Estimation of Background Radiation from e-LINAC for Direct Confirmation of Irradiated Area by Utilizing the Annihilation Photons.

In radiation therapy, there is no suitable method to confirm either the three-dimensional irradiated area or the absorbed dose during irradiation. If there were such a method it would allow verification of the absorbed dose as well as help to avoid extraneous irradiation. We previously proposed a method utilizing annihilation photons generated by therapeutic photon beams to measure the irradiated area directly during irradiation.

[Evaluation of therapeutic carbon-beam attenuation in inhomogeneous layered phantoms: Comparison with the present method using a water phantom.].

Carbon-beam therapy has been successfully carried out at HIMAC, Japan. This treatment offers two advantages over conventional radiation therapy: better dose concentration due to the Bragg peak and higher RBE. In treatment planning at HIMAC, the dose distribution is calculated based on dose measurements in water.