Journal of Medical Signals & Sensors 300 Vol 4 | Issue 4 | Oct-Dec 2014 INTRODUCTION In the last few years the focus in the field of radiation therapy has been on how to improve tumor control by increasing total dose per fraction, while keeping the dose to organs at risk as low as possible. [1] Many organs such as the spinal cord, salivary glands, lungs and eyes are relatively sensitive to radiation damage therefore they must be given special consideration during radiotherapy treatment planning. Explicit field shaping of the beam is required to reduce the amount of healthy tissue irradiated, and multiple beams are used to lower the dose absorbed by tissue outside the target volume. [2] It is achieved through high-precision and high-gradient dose irradiation techniques. Stereotactic treatment of brain metastases treated in a single session is the most significant example of this kind of approach. However, stereotactic radiation therapy is usually employed to treat lesions with a diameter smaller than 35 mm and an extremely simple shape. [3,4] ABSTRACT 0XOWLOHDI FROOLPDWRU 0/& LV DPRQJ WKH UDGLDWLRQ ｿHOG VKDSLQJ V\VWHPV XVHG IRU FRQIRUPDO UDGLRWKHUDS\ DQG LQWHQVLW\ PRGXODWLRQ UDGLDWLRQ WKHUDS\ WHFKQLTXHV 7KH 0/& V\VWHP WKDW KDV EHHQ GHVLJQHG DQG IDEULFDWHG LQ WKLV VWXG\ LQFOXGHV  OHDYHV  VWHSSHU PRWRUV  '& PRWRUV  SURJUDPPDEOH ORJLF FRQWUROOHUV 3/&V DQG RQH KXPDQ PDFKLQH LQWHUIDFH +0, 7KLV V\VWHP FDQ EH PRXQWHG RQ FRQYHQWLRQDO OLQHDU DFFHOHUDWRUV OLQDF DV DQ DGGRQ DFFHVVRU\ 7KH  OHDYHV DUH PRXQWHG RQ WZR FDUULDJHV WKDW DUH PRYHG LQGHSHQGHQWO\ 7KH OHDYHV VHTXHQFH DFTXLUHG IURP WKH LPDJH SURFHVVLQJ RI FRPSXWHG WRPRJUDSK\ LPDJHV LV XVHG WR DUUDQJH OHDYHV 7KLV VHTXHQFH LV VDYHG LQ D WH[W ｿOH 7KH OHDYHV DUH DUUDQJHG E\ +0, DQG ODE9,(: 8VLQJ +0, LW LV SRVVLEOH WR WHVW WKH RSHUDWLRQ RI 3/&V DQG PDQXDOO\ HQWHU WKH QXPHULFDO YDOXHV RI WKH OHDYHV HGJHV $Q H[HFXWDEOH ｿOH LV GHYHORSHG E\ ODE9,(: SURJUDP ZKLFK LV JUDSKLFDOO\ XVHU LQWHUIDFHG EHWZHHQ WKH RSHUDWRU DQG WKH 0/& FRQWURO V\VWHP 7KH SURMHFWHG ZLGWK RI HDFK OHDI RQ WKH LVRFHQWHU DFFHOHUDWRU XVXDOO\ DW  FP IURP WKH VRXUFH LV  PP 7KH SRVLWLRQLQJ DFFXUDF\ RI HDFK OHDI LV DSSUR[LPDWHO\  PP Key words: &RQWURO GHVLJQ IDEULFDWLRQ PXOWLOHDI FROOLPDWRU Design and Fabrication of the Control Part of a Prototype Multileaf Collimator System Abdolreza Hashemian 1,2 , Mohammad Taghi Bahreyni Toossi 1,2 , Shahrokh Nasseri 1,2,3 1 Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, 2 Medical Physics Research Center, Mashhad University of Medical Sciences, 3 Nuclear Medicine Research Center, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 6XEPLVVLRQ  $FFHSWHG  Among the shaping systems that are used to match the radiation field against the contour of target volume, can be mentioned to multileaf collimator (MLC). MLC has movable leaves, or shields, which can shield some fraction of the radiation beam; typical MLCs have 20-120 leaves, arranged in pairs. By using a computer control to position a large narrow, closely abutting leaves, an arbitrary shaped field can be generated. [2] There are many researchers to design a computer-controlled MLC system [5-7] and the effects on patient dose. [8,9] Design and construction stages of our prototype MLC were included the following sections: Mechanics, [10,11] image processing of CT slices [12] and control. [13] This article explains the control process of our MLC design and fabrication. The design of an alternative control section of MLC system that allows a high precision shaping of large fields is also presented in this article. In comparison with other MLC system that is controlled by the microcontroller, [14] this system is controlled precisely and easily by programmable logic controllers (PLCs) and can be improved in future studies. Address for correspondence: Dr. Shahrokh Nasseri, Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Medical Physics Research Center, Mashhad University of Medical Sciences, Mashahd, Iran. Nuclear Medicine Research Center, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. E-mail: naserish@mums.ac.ir, shahrokh.nasseri@gmail.com ZZZMPVVPXLDFLU Methodology article