Accuracy evaluation of a 3-dimensional surface imaging system for guidance in deep-inspiration breath-hold radiation therapy.
OBJECTIVE
To investigate the applicability of 3-dimensional (3D) surface imaging for image guidance in deep-inspiration breath-hold radiation therapy (DIBH-RT) for patients with left-sided breast cancer. For this purpose, setup data based on captured 3D surfaces was compared with setup data based on cone beam computed tomography (CBCT).


METHODS
Twenty patients treated with DIBH-RT after breast-conserving surgery (BCS) were included. Before the start of treatment, each patient underwent a breath-hold CT scan for planning purposes. During treatment, dose delivery was preceded by setup verification using CBCT of the left breast. 3D surfaces were captured by a surface imaging system concurrently with the CBCT scan. Retrospectively, surface registrations were performed for CBCT to CT and for a captured 3D surface to CT. The resulting setup errors were compared with linear regression analysis. For the differences between setup errors, group mean, systematic error, random error, and 95% limits of agreement were calculated. Furthermore, receiver operating characteristic (ROC) analysis was performed.


RESULTS
Good correlation between setup errors was found: R(2)=0.70, 0.90, 0.82 in left-right, craniocaudal, and anterior-posterior directions, respectively. Systematic errors were ≤0.17 cm in all directions. Random errors were ≤0.15 cm. The limits of agreement were -0.34-0.48, -0.42-0.39, and -0.52-0.23 cm in left-right, craniocaudal, and anterior-posterior directions, respectively. ROC analysis showed that a threshold between 0.4 and 0.8 cm corresponds to promising true positive rates (0.78-0.95) and false positive rates (0.12-0.28).


CONCLUSIONS
The results support the application of 3D surface imaging for image guidance in DIBH-RT after BCS.
Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Tanja
T
Alderliesten
Jan-Jakob
JJ
Sonke
Anja
A
Betgen
Joeri
J
Honnef
Corine
C
van Vliet-Vroegindeweij
Peter
P
Remeijer
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D062485:Breath Holding; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000592:standards*; D001239:Inhalation; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009068:Movement; D012372:ROC Curve; D061106:Radiotherapy Setup Errors / Q000517:prevention & control / Q000706:statistics & numerical data; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D012044:Regression Analysis