A three dimensional, automatic, anatomy-based system for portal verification has been developed based on an FFT implementation of Pearson's correlation coefficient (PCC). The PCC requires no anatomy or point-pair identification, is robust when encountering changes in scaling and shifts in image amplitudes and requires no priori knowledge of the anatomy, which makes it an ideal candidate for portal-to-DRR image registration. Features for matching are selected from orthogonal portal images and compared to the corresponding megavoltage DRR. The position of the highest correlation value is then converted into beam-to-patient geometry and compared with the actual patient setup. By continuously generating DRRs, the system is capable of verifying translation errors, in-plane rotation and out-of-plane rotation errors. The mean accuracy of translation and rotation registrations tests were 0.58 mm and 0.79° respectively for DRR-to-DRR matching, and 1.22 mm and 1.31° respectively for portal-to-DRR matching.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.21640 |
| Date | January 1999 |
| Creators | Sirois, Luc M. |
| Contributors | Fallone, B. G. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Medical Radiation Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001650120, proquestno: MQ50880, Theses scanned by UMI/ProQuest. |
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