Purpose: A novel design is presented for CBCT that uncouples the movement of OBI device from the treatment head and thereby reduce the amount of time necessary to obtain cone-beam CT image data.
Methods: A kV source and detector system is isocentric to, but decoupled from, the gantry C-arm rotation, capable of rotating around the patient to acquire diagnostic quality image dataset. The isolated kV source and detector system can also be retracted from the path of the accelerator to allow for treatment via the MV head, while the gantry is rotatable around an isocenter point.
Results: The particular advancement presented allows mounting the KV source and detector system on a slip ring, disassociating the movement of the kV source-detector system from the MV head. This allows for a more rapid rotation of the on-board imaging device (OBI) around the patient (~17-20 seconds) improved accuracy of treatment position by reducing time of patient setup. Moreover, this will significantly reduce the wear and tear on gantry C-arm.
Conclusion: In most modern therapeutic linear accelerators, the OBI device consisting of a kV source and a detector, is rigidly attached to the gantry of the LINAC resulting in the imaging requiring the MV head of the LINAC to also rotate around the patient. As result of the shielding requirements in the head of the LINAC, and the counterweight needed to balance this weight, the movement averages between 60-65 seconds in most patients, and significantly longer for gated patients. This new design provides for rapid acquisition of kV CBCT images using a low-mass rotational frame. In addition, the unnecessary movement of MV head with heavy and critically expensive parts is eliminated during the image acquisition.
Not Applicable / None Entered.