapy

Ultrasonography was evaluated as a measurement procedure for investigating the tumor regression of cervical lymph nodes. Preliminary results suggested that interobserver compatibility in the measurement of nodes deteriorates when the diameter of the node is less than 15 mm. There was no systematic disparity between ultrasonographic and manual measurements. The tumor regression line fit the exponential line with a correlation coefficient of more than 0.95 in seven of 16 nodes. During the sequential examination, a central low-echo area suddenly appeared in one node at 15 Gy/6 Fr.