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SU‐EE‐A4‐04: Evaluation of Two Optical Systems for Respiratory Sensing in 4DCT
Author(s) -
Spadea M,
Baroni G,
Sharp G
Publication year - 2009
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 - 10.1118/1.3181114
Subject(s) - scanner , imaging phantom , synchronizing , detector , synchronization (alternating current) , physics , optics , nuclear medicine , calibration , computer science , medicine , telecommunications , channel (broadcasting) , quantum mechanics , transmission (telecommunications)
Purpose: . The purpose of this study is to assess the temporal and reconstruction accuracy of two different optical systems for respiratory motion detection for 4DCT. Materials and methods: A clinical CT scanner, run in cine mode, was used with two optical devices, the Gate CT®, (Vision RT, London, UK) and the RPM® (Varian, Palo Alto, CA), to detect respiratory motion. A radiation detector, GM‐10 (Blackcat, Westminster, MD), triggers the Xray on/off to Gate CT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated a rigid plate along the antero‐posterior direction, and was used to assess the temporal synchronization of each optical system with the CT scanner. The second phantom consisted of 4 spheres that translated 3cm peak‐to‐peak in the superior inferior direction, used to assess the rebinned images created by Gate CT and RPM. Results: Calibration assessment showed a nearly perfect synchronization with the scanner for both the RPM and Gate CT systems, thus demonstrating the good performance of the radiation detector. Results for the volume rebinding test showed a variations in volumes for the 3D reconstruction of up to 15% for Gate CT and up to 12% for RPM. The mean of the standard deviations errors were 11% and 9% respectively. Errors are mainly due to phase detection inaccuracies and to the large motion of the phantom. Conclusions: This feasibility study assessed the consistency of our two optical systems in synchronizing the respiratory signal with the image acquisition. A new patient protocol based on both RPM and GateCT will be soon started.