Tracking systems relate anatomical position to a patient’s breathing cycle by analyzing time-resolved medical images or external respiratory signals. This relationship allows the system to estimate respiratory phase and identify how structures in the chest or abdomen shift over time. The resulting motion model provides a basis for synchronizing image acquisition or treatment with selected portions of the cycle.
Time-resolved images and external signals provide complementary ways to characterize breathing-related motion. Images show changes in anatomical position directly, whereas external signals represent respiratory activity and can support phase estimation. Using either source, or relating both when appropriate, helps clinicians choose a motion-tracking strategy suited to localization, cycle synchronization, or assessment of moving anatomy.
Respiratory phase estimation identifies where a patient is within the breathing cycle when an image is acquired or therapy is delivered. This timing helps coordinate clinical actions with the changing position of thoracic and abdominal structures. By reducing uncertainty about when anatomy is located at a particular position, phase information can improve localization and support more precise interventions.
A typical workflow collects time-resolved medical images or an external respiratory signal, examines changes associated with breathing, and estimates the patient’s respiratory phase. The resulting information can then be used to synchronize imaging or therapy with the cycle. This sequence converts breathing-related observations into a motion estimate that clinicians can apply to diagnosis, treatment planning, or image guidance.
For four-dimensional imaging, motion information adds a time-related description to anatomical images. Tracking helps associate observed anatomy with different points in the breathing cycle, allowing clinicians to assess how structures move rather than relying only on a static position. This is particularly relevant when evaluating disease or planning care for organs affected by thoracic or abdominal motion.
In radiotherapy, respiratory motion tracking provides information about the changing position of treatment-relevant anatomy during breathing. Therapy can be synchronized with the patient’s cycle or adjusted through motion-compensated approaches, reducing motion-related uncertainty. This supports more reliable localization of moving targets and can help clinicians pursue treatment precision while limiting the effects of anatomical movement.
Respiratory motion tracking is useful when image-guided procedures involve moving organs such as the lungs or liver. Monitoring breathing-related displacement helps clinicians interpret anatomy at the appropriate respiratory phase and account for changes during guidance. The same information can support safer interventions by improving localization and reducing uncertainty caused by motion during the procedure.