Dosimetry for a microbeam array generated by synchrotron radiation at SPring-8

A microbeam array was formed with a multi-slit collimator (MSC) for research on radiation therapy (MRT). Kodak EDR2 film was used to measure the dose distribution of the microbeam array. The calibration curve of optical density of the film with respect to a dose was established using a standard Farmer chamber and 60Co gamma-ray source. The peak dose of 3.6 Gy/s at the maximum was derived from the film dosimetry using the calibration curve. The uncertainty was estimated to be 5% which was mainly attributed to the uncertainty of the calibration. It was found that the ionization chamber used for monitoring the dose during the MRT experiments gave lower dose by about 30% than the dose derived from the film dosimetry.