COPENHAGEN, Denmark - A pioneer in image guided radiotherapy (IGRT) in Denmark, Copenhagen University Hospital (CUH, Herlev) was the first in the country to incorporate MRI in radiotherapy imaging simulation to guide radiotherapy of lung cancer patients. Continuing its tradition of IGRT firsts, CUH is the first hospital in Scandinavia to acquire Elekta's Clarity® soft tissue visualization system with Autoscan.

CUH medical physicist Mariwan Baker, M.Sc., will use Clarity to further quantify the value of non-invasive, non-ionizing 3D ultrasound in increasing radiation therapy precision.

"3D ultrasound is non-invasive and cost effective, and provides soft tissue information that is complementary to CT images," Baker observes. "Unlike CT, however, Clarity will enable daily imaging prior to treatment, which will help our oncologists account for interfraction variations in the target position and more precisely target the tumor by the prescribed planned dose."
The first projects will involve Clarity studies of gynecological and prostate targets.

Baker's research, the subject of his Ph.D. thesis, focuses on the potential to use Clarity for addressing the magnitude of uterus displacement in gynecological patients on a daily basis. Furthermore, the research encompasses the implementation of Clarity for 4D monitoring - to evaluate intrafraction changes in prostate position. Baker will first assess the extent of prostate shifts, a well-known phenomenon in radiotherapy, and will build on that knowledge by examining dosimetry variations caused by intrafraction prostate motion.

"It's not simply evaluating the magnitude of the displacement," he explains. "We have to get an idea about how much this displacement is influencing the dose distribution around the tumor, and of course, around the organs-at-risk."

To accomplish this, Baker will be using Clarity 3D with Autoscan along with a 4D phantom that will be developed by CUH for ultrasound tracking with embedded real-time detectors.

"The phantom will simulate the prostate, enabling us to compare the dose recorded by dosimeters with and without compensating for motion," he notes.

Breast imaging with Clarity

In addition to prostate and gynecological Clarity research, Baker mentioned the potential of an initial study on imaging the tumor cavity movement in post-operative breast cancer patients.

"A patient being treated post-operatively can have a least 25 fractions, so shrinkage of the cavity is an issue," he says. "Pre-treatment imaging with Clarity can address that."

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