ABSTRACT
Objective To compare the ExacTrac X-ray and CBCT image guide system for the head and neck cancer patients in radiotherapy. Methods Twenty head and neck cancer patients were randomly chosen and divided two Group. In group A ( 10 patients) ,the cross X-ray radiation photos were matched with the DRR after positioning with the infrared markers. Obtain the setup errors on three directions and rotation errors. Then adjustment of error with 6D treatment bed,record time set-up and registration. In group B ( 10 patients) ,the CBCTimages were matched with reference CT data after manual positioning. Obtain the setup errors on three directions and around the vertical axis direction errors. Then adjustment of error,record the time of set-up and registration. Groups were compared using the paired t-test. Results For group A and B group,the translation errors were (0.59±0. 25) mm,(0.62±0. 25) mm,(1.56±0. 28) mm,and (0.52± 0. 31) mm,(0.74±0. 17) mm,(1.58±0. 34) mm on horizontal,vertical,up-down directions,respectively (P=0.43,0.21,0.90).For group A,the rotation errors were (0.54±0.17)°,(0.72±0.27)°,(0.44± 0. 22)°,respectively;with (1.26±0. 33)°on vertical directions on B group (P=0. 01).The time of set-up registration on group A was significantly less than group B ( 108. 0 s vs . 165. 8 s , P= 0. 00 ) . Conclusions For the head and neck cancer patients in raditherapy,the image guide systems is feasible. The rotation errors of ExacTrac X-ray slightly less than CBCT.The time of set-up and registration of ExacTrac X-ray significantly less than CBCT,but the image resolution of ExacTrac X-ray inferior for CBCT.
ABSTRACT
Objective To study the ExacTrac X-ray image guide system for patients with head and neck cancer.Methods Ten patients were chosen foe this study.It was immoblized using the head mask and frame fixtures.The two KV X-ray units were matched with the digitally reconstructed radiographs after positioning with the infrared markers.Then the setup errors on x (horizontal axis),y (vertical axis) and z (up-down) directions and rotation errors were obtained.Paired t-test between any two direction difference errors.Results The setup errors with ExacTrac X-ray image guide system for the patients in x,y,z directions and rotation errors were (0.57 ± 0.24) mm,(0.68 ± 0.19) mm,(1.54 ± 0.29) mm,(0.54 ±0.13) °,(0.60 ± 0.23) °,(0.51 ± 0.15) °.The z-axis direction have slightly larger error (P =0.02,0.01).The others have not statistical significance (P =0.06,0.10-0.41).Conclusions To use ExacTrac X-ray image guide system cooperating with the six degree of freedom treatment couch in image guided radiotherapy for is feasible,the motion errors ＜ 2 mm,the rotation errors ＜ 2°.Reduced of the setup errors with replace the sphere or to reduce pollution of the sphere,improve the accuracy,it could provide a better quality assurance in radiation therapy.