How does a multileaf collimator work?
A multileaf collimator (MLC) is a Collimator or beam-limiting device that is made of individual “leaves” of a high atomic numbered material, usually tungsten, that can move independently in and out of the path of a radiotherapy beam in order to shape it and vary its intensity.
What is collimator in radiotherapy?
Collimators (beam limiting devices) are used in linear accelerators used for radiotherapy treatments. They help to shape the beam of radiation emerging from the machine and can limit the maximum field size of a beam.
What is a multi leaf collimator and what is its purpose?
The multi-leaf collimator (MLC) being one of them. An MLC is a device that is affixed to the collimator of the linear accelerator system. It contains several sets of metallic leaves, that when open and closed, can shape the beam of radiation as it exits the linear accelerator.
What is tongue and groove effect?
The tongue and groove effect is an underdosing effect which can occur in certain applications of multileaf collimators. It results from the need to overlap adjacent leaves of a multileaf collimator in order to limit leakage between leaves.
What is the difference between IMRT and VMAT?
VMAT is a type of IMRT technique. VMAT stands for Volumetric Arc Therapy. VMAT can also be called Rapid Arc. VMAT is different to normal IMRT in that the radiotherapy machine rotates around the patient during a radiotherapy beam in an arc shape.
Why is collimator used?
collimator, device for changing the diverging light or other radiation from a point source into a parallel beam. This collimation of the light is required to make specialized measurements in spectroscopy and in geometric and physical optics.
What is 4 sided tongue and groove?
All four sides of the floorboards have tongues and grooves. Tongue and groove are often used in conjunction with wood floorboards, sheet paneling, wainscot, and any number of other materials where a tight, solid seam is required between separate pieces. One tongue fits firmly into the groove of the adjoining board.
What are tongue grooves?
A fissured tongue is a benign (noncancerous) condition. It’s recognized by one or more deep or shallow cracks — called grooves, furrows, or fissures — on the top surface of your tongue. A fissured tongue is also called: cracked tongue.
What kind of radiation is TomoTherapy?
TomoTherapy uses intensity-modulated radiation therapy (IMRT) to match radiation intensity to tumor shapes, sparing more healthy tissue. It delivers radiation by rotating around the body, aiming targeted beams at tumors from many angles.
Do multileaf collimator systems with 10 mm leaf width compare?
The dosimetric characteristics of three multileaf collimator (MLC) systems (Elekta, Siemens and Varian) having 10 mm leaf width are compared. A 6 MV photon beam was used from each unit for measurements.
What is the difference between Elekta and Varian collimators?
The Siemens MLC produces reduced tongue-and-groove effect compared to the other two collimators (Elekta and Varian). The isodose undulation for a stepped edge is found to be significant for the collimator closest to the patient (Varian) and does not depend on the leaf-end shape.
What is the difference between Elekta and Varian MLC?
For example, the Varian MLC is placed as a tertiary system below the standard adjustable jaws and is much closer to the patient than the Elekta system which replaces the upper jaw of the standard collimator. Each approach gives rise to a series of advantages and compromises that are discussed in this report.
Which collimators have rounded leaf ends and flat ends?
Film dosimetry was performed for the measurements and the analysis techniques were exactly duplicated in each system. Two of the collimators have rounded leaf ends (Elekta and Varian) and the third (Siemens) has a flat end that follows beam divergence.