Fig. 3: The orthogonal kV x-ray system used at our proton center and exemplary kV and DRR images.

The orthogonal kV x-ray system is used for patient alignment at our proton center (left). An exemplary kV image (middle) captured by this system and its corresponding DRR image (right). Compared to the DRR image, the daily-used kV image is often noisy and contains unwanted artifacts from essential medical devices/accessories, such as dental implants or treatment couch attachments.