Application of forehead dot marking in radiotherapy for brain tumors / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the role of forehead dot marking in immobilization during radiotherapy for brain tumors.Methods A total of 84 patients with brain tumors were immobilized using the full-head mask from 2013 to 2014;among these patients, 36 received dot marking at the center of the forehead ( group A) , 27 received routine immobilization ( group B) , and 21 received dot marking at one side of the forehead ( group C) .Kilovoltage cone-beam computed tomography ( CBCT) was used to compare the deviation in spatial position.The t-test was used to compare the deviation of the first CBCT in group A with the errors of subsequent CBCT.Results The passing rates of 212 times of CBCT in group A and 158 times of CBCT in group B were 95.2%and 93.8%.The errors in x, y, and z directions in groups A and B were 0.868±0.618 mm vs.1.319±0.935 mm (P=0.005), 1.118±0.692 mm vs.1.149±0.807 mm (P=0.824) , and 0.868±0.790 mm vs.0.936±0.919 mm ( P=0.665) .In group C, the error in the x direction was 1.162±0.866 mm, similar to those in groups A and B ( P=0.070 and 0.430) .In group A, the error in the x direction showed a difference between the first time and the sixth time (0.790±0.656 mm vs.1.280± 0.724 mm, P=0.030) .Conclusions Compared with the routine technique, dot marking at the center of the forehead can improve the accuracy of positioning in the x direction and reduce rotation error, and provides a new method for immobilization in radiotherapy for brain tumors.