Assessment of cone beam CT registration for prostate radiation therapy : fiducial marker and soft tissue methods

Deegan, Timothy, Owen, Rebecca, Holt, Tanya, Fielding, Andrew, Biggs, Jennifer, Parfitt, Matthew, Coates, Alicia, & Roberts, Lisa (2014) Assessment of cone beam CT registration for prostate radiation therapy : fiducial marker and soft tissue methods. Journal of Medical Imaging and Radiation Oncology.

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This investigation aimed to assess the consistency and accuracy of radiation therapists (RTs) performing cone beam computed tomography (CBCT) alignment to fiducial markers (FMs) (CBCTFM) and the soft tissue prostate (CBCTST).


Six patients receiving prostate radiation therapy underwent daily CBCTs. Manual alignment of CBCTFM and CBCTST was performed by three RTs. Inter-observer agreement was assessed using a modified Bland–Altman analysis for each alignment method. Clinically acceptable 95% limits of agreement with the mean (LoAmean) were defined as ±2.0 mm for CBCTFM and ±3.0 mm for CBCTST. Differences between CBCTST alignment and the observer-averaged CBCTFM (AvCBCTFM) alignment were analysed. Clinically acceptable 95% LoA were defined as ±3.0 mm for the comparison of CBCTST and AvCBCTFM.


CBCTFM and CBCTST alignments were performed for 185 images. The CBCTFM 95% LoAmean were within ±2.0 mm in all planes. CBCTST 95% LoAmean were within ±3.0 mm in all planes. Comparison of CBCTST with AvCBCTFM resulted in 95% LoA of −4.9 to 2.6, −1.6 to 2.5 and −4.7 to 1.9 mm in the superior–inferior, left–right and anterior–posterior planes, respectively.


Significant differences were found between soft tissue alignment and the predicted FM position. FMs are useful in reducing inter-observer variability compared with soft tissue alignment. Consideration needs to be given to margin design when using soft tissue matching due to increased inter-observer variability. This study highlights some of the complexities of soft tissue guidance for prostate radiation therapy.

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1 citations in Scopus
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2 citations in Web of Science®

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ID Code: 75146
Item Type: Journal Article
Refereed: Yes
Keywords: Cone Beam CT, Image Guided Radiotherapy, Prostate, Fiducial Markers, Image Registration
DOI: 10.1111/1754-9485.12197
ISSN: 1754-9485
Subjects: Australian and New Zealand Standard Research Classification > PHYSICAL SCIENCES (020000) > OTHER PHYSICAL SCIENCES (029900) > Medical Physics (029903)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > ONCOLOGY AND CARCINOGENESIS (111200) > Radiation Therapy (111208)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2014 The Royal Australian and New Zealand College of Radiologists
Deposited On: 18 Aug 2014 03:20
Last Modified: 18 Aug 2014 21:46

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