
The respiratory gating radiotherapy technique is especially useful for 
tumors that move, such as those in lung and liver cancer. CGMH introduces 
the Real-time Position Management TM (RPM) respiratory gating system, 
which gates the beam delivery during treatment to account for organ 
motion. Information about tumor movement can be realized by using an 
infrared camera to detect the patient breathing in and out during 
treatment; then the respiratory gating signal can trigger the linac 
accelerator x-ray beam to treat the tumor within the gated phase to assure 
the accuracy of treatment position. A non-invasive marker box is placed on 
the patient’s body and the infrared system tracks the chest wall’s movement 
during the CT imaging. The big bore CT simulator with four-dimensional CT 
capability provides the correlation of respiratory phase and tumor location 
with a dynamic time frame. During the treatment, the radiation beam is 
gated to when the target falls within the treatment field while avoiding 
critical organs. In this case, we can treat patients with high accuracy while 
minimizing treatment errors, and the patient can breathe normally and 
remain comfortable and with high compliance during the treatment. This 
technique takes about five to ten minutes more than regular treatment 
time.

Video introduction