Fast kilovoltage/megavoltage (kVMV) breathhold cone-beam CT for image-guided radiotherapy of lung cancer.

TitleFast kilovoltage/megavoltage (kVMV) breathhold cone-beam CT for image-guided radiotherapy of lung cancer.
Publication TypeJournal Article
Year of Publication2010
AuthorsWertz, H, Stsepankou, D, Blessing, M, Rossi, M, Knox, C, Brown, K, Gros, U, Boda-Heggemann, J, Walter, C, Hesser, J, Lohr, F, Wenz, F
JournalPhysics in medicine and biology
Date Publishedaug
KeywordsCone-Beam Computed Tomography, Cone-Beam Computed Tomography: instrumentation, Cone-Beam Computed Tomography: methods, Humans, Imaging, Lung Neoplasms, Lung Neoplasms: physiopathology, Lung Neoplasms: radiography, Lung Neoplasms: radiotherapy, Phantoms, Radiation Dosage, Respiration, Rotation, Time Factors

Long image acquisition times of 60-120 s for cone-beam CT (CBCT) limit the number of patients with lung cancer who can undergo volume image guidance under breathhold. We developed a low-dose dual-energy kilovoltage-megavoltage-cone-beam CT (kVMV-CBCT) based on a clinical treatment unit reducing imaging time to < or =15 s. Simultaneous kVMV-imaging was achieved by dedicated synchronization hardware controlling the output of the linear accelerator (linac) based on detector panel readout signals, preventing imaging artifacts from interference of the linac's MV-irradiation and panel readouts. Optimization was performed to minimize the imaging dose. Single MV-projections, reconstructed MV-CBCT images and images of simultaneous 90 degrees kV- and 90 degrees MV-CBCT (180 degrees kVMV-CBCT) were acquired with different parameters. Image quality and imaging dose were evaluated and compared to kV-imaging. Hardware-based kVMV synchronization resulted in artifact-free projections. A combined 180 degrees kVMV-CBCT scan with a total MV-dose of 5 monitor units was acquired in 15 s and with sufficient image quality. The resolution was 5-6 line pairs cm(-1) (Catphan phantom). The combined kVMV-scan dose was equivalent to a kV-radiation scan dose of approximately 33 mGy. kVMV-CBCT based on a standard linac is promising and can provide ultra-fast online volume image guidance with low imaging dose and sufficient image quality for fast and accurate patient positioning for patients with lung cancer under breathhold.

Citation Key Wertz2010