Understanding High-Dose Rate (HDR) Brachytherapy – Insights from Nicole Bunda-Randall

 

High-Dose Rate (HDR) brachytherapy is a specialized cancer treatment that delivers targeted radiation directly to tumors. To help us understand the complexities of this treatment, we spoke with Nicole Bunda-Randall, a therapeutic medical physicist with CAMP who regularly provides medical physics support to Parkview Cancer Center. With years of experience in radiation oncology, Nicole provided insights into how HDR works, its benefits, and the challenges involved in this intricate procedure.

 

What is HDR brachytherapy, and how does it work?

“HDR brachytherapy involves placing a small, radioactive source inside or near the tumor. It’s different from external beam radiation because the radiation is delivered directly from within the body, giving us better control over the dose and limiting exposure to surrounding healthy tissue.

We primarily use HDR for prostate and gynecological cancers. The key is that we need a pathway—like a needle or applicator—to deliver the radioactive source. Once the applicator is in place, we use imaging, such as a CT scan, to guide our treatment planning and ensure precise dose delivery.”

 

How does HDR compare to other types of radiation treatments?

One of the biggest differences is that the radiation source we use in HDR is live—it’s always emitting radiation. For example, we use a small Iridium-192 source, about the size of a grain of rice. This is stored safely in a shielded afterloader, which houses the source when it’s not in use. Unlike external beam radiation, which only emits radiation during treatment, HDR allows us to deliver higher doses in shorter sessions.

HDR is highly effective because the radiation travels through pre-defined ‘dwell positions’—places where the source pauses briefly inside the applicator to deliver the optimal dose. We can adjust the treatment in real-time based on the patient’s anatomy that day, which isn’t always possible with other forms of radiation therapy.

 

What types of cancers are typically treated with HDR brachytherapy?

At our center, we focus primarily on prostate and gynecological cancers, but HDR can also be used for esophageal, rectal, and even skin cancers. The versatility of HDR is one of its biggest strengths, but it’s not suitable for every case. You need a clear pathway to the tumor to insert the applicator—so, unfortunately, it’s not something we can use for deep internal organs like the pancreas.

 

What does a typical HDR brachytherapy session look like?

A typical session takes about two and a half hours from start to finish. First, the patient receives an epidural to stay comfortable during the procedure. We place the applicator or needles into the treatment area and then perform a CT simulation to confirm placement. While the patient rests, we create the treatment plan in real-time. Once the plan is ready, the afterloader sends the radioactive source through transfer tubes into the applicator, following the predetermined dwell positions. The beauty of HDR is that everything happens in one session—planning, delivery, and recovery. By the time the patient wakes up, they’re done!

 

What are the main benefits of HDR brachytherapy?

The biggest advantage is precision. Since the radiation source is placed inside the tumor, we can deliver higher doses without exposing healthy tissue to unnecessary radiation. This targeted approach reduces side effects compared to other treatments like external beam radiation.

Another benefit is the efficiency. Patients typically need fewer sessions—sometimes just two or three—compared to traditional external beam therapy, which can require 20 to 40 sessions. This makes HDR especially helpful for patients who may find it difficult to travel for frequent treatments.

 

What are some of the challenges involved in HDR?

HDR requires a lot of coordination. It’s not just about the physics—you need a trained physician to place the applicators, an anesthesiologist for patient sedation, and an authorized medical physicist on the Radioactive Materials License to manage the radioactive source. On top of that, the procedure involves strict safety protocols since we’re working with live radiation.

 

There’s also a psychological component. Patients can find the procedure intimidating, especially when they hear terms like ‘radioactive source.’ Part of my job is to help ease those fears by explaining the process and what they can expect.

 

How do safety protocols work for HDR?

The radioactive source stays housed in an afterloader when it’s not in use. It only leaves its ‘home’ to travel through the applicator during treatment. No one is allowed in the room with the patient while the source is active, ensuring that staff aren’t exposed to radiation. After the treatment, everything is carefully checked to make sure the source is back in the afterloader.

 

There are a lot of checks and balances in place—before, during, and after the procedure. We follow strict state regulations and safety guidelines, and the equipment undergoes routine quality assurance testing to ensure everything functions properly.

 

How has HDR changed over the years?

Technology has come a long way. In the past, we might have had to send patients to specialized centers for certain treatments. Low Dose Rate (LDR) Brachytherapy was once more common than HDR and gave effective treatments, but it required the patient to stay at the hospital for multiple days and staff were exposed to low levels of radiation while caring for the inpatient. But now, with advancements in HDR, we can offer those same types of brachytherapy treatments closer to home as outpatient procedures. 

 

What I love about HDR is that it allows us to see everything in real-time. We’re not relying on images taken days or weeks earlier—we’re adjusting the plan based on what we see during the session. That flexibility makes a big difference in patient outcomes.

 

What advice would you give to someone interested in HDR brachytherapy?

If you’re a medical physicist, you’ll likely encounter HDR at some point. It’s a fascinating field, but it requires strong teamwork and problem-solving skills. The procedure is complex, but that’s also what makes it so rewarding—you’re working directly with patients and delivering treatments that can significantly improve their quality of life.

 

I was lucky to be introduced to brachytherapy early in my career by a professor who was passionate about the field. Since then, I’ve enjoyed working at centers where HDR is a regular part of the treatment options. If you get the chance to specialize in it, I highly recommend it!

 

Conclusion

HDR brachytherapy offers a precise and efficient way to treat certain cancers, providing patients with shorter treatment times and fewer side effects. While the procedure comes with unique challenges—like managing live radiation and coordinating with multiple specialists—its benefits make it a valuable tool in modern cancer care.

As Nicole Bunda-Randall explains, HDR is not just about delivering radiation—it’s about teamwork, precision, and improving patient outcomes. With advancements in technology, HDR continues to evolve, giving physicists like Nicole exciting new ways to make a difference in the lives of their patients.

 

Learn more about Nicole and her career in our “Day in the Life” feature article here.

 

Connect with CAMP

Looking to connect with Nicole? Send us a message on LinkedIn.

Want to learn more about health physics, veterinary radiation therapy, and the latest advancements? CAMP offers a wealth of resources and expertise to help you stay informed and engaged in this dynamic field. Whether you’re a healthcare professional, student, or simply curious about the science behind radiation therapy, CAMP is here to support your journey.

Visit our website to explore our services, discover educational opportunities, and join a community dedicated to advancing medical physics.

 

 

Video Transcript: 

So a form of therapy that we offer at a lot of our sites for cancer patients is known as brachytherapy. Brachytherapy is a form of treatment where we use a live radioactive source internally in the patient’s tumor to treat them. It might be used as the only type of therapy a patient gets or as part of a bigger scope of maybe like a boost along with like external beam or chemo or surgery as kind of one of the members of the team of therapy. So here at Parkview, this is our treatment console. So when a patient is getting treated, we’ll be sitting out here at the console. And you can see we have audio, visual of the patient inside the room. This is where we create the plan in our treatment planning system, send it over, and then actually treat it from this setup. So we can go inside the treatment room.

So at our site, we’re lucky enough to have our afterloader in a separate suite as opposed to being in the same room as an external beam. So the patients will come in here. So this is just a bed that they might be on. This is what’s known as an afterloader. An afterloader actually houses our Iridium-192 source. So there’s a live radioactive source in here. There’s just one source. So what happens is that a patient will have an implant done. and then we connect that implant, whether it’s needles or an applicator, using our transfer guidance tubes. Here, let show you a little example. If we pretend that this is a needle that’s been inserted in the patient’s tumor, so it’s directly inside the patient’s tumor, it’s implanted there by the physician, we then connect it to our transfer guidance tube, and then this gets connected to our afterloader.

Then we have a channel that goes from the afterloader right directly into the patient’s treatment, into their tumor. Instead of something like external beam where we’re working from the outside in, brachy is working from the inside out. We’re able to manipulate dose where we really can avoid sensitive structures. If we’re doing a prostate, we can really avoid rectal in their bladder because we’re going inside the prostate out. So there’s lots of checks, safety checks, that are done with this afterloader. During every treatment, we do a length check. And then a dummy wire comes out, does a measurement, and that’s actually when the source is finally released. But there’s lots of checks that happen prior to that before the actual source is allowed to come out. Like, I cannot be in the room when we’re actually the treatment. So when the patient, so we’ll have the patient all hooked up. We’ll do all of our tests.

We survey the patient. We do a nice little survey of the patient for their background. And then I’ll actually survey the afterloader. We’ll do this before and after the treatment. And it’s just a safety precaution to make sure that our radioactive source has gone back to its home. You can actually kind of hear it beeping a little bit. That’s the survey meter detecting the source that’s inside. It’s safe inside the afterloader. So once the patient’s hooked up, We are happy with all the connections. Then we’ll come outside the room during their treatment. Patient will stay in here. Everybody else will have to come out of the room. We will close the patient. And then we will administer their treatment. So we have emergency procedures. We’ll watch them the whole time. There are some potential little beeping noises that we let the patient know about. But all in all, very calm, very kind of a boring treatment for them, because once the implant’s done, the actual treatment might take anywhere from five minutes to maybe up to 20 minutes. Once that treatment is completed, we’ll go back into the room. We have a third-party radiation detector on the wall, and that’s what we want to make sure that that goes down to zero. It’s only detecting background. That’s how I know that it’s safe to go into the room. We’ll go in, and just like we surveyed before the treatment, we’ll survey the patient, survey the afterloader, make sure everything is back in its home and happy. The radiation is now contained back into the afterloader. And then we’ll disconnect the patient. So we would take the transfer guidance tube out, disconnect this, and then the physician will come in and remove whatever applicator is inside the patient.

It’s a really great form of treatment. We really can control dose. We control dose via dwell positions that are in each of the applicators. So it’s either we have the source hang out longer or shorter based on where in the needle it is. And yeah, patients do really well for it. Sometimes they have multiple fractions, so they’ll come back in a week, maybe get the same procedure done, and then they’ll be done. And that’ll be their boost. And that’s brachytherapy.