TY - GEN
T1 - Simple technique for calibrating imaging geometries
AU - Hoffmann, Kenneth R.
AU - Esthappan, Jacqueline
AU - Li, Shidong
AU - Pelizzari, Charles A.
PY - 1996
Y1 - 1996
N2 - We have developed a new, simple technique for accurate determination of the imaging geometry for calibration of projection imaging systems. Images of a phantom containing lead beads were obtained after it was placed at arbitrary, unknown locations which were near the isocenter of a radiation therapy simulator. The location of the lead beads were identified in the images. A computer model of the phantom was generated and positioned at an arbitrary location. Projection images of the model were generated and compared with the actual image locations. A modified projection-Procrustes algorithm was then used to translate and rotate the phantom model until it aligned optimally with the set of lines connecting the focal spot with the corresponding image points. The rotation matrix and translation vector relating the multiple projection geometries were then determined using a Procrustes algorithm and the calculated positions of the phantom for each projection. For a wide range of starting points, the technique converged to 3D locations with an approximate precision of 0.1 cm in position and approximately 0.2 degrees in orientation. The calculated angles and distances agreed with the readouts on the imaging systems to within approximately 0.25 degrees.
AB - We have developed a new, simple technique for accurate determination of the imaging geometry for calibration of projection imaging systems. Images of a phantom containing lead beads were obtained after it was placed at arbitrary, unknown locations which were near the isocenter of a radiation therapy simulator. The location of the lead beads were identified in the images. A computer model of the phantom was generated and positioned at an arbitrary location. Projection images of the model were generated and compared with the actual image locations. A modified projection-Procrustes algorithm was then used to translate and rotate the phantom model until it aligned optimally with the set of lines connecting the focal spot with the corresponding image points. The rotation matrix and translation vector relating the multiple projection geometries were then determined using a Procrustes algorithm and the calculated positions of the phantom for each projection. For a wide range of starting points, the technique converged to 3D locations with an approximate precision of 0.1 cm in position and approximately 0.2 degrees in orientation. The calculated angles and distances agreed with the readouts on the imaging systems to within approximately 0.25 degrees.
UR - http://www.scopus.com/inward/record.url?scp=0029701765&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:0029701765
SN - 0819420832
SN - 9780819420831
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 371
EP - 376
BT - Proceedings of SPIE - The International Society for Optical Engineering
A2 - Van Metter, Richard L.
A2 - Beutel, Jacob
T2 - Medical Imaging 1996: Physics of Medical Imaging
Y2 - 11 February 1996 through 13 February 1996
ER -