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Four‐dimensional cone beam CT with adaptive gantry rotation and adaptive data sampling
Author(s) -
Lu Jun,
Guerrero Thomas M.,
Munro Peter,
Jeung Andrew,
Chi PaiChun M.,
Balter Peter,
Zhu X. Ronald,
Mohan Radhe,
Pan Tinsu
Publication year - 2007
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 - 10.1118/1.2767145
Subject(s) - cone beam computed tomography , imaging phantom , scanner , image quality , nuclear medicine , image guided radiation therapy , rotation (mathematics) , contrast to noise ratio , dosimetry , cone beam ct , multislice , medicine , medical imaging , computer science , computer vision , artificial intelligence , radiology , computed tomography , image (mathematics)
We have developed a new four‐dimensional cone beam CT (4D‐CBCT) on a Varian image‐guided radiation therapy system, which has radiation therapy treatment and cone beam CT imaging capabilities. We adapted the speed of gantry rotation time of the CBCT to the average breath cycle of the patient to maintain the same level of image quality and adjusted the data sampling frequency to keep a similar level of radiation exposure to the patient. Our design utilized the real‐time positioning and monitoring system to record the respiratory signal of the patient during the acquisition of the CBCT data. We used the full‐fan bowtie filter during data acquisition, acquired the projection data over 200 deg of gantry rotation, and reconstructed the images with a half‐scan cone beam reconstruction. The scan time for a 200‐deg gantry rotation per patient ranged from 3.3 to 6.6 min for the average breath cycle of 3–6 s. The radiation dose of the 4D‐CBCT was about 1–2 times the radiation dose of the 4D‐CT on a multislice CT scanner. We evaluated the 4D‐CBCT in scanning, data processing and image quality with phantom studies. We demonstrated the clinical applicability of the 4D‐CBCT and compared the 4D‐CBCT and the 4D‐CT scans in four patient studies. The contrast‐to‐noise ratio of the 4D‐CT was 2.8–3.5 times of the contrast‐to‐noise ratio of the 4D‐CBCT in the four patient studies.