Insertion of pre-loaded, stranded RSRx seeds peripherally

5. Completion of contouring

• 4D Brachytherapy is a two-operator procedure, so the computer operator contours the anterior rectal wall then begins optimising the central needle and seed positions to obtain the optimal dosimetry according with the prescription. During this time the second operator begins inserting the preloaded stranded needles, leaving the needle tip in the mid-gland region.

6. Peripheral needle insertion

• The second operator begins inserting the preloaded stranded needles in order, in the transverse plane. When the anterior and lateral needles are all inserted, the positions are verified on the planning computer and the dosimetry checked before any seeds are inserted.

7. Stranded seed insertion

• Working in the longitudinal plane the base plane is verified and any adjustment of the prostate position on the planning computer in the antero-posterior plane (y axis) is made.
• The computer operator moves the cradle to focus on each needle in turn beginning with the anterior 4 needles then moving to the lateral needles. When each needle is identified on both the ultrasound and planning computer, the second operator advances the needle to the base of the prostate and the seeds are then deployed and their position recorded on the planning computer. (Technical note: In the lateral needles the needle tip will often be caudal to the prostate outline depending on the shape of the prostate) (Technical note: The posterior lateral strands especially, may move laterally having been deployed from their needle. Therefore, move the U/S cradle to ensure the image and therefore position is optimized before recording the strand position of the planning computer.) (Technical note: If a haematoma develops, typically when inserting the postero-lateral needles, stop. Raise the ultrasound probe anteriorly, when fully inserted, using the stepping unit. This will cause compression of the prostate, stop the bleeding and will allow the haematoma to disperse. Leave for 10 minutes before re-positioning the ultrasound probe and completing the procedure.)

8. Insertion of posterior needles

• Having inserted the anterior and lateral strands, the remaining 4 posterior needles are inserted. During this time further dosimetry optimisation is undertaken on the planning computer. Insert the middle two needles first, usually starting on the 1.5 row, which will help bring the prostate anteriorly to aid needle position if the posterior border of the prostate is below the 1.0 row.
• To account for the anterior movement of the prostate due to the insertion of the posterior 4 needles, align both the ultrasound and the planning computer in the transverse view at the zero plane. Scroll the U/S probe through to the middle of the prostate and move the image on the planning computer to obtain alignment. Following this movement align the planned needles to the inserted needles.
• Then switch to the longitudinal plane for both the U/S and planning computer, and again move the prostate outline on the planning computer anteriorly, to align with the position of the gland and the needles on U/S. The base plane must also be checked and adjusted at this stage as well.

9. Insertion of posterior seeds

• The posterior strands are then inserted up to the base of the prostate and their positions recorded on the planning computer. Leave the ultrasound probe fully inserted whilst the final dose planning is completed to disperse any bleeding that may have occurred.