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 compare set?up error and the positioning and error correction time between the infrared markers automatic positioning+ ExacTrac ( A) and the manual positioning+ cone?beam computed tomography ( CBCT) image?guided radiotherapy ( IGRT) ( B) in intensity?modulated radiotherapy ( IMRT) for lung cancer. Methods A total of 20 patients with lung cancer were randomly divided into Group A and Group B. In Group A, after automatic positioning, a group of orthogonal X?rays images were taken using kV X?rays, which matched digitally reconstructed radiographs to obtain errors before correction. In group B, after manual positioning, images were taken using CBCT, which matched reference computed tomography images to obtain errors before correction. The positioning and error correction time was recorded in both groups. After error correction, errors after correction were obtained in each group using IGRT. Between?group comparison was made using the paired t test. Results The errors in lateral, longitudinal, vertical, and spinning vertical directions were significantly reduced after correction in both Group A and B (A:1.8±1?3 vs. 0.4±0?1, P=0?000;2.7±1?9 vs. 0.5±0?1, P=0?000;2.8±1?7 vs. 0.4±0?1, P=0?000;1.6±1?0 vs. 0.3±0?9, P=0?000;B:2.6±1?9 vs. 0.5±0?5, P=0?000;3.1±2?5 vs. 0.6±0?6, P=0?000;2.1±1?8 vs. 0.5±0?5, P=0?000;0.9±0?7 vs. 0.3±0?1, P=0?000). There were no significant differences in errors after correction between Group A and Group B (0.4±0?1 vs. 0.5±0?5, P=0?204;0.5±0?1 vs. 0.6± 0?6, P=0?257;0.4± 0?1 vs. 0.5± 0?5, P=0?518;0.3± 0?9 vs. 0.3± 0?1, P=0?755 ) . However, the positioning and error correction time in Group A was significantly shorter than that in Group B (199.1±16?2 vs. 315.2±13?7, P=0?000). Conclusions The application of ExacTrac or CBCT IGRT can substantially reduce set?up errors and improve set?up accuracy in IMRT. In addition, the application of the ExacTrac system can substantially shorten the positioning and error correction time.