Technical and dosimetric aspects of respiratory gating using a pressure-sensor motion monitoring system. Med Phys 2006 Jan;33(1):145-54
Date
02/21/2006Pubmed ID
16485421DOI
10.1118/1.2147743Scopus ID
2-s2.0-31044436279 (requires institutional sign-in at Scopus site) 159 CitationsAbstract
This work introduces a gating technique that uses 4DCT to determine gating parameters and to plan gated treatment, and employs a Siemens linear accelerator to deliver the gated treatment. Because of technology incompatibility, the 4DCT scanner (LightSpeed, GE) and the Siemens accelerator require two different motion-monitoring systems. The motion monitoring system (AZ-773V, Anzai Med.) used for the gated delivery utilizes a pressure sensor to detect the external respiratory motion (pressure change) in real time. Another system (RPM, Varian) used for the 4DCT scanner (LightSpeed, GE) is based on an infrared camera to detect motion of external markers. These two motion monitoring systems (RPM and Anzai systems) were found to correlate well with each other. The depth doses and profile measured for gated delivery (with a duty cycle of 25% or 50%) were found to agree within 1.0% with those measured for ungated delivery, indicating that gating did not significantly alter beam characteristics. The measurement verified also that the MU linearity and beam output remained unchanged (within 0.3%). A practical method of using 4DCT to plan a gated treatment was developed. The duty cycle for either phase or amplitude gating can be determined based on 4DCT with consideration of set-up error and delivery efficiency. The close-loop measurement involving the entire gating process (imaging, planning, and delivery) showed that the measured isodose distributions agreed with those intended, validating the accuracy and reliability of the gating technique. Based these observations, we conclude that the gating technique introduced in this work, integrating Siemens linear accelerator and Anzai pressure sensor device with GE/Varian RPM 4DCT, is reliable and effective, and it can be used clinically to account for respiratory motion during radiation therapy.
Author List
Li XA, Stepaniak C, Gore EAuthor
Elizabeth M. Gore MD Professor in the Radiation Oncology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Imaging, Three-DimensionalLung Neoplasms
Manometry
Movement
Phantoms, Imaging
Radiographic Image Interpretation, Computer-Assisted
Radiometry
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Reproducibility of Results
Respiratory Mechanics
Sensitivity and Specificity
Tomography, X-Ray Computed
Transducers