Energy and intensity modulated electron beams for treatment of breast cancer
Albert DeNittis, MD
OncoLink Assistant Editor
Last Modified: November 1, 1999
Presenter: Charles Ma Affiliation: Stanford University School of Medicine
Summary: Breast cancer has traditionaly been treated with photon beams. The purpose of this study was to investigate the feasibility of using energy and intensity modulated electron beams for breast cancer treatment. The use of Electron Intensity Modulated Radiation Therapy (EIMRT) has the potential advantages of significantly improving dose uniformity in the target volume and decreasing the adverse effects to normal tissues including reducing the dose to the contralateral breast.
Methods: An inverse planning system based on Monte Carlo dose calculations was developed with the intention of optimizing electron beam energy and incident angles to achieve conformal doses near the skin surface. A specially manufactured multileaf collimator (MLC) was designed for electrons which would shape the incident beam, decrease scatter and replace cutouts. Electron beams from 4-20 MeV were analyzed. Ionization and field measurements were taken for comparison.
EIMRT described here seemed to have the advantages of reducing penumbra by 50% when compared to conventional photon beams.
The use of the Monte Carlo system is essential for to the accuracy of EIMRT dose distribution to account for heterogeneous target volumes and air gaps. Doses were found to be higher to the target volume and less to the lung and heart.
The contralateral breast did not recieve any dose.
EIMRT may result in more conformal dose administration than conventional photon therapy for breast cancer.
Use of EIMRT may reduce dose to the contralateral breast
EIMRT, while not currently in routine clinical use, may prove to be a better modality than conventional photons for the treatment of breast cancer.