Design optimization of intraoperative radiotherapy cones.
OBJECTIVE
Electron intraoperative cones (EIORCs) commonly used for intraoperative radiation therapy (IORT) often generate high-dose regions at superficial depths. This study was performed to optimize the use of rings in the EIORC design that reduces the high-dose region while minimizing the loss of the treatment volume at the prescribed depth.


METHODS
Monte Carlo simulations were performed to study the dosimetry properties of various EIORC designs. Simulations were conducted with EIORCs of various internal radii, lengths, and material compositions irradiated by available electron beam energies. The data were analyzed in terms of volume receiving > 105% and < 90% of the prescription dose, respectively.


RESULTS
The high-dose volume increases with the EIORC size and the electron beam energy. The use of a ring inside the EIORC reduces the 105% dose volume but also increases the sub-90% volume. The degree of change of these volumes depends on the ring thickness and position.


CONCLUSIONS
The optimal ring position is about 10 cm from the bottom of the EIORC, regardless of the EIORC material, geometry, or electron energy. The optimal thickness of the ring is dependent on its material composition, the beam energy, and the preferred compromise between a uniform dose profile and a loss of treatment volume.
Bernard
Damian
D
Departments of Radiation Oncology and Medical Physics, Rush Medical Center, Chicago, IL 60612, USA. jchu@rush.edu
Chu
James C H
JC
Rozenfeld
Martin
M
Lanzl
Lawrence H
LH
Pagnamenta
Antonio
A
Saxena
Amod
A
D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons / Q000627:therapeutic use*; D004867:Equipment Design; D005373:Film Dosimetry; D006801:Humans; D007430:Intraoperative Care / Q000295:instrumentation*; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D018714:Radiotherapy, Adjuvant / Q000295:instrumentation*; D011882:Radiotherapy, High-Energy / Q000295:instrumentation*; D012542:Scattering, Radiation