Soft Tissue Visualization Using a Highly Efficient Megavoltage Cone ...

Figure 13 shows neck/chest MVCT axial, coronal and sagittal images that were acquired with
receptors 1 and by delivering 13 cGy.
Figure 13: Neck/chest MV CBCT with receptor 1 using 13cGy
4. Summary
We have developed an imaging system that is optimized for MV and can acquire Megavoltage CBCT
images containing soft tissue contrast using a 6MV x-ray beam with irradiation in range of 3 to 16cGy.
The main components of this system are a high quantum efficient flat panel detector, readout interface
with linac, calibration/corrections process, image preprocessing with dose/resolution adaptive filter,
and scatter corrections. It can resolve a contrast resolution of 1%, gold seeds of 1mm x 3mm (1mm in
diameter and 3mm in length), and air structures of 2mm in diameter.
Clinical MV CBCT images revealed that structures such as prostate and optical nerve are visible with
irradiation of 3 to 8cGy. This system (using receptor 1) can also be used for routine portal imaging
applications without risk of saturation for high dose/high energy treatment/verification imaging, or
dosimetry applications. This system can also deliver good quality MV CBCT images with 1 cGy that
opens the possibility of the use of this system for 4D-CT.
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