Jul 28, 2017 2:00 PM


patient in ct scanner

Huntsman Cancer Institute (HCI) at the University of Utah is the first cancer center in the United States to use a new, state-of-the-art CT scanner that allows doctors to view higher quality, personalized images of a patient’s tumor. The scanner, called the Somatom Confidence 64 from Siemens, boasts numerous features that create more detailed images, giving physicians the ability to direct their therapy precisely where it’s needed.

The scanner is used to help doctors plan for radiation treatments. Using a patient’s CT scan, doctors identify the size, extent and specific location of the tumor that will then be targeted with radiation. The Confidence 64 arms the radiation oncologist with more detailed information than ever before.

Bill Salter, PhD, Director of Radiation Oncology at Huntsman Cancer Institute and Professor and Chief of the Division of Medical Physics at the University of Utah School of Medicine, says this pre-radiation step is one of the most important in treating the patient. “If we don’t accurately define where the tumor is, the quality of our treatment is compromised,” he says. “It’s exciting that our radiation oncologists are going to have more detailed information than ever before about a patient’s tumor.”

Dual Energy

Historically, radiation oncologists have used one set energy level at which all patients were scanned. But the Confidence 64 has the ability to scan the patient at two different energy levels, and then blend those images together to yield even more information.

Salter says, “When you combine those two scans, information can become visible that we couldn’t see before. For instance, edges of the tumor, the definition of exactly where the tumor is, can become visible. That’s hugely important because if we know precisely where the tumor is, we can target our radiation dose in that location only. That allows us to attack the tumor while sparing healthy tissues and structures.”

This will be particularly helpful in tumors that are right next to healthy organs. For example, the prostate sits against the rectum and bladder, and doctors don’t want to damage those healthy sites with radiation.

Sinus tumor taken with single energy (left) compared with dual energy (right). Photo courtesy of MAASTRO Clinic, The Netherlands
Sinus tumor taken with single energy (left) compared with dual energy (right). Photo courtesy of MAASTRO Clinic, The Netherlands

Personalized

In addition to scanning a patient using different energies, the new scanner also has the capability of tailoring the scan’s energy level to that particular patient. While this was technically possible in the past, other factors made it impractical, so it was rarely used. But the new Confidence 64 can determine the ideal energy level at which to scan each patient.

Salter explains, “The energy of the photons we use to make the best possible CT picture should be personalized to that patient and their body. If it’s a larger patient, we need to use higher energy to get a better image. If it’s a pediatric patient, using high energies would be like overexposing a picture – it’s more energy than we need for that small frame, and we wouldn’t actually get the best image.”

Acquiring the best possible images for each patient will help doctors better understand the nuances of a particular tumor, and how best to treat it.

man entering CT scanner

Predicting Accurate Doses

CT images aren’t just used to view and target tumors. They also help the radiation oncology team calculate the dose of radiation that will be delivered to kill the tumor. Once physicians have the images of a patient’s tumor, they virtually simulate and plan how they will fire beams of radiation to hit the tumor. Then doctors determine a plan for treating the patient, including how much radiation goes where. The goal is to target the highest radiation dose possible on the tumor with the lowest dose possible on healthy organs.

In the past, though, changing the energy level of a scan complicated the equation for calculating a patient’s radiation dose. However, the Confidence 64 uses a new algorithm that can accurately calculate the dose from whatever energy level was used for that particular patient.

“Before, if we had personalized the energy levels of the scan to the patient,” says Salter, “we would have introduced inaccuracy in our dose calculations, and that could compromise the quality of our treatments. With the new algorithm we can have our cake and eat it, too. That means we can scan the patient with an energy level that is personalized to their body and we can have accurate dose calculations for that scan. We get the best images we’ve ever had while not compromising in any way the accuracy of the dose.”

technician looking at CT scans on computer

Seeing Through Metal

If a patient has metal in their body near a tumor, that metal can significantly compromise a doctor’s ability to see the tumor on a CT scan.

Dr. Jonathan Tward, associate professor at the University of Utah and leader of the Radiation Oncology Genitourinary team at HCI, explains, “I recently treated a patient with a tumor of the spine. The problem was, it was impossible to know exactly where the tumor stopped and the spinal cord began because of metal rods that had been implanted to help support the patient’s spinal column. The metal prevents most of the X-rays from passing through them, essentially blurring everything adjacent to the metal.”

Getting a clear scan can be an issue for head and neck cancer patients with metal fillings in their teeth, or prostate cancer patients with metal hip replacements. But the Confidence 64 once again uses an effective algorithm that reconstructs the lost information, allowing the physician to see the tumor and nearby healthy tissues accurately. Tward says the difference is significant, allowing them to see parts of the anatomy that weren’t visible before.

Head scans of non-tumor patient with dental fillings. Scan of metal artifact reduction on right. Photo courtesy of MAASTRO Clinic, The Netherlands.
Head scans of non-tumor patient with dental fillings. Scan of metal artifact reduction on right. Photo courtesy of MAASTRO Clinic, The Netherlands.

Faster & 4D

The number 64 in the Confidence name means the scanner acquires 64 image slices at once, scanning a large area faster than ever before. For patients, this means more comfort and convenience as they spend less time being scanned. This speed also translates into improved accuracy of the treatment plan. If the patient moves even slightly during a CT scan, the image will be distorted and the physician’s understanding of where the tumor is will be compromised. Acquiring quicker images means the patient is more likely to hold still, leading to a better treatment plan for the patient.

The scanner also has 4D capability, which means doctors can choose to generate movies instead of static pictures.

“That will show us how the tumor is moving while the patient is breathing,” says Salter. “That’s important because patients breathe while we treat them and their tumor moves while we’re treating it with radiation. It’s very important we understand how it moves, especially in places near the diaphragm like the lungs, pancreas, liver, and kidneys. Respiratory motion translates to motion of these organs. So anything that moves, we would tend to image this way. We are very fortunate to have this capability here at Huntsman Cancer Institute. We think it’s going to mean a lot for our patients and our physicians.”

front view of CT scanner