SU-E-J-159: Intra-Patient Deformable Image Registration Uncertainties Quantified Using the Distance Discordance Metric

Journal Article · Sun Jun 01 04:00:00 EDT 2014 · Medical Physics

DOI:https://doi.org/10.1118/1.4888212· OSTI ID:22334051

Saleh, Z; Thor, M; Apte, A; Deasy, J ^[1]; Sharp, G ^[2]; Muren, L ^[3]

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1. Memorial Sloan Kettering Cancer Center, NY City, NY (United States)
2. Massachusetts General Hospital, Boston, MA (United States)
3. Aarhus University Hospital, Aarhus (Denmark)

Purpose: The quantitative evaluation of deformable image registration (DIR) is currently challenging due to lack of a ground truth. In this study we test a new method proposed for quantifying multiple-image based DIRrelated uncertainties, for DIR of pelvic images. Methods: 19 patients were analyzed, each with 6 CT scans, who previously had radiotherapy for prostate cancer. Manually delineated structures for rectum and bladder, which served as ground truth structures, were delineated on the planning CT and each subsequent scan. For each patient, voxel-by-voxel DIR-related uncertainties were evaluated, following B-spline based DIR, by applying a previously developed metric, the distance discordance metric (DDM; Saleh et al., PMB (2014) 59:733). The DDM map was superimposed on the first acquired CT scan and DDM statistics were assessed, also relative to two metrics estimating the agreement between the propagated and the manually delineated structures. Results: The highest DDM values which correspond to greatest spatial uncertainties were observed near the body surface and in the bowel due to the presence of gas. The mean rectal and bladder DDM values ranged from 1.1–11.1 mm and 1.5–12.7 mm, respectively. There was a strong correlation in the DDMs between the rectum and bladder (Pearson R = 0.68 for the max DDM). For both structures, DDM was correlated with the ratio between the DIR-propagated and manually delineated volumes (R = 0.74 for the max rectal DDM). The maximum rectal DDM was negatively correlated with the Dice Similarity Coefficient between the propagated and the manually delineated volumes (R= −0.52). Conclusion: The multipleimage based DDM map quantified considerable DIR variability across different structures and among patients. Besides using the DDM for quantifying DIR-related uncertainties it could potentially be used to adjust for uncertainties in DIR-based accumulated dose distributions.

• OSTI ID: 22334051
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 41; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
BLADDER
CAT SCANNING
CORRELATIONS
CURRENTS
GROUND TRUTH MEASUREMENTS
IMAGES
MANUALS
METRICS
NEOPLASMS
PATIENTS
PROSTATE
RADIATION DOSE DISTRIBUTIONS
RECTUM
STATISTICS
WHO