Motion is addressed by comparing the tumor’s position across images and using image registration to align those studies. When the tumor itself is difficult to identify consistently, fiducial markers or visible anatomical landmarks can provide reference points. This tracking helps distinguish changes in apparent location caused by motion from changes that may affect treatment targeting.
Image registration provides the matching step between scans. By aligning serial images, it helps clinicians compare where the tumor is located at different times and recognize positional differences that could affect treatment decisions. This is particularly relevant when anatomy changes or movement makes direct visual comparison unreliable.
Fiducial markers and visible anatomical landmarks serve as reference points when the tumor is not equally clear in every image. Markers can support localization, while landmarks provide an observable anatomic basis for matching scans. The choice matters because consistent references improve the ability to follow position across imaging studies.
A typical workflow uses serial images to establish the tumor’s location at multiple time points. Clinicians then use image registration to match those images, relying on the tumor, fiducial markers, or visible anatomical landmarks as references. Reviewing the matched studies supports decisions about localization, planning, guidance, or response assessment.
These capabilities support several clinical uses: image-guided radiation therapy, treatment planning, biopsy guidance, and assessment of therapeutic response. Their value differs by task, but each application depends on locating the tumor accurately enough to guide a decision. They therefore connect imaging information with targeting, sampling, or evaluation of treatment effects.
Tracking can reveal that tumor position or patient anatomy has changed over time. That information allows clinicians to consider care against updated anatomy rather than relying only on an earlier scan. In radiation treatment and other image-guided decisions, more accurate localization can help target the tumor while limiting exposure to nearby healthy tissue.