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Patient positioning, monitoring and respiratory gating

The Sentinel and Catalyst from C-Rad have integrated functionality for patient positioning, motion detection and gating. The Catalyst offer significant increased accuracy and efficiency in the patient set-up and positioning procedure prior to treatment start, motion detection during the critical beam delivery session and respiratory gating. It is designed for patient safety and accuracy.

Patient positioning The patient positioning function of the Catalyst offers a streamlined and efficient workflow. Results to correct for set-up errors are projected directly on the patient. The Catalyst save time and improve accuracy compared to positioning by means of line lasers and tattoos. As soon as the patient is placed on the treatment couch, the Catalyst detects actual position and posture of the patient and projects the result directly on the patient skin surface. Apart from indicating any posture errors, the system also presents a suggested couch shift (correction vector) which can be transferred to the couch control system for auto-setup.
Motion management IGRT and stereotactic technologies have improved the knowledge of actual tumor position prior to daily treatment start. This has enabled smaller margins, dose escalation and even hypo-fractionation with confidence that the tumor is being irradiated accurately. Even a small shift in patient position may ruin the accuracy, and small shifts are difficult to detect. Tools and checks to make sure that the patient stays in an accurate position all through the beam delivery have not changed over the years. It is often still manually checked by viewing the patient on a monitor in the control room. This procedure does not detect smaller movements. The motion detection functionality in Catalyst is started while the personnel are in the treatment room and has determined that patient is in correct position. The Catalyst automatically detects normal breathing and excludes that from the alarm levels. The system will constantly monitor the patient and in case of movement will generate a clear signal for the personnel to react upon, as well as an accurate record of the movement. Motion detection by Catalyst can be selected to be based on surface motions or in combination with target movements calculated by non-rigid algorithms and deformable models.
Respiratory gating system The Catalyst system continuously detect and monitor the breathing motion of a patient and can generate a real time gating signal. Software functionality required for a complete gating solution includes the following:
• ”Prospective” and ”retrospective” (4D) gating of a CT.
• Gating of treatment beam from accelerator.
• Parallel monitoring of two (2) detection points – thoracic + abdominal.
• Audio and/or visual support of patients breathing pattern.
• Detection of changes in a patient’s breathing pattern.
• Support of “breath-hold” techniques.
• Detection of sudden irregularities in breathing pattern such as coughing.