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Impact of computed tomography image quality on image-guided radiation therapy based on soft tissue registration. Int J Radiat Oncol Biol Phys 2012 Apr 01;82(5):e733-8 PMID: 22349041

Pubmed ID





PURPOSE: In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients.

METHODS AND MATERIALS: Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan.

RESULTS: Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively.

CONCLUSIONS: Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

Author List

Morrow NV, Lawton CA, Qi XS, Li XA


Colleen A. Lawton MD Vice Chair, Professor in the Radiation Oncology department at Medical College of Wisconsin
X Allen Li PhD Professor in the Radiation Oncology department at Medical College of Wisconsin
Natalya V. Morrow PhD Assistant Professor in the Radiation Oncology department at Medical College of Wisconsin


2-s2.0-84862816268   22 Citations

MESH terms used to index this publication - Major topics in bold

Cone-Beam Computed Tomography
Connective Tissue
Observer Variation
Patient Positioning
Prostatic Neoplasms
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Image-Guided
Reproducibility of Results
Tomography, X-Ray Computed
jenkins-FCD Prod-353 9ccd8489072cb19f5b9f808bb23ed672c582f41e