Radiology & Medical Imaging

WHAT IS RADIOLOGY?
 Radiology represents a branch of medicine that deals with radiant energy in the diagnosis
and treatment of diseases by using imaging technologies (Modalities), This field can be
divided into two broad areas
 Diagnostic radiology
 Interventional radiology.

DIAGNOSTIC RADIOLOGY
 Diagnostic radiologists use medical images such as X-rays, ultrasound, CT scans and MRI scans
to diagnose diseases anywhere in the body.

DIAGNOSTIC RADIOLOGY
 Neuroradiology
 Paediatric radiology
 Breast imaging
 Cardiovascular radiology
 Chest radiology
 Gastrointestinal radiology
 Genitourinary radiology
 Musculoskeletal radiology
 Emergency radiology
 Nuclear radiology

INTERVENTIONAL RADIOLOGY
A subspecialty of radiology that focuses on the diagnosis and treatment of patients utilizing
minimally invasive interventional techniques (non-surgical procedures)
 These include
 Imaging & treatment of blood vessels (angiography)
 Biopsy procedures,
 Cardiac Catheterization,
 Angioplasty (balloon dilation of blood vessels)
 Stents
 laser treatment of varicose veins
 fluid abscess drainage

WHAT IS MEDICAL IMAGING?
 Medical imaging is the visualization of body parts, tissues, or organs, for use in
clinical diagnosis, treatment and disease monitoring. Imaging techniques
encompass the fields of radiology, nuclear medicine and optical imaging and
image-guided intervention

NUCLEAR MEDICINE
 Branch of medical imaging that uses small amounts of radioactive material (radioisotopes), to diagnose
and determine the severity of or treat a variety of diseases
 Including many types of cancers, heart disease, gastrointestinal, endocrine, neurological disorders & other
abnormalities within the body
 Most common nuclear medicine modalities used in clinical practice
 Single-photon emission computed tomography (SPECT)
 Positron emission tomography (PET).

RADIOLOGY TECHNIQUES (MODALITIES)
 X-ray radiography
 Fluoroscopy
 CT - computer tomography
 MRI - magnetic resonance imaging
 PET - positron emission tomography
 SPECT - single photon emission computed tomography
 Ultrasound

SOURCES OF IMAGES
 Structural/anatomical information (CT, MRI, US, VH) - within each elemental
volume, tissue-differentiating properties are measured.
 Information about function (PET, SPECT)
 SPECT/CT & PET/CT
 Anatomic information and functional information, resulting in better localization and
definition of scintigraphy findings.

PROJECTION (PLAIN) RADIOGRAPHY / X-RAY
RADIOGRAPHY
Radiographs are produced by the transmission of X-Rays (without added contrast materials such as
barium or iodine) through a patient to a capture device then converted into an image for
diagnosis.

X-RAY PRODUCTION
 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
 Bremsstrahlung radiation.
 Advantages - relative inexpensiveness and the possibility to obtain them by using
mobile or portable machines
 Disadvantages are the limited range of densities it can demonstrate and the use of
ionizing radiation.

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.

Ultrasound
 High-frequency sound waves are used to visualize soft tissue structures in
the body in real time.
 Ionizing radiation is not utilized in the technique, but the quality of the
images obtained using ultrasound is highly dependent on the skill of the
person performing the exam.
 Ultrasound probes utilize acoustic energy above the audible frequency of
humans in order to produce images.
 As there is no ionizing radiation with this modality, it is particularly useful in
imaging of children and pregnant women.

Ultrasound
DRAWBACKS:
gas filled and bony structures cannot be image (they
absorb ultrasound beam)
ADVANTAGES:
 good for cysts/ cystic structures and fetus in its
amniotic fluids

CT (COMPUTED TOMOGRAPHY) SCANNING

CT SCAN - USES
 Diagnose muscle and bone disorders - such as bone tumors and fractures
 Pinpoint the location of a tumor, infection or blood clot
 Guide procedures such as surgery, biopsy and radiation therapy
 Detect and monitor diseases and conditions - such as cancer, heart disease, lung
nodules and liver masses
 Monitor the effectiveness of certain treatments, such as cancer treatment
 Detect internal injuries and internal bleeding

TYPES OF CT SCANS
 Head or brain CT
 Neck CT
 CT of the chest
 Abdominal and pelvic CT (CT Scanning of the Abdomen)
 Sinus CT
 Spine CT
 CT Angiography (computed tomography technique used to
visualize arterial and venous vessels throughout the body)

HOW DOES CT WORK?
 Unlike a conventional x-ray—which uses a fixed x-ray tube— a CT scanner uses a
motorized x-ray source that rotates around the circular opening called a gantry.
 During a CT scan, the patient lies on a bed that slowly moves through the gantry while
the x-ray tube rotates around the patient, shooting narrow beams of x-rays
(Collimated) through the body.
 CT scanners use special digital x-ray detectors, which are located directly opposite the
x-ray source.
 As the x-rays leave the patient, they are picked up by the detectors and transmitted to
a computer.
 Each time the x-ray source completes one full rotation, the CT computer generated a
2D image slice of the patient.
 Image slices can either be displayed individually or stacked together by the computer
to generate a 3D image

WHAT IS A CT CONTRAST AGENT?
As with all x-rays, dense structures within the body—such as bone, are easily imaged, whereas soft
tissues vary in their ability to stop x-rays and, so, difficult to see.
 Radiocontrast agents are substances used to enhance the visibility of internal structures in X-
ray-based imaging techniques such as CT & fluoroscopy.
 Radiocontrast agents are typically iodine or barium compounds..
 Iodine-based compounds is injected into the bloodstream to help illuminate blood vessels , including
those in the heart.
 Barium-based compounds, are used for imaging the digestive system, including the oesophagus,
stomach, and GI tract.

IMPORTANT FEATURES OF CT SCANNERS
 CT Scanner Price
 Slice Count (4. 16, 32 , 64 & 128)
 Dose Optimization (minimize radiation dose for obtaining diagnostic quality of CT images)
 Technical Considerations
 Air-cooled vs. water-cooled technology
 Gantry rotation time
 Detector array length
 X-ray tube performance and lifespan
 Spatial and contrast resolutions
 Sustainability and maintenance needs
 Service costs,

TOP CT MANUFACTURERS
 GE - is easy maintenance
 Philips - is affordability
 Siemens - is innovation
 Toshiba - is power and quality

GE CT SCANNERS
GE Healthcare scanners have an acclaimed reputation for durability & ease
of maintenance but cost more than others
• They often have lower costs of service, labor, and replacement parts
• GE scanners are air-cooled, which means they are easier to maintain
Some popular GE scanner model lines include
• GE Bright-Speed
• GE Discovery
• GE Light-speed
GE Discovery CT750 HD

PHILIPS CT SCANNERS
Philips Brilliance 16
 The Philips Brilliance line of CT scanners includes some of the most affordable
options available
 Some popular Philips scanner model lines include
 Philips Brilliance (16, 40 & 64, iCT)
 Philips Gemini

SIEMENS CT SCANNERS
 Siemens is known for its pioneering spirit and innovation.
 Siemens’ UFC (Ultra Fast Ceramics) detector technology offers high X-ray
absorption, short decay times, and low afterglow, all of which are key
parameters for high spatial resolution. This allows for sharper images with the
highest standards for dose minimization.
 Some popular Siemens scanner model lines include
• Siemens Emotions (up to 16 slices, air-cooled)
• Siemens Sensation (up to 64 slices, water-cooled- need outdoor chiller)
• Siemens Definition AS & AS +(up to 128 slices, low dose CT, water/air cooled)
• Siemens Biograph (PET/CT)
.

TOSHIBA CT SCANNERS
Toshiba Aquilion One
 The Aquilion 16 is a robust 16-slice scanner, known for its ability to complete a
rotation in .4 seconds and reconstruct high-quality images at 12 frames per
second.
 Some popular Siemens scanner model lines include
 Aquilion ( 16,32 & 64) (Oil/air cooling)
 Aquilion One (Oil/air cooling)
 Aquilion Premium. (Oil/air cooling)

MRI (Magnetic Resonance Imaging)

WHAT IS AN MRI SCAN?
 A magnetic resonance imaging (MRI) uses a strong magnetic field and
radio waves to create detailed images of the organs and tissues within
the body.
 An MRI scan uses a large magnet, radio waves, and a computer to
create a detailed cross-sectional image of the patient's internal organs
and structures.
 The scanner itself typically look like a large tube with a table in the
middle, allowing the patient to slide into the tunnel.
 An MRI scan differs from CT scans and X-rays because it does not use
ionizing radiation that can be potentially harmful to a patient.

WHAT ARE MRI SCANS USED FOR?
 Abnormalities of the brain and spinal cord
 Tumors, cysts, and other abnormalities in various parts of the body
 Injuries or abnormalities of the joints, such as back pain
 Certain types of heart problems
 Diseases of the liver and other abdominal organs
 Causes of pelvic pain in women (e.g. fibroids, endometriosis)
 Suspected uterine abnormalities in women undergoing evaluation for infertility
• Sometimes, patients will be injected with intravenous (IV) contrast liquid to
improve the appearance of a certain body tissue.

HOW DOES AND MRI SCANNER WORK?
 An MRI scanner contains two powerful magnets
 The human body is largely made of water molecules, comprised of hydrogen
& oxygen atoms are randomly arranged
 Magnetic resonance imaging (MRI) makes use of the potential energy stored
in the body’s hydrogen atoms. At the center of each atom lies protons, which
serves as a magnet and is sensitive to any magnetic field.
 Those atoms are manipulated by very strong magnetic fields and
radiofrequency pulses upon entering an MRI scanner, the first magnet causes
the body's water molecules to align in one direction,(Radio waves 10,000 to
30,000 times stronger than the magnetic field of the earth)

MRI SCANNER WORK?
 The second magnetic field is then turned on and off in a series of quick pulses,
causing each hydrogen atom to alter its alignment and then quickly switch back to
its original relaxed state when switched off.
 The magnetic field is created by passing electricity through gradient coils, which also
cause the coils to vibrate, resulting in a knocking sound inside the scanner.
 Although the patient cannot feel these changes, the scanner can detect with a
computer, can create a detailed cross-sectional image for the radiologist to interpret.
 Different protons send out different signals, depending on which tissue the proton
can be found in. For example, a proton found in bone will emit a very different radio
wave signal when compared to a proton found in blood.

MRI COMPONENTS
 Primary magnet
 Gradient magnet
 Radio Frequency (RF) coils
 Computer System

Functional Magnetic Resonance Imaging (fMRI)
 fMRI uses MRI technology to measure brain activity by monitoring blood flow in
the brain by activation of brain areas by different types of physical sensation
 This gives an insight into the activity of neurons in the brain as blood flow
increases in areas where neurons are active.
 This technique has revolutionized brain mapping by allowing researchers to
assess the brain and spinal cord without the need for invasive procedures or
injections of drugs.
 fMRI helps researchers learn about the function of a normal, diseased, or injured
brain.

WHAT DOES AN MRI SCAN SHOW?
 Using an MRI scanner, it is possible to make pictures of
almost all the tissue in the body.
 The tissue that has the least hydrogen atoms (such as
bones) turns out dark, while the tissue that has many
hydrogen atoms (such as fatty tissue) looks much brighter.
 By changing the timing of the radio-wave pulses it is
possible to gain information about the different types of
tissues that are present.

CT SCAN vs MRI SCAN
 A CT Scan is best suited for viewing bone injuries, diagnosing lung and chest
problems, and detecting cancers.
 An MRI is suited for examining soft tissue in ligament and tendon injuries,
spinal cord injuries, brain tumors, etc.
 CT scans are widely used in emergency rooms because the scan takes fewer
than 5 minutes. An MRI, on the other hand, can take up to 30 minutes.
 An MRI typically costs more than a CT scan. One advantage of an MRI is that
it does not use radiation while CT scans do. This radiation is harmful if there is
repeated exposure.

PHYSICS OF MRI SCAN ?
 Hydrogen atoms have an inherent magnetic moment as a result of their nuclear
spin.
 When placed in a strong magnetic field, the magnetic moments of these hydrogen
nuclei tend to align.
 Proper stimulation by a resonant magnetic or RF field at the resonant frequency of
the hydrogen nuclei can force the magnetic moments of the nuclei to partially, or
completely,
 When the applied RF-excitation field is removed, the magnetic moments of the
nuclei precess in the static field as they realign.
 This signal is detected by the MRI imaging system and used to generate an image.

STATIC MAGNETIC FIELD
 MRI imaging requires the patient to be placed in a strong magnetic field in order to align
the hydrogen nuclei. There are typically three methods to generate this field:
 Fixed Magnets
 Resistive Magnets (current passing through a traditional coil of wire),
 Super-conducting Magnets
 Fixed magnets & resistive magnets are generally restricted to field strengths below 0.4T &
cannot generate the higher field strengths typically necessary for high-resolution imaging.
 Most high-resolution imaging systems use super-conducting magnets.
 The super-conducting magnets are large and complex; they need the coils to be soaked in
liquid Helium to reduce their temperature to a value close to absolute zero.

GRADIENT COILS
 To produce an image, the MRI system must first stimulate hydrogen nuclei in a
specific 2D image plane in the body,
 An MRI system must have x, y, and z gradient coils to produce gradients in three
dimensions and thereby create an image slice over any plane within the
patient's body.
 There are also three gradient magnets inside the MRI machine. These magnets
are much lower strength compared to the main magnetic field; they may range
in strength from 180 gauss to 270 gauss. While the main magnet creates an
intense, stable magnetic field around the patient, the gradient magnets create a
variable field, which allows different parts of the body to be scanned.

TESLA & GAUSS
 MRI system is rated using a unit of measure known as a tesla.
 Another unit of measure commonly used with magnets is the gauss (1
tesla = 10,000 gauss).
 The magnets in use today in MRI systems create a magnetic field of 0.5-
tesla to 2.0-tesla
 Most MRI systems use a superconducting magnet, which consists of
many coils or windings of wire through which a current of electricity is
passed,

TOP Manufactures of MRI
 GE Healthcare
 Hitachi Medical Systems
 Philips Healthcare
 Siemens Healthineers
 Toshiba Medical Systems
 Common 1.5T & 3.0T

GE HEALTHCARE - MRI
 GE MRI systems upfront costs (the purchase of the equipment) will be higher
than with other manufacturers,
 Ongoing service costs will be significantly lower.
 Parts availability is very high for GE scanners
 GE also makes their systems very upgradeable and taking a scanner to the
next level frequently
 Some popular GE – MRI scanners (1.5T & 3.0T )
 SIGNA – Pioneer, (3T)
 SIGNA - Voyager (1.5T wide bore system)
 Optima MR450w (1.5T)
 Discovery MR750w (3T- wide bore)

SIEMENS- MRI
 Upfront cost for a Siemens MRI scanner will be comparable to Philips.
 The ongoing service costs will be more in line with those of a GE scanner.
 In terms of features, Siemens scanners have some offerings that other makes do not.
 Siemens also offers TIM (Total Imaging Matrix) which allows for whole-body imaging without
patient repositioning.
 Unlike Philips, Siemens has ”zero boil-off” magnet designs which are incredibly efficient and
burn very little cryogen.
 Some popular Siemens – MRI scanners (0.35T to 1.5T)
 MAGNETOM Aera (1.5T)
 MAGNETOM Sempra(1.5T)
 MAGNETOM Amira (1.5T)
 MAGNETOM ESSENZA (1.5T)

PHILIPS - MRI
 Philips MRI scanner lower in upfront costs
 Higher ongoing service costs
 Philips magnets typically have very powerful gradients and offer best images
available
 Most Philips magnet designs do consume cryogen.
 If you choose a Philips system, recommend also purchasing a service contract that
includes cryogen coverage for liquid helium loss.
Cryogens (Liquid helium) are released to keep the magnet cool
 Some popular PHILIPS – MRI scanners (0.35T to 1.5T)
 Ingenia 3.0T
 Ingenia 1.5T

TOSHIBA - MRI
 Upfront cost for a Toshiba MRI is low .
 The ongoing Service costs will be higher.
 In All of their models are “wide-bore” (65cm or 71cm)
 Excellent gradients for superior images.
 Toshiba also has Pianissimo technology in their magnets which allows for near-
silent scanning for some sequences
 Some popular TOSHIBA – MRI scanners (1.5T to 3T)
 Vantage Titan (1.5T)
 Vantage Titan (3T)
 Vantage Galan (3T)
 Vantage Elan 1.5T

PET - POSITRON EMISSION
TOMOGRAPHY

WHAT IS PET
 PET is Nuclear medicine functional imaging technique for
metabolic processes/ functions in the human body.
 Positron emitting tracer is injected into the body which emits
positrons causing annihilation that results two gamma rays.
 These rays are detected by opposing detectors.
 Then these signal is transfer to amplifier and other
electronic circuit.

 The tracer may be injected, swallowed or inhaled, depending on which
organ or tissue is being studied by the PET scan.
 The tracer collects in areas of your body that have higher levels of
chemical activity, which often correspond to areas of disease. On a PET
scan, these areas show up as bright spots.

What is a POSITRON & How it
produced GAMMA RAYS
 A Positron is an anti-matter electron, it is identical in mass
but has an apposite charge of +1.
 Positron can come from different number of sources, but for
PET they are produced by nuclear decay.
 The positron will encounter an electron and completely
converting all their masses into energy.
 This is the result of two photons, or gamma rays

Tracer in PET
Special form of substance such as glucose in injected in body
is FDG (Flouro-dehydroxy glucose) that collects in cells that
are using a lot energy such as cancer cells
Why glucose ?
When radio pharmaceutical inserted in body. Body consume
energy in the form of glucose
Tumor has high rate of consumption

WHAT ARE THE PRIMARY FUNCTIONS OF
THE PET SCANNER?
 Detect and Stage a Cancer (Earlier than CT / MRI)
 Determine whether a Cancer has spread throughout the body
 Find the place in the body where the Cancer first started (primary site)
 Make decisions on whether the Cancer can be removed surgically
 Make decisions about treatment plans
 Assess the effectiveness of a treatment plan, such as chemotherapy
 Show the difference between a scar tissue and an active Cancer tissue
 Determine if a Cancer has recurred after treatment
 Evaluate brain abnormalities such as Tumors
 Useful in evaluating some heart diseases.

PET/CT SCANNERS
 Philips Healthcare (Ingenuity TF, Vereos)
 GE Healthcare (Discovery - IQ, PET/CT 610, PET/CT 710)
 Siemens (Biograph mCT)
 Toshiba (Celesteion PET/CT)

SINGLE-PHOTON EMISSION
COMPUTED TOMOGRAPHY (SPECT)

SINGLE-PHOTON EMISSION COMPUTED
TOMOGRAPHY (SPECT)
 Nuclear medicine tomographic imaging technique using gamma rays.
 Detect single photons emitted by radionuclide tracers
 Determine the origin and direction of emitted gamma
 Reconstruct 3D images of the source or anatomy
 Used as a diagnostic tool to image tumors, disease, and perform bone
scans
 The images reflects functional information about patients similar to that
obtained with PET
 The technique requires delivery of a gamma-
emitting radioisotope (a radionuclide) into the patient, normally through
injection into the bloodstream.

SINGLE-PHOTON EMISSION COMPUTED
TOMOGRAPHY (SPECT)
 a nuclear medicine tomographic imaging technique
using gamma rays. It is very similar to conventional nuclear
medicine planar imaging using a gamma camera (that
is, scintigraphy). However, it is able to provide true
3D information. This information is typically presented as
cross-sectional
 The technique requires delivery of a gamma-
emitting radioisotope (a radionuclide) into the patient,
normally through injection into the bloodstream.

PRINCIPLE OF SPECT
 SPECT imagers have gamma camera detectors that can detect the Gamma-ray photons
emitted from the tracers that have been injected into the patient.
 The cameras are mounted on a rotating gantry that allows the collimated radiation
detectors to be moved in a tight circle around a patient
 In SPECT, projection data are acquired from different views around the patient.
 The 3D images are computer generated from a large number of projection images of the
body recorded at different angles.
(Gamma rays are a form of light that moves at a different wavelength than visible light)

SPECT/ PET
SPECT PET
SPECT imaging is inferior to PET less
resolution and sensitivity
Superior to SPECT
Lower cost Very expensive
uses gamma emitting radioisotope
(tracer) – half-life around 6h
uses positron emitting radioisotope
(tracer) - half-life 75 seconds
SPECT radio tracers are cheaper SPECT radio tracers are expensisve

SPECT - MANUFACTURERS
 GE Healthcare
 Discovery NM/CT 670
 Siemens Healthcare
 Symbia Evo
 Symbia S - can be upgraded to diagnostic SPECT/CT
 BrightView- DS
 BrightView X - can be upgraded to diagnostic SPECT/CT

SPECT/CT - MANUFACTURERS
 GE Healthcare
 Brivo NM615
 Discovery NM630)
 Siemens Healthcare
 Symbia Intevo
 Symbia T
 BrightView -XCT

ADDING CT TO SPECT AND PET
(SPECT/CT & PET/CT)
 The incorporation of a CT scanner with a gamma camera for combined
SPECT/CT or PET/CT imaging is designed to give anatomic with other than
functional
 Innovative hybrid technology seamlessly integrates the functional images of
advanced SPECT with the precise anatomical detail of multi-slice high-resolution
CT.

What Hybrid Cath-lab?
 Hybrid cath labs provide advanced imaging and at the same time fulfill the
requirements for treating complex cases like high risk patients and structural heart
disease.
 Therefore, next-generation cath labs are ideally suited for performing new
therapeutic procedures such as aortic valve replacements, mitral valve repairs, and
epicardial ablations of ventricular tachycardias.
 They also help to improve the quality and cost-effectiveness of patient care by
expanding your room capabilities and broadening your procedure mix.

GE - HYBRID CARDIAC CATHETERIZATION LAB
 The Discovery* IGS 730 angiography system brings both extremely high-quality
imaging and complete workspace freedom to the hybrid operating room to
perform cardiac angulations without compromising detector coverage for
endovascular procedures.

SIEMENS - HYBRID CATH LAB
 ARTIS pheno is a unique angiography
 optimally treat any patient - regardless of patient size, condition, or positioning needs.
Engineered to be truly patient-oriented,
 Optimal patient positioning with flexible isocenter and multi-tilt table
 Sufficient room to navigate complex imaging setups thanks to wide-space C-arm
 Short syngo DynaCT scan times reduce contrast agent
 Structure-Scout provides optimized visibility at lowest dose
 Multi-tilt table accommodates maximum patient weight of 280 kg

TOSHIBA - HYBRID CATH LAB
 Angiography system in which the catheterization table is
replaced with an operating table
 Combined with Maquet Operating Table
 The ceiling-suspended C-arm can be moved longitudinally,
supporting efficient use of the operating room. In
procedures requiring fluoroscopy in combination, the C-arm
can be set near the operating table. When fluoroscopy is not
needed, the arm can be moved away from the table. The
system permits flexible layout of the operating room
according to the type of procedure required.
 The system is provided with the option to reconstruct 3D
images from various types of images.

PHILIPS - HYBRID CATH LAB
The Azurion angiography system for interventional labs

Radiology & Medical Imaging

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Radiology & Medical Imaging