Instrumentation of Fluoroscopy

Instrumentation of Fluoroscopy

 The components of this fluoroscopic imaging chain from this illustration you can see has a generator x-ray tube collimator filtration a table for the patient and the patient grid image intensifier optical coupling video camera and a monitor finally to visualize the image let's go step by step on this fluoroscopic imaging chain the x-ray generator the work of the accelerate generator is to enable selection of kilovolt edge and tube current that is Kaylyn MA for the accelerator the kV Mme can be altered using automatic brightness control it's called ABC now why do we need an automatic brightness control it maintains the overall image brightness at a constant level as the imagined inspire is panned across different parts of the body next, we move on to the x-ray tube requires high tube loading for extended views because fluoroscopy is a continuous process it's not like the exposures which are taken in routine radiography it can have a grid control Xterra tube for instance, switching between exposures it may have about three focal spots for improved image resolution it can have fixed fluoroscopic machine

The small CR machines have stationary anode x-ray tube in fixed machines their x-ray tube rating is up 2,100 MA in mobile machines with a stationary and/or x-ray tube the rating is about 8 to 11 MA as seen in the image the next component of this fluoroscopic imaging chain is the collimator the collimator is similar to the radiographic imaging machine but except it has something called the iris similar to what we see in a digital camera or an old manual camera is a device used to limit the x-ray beam falling on the patient it contains multiple sets of radiopaque shutters which can be made of lead proper use of this collimator can reduce scatter as well as improves image quality after that we have the filters the work of the filter is to reduce a low-energy x-rays that can be absorbed by the patient tissue without being transmitted to the detectors aluminum or copper is commonly used as an added filtration material patient table patient table provides adequate strength to support large patients as well as resulting minimal x-ray attenuation carbon fiber composite material is generally used as a patient table which has about point 5 to point 7 5 aluminum equivalence grid is used to reduce the scatter from the patient which is reaching the detector and it also improves image contrast the use of grid increases radiation exposure in fluoroscopy systems the grid ratios range from 6 6 to 1 to 10 is to 1 but during pediatric cases to remove grades while imaging pediatrics and thin patients in fluoroscopy system the grid ratios range from 6 is to 1 to 10 is to 1 it is good to remove grades while imaging pediatrics and thin patients we then move to image intensifier the function of the image in this fire is to convert incident x-rays into visible light image to be viewed using monitors it just resembles an old fluoroscopic screen but however this image that was converted to light has to be converted into electrons so that you're going to get a digital image what are the main components of this image and fire it has an input phosphor and photo cathode

Elmo static focusing lens and accelerating anode output phosphor.we see various types of image in a sphere tube that is generally used for ceiling mounted or floor mounted fluoroscopy systems small image in steerer tube or AI tubes are used in CI machines CR machines are used in the operation theatre let's go ahead with the III machine the input layer as you see in the image has an input window a substrate input phosphor and the photocathode the input window is curved in shape with a layer of metal or glass when x-rays pass through the input window and the aluminum substrate it reaches the input phosphor the input phosphor is made out of cesium iodide crystals or other cases gadolinium oxy sulphide the function of these crystals is to convert x-ray pattern into a visible light pattern the photocathode is a thin layer of antimony and an alkali metal the function of this photo cathode is to emit electrons when struck by visible light produced by the input phosphor so when x-rays fall on the input phosphor it gets converted into light and the light gets converted into electrons with the use of a photo cathode then we have the electrostatic focusing lens a potential of about 25 to 35-kilo volt is applied in the electrode and an anode plate is placed inside the glass in the lab the electrodes focus the electron beam from the photocathode towards the output phosphor because electrons can be accelerated by electrical and magnetic field the electrostatic focusing lens inwards and reverses the image on the way to the output phosphor as seen in the image the energy of each electron is substantially increased and gives rise to something called the electronic gain now the output phosphor what is it made out of outward phosphor is made of zinc cadmium sulphide doped with silver and it emits green light converts the electron pattern into bright light pattern the diameter of this output phosphor ranges from 0.5 to 1 inch then we move on to an optical coupling till now what we saw was the input phosphor converts x-rays to light, the photocathode converts light into electrons electrostatic single ends will attract these electrons towards the output phosphor and finally the output phosphor converts the electronic image into a light pattern this light pattern should be captured using optical coupling the optical coupling is similar to what we see on a lens which is used for our cameras it consists of the lens assembly to couple the video camera to the output of the image in its file, the lens has focused the incoming light from output phosphor on to a focal plane of the camera as a small aperture in the lens assembly which varies the proportion of light entering the video camera this is how a video camera looks like it is a vide current camera which uses semiconductor material such as amorphous selenium which is sensitive to the intensity of light falling on it let's consider how the camera captures the image the optical image formed in the output phosphor of the image Innes fire is focused on the signal plate of the camera as seen in the illustration conductivity of the corresponding point on the target in the signal plate is altered because there is an impinging of light photons onto the selenium plate of the camera the electron gun present in the camera gives out a narrow beam of electrons the electron beam scans the target using accelerating anodes a1 and a2 and the deflecting coils c1 and c2 as shown in the figure and converts the electrons in the image into the current flowing through the resistor are connected to the external circuit this camera produces a signal voltage which can be amplified and fed into the television monitor for viewing there is an illustration which saw in the image a fluoroscopic image from a barium swallow procedure fluoroscopic equipment fluoroscopic equipment may have imaginisce fires or the recent ones have flat-panel detectors for real-time imaging it can be equipped with either an under coach or an over coach x-ray tube Mobile cm what do we see in a mobile cm the mobile cm is used in operation theater for orthopedic and neurological surgeries that's how a mobile cm looks like we have seen the image intensifier on top and the x-ray tube below that's called an undercoat accelerative CR machine this kind of machine are usually having station VN or x-ray tube and can be used for orthopedic and neurological surgeries some of these cases where there is a fixed set x-ray tube fixate fluoroscopic equipment it has an x-ray tube on top and since it's called an overcoat x-ray tube and there's a table where a patient can lie down and underneath that table is the image intensifier it's generally used for performing gastrointestinal and genitourinary procedures one 

such example we see here is a barium swallow procedure and a barium enema procedure the undercoat Axela tube machines are available in angiography suits which can be used for Cardiology purposes or radiological interventions this is higher tube rating and the size of the image intensifier can range from 12 to 16 inches so that the end so that the entire abdomen can be covered due to its high cube loading of x-ray tube it has high heat units so separate assembly for cooling the axilla tube is required  an image rotate where one can rotate the image also we can image reverse or we can reverse the image and we have the acquired images to be saved and to be sent to the picture archival communication system there are also magnification modes in these machines in some machines there may be about 6 magnification views but in these smaller machines there may be 2 magnification modes however one should justify the use of magnification mode use of magnification more increases the radiation dose imparted to the patient now there is also a collimator you can either open the collimator wide or collimated tightly if we call him it the image tightly the images have better contrast, as well as the, scatter to the operators are reduced we see here the iris of that kilometer as well as some wedge filters are available to have uniform intensity in the X rays so that our image has uniform intensity now suppose a manual contrast what we see here that can be not a contrast which can be set according to the automatic brightness control and also in case we need to have separate images onto a film or onto a CR plate, we can have K V P separately and mas and certain images can be acquired for floors could be mood we have pulsed or continuous fluoroscopy mode in the past mode radiation dose can be reduced compared to the continuous mode pass modes vary from 0.5 to 15 or 30 frame rates or pulse per second there is also a low dose option for an indian patient it's always good to use low dose and it depends on the patient's habitus, there is also a five-minute alarm reset button this is an integrated timer.