Nuclear Instruments and Methods in Physics Research A 479 (2002) 656–660 A white-beam fast-shutter for microbeam radiation therapy at the ESRF M. Renier*, T. Brochard, C. Nemoz, W. Thomlinson Medical Research Group, European Synchrotron Radiation Facility(ESRF),Experiments Division, BP 220, F-38043 Grenoble Cedex, France Received 19 October 2000; accepted 3 March 2001 Abstract The ID17 Medical Beamline port at the European Synchrotron Radiation Facility (ESRF) delivers white beam generatedbya1.4Twiggler.Itisdevotedtomedicalapplicationsofsynchrotronradiation.Onemajorprogramofthe beamline is called Microbeam Radiation Therapy (MRT). In this radiotherapy technique, still under development, the white beam fan is divided into several microbeams before reaching the target which is a tumoral brain. The maximum skin-entrance absorbed dose can reach extremely high values (over 1000Gy) before causing tissue necrosis, while causing tumor necrosis. One of the key parameters for the success of the MRT is the accurate control of the radiation dose delivered to the target, as well as its location with respect to the tumor, to prevent unnecessary damage to normal tissues. Therefore, the opening and closing positions of the shutter while the target is moving vertically at a constant speed reaching 150mm/s must be carefully controlled. Shutter opening times as short as 570.5ms must be achieved. The total power of the white beam generated by the wiggler may reach 14.5kW. It is essential to maintain vacuum continuity in the entire beamline and therefore the shutter had to be built to be vacuum compatible to a level of 10 @8 mbar.Thispaperdescribesthefastshuttermechanicsanditsassociatedelectronics. r 2002ElsevierScienceB.V. All rights reserved. PACS: 29.20.Lq; 29.27.Eg Keywords: Synchrotron; White-beam; Fast shutter; Wiggler; Ultra-high vacuum 1. Introduction The wiggler source at the ID17 port of the ESRF delivers a synchrotron radiation beam which is 2.5mrad wide and 0.1mrad high. The maximum power reaches 14.5kW for a 200mA current in the storage ring for a beam critical energy of 33keV. The first hutch of the beamline, specially designed to handle a white beam with such a high critical energy and intensity, houses the Microbeam Radiation Therapy (MRT) experi- ment[1,2].Thisradiotherapytechniqueisintended to treat brain tumors by cross-firing the lesions with arrays of parallel, microscopic high-energy X-rays. Due to the micro-division of the beam the radiation damage to the normal tissues is *Corresponding author. Tel.: +33-476-88-21-29; fax: +33- 476-88-21-60. E-mail addresses: renier@esrf.fr (M. Renier). 0168-9002/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)00905-6