Figure 1.

(A) Multi-slice axial CT images of the right obturator node (cyan line), uterine target (pink line), bowel (green line), external/internal iliac vessel (yellow line), rectum (brown line), and bladder (purple line) receiving 50% (blue lines), 100% (red lines), and 150% (white lines) of the prescription dose (6 Gy) in a representative patient with a right obturator node metastasis. One interstitial flexible catheter (white arrows) was inserted in the lithotomy position passing from the inside of the pubic bone through the outside of the bladder up to the front of the right sacroiliac joint using TRUS and CT guidance in the HDR room with dedicated CT, while avoiding bladder and external/internal iliac vessels. TRUS is commonly used for implantation from the perineum, and CT is used to adjust catheter positions at a deeper level. An iterative approach of catheter adjustment and CT image acquisition allows precise placement of the catheter in the target volume. (B) A coronal CT image of the uterine target (pink dashed line), the right obturator node (cyan dashed line), bowel (green dashed line), external/internal iliac vessel (yellow dashed line), rectum (brown line), and bladder (purple dashed line) receiving 50% (blue lines), 100% (red lines), and 150% (white lines) of the prescription dose (6 Gy) from interstitial and intracavitary applicators in a representative patient with a right obturator node metastasis. It is apparent that one interstitial flexible catheter (light green) is implanted, passing from the inside of the pubic bone through the outside of the bladder, so that the catheter can be inserted to the central part of the node.