Multi-leaf collimator (MLC) is a mechanical moving device to produce a conformal radiation field, commonly known as multi leaf grating, multi leaf iris, etc.

MLC, one of the important equipments implemented as a three-dimensional, precise and rapid conformal radiotherapy program, is widely used in tumor radiotherapy.

 

In terms of components, MLC consists of 120 tungsten alloy grating blades with main role of replacing the hand-made irregular lead block. The collimator is mainly two sets of blades, drive motor and blade position sensor. The motor drives the blade movement through the transmission mechanism, and the drive mechanism is linked with the two sensors at the same time so that the CPU knows the current position and movement direction of the blade at any time. In the course of treatment, the movement of each leaf is controlled by a computer, to form the desired irregular shape of field to irradiate. The leave is made of tungsten alloy, which has much less harm than lead. 

 

 

MLC is usually used with the secondary collimator of the radiation head. It is divided into manual and electric which is the main form, and the latter’s function is much larger than the former. The manual multi leaf collimator adjusts the radiation field contour through manual driving each blade. While electric multi leaf collimator independently drives each blade to move separately by a plurality of micro motors that are controlled by a computer, to achieve dynamic or static forming of the projection field.

 

MLC is widely applied to radiotherapy, mainly based on the shielding effect of tungsten alloy on radioactive materials. Tungsten alloy has the characteristics of high density, high radiation shielding and environmental friendly, so it’s the first choice for manufacturing medical radiation shielding. In addition, tungsten alloy has been widely used in various industries for its special advantages in economic, geographic, and performance. MLC is only one aspect of the application of tungsten alloy medical industry.