Translational and rotational intra- and inter-fractional errors in patient and target position during a short course of frameless stereotactic body radiotherapy

TY - JOUR

T1 - Translational and rotational intra- and inter-fractional errors in patient and target position during a short course of frameless stereotactic body radiotherapy

AU - Josipovic, Mirjana

AU - Persson, Gitte Fredberg

AU - Logadottir, Ashildur

AU - Smulders, Bob

AU - Westmann, Gunnar

AU - Bangsgaard, Jens Peter

PY - 2012/5

Y1 - 2012/5

N2 - BACKGROUND: Implementation of cone beam computed tomography (CBCT) in frameless stereotactic body radiotherapy (SBRT) of lung tumours enables setup correction based on tumour position. The aim of this study was to compare setup accuracy with daily soft tissue matching to bony anatomy matching and evaluate intra- and inter-fractional translational and rotational errors in patient and target positions.MATERIAL AND METHODS: Fifteen consecutive SBRT patients were included in the study. Vacuum cushions were used for immobilisation. SBRT plans were based on midventilation phase of four-dimensional (4D)-CT or three-dimensional (3D)-CT from PET/CT. Margins of 5 mm in the transversal plane and 10 mm in the cranio-caudal (CC) direction were applied. SBRT was delivered in three fractions within a week. At each fraction, CBCT was performed before and after the treatment. Setup accuracy comparison between soft tissue matching and bony anatomy matching was evaluated on pretreatment CBCTs. From differences in pre- and post-treatment CBCTs, we evaluated the extent of translational and rotational intra-fractional changes in patient position, tumour position and tumour baseline shift. All image registration was rigid with six degrees of freedom.RESULTS: The median 3D difference between patient position based on bony anatomy matching and soft tissue matching was 3.0 mm (0-8.3 mm). The median 3D intra-fractional change in patient position was 1.4 mm (0-12.2 mm) and 2.2 mm (0-13.2 mm) in tumour position. The median 3D intra-fractional baseline shift was 2.2 mm (0-4.7 mm). With correction of translational errors, the remaining systematic and random errors were approximately 1°.CONCLUSION: . Soft tissue tumour matching improved precision of treatment delivery in frameless SBRT of lung tumours compared to image guidance using bone matching. The intra-fractional displacement of the target position was affected by both translational and rotational changes in tumour baseline position relative to the bony anatomy and by changes in patient position.

AB - BACKGROUND: Implementation of cone beam computed tomography (CBCT) in frameless stereotactic body radiotherapy (SBRT) of lung tumours enables setup correction based on tumour position. The aim of this study was to compare setup accuracy with daily soft tissue matching to bony anatomy matching and evaluate intra- and inter-fractional translational and rotational errors in patient and target positions.MATERIAL AND METHODS: Fifteen consecutive SBRT patients were included in the study. Vacuum cushions were used for immobilisation. SBRT plans were based on midventilation phase of four-dimensional (4D)-CT or three-dimensional (3D)-CT from PET/CT. Margins of 5 mm in the transversal plane and 10 mm in the cranio-caudal (CC) direction were applied. SBRT was delivered in three fractions within a week. At each fraction, CBCT was performed before and after the treatment. Setup accuracy comparison between soft tissue matching and bony anatomy matching was evaluated on pretreatment CBCTs. From differences in pre- and post-treatment CBCTs, we evaluated the extent of translational and rotational intra-fractional changes in patient position, tumour position and tumour baseline shift. All image registration was rigid with six degrees of freedom.RESULTS: The median 3D difference between patient position based on bony anatomy matching and soft tissue matching was 3.0 mm (0-8.3 mm). The median 3D intra-fractional change in patient position was 1.4 mm (0-12.2 mm) and 2.2 mm (0-13.2 mm) in tumour position. The median 3D intra-fractional baseline shift was 2.2 mm (0-4.7 mm). With correction of translational errors, the remaining systematic and random errors were approximately 1°.CONCLUSION: . Soft tissue tumour matching improved precision of treatment delivery in frameless SBRT of lung tumours compared to image guidance using bone matching. The intra-fractional displacement of the target position was affected by both translational and rotational changes in tumour baseline position relative to the bony anatomy and by changes in patient position.

KW - Adult

KW - Aged

KW - Aged, 80 and over

KW - Algorithms

KW - Carcinoma, Non-Small-Cell Lung/pathology

KW - Cone-Beam Computed Tomography

KW - Dose Fractionation

KW - Female

KW - Follow-Up Studies

KW - Humans

KW - Immobilization

KW - Lung Neoplasms/pathology

KW - Male

KW - Melanoma/pathology

KW - Middle Aged

KW - Movement

KW - Multimodal Imaging

KW - Patient Positioning

KW - Positron-Emission Tomography

KW - Prognosis

KW - Radiosurgery

KW - Radiotherapy Planning, Computer-Assisted

KW - Radiotherapy, Computer-Assisted

KW - Rectal Neoplasms/pathology

KW - Stomach Neoplasms/pathology

KW - Survival Rate

KW - Tomography, X-Ray Computed

U2 - 10.3109/0284186x.2011.626448

DO - 10.3109/0284186x.2011.626448

M3 - Journal article

C2 - 22263924

SN - 1100-1704

VL - 51

SP - 610

EP - 617

JO - Acta Oncologica, Supplement

JF - Acta Oncologica, Supplement

IS - 5

ER -