When performing GYN HDR brachytherapy with freehand needles, what strategies do you employ to immobilize the needles and prevent changes to your implant?

For over two decades, we have employed a technique using dental putty and friction collars to secure brachytherapy catheters. Initially developed to address needle migration issues in HDR prostate brachytherapy, we have successfully applied this technique to various other sites, including gynecological cases. Multiple brands of dental putty are suitable for this purpose, and we prefer those that harden within approximately three minutes after mixing, allowing us enough time to mold it into the d...

We are using less of it for the cervix with a hybrid applicator with straight and oblique needles.

For vaginal cancer, we do use free hand and tape it to the applicator and repeat imaging if any concern about displacement.

Mulherkar et al., PMID 36266203

We have found that taping it with silk tape to the various aspects of the applicator and labeling them is very reproducible.

Make sure the needles don't cross or your physicists will be cross with you!

For freehand needle applications, I occasionally trim a red rubber catheter to the desired length. I then evenly space (usually 0.5-1 cm apart) and pass/pierce the free needles through the red rubber catheter. Occasionally use two red rubber catheters, I position one intravaginally and the other externally to secure/tie along the applicator, ensuring the needles remain somewhat parallel and avoiding any crossing. I make sure to mark/flag needles before implantation. Alternatively, can also use b...

Similar to others, I’ve found that silk tape wrapped around the applicator holds the needles firm. If you’re unsure of depth, wait to tape until after you’ve scanned, otherwise you’ll have to cut off your tape and re-wrap.

I also call out the locations of the needles as I place them, either in cardinal directions or hands on a clock, and have a therapist make silk tape labels with the location written and add those to the needles to make sure my physicist can accurately reconstruct but also co...

I concurred with the recommendations from both Drs. @Dr. First Last and @Dr. First Last. Another check is to use a permanent marker to mark the contact area between the needles and the template, measure the length of each needle outside of the template, and document these in a diagram. This should be done at the time of CT or MRI sim. Afterward, we can double-check these markers and adjust if necessary prior to each sim and treatment.