1992 Volume 48 Issue 10 Pages 1828-1835
Helical scanning, a computed tomographic technique using a continuously rotating X-ray tube in combination with a continuously moving table, was applied to chest scans. The usefulness of this procedure as a tool for mass-screening was evaluated. Conventional chest CT has a drawback because the entire process for scanning takes a long time. Namely, the prolonged scanning requires the patient to renew the air in his/her lungs during the course of scanning, resulting in a change in respiratory phase thereafter. This gives rise to inconsistency among the resultant serial tomograms. The helical scanning at a table speed of 20-25mm/sec reduces the scanning time of the entire lungs to about 10-15 sec. Consequently, it can be completed without changing the position of the lungs while the patient has stopped his/her breathing. This technique, which can easily detect even a lesion as small as about 5mm in diameter in the lungs, is very useful for mass-screening of chest diseases. In future, detection of early lung cancer by mass-screening for a high risk group will become possible when high-speed helical scanning becomes available.
