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SU-E-J-241: Creation of Ventilation CT From Daily 4D CTs Or 4D Conebeam CTs Acquired During IGRT for Thoracic Cancers. Med Phys 2014 Jun;41(6):213



Pubmed ID



PURPOSE: To develop a method to create ventilation CTs from daily 4D CTs or 4D KV conebeam CTs (4DCBCT) acquired during image-guided radiation therapy (IGRT) for thoracic tumors, and to explore the potential for using the ventilation CTs as a means for early detection of lung injury during radiation treatment.

METHODS: 4DCT acquired using an in-room CT (CTVision, Siemens) and 4DCBCT acquired using the X-ray Volume Imaging (XVI) system (Infinity, Elekta) for representative lung cancer patients were analyzed. These 4D data sets were sorted into 10 phase images. A newly-available deformable image registration tool (ADMIRE, Elekta) is used to deform the phase images at the end of exhale (EE) to the phase images at the end of inhale (EI). The lung volumes at EI and EE were carefully contoured using an intensity-based auto-contour tool and then manually edited. The ventilation images were calculated from the variations of CT numbers of those voxels masked by the lung contour at EI between the registered phase images. The deformable image registration is also performed between the daily 4D images and planning 4DCT, and the resulting deformable field vector (DFV) is used to deform the planning doses to the daily images by an in-house Matlab program.

RESULTS: The ventilation images were successfully created. The tide volumes calculated using the ventilation images agree with those measured through volume difference of contours at EE and EI, indicating the accuracy of ventilation images. The association between the delivered doses and the change of lung ventilation from the daily ventilation CTs is identified.

CONCLUSIONS: A method to create the ventilation CT using daily 4DCTs or 4D KV conebeam CTs was developed and demonstrated.

Author List

Tai A, Ahunbay E, Li X


Ergun Ahunbay PhD Associate Professor in the Radiation Oncology department at Medical College of Wisconsin
An Tai PhD Associate Professor in the Radiation Oncology department at Medical College of Wisconsin

jenkins-FCD Prod-480 9a4deaf152b0b06dd18151814fff2e18f6c05280