It is also possible to manually enter the numerical
values of the leaves edges in two columns. The environment of this program and the MLC configuration are shown in Figures Figures66 and and77. Figure 6 A view of multileaf collimator.vi program Figure 7 Multileaf collimator configuration CONCLUSIONS The projected width of each leaf on the isocenter p38 MAPK signaling accelerator (usually at 100 cm from the source) is 10 mm. The positioning accuracy of each leaf is approximately 1.4 mm. Since the screws inherently have an axial backlash, they are not suitable choice for positioning. Therefore, it is suitable to use ball screws and roller cage. In this MLC prototype, the control part is designed and fabricated by using the PLCs. The advantages of PLC with respect to the microprocessors are described as following: The capability to easily develop the dynamical part such as in changing the geometrical design of the leaf The capability to detect leaf position in achieving safe and reliable position control using the mechanism such as video-optical system, without making important changes in wiring. The feedback received directly from the encoder is valuable, but in the view point of the positioning leaves is not reliable. Because if for any reason the transmission path of the DC motors of leaves it is disconnected (such as
screws couplings relaxes and finally separated from the coupling DC motors and motor screws) feedback encoder was received. Actually leaves are fixed, and this event is very undesirable. Because the need is to install sensors to place directly from the leaves position status Information is more accurate. If for any reason MLC leaves are fixed in place to the system, it is possible that the relevant residual DC motors work and will cause serious damage to the engine is entered. Hence, it is worthy, if the feedback from the motor encoder is not received; the system power supply automatically cut, and the user notify it. In a typical MLC configuration, each leaf is moved to
the opposing leaves or vice versa by using the power relay, simultaneously. It is a potential limitation to decrease the GSK-3 time for the MLC configuration. It is hoped that this limitation is removed in the future designs via to develop the control part. BIOGRAPHIES Abdolreza Hashemian Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Tel: 098 5138002328 Fax: 098 5138002320 Postal address: Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. E-mail: moc.oohay@rnaimehsah Mohammad Taghi Bahreyni Toossi Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Tel: 098 5138002316 Fax: 098 5138002320 Postal address: Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.