Design and development of a collimator mechanism that will be utilized in radiation therapy

This thesis focuses on a Multileaf Collimator design that can shape the beam contour to fit the shape of target geometry and its design improvements. Main purpose of this design is lowering the number of leaves on the multileaf collimator and making the system easier to be controlled. As the Collimator devices undertake the most important point of the beam shaping procedure, ease of control and precision of collimator devices are the major points of operation.
As the radiation therapy is one of the most complex and vital medical operations, this thesis started with the deep literature survey that formed the main constraints and goals of the study. Additional constraints and goals were formed after the examination of commercial purpose collimators with respect to their advantageous and disadvantageous sides. Collimator devices either primary or secondary are integratedly used with Linear accelerators thus, linear accelerator devices were taken as another important factor that formed the constraints of design.
First design of the collimator mechanism was started with the type and number synthesis. After this procedure, collimator mechanism was decided to be four degree of freedom decoupled manipulator that works in Cartesian coordinate system. After the main design was finished, study of the kinematic analysis of the decoupled mechanism was performed.
Due to the fact that radiation therapy robot manipulators carry the collimator mechanisms and motion of the overall system may generate high inertia forces, weight of the collimator mechanism and footprint of the collimator mechanism were also aimed to be reduced.
After the first design, upper jaws were modified to be work in polar coordinates instead of cartesian coordinate system. This modification was not only reduced footprint of the device but also reduced scattering issues caused from angular relation between beam and leaf side surface. This modification followed by manufacturing of the first prototype. Examination of the first prototype gave the final shape to the constraints and goals to the collimator design as further advancing in weight and footprint reduction. By using these final constraints second modification was performed to the system and second prototype was manufactured.