The serum level of tumor-antigen 4 (TA-4) was measured in 401 patients with squamous cell carcinoma (SCC) of various organs (76 lung, 82 esophagus, and 234 head and neck). The mean serum level of TA-4 in patients with lung SCC was 3.6 times higher than that in healthy controls and even higher in the advanced stages of disease (III, IV). In patients with benign diseases or other types of lung cancer, however, the TA-4 serum level was not different from the controls regardless of the clinical stage. During radiation therapy, the TA-4 levels in patients with lung SCC decreased with reduction in tumor size. It increased again markedly during recurrence. Similarly, patients with SCC of the esophagus and head and neck also showed elevated TA-4 levels but only at advanced stages and in recurrence. It was concluded that TA-4 is highly related to SCC not only of the uterine cervix but also of other organs and that serum level determinations are useful for monitoring therapeutic effects and recurrence of these diseases, despite some limitations.

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The effect of respiratory motion on the image quality of single photon emission computed tomography (SPECT) was investigated by computer simulation and experimentation. In the computer simulation, the phantom was assumed to be cylindrical with a uniform background and a spherical cold or hot spot. To simulate respiratory motion, a cyclic linear motion parallel to the axis of rotation of a gamma camera was assumed. The contrast in the transaxial images was calculated for various respiratory amplitudes and its dependence on lesion size and object contrast was investigated. In the experiments, a moving phantom was used to simulate respiratory motion. The simulation and the experimental results were in good agreement within the range of statistical error. The effect on the lesion detectability was investigated using receiver operating characteristics (ROC) analysis, and a method for correcting respiratory motion was devised.

A computer based simulation method was developed to assess the relative effectiveness and availability of various attenuation compensation algorithms in single photon emission computed tomography (SPECT). The effect of the nonuniformity of attenuation coefficient distribution in the body, the errors in determining a body contour and the statistical noise on reconstruction accuracy and the computation time in using the algorithms were studied. The algorithms were classified into three groups: precorrection, post correction and iterative correction methods. Furthermore, a hybrid method was devised by combining several methods. This study will be useful for understanding the characteristics, limitations and strengths of the algorithms and searching for a practical correction method for photon attenuation in SPECT.