Elekta Clarity 3D system transforms prostate radiotherapy at UHG

Soft tissue imaging with 3D ultrasound both at therapy simulation and just before treatment has transformed prostate radiotherapy at University Hospital Galway (UHG). The majority of radiotherapy patients with prostate cancer who visit the clinic will benefit from a new technology that can accurately track the prostate's position before each treatment. The Elekta Clarity® 3D system provides ultrasound-assisted image guidance to radiation therapy (IGRT), and avoids the additional radiation dose that comes with other IGRT techniques.

"The big advantage of Clarity is you're not adding any radiation dose – you're getting pictures of the prostate for 'free,'" says Margaret Moore, UHG's Head of Radiation Physics. "For planning treatments, CT simulation and Clarity are a great combination. Both modalities add their bit of intelligence to create the certainty that you're seeing the target."

Reliably localizing the prostate is critical as its position can change due to bladder and rectal filling, in addition to patient breathing, she adds.

"If you aim the treatment beams at the same spot every day, but the anatomy you want to treat is moving in and out of the spot, then it's not getting the full dose it should," Ms. Moore explains. "Clarity allows us to track the prostate's position before each treatment, and keep the treatment beam on target."

UHG, which opened clinically in 2005, acquired Clarity in 2008 and began using it with one of its three linear accelerators. Clarity is capable of integrating with any external beam radiation therapy workflow and equipment to support simulation, planning and treatment.

"In the equipment evaluation, we liked the idea of matching the planning ultrasound to the treatment room ultrasound that Clarity offered," Ms. Moore recalls. "Other similar IGRT options try to match ultrasound to CT, which could affect alignment accuracy. Clarity also wouldn't require reconfiguring our linear accelerator – we could integrate the system easily."

Versatile Clarity

Radiation oncologists at UHG have been able to use Clarity routinely to fine-tune prostate contouring, superficially at the bladder junction.

"In some cases, the lobes of the prostate reach up to the bladder, so distinguishing bladder tissue from prostate tissue is difficult using CT," Ms. Moore observes. "On ultrasound, there's a huge difference. The bladder is much more distinctive than the prostate gland."

Clarity has been also been indispensable in facilitating soft tissue imaging of prostate cancer patients with single or bilateral hip prostheses, Ms. Moore adds.

"The metal in artificial hips soaks up the planning CT imaging dose, which creates an artifact that blocks out the view of the prostate and prevents contouring," she says. "Ultrasound is unaffected by these implants. Clarity is our savior for planning these patients."