Does Changing Image Guidance Processes Impact Patient Setup Practice?

Abstract

Purpose/Objective(s)To investigate whether the implementation of various daily image-guidance processes have altered initial (pre-imaging) patient setup practice for thoracic radiotherapy patients.Materials/MethodsDaily cone-beam CT (CBCT) images of 73 thoracic patients undergoing radical radiotherapy were retrospectively reviewed under ethics approval. For analysis, these patients were divided into 3 consecutive cohorts determined by the image-guidance process used during their radiotherapy. After initial alignment of skin marks and lasers; Process A (24 patients) - CBCT images were registered to the reference CT with an action level of 3 mm, correction applied via manual couch adjustment, followed by a verification CBCT; Process B (23 patients) - CBCT alignment with an action level of 3 mm, correction applied via remote couch adjustment, followed by a verification CBCT. Then, after the implementation of routine automated couch quality assurance procedures; Process C (26 patients) - CBCT alignment with an action level of 0 mm for correction, and correction applied via automated couch adjustment. Initial patient setup displacements were determined by registering the initial alignment CBCT to the planning CT using automatic matching of the thoracic spine. Initial patient setup displacements were then compared between the 3 image-guidance processes in the left/right (L/R), superior/inferior (S/I), and anterior/posterior (A/P) directions.ResultsThe mean ± standard deviation of initial patient setup displacements were calculated for each process. During Process A, the results were 1.2 ± 2.4 mm (L/R), 0.6 ± 3.5 mm (S/I), and -0.8 ± 2.0 mm (A/P). With the implementation of remote couch, the results were 0.5 ± 2.7 mm (L/R), 1.2 ± 3.4 mm (S/I) and -1.7 ± 2.0 mm (A/P). With no verification CBCTs, the results were 1.0 ± 2.5 mm (L/R), 0.1 ± 3.5 mm (S/I), and -2.3 ± 2.2 mm (A/P). The means, systematic and random uncertainties were comparable between the 3 processes, showing similar set-up error distributions.ConclusionsThe accuracy of initial patient alignment using skin marks and lasers remains unaffected by the introduction of image-guidance technology. The introduction of various image-guidance processes and technology for volumetric radiotherapy localization has minimal effect on initial patient setup practice. Purpose/Objective(s)To investigate whether the implementation of various daily image-guidance processes have altered initial (pre-imaging) patient setup practice for thoracic radiotherapy patients. To investigate whether the implementation of various daily image-guidance processes have altered initial (pre-imaging) patient setup practice for thoracic radiotherapy patients. Materials/MethodsDaily cone-beam CT (CBCT) images of 73 thoracic patients undergoing radical radiotherapy were retrospectively reviewed under ethics approval. For analysis, these patients were divided into 3 consecutive cohorts determined by the image-guidance process used during their radiotherapy. After initial alignment of skin marks and lasers; Process A (24 patients) - CBCT images were registered to the reference CT with an action level of 3 mm, correction applied via manual couch adjustment, followed by a verification CBCT; Process B (23 patients) - CBCT alignment with an action level of 3 mm, correction applied via remote couch adjustment, followed by a verification CBCT. Then, after the implementation of routine automated couch quality assurance procedures; Process C (26 patients) - CBCT alignment with an action level of 0 mm for correction, and correction applied via automated couch adjustment. Initial patient setup displacements were determined by registering the initial alignment CBCT to the planning CT using automatic matching of the thoracic spine. Initial patient setup displacements were then compared between the 3 image-guidance processes in the left/right (L/R), superior/inferior (S/I), and anterior/posterior (A/P) directions. Daily cone-beam CT (CBCT) images of 73 thoracic patients undergoing radical radiotherapy were retrospectively reviewed under ethics approval. For analysis, these patients were divided into 3 consecutive cohorts determined by the image-guidance process used during their radiotherapy. After initial alignment of skin marks and lasers; Process A (24 patients) - CBCT images were registered to the reference CT with an action level of 3 mm, correction applied via manual couch adjustment, followed by a verification CBCT; Process B (23 patients) - CBCT alignment with an action level of 3 mm, correction applied via remote couch adjustment, followed by a verification CBCT. Then, after the implementation of routine automated couch quality assurance procedures; Process C (26 patients) - CBCT alignment with an action level of 0 mm for correction, and correction applied via automated couch adjustment. Initial patient setup displacements were determined by registering the initial alignment CBCT to the planning CT using automatic matching of the thoracic spine. Initial patient setup displacements were then compared between the 3 image-guidance processes in the left/right (L/R), superior/inferior (S/I), and anterior/posterior (A/P) directions. ResultsThe mean ± standard deviation of initial patient setup displacements were calculated for each process. During Process A, the results were 1.2 ± 2.4 mm (L/R), 0.6 ± 3.5 mm (S/I), and -0.8 ± 2.0 mm (A/P). With the implementation of remote couch, the results were 0.5 ± 2.7 mm (L/R), 1.2 ± 3.4 mm (S/I) and -1.7 ± 2.0 mm (A/P). With no verification CBCTs, the results were 1.0 ± 2.5 mm (L/R), 0.1 ± 3.5 mm (S/I), and -2.3 ± 2.2 mm (A/P). The means, systematic and random uncertainties were comparable between the 3 processes, showing similar set-up error distributions. The mean ± standard deviation of initial patient setup displacements were calculated for each process. During Process A, the results were 1.2 ± 2.4 mm (L/R), 0.6 ± 3.5 mm (S/I), and -0.8 ± 2.0 mm (A/P). With the implementation of remote couch, the results were 0.5 ± 2.7 mm (L/R), 1.2 ± 3.4 mm (S/I) and -1.7 ± 2.0 mm (A/P). With no verification CBCTs, the results were 1.0 ± 2.5 mm (L/R), 0.1 ± 3.5 mm (S/I), and -2.3 ± 2.2 mm (A/P). The means, systematic and random uncertainties were comparable between the 3 processes, showing similar set-up error distributions. ConclusionsThe accuracy of initial patient alignment using skin marks and lasers remains unaffected by the introduction of image-guidance technology. The introduction of various image-guidance processes and technology for volumetric radiotherapy localization has minimal effect on initial patient setup practice. The accuracy of initial patient alignment using skin marks and lasers remains unaffected by the introduction of image-guidance technology. The introduction of various image-guidance processes and technology for volumetric radiotherapy localization has minimal effect on initial patient setup practice.