Purpose: In stereotactic body radiation therapy (SBRT) of lung tumors, to reduce the target motion and to minimize lung volume treated, the generally accepted procedure is to use abdominal compression, but sometimes abdominal compression is not enough to reduce target motion, particularly the lower lobe lesions.
Methods: When we didn’t have abdominal compression device in our department at the start of our SBRT program, to reduce the target motion, we did CT simulation of patients in both supine and prone position to see if there would be any reduction in the target motion. We planned
and treated four patients in a prone position taking the substantial reduction in target motion into consideration.
Results: It was observed that there was a significant reduction in the target motion ranging from 1.5 cm to 3.0 cm in prone position, the reduction in motion of target is seen mostly in middle and particularly lower lobe lesions, and there was not much change in target motion in upper lobe lesions.
Conclusions: Abdominal compression is both patient and operator oriented and could be uncomfortable to the patient depending on the pressure exerted with compression, whereas prone position is only patient oriented and self-adjusting and settling in a comfortable position prior to CT simulation and prior to initiation of treatment which is verified by image guided radiation therapy (cone based CT). It may not be practical in every patient but could be an option in some patients and particularly in for lower lobe lesions.
