Figure 2.

Case illustration of stereotactic body radiation therapy (SBRT): A 63-year-old male patient with a new primary cancer that involved the central base of the tongue after previously receiving radiation therapy to the mucosal axis with concurrent cisplatin approximately 10 years earlier for an unknown primary cancer. The patient was reirradiated to a dose of 40 Gy in 5 fractions on nonconsecutive days with magnetic resonance image guided SBRT. The axial (A) and coronal (B) sections of the SBRT treatment plan are displayed. The red line represents the prescription dose that encompasses the planning target volume, which comprised the gross tumor volume plus a 0.1 cm margin circumferentially (blue color wash). The blue, orange, yellow, and green lines represent the 95%, 90%, 75%, and 50% isodose lines, respectively. Notably, an effort was made to avoid dose spillage to the neighboring larynx (in maroon contour).