FIGURE 2.
68Ga-PSMA PET enables identification of areas of gross disease that are missed on CT. Intensity-modulated radiotherapy can be used to deliver higher dose to areas with gross disease. At top is example of SRT plan and dose–volume histogram for patient with rising PSA level after radical prostatectomy planned without radiographic evidence of visible gross disease. Pelvic nodal and prostate bed volumes are prescribed doses of 45 and 72 Gy, respectively. At bottom is example of SRT plan and dose–volume histogram for patient who underwent 68Ga-PSMA PET before planning. 68Ga-PSMA PET enabled identification of 68Ga-PSMA–positive left internal iliac pelvic node. Intensity-modulated radiotherapy was used to focally increase dose to gross disease to beyond 65 Gy while adequately sparing normal organs at risk. Dose-color-wash displays simulate dose on CT simulation scan with color scale of blue (45 Gy) to red (72 Gy). Dose–volume histograms are plotted with bin doses along horizontal axis and percentage of structure that receives dose greater than or equal to that dose on vertical axis. Each line on dose–volume histogram represents a particular volume (e.g., CTV and relevant organs at risk).