, according to a results from a randomized trial presented at the annual meeting of the American Society for Radiation Oncology.
The aim of this same-day CT scan, called a CT simulation scan, is to optimize radiation targeting by mimicking the conditions under which radiation is delivered using the latest information on the size and location of lesions.
But investigators reported that skipping the CT simulation scan saves patients hours in the clinic, allows patients to experience pain relief faster, and saves radiation oncologists time without compromising dosimetric coverage of cancerous lesions.
“This is huge in a symptomatic patient population,” said Melissa O’Neil, an advanced practice radiation therapist at the London, Ont., Health Sciences Centre and the lead investigator on the trial, dubbed DART (Diagnostic CT-Enabled Radiation Therapy).
“Diagnostic CT-based radiation planning substantially reduces time in the [treatment] center without a detriment in plan deliverability or quality,” Ms. O’Neil said.
In addition, patients are exposed to less radiation, and staff doesn’t have to spend as much time tending to symptomatic patients before treatment. Omitting this scan “should be considered for patients with a recent diagnostic CT scan who are undergoing simple palliative radiation,” Ms. O’Neil said.
CT simulation scans are standard of care in cases involving palliative radiation, but they create bottlenecks in the workflow. When a CT simulation is performed on the day of treatment, patients must wait hours as the results are translated into a treatment plan.
In the DART analysis, 33 patients with 42 treatment sites were randomly assigned to CT simulation planning or diagnostic CT planning.
Patients received up to 30 Gy in up to 10 fractions for bone or soft tissue metastases or primary tumor targets in the thorax, abdomen, pelvis, or proximal limbs. Single-fraction treatments were most common.
Three-quarters of the patients were men (median age, 72 years). Lung cancer was the most common type of primary tumor, followed by prostate and breast cancer.
The eight participants for whom the CT simulation approach was used waited 3-4 hours for treatment planning and overall spent a median of 4.8 hours in the cancer center on their day of treatment.
The 25 patients for whom diagnostic CT planning was used spent a median of 0.4 hours, or about 24 minutes, in the center on their day of treatment because radiation plans were completed before they arrived. The median time between their diagnostic CTs and radiation treatment was 13 days (range, 8-22 days).
Ms. O’Neil and her team found that if the original diagnostic CT was performed within 28 days, lesion anatomy would not have changed enough to warrant a new scan.
On the day of treatment, the study team used surface-guided radiation therapy techniques to ensure patients in the diagnostic CT planning group were positioned within 3 mm of where they were during their diagnostic scans, an essential step to ensure that radiation is delivered to the correct location. Ms. O’Neil noted that other investigators have used anatomic landmarks, a simpler approach, to achieve these results.
Overall, radiation oncologists rated radiation dose distribution as “acceptable” in about 80% of cases in both arms of DART and “acceptable with minor deviation” in the remaining 20% of cases.
Every radiation oncologist and medical physicists in the trial gave the workflow with diagnostic CT planning a 5 out of 5 rating for acceptability, and 90% of patients in this group rated the amount of time they spent for treatment as “acceptable.”
In contrast, only half of patients in the simulation arm said the amount of time spent was acceptable.
These findings align with several previous studies that support the diagnostic approach.
Jacob Scott, MD, a radiation oncologist at the Cleveland Clinic, said, “The comparable results using a recent diagnostic CT in place of a CT simulation for palliative radiation is an exciting step forward in radiation oncology. We may soon be in a world where we no longer need simulations.”
Dr. Scott also noted that combining diagnostic scans with cone beam or surface-guided positioning in lieu of CT simulations could further save “the health system and patients time and money.”
No external funding for the study was reported. The investigators, Ms. O’Neil, and Dr. Scott have disclosed no relevant financial relationships. One investigator reported receiving honoraria from Knight Therapeutics, AbbVie, Tersera, and Eisai and owns stock in Myovant.
A version of this article first appeared on Medscape.com.