In the first paper of its kind for lung cancer treated with stereotactic body radiation therapy (SBRT), a team of UC Davis researchers has published a precedent-setting study outlining methods for clinics to analyze their processes in order to minimize human or computer errors.
The study, "Failure Mode and Effects Analysis for Delivery of Lung Stereotactic Body Radiation Therapy," published online in the International Journal of Radiation Oncology, details the team's successful efforts to pinpoint and correct weak links in the UC Davis Cancer Center's delivery of SBRT to patients with small-cell lung cancer. It serves as a template for other clinics that deliver SBRT to lung cancer patients to develop quality assurance-based analyses of their own processes.
"This study is unique in that it applies methods of process improvement to enhance safety in the clinical practice of radiation oncology, said Richard Valicenti, professor and chair of the UC Davis Department of Radiation Oncology and a co-author of the study.
In SBRT, the radiation oncologist locates the tumor or target of a radiation dose by means of a three-dimensional coordinate system. It differs from conventional radiotherapy because it kills the tumor in a few potent doses -- between one and five sessions -- while maintaining a very high degree of accuracy to largely avoid delivering radiation to the surrounding healthy tissue. Traditionally found primarily in university medical settings, SBRT is now more widely available across the country.
"Errors in treatment delivery are an issue in any setting, but, when you're giving up to 20 percent of the radiation dose in one session, it's more important than ever," explains UC Davis Assistant Professor Megan Daly, who heads up UC Davis Cancer Center's SBRT program. "There's variability from clinic to clinic, so each clinic will need to do its own analysis of its process. This paper serves as a model on how to do that analysis and thus provide extra patient safeguards."
A failure modes and effects analysis (FMEA) is an operations management procedure used to evaluate potential failure modes within a system and classify failures by severity and likelihood. A successful FMEA activity helps a team identify potential failure modes based on past experience with similar processes, enabling it to design those failures out of the system.
"In lung cancer SBRT, clinics always seek a precise alignment of the beam to the target area," said lead author Julian Perks, an associate professor in the UC Davis Department of Radiation Oncology. "We've made some changes to our treatment delivery as a result of this analysis to eliminate one very unlikely -- but potential -- occurrence related to how we position the treatment couch. We hope that this paper will show other centers how they could perform this analysis to look at their own processes."
Before the FMEA, the clinic's practice for SBRT involved imaging the patient with an X-ray technique called "cone-beam computed tomography," marking the patient's chest against the projection of the ceiling laser, and documenting the couch positions. After group discussions as part of the FMEA, the treatment team changed the planning techniques and beam directions to ensure that the patient would not be translated away from isocenter after the cone beam image is obtained--ensuring the target is always at the point where the radiation beams intersect. This procedural change led to a significant increase in the team's ability to detect a potential misalignment error, and ensure pinpoint treatment accuracy.
Other authors, all from UC Davis, are Sinisa Stanic, Robin L. Stern, Barbara Henk, Marsha S. Nelson, Rick D. Harse, Mathew Mathai, James A. Purdy, Allan D. Siefkin, and Allen M. Chen.