Study of radiotherapy positioning repeatability of kyphosis patients with head and neck cancer

Abstract

Objective To compare the repeatability of radiotherapy placement between negative pressure vacuum pad (A group) and common soft pillow (B group) combined with a thermoplastic membrane immobilization technology in severe kyphosis patients with head and neck cancer. Methods From September 2013 to December 2014, 22 cases of severe kyphosis patients with primary or secondary head and neck cancer who received radiotherapy were randomly divided into group A and group B. Padding waist hips with negative pressure vacuum pad and ordinary soft pillow were used so that the patients could lay in CT-Sim bed, and the head cushion was set on the headrest. After the fixing of thermoplastic head and neck shoulder membrane, CT-Sim was located. Every five times of radiotherapy were accompanied by CT-Sim school position once. In the direction of the last layer of right styloid process center point as the reference point, CT-sim software was used to measure the location change with left and right sides, head, and under direction (x, y, z, respectively) in patients, and the data were analyzed. Results Group A significantly reduced the osseous placement error between tags compared with group B (P < 0.05). The average placement errors were as follows, x: (0.68±0.14) mm vs (1.15±0.77) mm, y: (0.48±0.23) mm vs (1.49±1.24) mm, z: (0.76±0.54) mm vs (2.11±1.02) mm, while the average transfer errors were as follows, x: (0.70±0.21) mm vs (1.15±0.93) mm, y: (0.50±0.31) mm vs (1.50±1.28) mm, z: (0.85±0.26) mm vs (1.77±0.88) mm. Conclusion Vacuum suction pad combined with thermoplastic membrane has good repeatability on radiotherapy positioning for severe kyphosis patients with head and neck cancer. Key words: Head and neck neoplasms; Vacuum pad, head and neck shoulder membrane; Radiotherapy positioning repeatability; Errors; Hunchback