An Adjustable Multiplexing Parallel Beam Collimator

Single photon emission computed tomography(SPECT)is the imaging of radiopharmaceuticals distribution in the body.It is widely used as a nuclear medicine imaging technique in clinical diagnosis of tumors,heart and other diseases.Collimator is the core component of SPECT imaging system.Its structure,size,shape and other aspects will affect its imaging performance,such as sensitivity,spatial resolution.The design of the collimator is to balance and optimize these performances.Parallel beam collimator(PB)is widely used in clinical diagnosis,it has the advantage of a large field of view.But low sensitivity limits its clinical effect.Our previous work,introduced a set of y ray channels only in the transverse direction,came into being two oblique parallel beams(OPB)and formed a multiplexing parallel beam collimator(MPB).The preliminary work pointed out that MPB retains the characteristics of PB collimator,and still obtains high spatial resolution when improving sensitivity.It also indicated that parallel beam and oblique parallel beams did not influence each other.These provide support for introducing more y-ray channels,and coming into more oblique parallel beams.PB collimator is a one-time manufacturing high-precision instrument and cannot change its performance parameters after the completion.In clinical imaging,collimators with different performance are used for meeting the needs of imaging by changing different PB collimators.Based on previous work,a kind of MPB collimator is designed in this work,which can adjust the width of oblique y-ray channel and has 1 parallel beam and 8 oblique parallel beams.The MPB has higher sensitivity compared with previous MPB collimator and can change some properties of the collimator by adjusting the width of y-ray channel,to meet the different needs of clinical imagingAn adjustable multiplexing parallel beam collimator which can change the width of y-ray channel is designed.This MPB collimator contains one parallel beam and eight oblique parallel beams.The compensation performance of sensitivity of oblique parallel beams can make the adjustable MPB collimator to achieve higher sensitivity.In two adjustable ways,the projection performance of point source and plane source are calculated and simulated.The adjustable MPB collimator has the same characteristics as a PB collimator when it responses to a point source,it could be regarded as nine parallel beam collimators superpose together which can accept more y photons.The calculation and simulation of MPB collimator under plane source indicate that the projection change with 1 is obviously different from PB's.The MPB projection can be divided into three components:PB projection,OPBA projection and OPBQ projection.While stretching l,projections in OPBA and OPBQ have a changing process:concave,horizontal level and convex,this changing process provides the foundation of data acquisition of MPB collimator.Compared with PB collimator,the MPB collimator receives more ? photons and has the advantage of higher sensitivity and higher signal noise ratio.