In the presented paper, "Treatment Plan Validation of the Xoft Axxent X-Ray Source," researchers compared the dose delivered by the Electronic Brachytherapy system to treatment plans generated with the commercially-available BrachyVision™ planning system from Varian Medical Systems, Inc. The accuracy of the delivered dose was tested using both a calibrated miniature air ionization chamber to measure dose at the prescription point, and radiochromic film to map isodose contour lines. Results demonstrated that dosimeter based dose measurements agreed with prescription to within 11% worst case, with an RMS error of 8%. This work is presented by Steve Axelrod, Principal Scientist at Xoft.
"We are proud of the growing scientific support for Electronic Brachytherapy and its ability to effectively deliver radiation therapy without radioactivity," said Michael Klein, president and CEO of Xoft, Inc. "These studies demonstrate numerically with validation through bench top studies that the system accurately and consistently delivers the therapeutic dose as predicted though treatment planning."
A second study used extensive Monte Carlo modeling to characterize the Xoft Axxent miniature x-ray source for Electronic Brachytherapy. Using Monte Carlo code MCNP5, this study assessed the dose distribution, dosimetry parameters and the sensitivity of results to source geometric parameters and choices of computational parameters. Another study validated system performance during the safe delivery of ten fractions in a five day period in animals. The final study validated the ability of the Xoft FlexiShield™ shielding material to lower the ambient radiation level in a treatment room during dose delivery to goats in the course of simulated accelerated partial breast irradiation (APBI).
Xoft is also hosting a technology symposium in conjunction with the AAPM Meeting. Titled "The Physics of Electronic Brachytherapy," the panel of leading radiation oncologists and physicists will focus on implementing the breakthrough technology which has significant potential to improve cancer treatment.
The studies involving Electronic Brachytherapy are detailed in the following posters and oral presentation:
Treatment Plan Validation of the Xoft Axxent™ X-ray Source
S. Axelrod, T. W. Rusch
Presentation July 26, 2:42 pm
Stability of the Xoft Axxent™ X-ray Source during Irradiation in a
Goat Mammary Model for APBI
J.W. Rieke, M.J. Rivard, S. Axelrod, R.R. Burnside, E.W. Chell, S.D.
Hansen, T.W. Rusch, D.L. Stewart
Poster SU-FF-T-219
Monte Carlo Modeling of the Xoft Axxent™ X-ray Source
T. W. Rusch, T. D. Bohm, M.J. Rivard
Poster SU-FF-T-293
Performance of Xoft FlexiShield™ Flexible X-ray Shielding in
Laboratory Tests and in a Goat Mammary Model
T.W. Rusch, S. Axelrod, P.C. Smith
Poster SU-FF-T-46
The Axxent Electronic Brachytherapy System, pending FDA clearance, uses disposable micro-miniature X-ray radiation sources to deliver treatment. Designed to deliver electronically generated ionizing radiation directly to tumor beds, this localized approach minimizes exposure of the patient's healthy tissue to unnecessary radiation. A unique advantage is that it also minimizes radiation exposure to the treatment staff. With Xoft's electronic brachytherapy technology, users can control X-ray energy allowing more flexibility than radioisotope-based brachytherapy systems that are currently cleared by the FDA. Because Xoft's portable system does not require a heavily shielded environment, it can be used in virtually any clinical setting under the supervision of a radiation oncologist.
In its first indication for use, the Axxent Electronic Brachytherapy System will reduce the time required for radiation therapy for early stage breast cancer from seven weeks (for external beam radiation therapy) down to five days. As a result, tens of thousands of patients will have greater access to therapy that is delivered more easily and conveniently. This may advance increase the choice for breast sparing lumpectomy surgery over the alternative full mastectomy -- which typically does not require a long course of radiation.