This document provides an overview of medical x-ray equipment and radiological concepts. It discusses the nature and properties of x-rays, including their electromagnetic properties and interaction with matter. It describes the components of an x-ray tube, including the cathode, anode, window, and how x-rays are generated via the interaction of electrons with the anode. It also covers x-ray units and measurements, tissue contrast, the line focus principle, anode heel effect, x-ray spectra, tube ratings and heat load calculations to prevent thermal damage to tubes. Grids and collimators are discussed as methods to reduce dose by limiting the beam to the area of interest.

1. BM8702 – RADIOLOGICAL EQUIPMENTS
VII SEMESTER / IV YEAR
R2017 - BIOMEDICAL ENGINEERING
LECTURE NOTES
PREPARED BY
RAJESHWARI R,ASSISTANT PROFESSOR (Sr.Gr)
DEPARTMENT OF BIOMEDICAL ENGINEERING

2. UNIT 1
MEDICAL X-RAY EQUIPMENT

3. NATURE OF X-RAYS
X-rays are electromagnetic radiation located at the low wavelength end of the electromagnetic spectrum.
• The X-rays in the medical diagnostic region have wavelength of the order of 10^–10m.
• They propagate with a speed of 3 x10^10 cm/s.
• According to the quantum theory, electromagnetic radiation consists of photons, which are
conceived as ‘packets’ of energy.
• Their interaction with matter involves an energy exchange and the relation between the
wavelength and the photon is given by
E = hƔ = h* (c/ l)
where h = Planck’s constant = 6.32 * l0^-34 J s
c = velocity of propagation of photons = 3 *10^10cm/s
Ɣ = frequency of radiation
l = wavelength

4. PROPERTIES OF X-RAY
• X-rays are able to penetrate through materials which readily absorb and reflect visible light. This forms the
basis for the use of X-rays for radiography and even for their potential danger.
• X-rays are absorbed when passing through matter. The extent of absorption depends upon the density of the
matter.
• X-rays produce secondary radiation in all matter through which they pass. This secondary radiation is
composed of scattered radiation, characteristic radiation and electrons. In diagnostic radiology, it is scattered
radiation which is of practical importance.
• X-rays produce ionization in gases and influence the electric properties of liquids and solids.
• The ionizing property is made use of in the construction of radiation-measuring instruments.
• X-rays also produce fluorescence in certain materials to help them emit light. Fluoroscopic screens and
intensifying screens have been constructed on the basis of this property.
• X-rays affect photographic film in the same way as ordinary visible light.

5. UNITS OF X-RAY RADIATION
• The International Commission on Radiological Units and Measurements has adopted
Rontgen as a measure of the quantity of x-radiation.
• One R is the amount of x-radiation which will produce 2.08 x 10^9 ion pairs per cubic
centimetre of air at standard temperature (0°C) and pressure (760 mmHg at sea level and
latitude 45°). Other units derived from the Rontgen are the millirontgen (mR = 1/1000 R)
and the microrontgen ( = 10^–6 R).
•Unit of x-radiation has been based on the ionization produced by the rays and not on
other effects like the blackening of a photographic film due to the ease and accuracy with
which ionization in the air can be measured.

6. X-RAY ABSORPTION
The biological effects of X-rays are due to energy imparted to matter: Therefore, these effects are
more closely correlated with the absorbed dose than with exposure.
• One rad is the radiation dose which will result in an energy absorption of 1.0x10^–2 J/kg
in the irradiated material. It is approximately equal to the dose absorbed by soft tissue
exposed to one Rontgen of X-rays.
• The Rontgen and the absorbed dose D are related as D = ¶ R
where ¶ is a proportionality constant and depends upon both the composition of the
irradiated material and quality of the radiation beam.
The value of ¶ for air is 0.87 rad/R. For soft tissues, ¶ = 1 rad/R and hence the absorbed
dose is numerically equal to the exposure. However, for bone, ¶ is larger but significantly
decreases with an increase in kV.
• Another concept is that of the so-called dose equivalent (DE) . DE is defined as the product of the
absorbed dose D and a modifying quality factor (QF), i.e.
DE = (QF)D
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7. X-RAY ABSORPTION
• The film badge readings and radiation guides in the form of a maximum
permissible dosage are expressed in rems or millirems.
• In short, Rontgens express incident energy, rads give an indication of how much
of this incident energy is absorbed and rems are a measure of the relative
biological damage caused.

8. TISSUE CONTRAST
Contrast within the overall image depends on differences in both the density of structures
in the body and the thickness of those structures. The greater the difference in either
density or thickness of two adjacent structures leads to greater contrast between those
structures within the image.

9. EXAMPLE –CHEST RADIOGRAPH
9
X -Ray pictures are called Radiographs.

10. Practice like a Professional
Radiographer
https://www.radiologymasterclass.co.uk/tutorials/chest/chest_home_anatomy/chest_anatomy_start
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11. X-RAY EQUIPMENT – BLOCK DIAGRAM

12. X-Ray Tube
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13. X- RAY TUBE
X-rays are generated via interactions of the
accelerated electrons with electrons of tungsten
nuclei within the tube anode. There are two
types of X-ray generated: characteristic
radiation and bremsstrahlung radiation.

14. Cathode & Focusing Cup
• Filament
Made of thin (0.2 mm) tungsten wire because tungsten:
• has a high atomic number (A 184, Z 74)
• is a good thermionic emitter (good at emitting electrons)
• can be manufactured into a thin wire
• has a very high melting temperature (3422°c)
• The size of the filament relates to the size of the focal spot. Some cathodes have two filaments for
broad and fine focusing.
• Focusing cup
Made of molybdenum as:
• high melting point
• poor thermionic emitter so electrons aren't released to interfere with electron beam from filament
• Negatively charged to focus the electrons towards the anode and stop spatial spreading
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15. Anode
• Target made of tungsten for same reasons as for filament
• Rhenium added to tungsten to prevent cracking of anode at high temperatures
and usage
• Set into an anode disk of molybdenum with stem
• Positively charged to attract electrons
• Set at angle to direct x-ray photon beam down towards patient.
Usual angle is 5º - 15º
Some Important Terms
• Target, focus, focal point, focal spot: where electrons hit the anode
• Actual focal spot: physical area of the focal track that is impacted
• Focal track: portion of the anode the electrons bombard.
On a rotating anode this is a circular path
• Effective focal spot: the area of the focal spot that is projected out of a tube
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16. Line Focus Principle
• The line focus principle in radiography explains the relationship
between the actual focal spot on the anode surface and the
effective focal spot size.
• The lower the target angle, the smaller the effective focal spot size.
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18. Anode Heel Effect
• In X-ray tubes, the heel effect, or, more precisely, the anode heel effect is a
variation of the intensity of X-rays emitted by the anode depending on the
direction of emission along the anode-cathode axis
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19. X-RAY GENERATION

20. X-RAY SPECTRUM
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21. X-Ray Tube -other parts
• Window: made of beryllium with aluminium or copper to filter out the soft x-rays. Softer
(lower energy) x-ray photons contribute to patient dose but not to the image production as
they do not have enough energy to pass through the patient to the detector. To reduce this
redundant radiation dose to the patient these x-ray photons are removed.
• Glass envelope: contains vacuum so that electrons do not collide with anything other than
target.
• Insulating oil: carries heat produced by the anode away via conduction.(cooling system)
• Filter: Total filtration must be >2.5 mm aluminium equivalent (meaning that the material
provides the same amount of filtration as a >2.5 mm thickness of aluminium) for a >110 kV
generator
• Total filtration = inherent filtration + additional filtration (removable filter)
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22. X-RAY TUBE RATING
• Tube ratings are the defined input parameters (kVp, mA, exposure) that can be safely used
during its operation without causing damage to the x-ray tube itself and unique to each
individual x-ray tube model. An x-ray tube rating is the maximum allowable kilowatts
(kW) in 0.1 second .
• When the electron beam strikes the target material in the anode only 1% of the kinetic energy of the
electrons is converted into x-rays whilst the rest is converted into thermal energy. Increasing the
kVp, mA, or exposure time increases the thermal energy produced per examination. Thermal
energy is dissipated in the anode and surrounding x-ray tube. If too much heat is created (or not
enough is dissipated), excess residual thermal energy will damage the anode and tube.
Typical x-ray tube ratings are between 5-100kW and are dependent on focal spot size

23. X-RAY TUBE RATING
Exposure factors that determine radiographic output:
1.Operating voltage (kV)
2.Tube current (mA)
3.Exposure time (sec)
These factors determine radiographic output and heat generated on tube anode .
Anode should not be heated above the melting point of target material ( about
3000 0 C for tungsten)
Rating charts & cooling curves help to avoid thermal damage to x-ray tube.

24. Heat units / Thermal load calculation
• Thermal energy generated on anode will be proportional to exposure factors (kV, mA and
sec.).
• Thermal load is therefore proportional to the product of these factors and it is expressed in
heat units (HU).
HU = Peak voltage (kVp) x Tube current (mA) x Exposure time (sec) x Rectification factor.
Rectification Constant
Single-phase, Full-wave -1.0
3-phase, 6-pulse -1.35
3-phase, 12 pulse - 1.41
High-Frequency -1.45

25. Example
• How many heat units are generated by an exposure of 70 kVp,
300 mA and 0.15 sec on a three phase 6 pulse unit ?
Ans: 70 kVp x 300 mA x 0.15 sec x 1.35 = 4253 HU

26. Tube Rating Chart
• Find it is safe or Unsafe?
700 mA, 230 ms, 120 kVp
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27. Which condition is unsafe?
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28. Anode Cooling Curve
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29. Time to Answer
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30. Collimators & Grids
To increase the image contrast and to reduce the dose to the patient, the X-ray beam must be
limited to the area of interest. Two types of devices are used for this purpose, viz. collimators
and grids.

31. Collimators
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• The collimator is placed between the X-ray tube and the patient It consists of a
sheet of lead with a circular or rectangular hole of suitable size. Alternatively, it
may consist of four adjustable lead strips which can be moved relative to each
other. This results in a low dose to the patient and simultaneously increases the
image contrast, because less scattered radiation reaches the image plane.
• Collimators are usually provided with an optical device, by which the X-ray field
can be exactly simulated by a light field. This can be projected on the patient to
ensure proper positioning of the apparatus.

32. Bucky Grids
• Grids are inserted between the patient and the film cassette in order to reduce the loss of contrast
due to scattered radiation. A grid consists of thin lead strips separated by spacers of a low
attenuation material. The lead strips are so designed that the primary radiation from the X-ray
focus, which carries the information, can pass between them while the scattered radiation from the
object is largely attenuated.
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33. POWER SUPPLY
• AC power will supply x-ray units with sinusoidal currents, resulting in 'peaks and
troughs', limiting an x-ray tube to produce x-rays only half of the 1/60th of s
second cycle.
• A single-phase high voltage generator converts this AC power into a half or full
wave rectified supply with a measure in the thousands of volts.
• Kilovoltage peak (kVp) is the peak potential applied to the x-ray tube, which
accelerates electrons from the cathode to the anode in radiography or computed
tomography Tube voltage, in turn, determines the quantity and quality of
the photons generated.An increase in kVp extends and intensifies the x-ray
emission spectrum, such that the maximal and average/effective energies are
higher and the photon number/intensity is higher.

34. POWER SUPPLY
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Along with the mAs (tube current and exposure time product) and filtration, kVp
(tube voltage) is one of the primary settings that can be adjusted on x-ray machines
to control the image quality and patient dose.

35. Transformers in Radiography
• A transformer is a passive electrical device used to transfer electrical energy from one circuit to another, via
the phenomenon of electromagnetic induction
• It is fundamental in the modulation of voltage and current in the x-ray generator.
• Electromagnetic induction is the induction of electric current via changing magnetic
fields. Magnetic fields are generated by moving charges (equivalent to electrical current).
Ampere’s law or Fleming’s right-hand rule determines the magnitude and direction (i.e. clockwise
or anti-clockwise) of the magnetic field with respect to the direction of the flow of current. That is,
if you point your right thumb in the direction of the current, the magnetic field will follow the curve
of your finger
• The laws of electromagnetic induction state that the induced EMF(KvP) is:
proportional to the rate of change of magnetic field and the area of the circuit
Induced in a direction so that it opposes the change in magnetic field which causes it
(Lenz’s law)
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36. • Primary coil
• a set of insulated wires attached to the input current
• Iron core
• the conduit for the changing magnetic field
• Secondary coil
• a set of insulated wires attached to the output current
• The primary and secondary coils both have winding turns which will vary in number with respect
to each other depending on the type of transformer
• In the high-voltage circuit of the X-ray generator, step-up transformers are used to convert the
mains voltage (120 - 240 V) to the high voltages (20,000 - 150,000 V) required for x-ray
production
• In the filament circuit of the X-ray generator, step-down transformers are used to increase the
heating current applied to the filaments of the cathode for thermionic emission
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37. Thermionic Emission
• Thermionic emission is the emission of electrons from a heated metal (cathode).
• The cathode has its filament circuit that supplies it with necessary filament current to heat it up. As the
temperature increases, the surface electrons gain energy. The energy acquired by the surface electrons allows
them to move a short distance off the surface thus resulting in emission.
• A pure tungsten filament must be heated to a temperature of 2200°C to emit a useful number of electrons.
• The electrons emitted from the surface are limited by the space charge effect.
• Space charge refers to the collection of electrons which are emitted from the metal surface, after the
application of tube current, at a short distance away from the metal surface.
• These electrons collect and form a cloud of negative charge around the metal surface. This space charge repels
and limits the further emission of electrons from the surface and is referred to as the space charge effect.
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38. X-Ray Tube Failure
• Normal Aging
Normal Filament Burn Out, Accelerated Filament Burn Out, Slow Leaks, Inactivity
Glass Crazing, Arcing ,Target Micro-cracking, Accidental Damage. Bearings
• Deficiencies in Manufacturing
• Application Mismatch
• Improper Drive by the Power Supply
• Tube Enclosure Considerations
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39. Electron Arcing
An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a
prolonged electrical discharge. The current through a normally nonconductive medium such
as air produces a plasma; the plasma may produce visible light.
• Arcing is a common problem in all high voltage systems. Some causes have been mentioned
above:
• high gas levels in the vacuum,
• evaporation of conducting metal on insulator
• surfaces, and crazing or etching of insulators
• which in turn produce higher gas pressure or
• degrade the insulators ability to hold off the
high voltage.
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40. Filament Burn Out
• Filament failures due to burn-out are caused by high operating temperatures; the
higher the temperature, the sooner the filament burns open. Tungsten evaporates
from the filament surface but in a non-uniform way, so hot spots are formed which
evaporate more rapidly. Hot spots occur at tungsten crystal faces which evaporate
preferentially at different crystal surfaces. The higher the temperature of the
filament and the longer it operates there, the larger the crystals grow.
• Long life is achieved by having the crystals long and narrow along the axis of the
wire and keeping the temperature as low as possible.
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41. Failure to warm up
• Overheating: Overheating can cause acing not only in the tube but in the housing. Many
systems have a heat exchanger which utilizes a fan and sometimes a pump to circulate
the oil. It is imperative that these exchangers be kept clean. Dust is the major culprit and
will inhibit both natural air convection and forced (fan) air convection. The result is that the
housing becomes overheated, a maintenance schedule should be established.
• Ambient Temperatures: Ambient temperatures need to be adhered to as specified by
the manufacturer. A typical ambient is 25 or 30 Celsius, and under high load conditions,
the housing can rise to 75 or 80 Celsius, a typical limit. Thus the temperature increase
can be about 50 degrees and if the ambient is higher than specified, this temperature rise
will be added to the ambient so that over temperature results. Enclosures, often used in
test and to stop radiation leakage can cause ambient temperatures to rise above
recommendations. Also it is not uncommon to find plastic or cloth covers used to “protect”
the equipment, but these only frustrate the convection air flow and can easily lead to
overheating.
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42. Failure to warm up
• Housing Attitude: A tube housing, with or without a heat exchanger can become
hot on the top part and not on the bottom. This is because the dielectric cooling oil
forms strong convection currents which rise like the smoke from a cigarette and
carry heat to the top of the housing. Care must be exercised to insure the best
housing attitude for operation. Often thermocouples can guide and reveal hot
areas, but good thermal contact is necessary for accurate measurements.
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43. X ray tube – Image Intensifier(II)
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44. FOV of II
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45. Fluoroscopy
• Fluoroscopy is a type of medical imaging that shows a continuous X-ray image on a monitor, much
like an X-ray movie. During a fluoroscopy procedure, an X-ray beam is passed through the body.
The image is transmitted to a monitor so the movement of a body part or of an instrument or
contrast agent (“X-ray dye”) through the body can be seen in detail.
Image Courtesy of Siemens Healthcare USA
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46. How Are X-Ray and Fluoroscopy
Different?
• X-rays are static images. They provide images of the inside of the body in still
form. Fluoroscopy imaging provides a live “video” format image, which will
show movement in the body.
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47. Fluoroscopy Components
• The key components include an X-ray tube, spectral shaping filters, a field restriction
device (aka collimator), an anti-scatter grid, an image receptor, an image processing
computer and a display device. Ancillary but necessary components include a high-
voltage generator, a patient-support device (table or couch) and hardware to allow
positioning of the X-ray source assembly and the image receptor assembly relative to
the patient.
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48. Specific Details of Fluoroscopic
Components
• X-ray Source
Special X-ray tubes are generally found in such systems. Focal spot sizes in fluoroscopic tubes can
be as small as 0.3 mm (when high spatial resolution is required but low radiation output can be
tolerated) and as large as 1.0 or 1.2 mm when higher power is needed. The radiation output can be
either continuous or pulsed, with pulsed being more common in modern systems. Automatic
exposure rate control maintains the radiation dose per frame at a predetermined level, adapting to
the attenuation characteristics of the patient’s anatomy and maintaining a consistent level of image
quality throughout the examination.
• Beam Filtration
It is common for fluoroscopic imaging systems to be equipped with beam hardening filters
between the X-ray tube exit port and the collimator. Added aluminum and/or copper filtration can
reduce skin dose at the patient’s entrance surface, while a low kVp produces a spectral shape that is
well-matched to the barium or iodine k-edge for high contrast in the anatomy of interest.
48

49. Specific Details of Fluoroscopic Components
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Insertion of this added filtration in the beam path may be user-selectable, providing the operator
with the flexibility to switch between low dose and higher dose modes as conditions dictate during
a fluoroscopic procedure. In other systems the added filtration is automatic, based on beam
attenuation conditions, to achieve a desired level of image quality and dose savings. In addition to
beam shaping filters, many fluoroscopy systems have “wedge” filters that are partially transparent
to the X-ray beam. These moveable filters attenuate the beam in regions selected by the operator to
reduce entrance dose and excessive image brightness.
• Collimation
Shutters that limit the geometric extent of the X-ray field are present in all X-ray equipment. In
fluoroscopy, the collimation may be circular or rectangular in shape, matching the shape of the
image receptor.

50. Specific Details of Fluoroscopic Components
• Patient Table and Pad
Carbon fiber technology offers a good combination of high strength and minimal radiation
absorption, making it an ideal table material. Foam pads are often placed between the patient and
the table for added comfort, yet with minimal radiation absorption.
• Anti-Scatter Grid
Anti-scatter grids are standard components in fluoroscopic systems, since a large percentage of
fluoroscopic examinations are performed in high-scatter conditions, such as in the abdominal
region. Typical grid ratios range from 6:1 to 10:1. Grids may be circular (XRII systems) or
rectangular (FPD systems) and are often removable by the operator.
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51. Image Receptor — Flat Panel Detector (FPD)
• When flat panel X-ray detectors first appeared in radiography, they offered the advantages of a
“digital camera” compared with existing technologies. In fluoroscopic applications, the challenge for
FPDs has been the requirement of low dose per image frame, meaning that the inherent electronic
noise of the detector must be extremely low, and the required dynamic range is high.
• Flat panel detectors consist of an array of individual detector elements. The elements are square,
140–200 microns per side and are fabricated using amorphous silicon thin-film technology onto
glass substrates.
• Detector arrays used for fluoroscopy range from about 20 x 20 cm up to 40 x 30 cm. A single
detector may contain as many as 5 million individual detector elements. A cesium iodide (CsI)
scintillation layer is coated onto the amorphous silicon, with thin-film photodiodes and transistors
capturing the visible light signal from the scintillator to form the digital image, which is then
transferred to a computer at a frame rate selected by the user (Figure 3). Frame rates can be as
high as 30 frames per second.
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52. Image Display
• Fluoroscopy requires high-quality video displays that allow users to appreciate
fine details and subtle contrast differences in the anatomy of interest.
• Modern systems feature high resolution flat-panel LCDs with high maximum
luminance and high-contrast ratios. These displays should be calibrated to a
standard luminance response function (such as the DICOM part 14 Grayscale
Standard Display Function) to ensure that the widest range of gray levels are
visible.
• The newest interventional/angiographic systems feature 60” diagonal high-
definition displays supporting up to 24 different video input sources that can be
arranged in various ways on the single large display monitor. Display layouts can
be uniquely customized and saved for individual physician preference.
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53. System Configuration
• System Configurations
Fluoroscopic systems are manufactured in a variety of configurations to optimize usability for
the clinical task(s) for which they are intended. “Conventional” radiography/fluoroscopy systems
consist of a patient table that often tilts all the way to vertical position permitting fluoroscopy while
the patient stands upright. These systems have the X-ray tube positioned under the table-top, with
the image receptor above the table, and are most often used for gastrointestinal imaging.
The tilting capability of the patient table allows the operator to utilize gravity to assist the movement
of the barium contrast material through the esophagus, stomach and bowel. Older systems may
contain a “spot film” device that allows placement of a radiographic cassette in front of the
fluoroscopic image receptor, facilitating the acquisition of radiographs using the fluoroscopic X-ray
source. In modern systems, static images are routinely acquired using the same digital image
receptor that is used for fluoroscopy, so the spot film is going away.
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54. • The tilting capability of the patient table allows the operator to utilize gravity to assist the
movement of the barium contrast material through the esophagus, stomach and bowel.
Older systems may contain a “spot film” device that allows placement of a radiographic
cassette in front of the fluoroscopic image receptor, facilitating the acquisition of
radiographs using the fluoroscopic X-ray source. In modern systems, static images are
routinely acquired using the same digital image receptor that is used for fluoroscopy.
• A variation on this conventional R/F configuration is the remote controlled system, in
which the X-ray tube and image receptor positions are reversed with the tube above the
patient table and the image receptor below. These systems can be fully controlled,
including table movements, at an operator’s console featuring a joystick-type controller in
a shielded control booth. This protects the staff from secondary radiation exposure.
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55. Angiogram
• An angiogram is a diagnostic test that uses x-rays to take pictures of your blood vessels. A long
flexible catheter is inserted through the blood stream to deliver dye (contrast agent) into the arteries
making them visible on the x-ray. This test can help diagnose a stroke, aneurysm, arterio-venous
malformation, tumor, clots, and arterial stenosis.
• An angiogram works similar to an x-ray. The body casts a "shadow" on film when it is exposed to
the x-ray, much like when you hold a flashlight up to your hand and cast a shadow on a wall.
Normally your blood vessels cannot be seen in an x-ray, but adding a dye (contrast agent) into the
blood stream makes your arteries and veins visible . Contrast agent contains iodine, a substance
that x-rays cannot pass through.
• To deliver the contrast agent, a catheter is advanced from the femoral artery in the leg to one of four
arteries in the neck that lead to the brain. The doctor steers the catheter through the blood vessels
while watching a monitor. A fluoroscope machine, called a C-arm, is an arc shaped piece of
equipment that generates x-rays from one side and photographs them on the other side . Contrast
is injected into the bloodstream to make the blood vessels visible on the monitor. The result is a
kind of roadmap of the arteries.
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56. • Today many catheter angiographic studies have been replaced by less invasive methods such
as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) that do
not require a catheter be inserted. Catheter angiography has the benefit of combining diagnosis and
treatment in patients who may undergo surgery or other endovascular procedure such as
angioplasty, aneurysm coiling, or stent placement. Angiograms are very good at detecting problems
with the blood vessels such as an aneurysm, arteriovenous malformation (AVM), arterial stenosis
from plaque build-up, tumors, and clots.
• Example : SpinalAngiogram
Angiography of the blood vessels that feed the spine and spinal cord is performed in the same
fashion as cerebral angiography. It may include the same vessels in the neck (like the carotid and
vertebral arteries that feed the brain) but will also include arteries in the chest and abdomen.
Imaging of these vessels can be blurred by movement from breathing or talking. For this reason,
spinal angiography may be performed under general anesthesia in some cases. The physician can
more precisely control your breathing and movement. The blood supply to the spinal cord varies
greatly between individuals. Spinal angiography can be a tedious process because there is one
spinal artery for each rib. Every artery that may supply the spinal cord must be imaged, which can
make the procedure longer than a cerebral angiogram.
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57. 05-12-2020 57

58. Mammogram
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• Mammogram Equipment

59. Mammogram
• Mammography is a specific type of imaging that uses a low-dose x-ray system to
examine breasts.
• A mammography exam, called a mammogram, is used to aid in the early
detection and diagnosis of breast diseases in women.
• An x-ray (radiograph) is a noninvasive medical test that helps physicians
diagnose and treat medical conditions.
• Imaging with x-rays involves exposing a part of the body to a small dose of
ionizing radiation to produce pictures of the inside of the body.
• X-rays are the oldest and most frequently used form of medical imaging.
• Three recent advances in mammography include digital mammography,
computer-aided detection and breast tomosynthesis.
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60. Digital mammography
• Also called full-field digital mammography (FFDM), is a
mammography system in which the x-ray film is replaced by solid-state
detectors that convert x-rays into electrical signals.
• These detectors are similar to those found in digital cameras.
• The electrical signals are used to produce images of the breast that
can be seen on a computer screen or printed on special film similar to
conventional mammograms
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61. Common Usage of Mammography
• Mammograms are used as a screening tool to detect early breast cancer in women experiencing
no symptoms.It can also be used to detect and diagnose breast disease in women experiencing
symptoms such as a lump, pain or nipple discharge.
Screening Mammography
• Mammography plays a central part in early detection of breast cancers because it can show
changes in the breast up to two years before a patient or physician can feel them.
• Current guidelines from the U.S. Department of Health and Human Services (HHS), the
American Cancer Society (ACS), the American Medical Association (AMA) and the American
College of Radiology (ACR) recommend screening mammography every year for women,
beginning at age 40.
Diagnostic Mammography
• Diagnostic mammography is used to evaluate a patient with abnormal clinical findings—such as
a breast lump or lumps—that have been found by the woman or her doctor.
• Diagnostic mammography may also be done after an abnormal screening mammogram in order
to evaluate the area of concern on the screening exam
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62. Mammography X ray Equipment
• Mammographic X-ray equipment can either be used with special film/screen cassette or as xero-
radiographic units. The units intended for film/screen use have a molybdenum target X-ray tubes
with a beryllium window and a 0.03 mm molybdenum filter. Radiographs are usually taken at 28–35
kV. Xero-radiographic systems use X-ray tubes with tungsten targets and about 1 mm aluminum
filter. Radiographs with this technique are taken at 40–50 kV. Hence, both types of mammographic
units operate at low peak voltages.
• Film-based mammography has several disadvantages such as limitations in detection of
microcalcifications and other fine structures within the breast, and inefficiency of grids in removing
the effects of scattered radiation. Many of these limitations can be effectively removed by using a
digital mammography system in which image acquisition, display and storage are performed
independently, allowing for optimization of each process. However, the availability of a suitable
• X-ray detector for this purpose is still a challenge that precludes the widespread use of digital
mammography. Various detector technologies which are under evaluation in digital mammography
are large area CCDs (Charge Coupled Devices), photo-stimulable phosphors, amorphous silicon
coupled to scintillators, amorphous selenium and other solid-state devices.
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63. Dental X ray Equipment
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64. Components of Dental X-Ray Unit
• The most commonly used X-ray machine is thewall-mounted dental X-ray unit (fig. 1-2). Because the basic
components and operating techniques of all dental X-ray machines are similar, we will only discuss the wall-
mounted unit. The component parts of the wall-mounted machine discussed here are the tube head, cylinder,
extension arm, ready light, and a separate control panel.
TUBE HEAD
• The tube head (fig. 1-3) contains the X-ray tube and other components necessary for generating X-rays. When
an exposure is made, X-rays pass through an aluminum filter that screens out unnecessary radiation.
• Angulation scales are on both sides of the tube head for precise positioning technique.
CYLINDER
• The cylinder (or cone) is affixed to the tube head and is used to align the tube head with the patient and the X-
ray film. It is open-ended and composed of lead laminated material that establishes the minimum distance
from the X-ray source to the patient’s skin.
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65. • The X-ray beam passes from the aluminum filter through an opening in a lead diaphragm, which
restricts the beam to 2.6 inches at the cylinder tip. There are two commonly used cylinder lengths.
A tube head with an X-ray source to cylinder end distance of 8inches is referred to as a "short
cone" machine, while a tube head with an X-ray source to cylinder end distance of 16 inches is
referred to as a "long cone" machine. It is essential that the technician knows the X-ray source to
cylinder end distance in order to set the appropriate exposure settings.
• The tube head is attached to an extension arm. The extension arm is movable, allowing you to
adjust the position of the tube head for each patient.
CONTROL PANEL
• The operational controls on the control panel are covered in the discussion on the operational
check
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