Mobile Radiography CourseMobile Radiography Course

RAD 1304RAD 1304

Instructor :TAGELDIN ABUGROON

Mobile Equipment Feature

What is mobile x-ray equipment?What is mobile x-ray equipment? It It is equipment which can be moved from one is equipment which can be moved from one

place to another and used at the patientplace to another and used at the patient ’’s bedside.s bedside.

What is used for?What is used for? It can be used to provide facilities for the following It can be used to provide facilities for the following

cases:cases:

(1) In-patients who could not leave their beds, (1) In-patients who could not leave their beds, especially those who cannot be moved away from especially those who cannot be moved away from their ward.their ward.

(2) Surgeons who required X-ray control guidance (2) Surgeons who required X-ray control guidance during the course of their work in the operation during the course of their work in the operation theatre. theatre.

IntroductionIntroduction

These days bedridden patients who are in need of These days bedridden patients who are in need of radiography are now transferred safely from their ward radiography are now transferred safely from their ward to the imaging department, where they can be to the imaging department, where they can be examined with all the efficiency that the department examined with all the efficiency that the department can offer.can offer.

These facilities include full radiation protection: for the These facilities include full radiation protection: for the patient, of course, but also for other personnel who patient, of course, but also for other personnel who otherwise, in the hospital ward, could have been at otherwise, in the hospital ward, could have been at risk. Therefore, their use should be restricted. risk. Therefore, their use should be restricted.

Despite these points, the service of mobile X-ray Despite these points, the service of mobile X-ray equipment can be in demand all day especially in a equipment can be in demand all day especially in a busy hospital and with complicated situation patient. busy hospital and with complicated situation patient. Study of the principal features of their construction and Study of the principal features of their construction and operation is necessary, as always, for correct and safe operation is necessary, as always, for correct and safe use. use.

X-Ray Equipments

Major X-ray Unit

Mobile Units

Portable Units

What are the differences between What are the differences between mobile & portable unit?mobile & portable unit?

The broad distinction between the two being the The broad distinction between the two being the difference in difference in power outputpower output and the and the ability to transfer ability to transfer equipmentequipment. .

Portable units are Portable units are smallsmall and and lightlight in weight, which in weight, which normally can be normally can be dismantleddismantled and carried, usually by and carried, usually by one person, and have relatively one person, and have relatively low radiation low radiation outputoutput..

While MobileWhile Mobile x-ray units are x-ray units are biggerbigger and and heavierheavier than than ‘‘PortablePortable’’ units which is movable but because of its units which is movable but because of its weight and size can only be wheeled along flat weight and size can only be wheeled along flat surfaces to place where required, they are usually surfaces to place where required, they are usually have have higher radiation outputhigher radiation output..

Portable unit which can be dismantled & carried by one person

Portable units featuresPortable units featuresAdvantagesAdvantages::1- Light weight. 1- Light weight.

2- Standard power supply. 2- Standard power supply. DisadvantagesDisadvantages1- Low output. 1- Low output. 2- Lack of stability. 2- Lack of stability. 3- Lack of precision.3- Lack of precision. The output of the machine can be determined by The output of the machine can be determined by

The following equation: The following equation:

Where: P= Power (Watt)Where: P= Power (Watt) I= Current (Amper) I= Current (Amper) E= Voltage (Volt)E= Voltage (Volt)

P=I.E

Example:Example: Exposure factors: 100 kVp, 50 mA. Exposure factors: 100 kVp, 50 mA. SupplySupply: 240 V: 240 V• P= P= _50_ _50_ A × 100,000 = 5000VA A × 100,000 = 5000VA 10001000• I= I= 5000 5000 = 21A= 21A 240 240 if we change the Volts to 480V, what would be

happened? • I= I= 50005000 =10.5 A =10.5 A 480 480 As we increase the line voltage, the current flowing As we increase the line voltage, the current flowing

is reduced. Therefore the output of the machine will is reduced. Therefore the output of the machine will be decreased.be decreased.

Remember that changing the exposure factors Remember that changing the exposure factors change the current requirements. Therefore you need change the current requirements. Therefore you need to know the current required and the voltage of the to know the current required and the voltage of the power supply before you do exposure.power supply before you do exposure.

Components of Portable units:Components of Portable units:1- Oil-Filled lead lined tank:1- Oil-Filled lead lined tank:In order to make the equipment simpler, lighter, lessIn order to make the equipment simpler, lighter, lessexpensive and easy to carry, it is usually constructed expensive and easy to carry, it is usually constructed

with:with:

(A) X-ray tube: Self-rectified, Stationary anode.(A) X-ray tube: Self-rectified, Stationary anode. (B) High-tension transformer. (HTT)(B) High-tension transformer. (HTT)(C) Filament transformer.(C) Filament transformer. This is described as a tank construction and the This is described as a tank construction and the

whole enclosure is called the tube head. whole enclosure is called the tube head. 2- A small control unit:2- A small control unit:(A) Rheostats: to vary the mA and kV.(A) Rheostats: to vary the mA and kV. (B) Timer (S). (C) Exposure switches.(B) Timer (S). (C) Exposure switches.

OutputOutput: : The maximum output is usually 80 kVp and 20 The maximum output is usually 80 kVp and 20 mA. mA.

Mobile units featureMobile units feature:: Capable of being moved either manually or Capable of being moved either manually or

motorized drive. motorized drive. AdvantagesAdvantages 1. Great stability. 2. High output.1. Great stability. 2. High output.

3. Wide range of KV & mA selections. 3. Wide range of KV & mA selections.

4. The control panel and the high tension generator 4. The control panel and the high tension generator (with full-wave rectification) all are carried by (with full-wave rectification) all are carried by strong machine base, away from the tube which strong machine base, away from the tube which have an advantage to greatly increased the x-ray have an advantage to greatly increased the x-ray output. output.

5. It has a rotating anode.5. It has a rotating anode.

6.Flexible tube movement.6.Flexible tube movement.

DisadvantagesDisadvantages::

1. It is heavy in weight. 1. It is heavy in weight.

2. It needs especial maintenance.2. It needs especial maintenance.

OutputOutput Up to 300 mA and maximum of 125 kVp.Up to 300 mA and maximum of 125 kVp.

Mobile Unit in 1940 -1955

Mobile units

1

2

34

567

8

9

10

11

12

Construction of Mobile UnitConstruction of Mobile Unit::1.High generation tank containing the HT 1.High generation tank containing the HT

transformertransformer

2. Handle for pushing the unit. 2. Handle for pushing the unit.

3. Control unit. 4. Lock. 5. Tube Column.3. Control unit. 4. Lock. 5. Tube Column.

6. Bowden cable allowing vertical movement of6. Bowden cable allowing vertical movement of

the cross arm.the cross arm.

7. Movement of the cross arm. 7. Movement of the cross arm.

8. Hinge joint to allow extension of the cross arm.8. Hinge joint to allow extension of the cross arm.

9. HT cables.9. HT cables.

10. Column base allowing rotation of the cross 10. Column base allowing rotation of the cross armarm

around column.around column.

11. Base plate.11. Base plate.

12. Large wheels for easy movement.12. Large wheels for easy movement.

Mobile units ClassificationMobile units Classification They are classified by two ways: output & Power They are classified by two ways: output & Power

SupplySupply..((AA ) )By outputBy output::

11--Low Power MobilesLow Power Mobiles : :These operate at max. x-ray current (mA) of 10 to 30 These operate at max. x-ray current (mA) of 10 to 30 with a range of 40 to 90 kVpwith a range of 40 to 90 kVp . .Example: Dental, war x-ray equipmentExample: Dental, war x-ray equipment..

22 - -Average Power MobilesAverage Power Mobiles : : These operate at a range x-ray current (mA) of 50 to These operate at a range x-ray current (mA) of 50 to

60, 100 to 150 mA with a range of 40 to 90 kVp, 95 60, 100 to 150 mA with a range of 40 to 90 kVp, 95 kVpkVp . .Example:Example: for skull, limbsfor skull, limbs..

33--High power mobilesHigh power mobiles: :

These operate at max. of 300 mA, at a max. 125 kVpThese operate at max. of 300 mA, at a max. 125 kVp..ExampleExample:: for CXR , abdomen, skull, Pelvimetry, IVU, for CXR , abdomen, skull, Pelvimetry, IVU, pediatricspediatrics..

By Power Supply

Main Supply Equipment

Capacitor Discharge Equipment

Battery powered Equipment

Main Supply EquipmentMain Supply Equipment Advantages & disadvantagesAdvantages & disadvantages::

Energy may be drawn for X-ray exposure directly Energy may be drawn for X-ray exposure directly from the mains voltage supply. This is convenience from the mains voltage supply. This is convenience if there is no need for the energy to be carried if there is no need for the energy to be carried around within the mobile unit.around within the mobile unit.

But cable resistance and supply variation at But cable resistance and supply variation at different locations where the unit is used can raise different locations where the unit is used can raise difficulties affecting image quality. difficulties affecting image quality.

Special FeaturesSpecial Features This kind of equipment must have a robust This kind of equipment must have a robust

connection cable. This encloses 3 low resistance connection cable. This encloses 3 low resistance conductors, each with a relatively large cross-conductors, each with a relatively large cross-sectional area. Two of the conductors carry the sectional area. Two of the conductors carry the current, which the generator draws when an current, which the generator draws when an exposure is made. The third provides a safe, reliable exposure is made. The third provides a safe, reliable connection to earth. connection to earth.

The cable must be long enough (2 meter) for The cable must be long enough (2 meter) for equipment to be used in most locations, provided equipment to be used in most locations, provided there is a convenient mains outlet socket, but not so there is a convenient mains outlet socket, but not so long that its resistance becomes significant. The long that its resistance becomes significant. The cable should be manufactured to tolerate physical cable should be manufactured to tolerate physical damage. damage.

Capacitor Discharge EquipmentCapacitor Discharge Equipment Advantages & disadvantagesAdvantages & disadvantages

11..Small in size and light in weight, because there is no Small in size and light in weight, because there is no H.T.TH.T.T..

22..This unit has the advantage of storing energy in the This unit has the advantage of storing energy in the form of electric charge for later use for X-ray form of electric charge for later use for X-ray exposuresexposures . .

Therefore, it can be used in places where there is no Therefore, it can be used in places where there is no electricity, or no a convenient mains outlet socket, or electricity, or no a convenient mains outlet socket, or there is electrical power but not adequate (not enough there is electrical power but not adequate (not enough to operate the X-ray unit), or suffers to operate the X-ray unit), or suffers ‘‘dropsdrops’’ in its in its values. values.

33..The unit has the advantage of providing high X-ray The unit has the advantage of providing high X-ray output (usually high mA). The given kVp is from 30 or output (usually high mA). The given kVp is from 30 or 40 up to 100 to 125 kVp and 500 mAs40 up to 100 to 125 kVp and 500 mAs..

44..Shorter exposure time. By using grid-controller, this Shorter exposure time. By using grid-controller, this grid plate is exist between the anode and the grid plate is exist between the anode and the cathode in the tubecathode in the tube . .

This grid allow the electrons to pass through it and This grid allow the electrons to pass through it and reach the anode (by carrying zero charge or no reach the anode (by carrying zero charge or no charge on it), this grid can stop the electrons charge on it), this grid can stop the electrons passage after a specific time by carrying -ve charge passage after a specific time by carrying -ve charge on it which will reverse action and stop the exposure.on it which will reverse action and stop the exposure.

55..It has no timing control device since only the kVp has It has no timing control device since only the kVp has to be selected, so the mAs depends on the kVp. As to be selected, so the mAs depends on the kVp. As the kVp in the capacitor discharge falls the mAs does the kVp in the capacitor discharge falls the mAs does soso . .

6.Simple in operation, it can be supplied by any voltage 6.Simple in operation, it can be supplied by any voltage from 60V to 220V (so we shouldnfrom 60V to 220V (so we shouldn’’t worry from t worry from voltage fluctuation).voltage fluctuation).

7.Provides consistently reliable output and results 7.Provides consistently reliable output and results (uniform wave), which has the advantage of less (uniform wave), which has the advantage of less absorbed dose to the patient and good image quality. absorbed dose to the patient and good image quality.

This consistency happened because the main voltage This consistency happened because the main voltage and resistance variations only have their effects upon and resistance variations only have their effects upon the act of charging the capacitor, which takes place the act of charging the capacitor, which takes place just before the X-ray exposure is made. just before the X-ray exposure is made.

While in the mobile unit that use the conventional While in the mobile unit that use the conventional generator provide the X-ray tube with a pulsating generator provide the X-ray tube with a pulsating waveform voltage which varies from peak to zero then waveform voltage which varies from peak to zero then go back to peak which effect the image quality and go back to peak which effect the image quality and patient protection.patient protection.

8.Capacitor discharge is usually limited so that the drop 8.Capacitor discharge is usually limited so that the drop in kVp is only 35% on heavy exposure.in kVp is only 35% on heavy exposure.

9.The disadvantage that it has the limitation in 9.The disadvantage that it has the limitation in exposures. Few times of exposure needs capacitor exposures. Few times of exposure needs capacitor charge.charge.

Working of the CapacitorWorking of the CapacitorCharging StageCharging Stage

After the radiological Technologist connects the unit to After the radiological Technologist connects the unit to the mains and selects a kVp value, the switch the mains and selects a kVp value, the switch operated to charge the capacitor to the required kVp operated to charge the capacitor to the required kVp (G1 & G2 will be connected), via the high tension (G1 & G2 will be connected), via the high tension generator, then the capacitor acts as a store or generator, then the capacitor acts as a store or source of energysource of energy..

Discharging-exposure stageDischarging-exposure stage

By pressing the exposure switch the X1 & X2 will be By pressing the exposure switch the X1 & X2 will be connected then the capacitor will discharges connected then the capacitor will discharges electrons through the X-ray tube and produce X-ray electrons through the X-ray tube and produce X-ray exposureexposure..

Special FeaturesSpecial Features1.Charging circuit contains solid-state rectifiers 1.Charging circuit contains solid-state rectifiers

(selenium types) and capacitors these two acts as (selenium types) and capacitors these two acts as energy storing elements and as voltage multipliers energy storing elements and as voltage multipliers (raise voltage to higher kV values, instead of the (raise voltage to higher kV values, instead of the high-tension transformer).high-tension transformer).

2.The size of the capacitor determines the maximum 2.The size of the capacitor determines the maximum output (mAs); this is called Capacitance Value (C.V.). output (mAs); this is called Capacitance Value (C.V.). For example; if the typical C.V. for charging For example; if the typical C.V. for charging capacitor is 1.0 the typical mAs are between 0.4-60 capacitor is 1.0 the typical mAs are between 0.4-60 mAs. After every exposure we do the mAs will be mAs. After every exposure we do the mAs will be reduced.reduced.

3.Its tube has rotating anode and grid-controller.3.Its tube has rotating anode and grid-controller.

Battery Powered GeneratorBattery Powered Generator This is called also cordless mobile unit (mains-This is called also cordless mobile unit (mains-

independent). This unit use batteries as a source of independent). This unit use batteries as a source of energy for X-ray exposure.energy for X-ray exposure.

Advantages:Advantages:

(1) This machine can be used freely, provides wide (1) This machine can be used freely, provides wide range of satisfactory kVp & mAs. range of satisfactory kVp & mAs.

(2) This machine could be recharging less frequently (2) This machine could be recharging less frequently that the capacitor one. Some machine allows you to that the capacitor one. Some machine allows you to take up to 500 exposures without re-charging.take up to 500 exposures without re-charging.

Disadvantages:Disadvantages: It needs special care and maintenance.It needs special care and maintenance.

Special Features:Special Features: This kind of machine usually uses 2 batteries of car This kind of machine usually uses 2 batteries of car

kind 12V (24v d.c.). All batteries are sealed for kind 12V (24v d.c.). All batteries are sealed for safety. safety.

Charging is achieved by connecting the generator to Charging is achieved by connecting the generator to the mains at times when it is not required for the mains at times when it is not required for radiography. These batteries also used as a motor radiography. These batteries also used as a motor for the unit wheels that makes the driving of the for the unit wheels that makes the driving of the machine much easier. machine much easier.

The batteries need regular care and maintenance. If The batteries need regular care and maintenance. If the machine is well maintained, it could last up to the machine is well maintained, it could last up to two years of their working life. two years of their working life.

Care & Maintenance of Battery powered Care & Maintenance of Battery powered GeneratorGenerator

This care and maintenance includes: This care and maintenance includes:

(A) The unit should be left connected to the mains power (A) The unit should be left connected to the mains power supply of (200v or 115v): supply of (200v or 115v):

–– Every night. Every night. –– During weekends. During weekends.

–– At all times when the unit is idle (not being used).At all times when the unit is idle (not being used).

(B) Naked flames or lighted cigarettes should not be held (B) Naked flames or lighted cigarettes should not be held near the batteries when they are being charging up near the batteries when they are being charging up (because of the risk of the hydrogen gas explosion).(because of the risk of the hydrogen gas explosion).

(C) The acid level in the batteries should be checked (C) The acid level in the batteries should be checked every 2 weeks. Its proper recommended level is 6.0 every 2 weeks. Its proper recommended level is 6.0 mm above the plate separation. If the level drops mm above the plate separation. If the level drops below this, distilled water (only) must be added.below this, distilled water (only) must be added.