How can the center of the clinical target volume (CTV) be determined?

Determining the center of the clinical target volume (CTV) is a critical step in treatment planning for radiation therapy. The use of orthogonal radiographs is especially effective for this purpose. These radiographs provide images from two perpendicular angles, allowing for a more accurate localization of the tumor. By analyzing the images from different perspectives, clinicians can better visualize the spatial relationship of the tumor to surrounding anatomy, which aids in pinpointing the tumor's precise center and consequently the CTV.

Other methods, while potentially useful for different purposes, may not provide the same level of accuracy and reliability needed for defining the CTV. For example, palpation may offer an initial idea of the tumor's location, but it cannot give a precise measurement or account for the tumor's extent. Patient history can provide context about the tumor's growth and treatment but lacks the specificity of imaging techniques. Relying solely on MRI scans may also present limitations, as they might not always offer the necessary orthogonal views or the same detail in evaluating the multidimensionality of the tumor. Thus, orthogonal radiographs are the most effective tool for accurately determining the center of the CTV.