Clinique Claude Bernard’s Private Radiotherapy Center of Metz (PRCM) uses Elekta’s definitive arc-based Volumetric Modulated Arc Therapy (VMAT) method to boost efficiencyAfghanistan — Tuesday, March 9, 2010
The quality and efficiency of arc-based radiation therapy has prompted PRCM (Metz, France) to use Elekta VMAT for nearly all cases. Eleven months after using VMAT on its first patient, PRCM has used the technique for more than 500 patients, half of which were prostate cancer* cases. With Elekta VMAT, single or multiple radiation beams sweep in uninterrupted arc(s) around the patient, significantly reducing treatment times.
To enhance the quality of its radiation treatments, PRCM began using Intensity Modulated Radiation Therapy (IMRT) for increasing numbers of patients. IMRT is an advanced radiotherapy method that enables doctors to conform more precisely to the 3D shape of the tumor—using radiation beams that vary in intensity and that come from different directions. While IMRT can create a treatment that maximizes dose to the target and minimizes dose to healthy tissues, it can lead to longer delivery times compared with standard radiation therapy, says Guillaume Faure, M.D., co-director of radiation oncology at PRCM, the first center in France to use Elekta VMAT.
Although integrating IMRT as our technique of choice increased treatment quality, treatment times increased, which led to an overall productivity decrease,” he notes. “We realized that VMAT’s one to two, or more, non-stop beams would be more efficient than the standard IMRT delivery method, which requires five to seven beams and time-consuming data transfer between the treatment console and the linear accelerator for each beam.”
PRCM acquired Elekta VMAT option in January 2009 and began treating the following month. Clinicians selected prostate cancer cases as the first Elekta VMAT cases due to their straightforward treatment requirements, but gradually added a wide range of cases, including head and neck, pelvis and metastases.
“Our radiation therapy technicians found learning Elekta VMAT to be extremely simple,” Dr. Faure observes. “After only five months we were using VMAT to treat an average of 70 patients per day in an 11 to 12-hour day. At six months, almost everything apart from breast cancer cases was being done with the VMAT technique. Most importantly, the reduction in the length of treatment sessions is striking when compared to standard IMRT. VMAT treatment session times averaged half as long as those of IMRT.”
A VMAT treatment session consists of pre-treatment image guidance time, patient set-up time and “beam-on time,”—the latter is when radiation is applied to the target. Depending on several factors, pre-treatment image guidance and set-up times can lead to treatment sessions ranging from five to nine minutes. Therefore, PRCM adopted an average treatment session time of seven minutes for all cases. Because VMAT beam-on time for all indications measures in tens of seconds, it now contributes less significantly to the total treatment session time. At PRCM, average VMAT beam-on times for five major indications are:
The average VMAT beam-on time across these five case types is just 88 seconds.
Compared with total treatment session times for IMRT, an average VMAT treatment session (seven minutes) is typically twice as fast. Examples include prostate IMRT at 14 minutes; head and neck IMRT at 22 minutes and rectal IMRT at 11 minutes.
“The time-savings with VMAT is critical, because in addition to affording the patient a shorter time on the treatment table, it also frees up time to further adjust the patient’s treatment position using the treatment system’s integrated imaging technology,” explains Dr. Faure.
PRCM performs a total of 215 treatments daily on its three Elekta Synergy® linear accelerators, for a total of 2,000 patients treated annually. It recently upgraded its two other Elekta Synergy: one dedicated for VMAT cases and the other for breast cases. The first breast VMAT cases are planned for March.
In the design of Elekta VMAT, Elekta has integrated the latest version of its digital control system, which facilitates clinical use of VMAT while emphasizing optimal patient safety.
*Note: A clinical research paper on PRCM’s prostate cancer work is currently under review by the International Journal of Radiology Oncology Biology Physics. PRCM investigators present the observed early toxicities and conclude that VMAT enables a substantial efficiency increase without compromising the dosimetric quality of treatment plans.