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Automated 2D‐3D registration of a radiograph and a cone beam CT using line‐segment enhancement a)
Author(s) -
Munbodh Reshma,
Jaffray David A.,
Moseley Douglas J.,
Chen Zhe,
Knisely Jonathan P. S.,
Cathier Pascal,
Duncan James S.
Publication year - 2006
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2192621
Subject(s) - imaging phantom , radiography , cone beam computed tomography , image guided radiation therapy , nuclear medicine , projection (relational algebra) , orientation (vector space) , image registration , pixel , line (geometry) , digital radiography , artificial intelligence , medical imaging , computer vision , computer science , medicine , mathematics , computed tomography , radiology , image (mathematics) , geometry , algorithm
The objective of this study was to develop a fully automated two‐dimensional (2D)–three‐dimensional (3D) registration framework to quantify setup deviations in prostate radiation therapy from cone beam CT (CBCT) data and a single AP radiograph. A kilovoltage CBCT image and kilovoltage AP radiograph of an anthropomorphic phantom of the pelvis were acquired at 14 accurately known positions. The shifts in the phantom position were subsequently estimated by registering digitally reconstructed radiographs (DRRs) from the 3D CBCT scan to the AP radiographs through the correlation of enhanced linear image features mainly representing bony ridges. Linear features were enhanced by filtering the images with “sticks,” short line segments which are varied in orientation to achieve the maximum projection value at every pixel in the image. The mean (and standard deviations) of the absolute errors in estimating translations along the three orthogonal axes in millimeters were 0.134 (0.096) AP(out‐of‐plane), 0.021 (0.023) ML and 0.020 (0.020) SI. The corresponding errors for rotations in degrees were 0.011 (0.009) AP, 0.029 (0.016) ML (out‐of‐plane), and 0.030 (0.028) SI (out‐of‐plane). Preliminary results with megavoltage patient data have also been reported. The results suggest that it may be possible to enhance anatomic features that are common to DRRs from a CBCT image and a single AP radiography of the pelvis for use in a completely automated and accurate 2D–3D registration framework for setup verification in prostate radiotherapy. This technique is theoretically applicable to other rigid bony structures such as the cranial vault or skull base and piecewise rigid structures such as the spine.