Easing Pelvic Cancer Treatment
Device measures bladder fullness before radiation therapy
Nov. 11, 2025
3 minute read
Device measures bladder fullness before radiation therapy
For people with a pelvic cancer such as prostate cancer, radiation therapy can be complicated and time consuming. The patient’s bladder must be full to a specific level at each treatment session to push nearby organs out of the way, allowing a radiation dose to be beamed directly at the tumor while minimizing the dose to other structures in the abdomen.
“A full bladder makes it easier for us to deliver radiation therapy safely and to meet our dose goals,” said Peter Zhu, MD, radiation oncologist and Medical College of Wisconsin faculty member.
Balancing safety and effective dosing can be tricky. In most cases, patients must come in for daily treatment. When they arrive, they lie on a treatment table connected to a large machine called a linear accelerator. This machine takes a quick computed tomography (CT) scan of the bladder to make sure it is the right size and shape for treatment. If it is, the radiation therapist directs the planned dose of radiation at the tumor. Unfortunately, in many cases, bladders are not ready. Patients must come off the treatment table to drink more fluids and wait until the bladder fills.
“Moving on and off the table can be uncomfortable for anyone with a full bladder, especially older adults,” Dr. Zhu said.
“It’s a cumbersome, difficult process that can be emotionally distressing for patients,” said William A. Hall, MD, radiation oncologist and MCW faculty member. “The unpredictability of the process makes schedule delays common.”
In 2022, Dr. Hall was considering this problem when he was struck with inspiration. Would it be possible to create a wearable device that would collect information about the patient’s bladder while they were still in the waiting room?
Dr. Hall worked with Eric Paulson, PhD, radiation physicist and MCW faculty member, to invent a belt equipped with ultrasound transducers. They worked with a team of experts, at MCW and internationally, to provisionally patent the device and form a company to develop the device.
Patients wear the belt for a few minutes while waiting for treatment. It collects data about the size and shape of the bladder, as well as the rate at which it is filling. The patient holds a tablet device that gives the patient and the treating Radiation Oncology team real-time information about their bladder. Patients gain a greater sense of control of their body that may be calming.
“The goal is to start treatment only when we are confident a patient’s bladder is ready — within 90% of where it needs to be for accurate treatment,” Dr. Hall said.
In June 2025, Dr. Zhu opened and is leading a small clinical trial to determine if the device works as hoped. The team is testing the device on a group of healthy volunteers who did not have cancer and with patients receiving radiation therapy for pelvic cancers. This investigator-initiated trial was available only through the Froedtert & MCW Cancer Network.
Dr. Hall and his colleagues hope their imaging device will reduce radiation exposure because patients will need fewer CT scans to check bladder fullness, and that treatment will be less time consuming.
“We’re also hypothesizing that the process will be a little more relaxing, with patients experiencing less anxiety and uncertainty,” Dr. Hall said.
