1. LECTURE – 1 – RHPT – 485 READING IN MEDICAL IMAGING LEVEL - 8

2. X-RAY INTRODUCTION Discovered and named by Dr. W. C. Röentgen at
University of Würzburg, 1895
Awarded first Nobel prize for physics, 1901

3. In 1895 Wilhelm Conrad Roentgen discovered X-rays, so paving the way for the development of a new branch of medicine called radiology.
Initially, radiology was the science of 'X-rays', but today it involves a variety of imaging techniques to study and investigate patients so that a diagnosis can be achieved.
In addition, therapeutic procedures are performed by radiologists under image guidance, a branch also known as interventional radiology.

4. FIRST X-RAY
Roentgen’s wife's hand

5. What are the Different Imaging Modalities
Radiography “plain films”
Computed axial tomography “CT”
Magnetic resonance imaging “MRI”
Ultrasound “US”
Interventional radiology “angio”

6. RADIOLOGY TOOLS X- RAY ULTRASOUND NUCLEAR MEDICINE MAGNETIC RESONANCE
COMPUTED TOMOGRAPHY

7. HOW IS IMAGING DONE?
IONIZING RADIATION
X-ray, CT, Nuclear Medicine
SOUND WAVES
Ultrasound
MAGNETIC FIELDS / RADIO WAVES
Magnetic Resonance
To image the patient a energy source is directed into a volume of tissue and an image is created of the tissue interaction.

8. How to Approach Reading any Image
Identify the patient
When was the image taken
Are these the proper images
The five densities
Are the images technically adequate

9. Radiography – X - Ray Also called “plain films” or “standard films”
Image formed using broad beam ionizing radiation
The image formed is related to the subjects density
May involve the use of contrast agents
Iodinated
Barium
Air

10. X-RAY High Energy Photon --Kilo Electron Volts Ionizing Radiation
Exposes Film / Detector
Projection Data
X-RAY
X-ray beam
detector
X-rays are short-wave electromagnetic radiation produced by accelerating electrons across an evacuated tube onto a tungsten anode using a high voltage.

11. An X-ray tube is similar to a light bulb with a filament and a current to heat the filament.
There is also a high voltage to accelerate the electrons from the filament at a target.
This collision releases the x-ray radiation that is used to image the patient.

12. X-RAYS PLAIN FILM RADIOGRAPHY - Clinical uses
Chest
Bones
Spine / Extremities / Skull
Soft tissue
Mammography / Abdomen
These are typical body regions that plain x-ray is used to evaluate.

13. X - RAY --- FIVE BASIC DENSITIES
Air / Gas
Soft Tissue / Fluid filled space
Bone
Fat
Metal

14. The x-rays can traverse tissue to create the image.
We can only separate the 5 basic densities noted. Air / Gas, Soft tissue / Fluid filled space, Bone, Fat & Metal.
Here we see the Air in the lungs, the soft tissue of the heart and the bone density of the ribs.
Water will appear of the same density as soft tissue and cannot be separated. Fat is difficult to see on the chest and better noted on abdominal x-rays

15. Plain film projections
There are a number of projections or views commonly used when taking plain films.
If a beam passes through the patient's ventral (anterior) surface first then through the dorsal (posterior) surface to reach the film, it is called an anteroposterior projection.
Similarly, if the beam passes from dorsal to ventral through the body then a posteroanterior view is obtained.

16. Advantages cheap good first line imaging test readily available
low radiation dose
non-invasive
standardized techniques

17. Disadvantages two-dimensional imaging no cross section imaging
poor soft tissue contrast
poor for individual organs

18. CONTRAST RADIOGRAPHY
Injection, ingestion, or other placement of opaque material within the body.
Improves visualization and tissue separation.
Can demonstrate functional anatomy and pathology.

19. Administering a contrast agent modifies the image to give more information.
Clinical uses :-
Typical ones are barium, an inert particulate contrast used in GI tract evaluation.
Iodine, a water soluble agent which can be injected into the vascular tree.(ANGIOGRAPHY) + intravenous agents to visualize the renal tract (intravenous pyelogram - IVP)
Interventional procedures

20. ARTERIOGRAM UPPER GI--(GASTRO INTESTINAL)
ORAL BARIUM CONTRAST
ARTERIOGRAM
INTRAARTERIAL IODINE CONTRAST

21. The contrast agent -Barium- will outline the GI tract, determine size and show patency or obstruction.
The contrast agent-Iodine can be injected and is water soluble.
In the blood stream, it will outline the vessel and demonstrate anatomy.
Iodine is also filtered by the kidney and can show information about tissue function.

22. Reactions and side effects
slight nausea or sensation of heat,
to anaphylactoid shock and death.
The mechanism of idiosyncratic reactions, such as urticaria, angioneurotic oedema, bronchospasm, vasomotor collapse and respiratory arrest, is poorly understood.

23. Risk factors asthma, allergies, renal or cardiac impairment,
diabetes and myeloma.

24. Contrast agent administration
Intra-arterial and intravenous contrast agents
These water soluble non-ionic contrast agents.
used for evaluation of the venous and arterial systems.
Injected either directly into the veins (eg for intravenous pyelography, venography, or CT) or intra-arterially (eg for evaluation of carotid, renal, coronary, abdominal and limb arteries)
Their excretion is via the renal tract.

25. Intrathecal (water soluble) contrast agents
Water soluble intrathecal contrast agents are used for evaluation of the cervical, thoracic and lumbar subarachnoid space.
Oral and rectal contrast
Barium sulphate is the agent used for the detailed evaluation of the gastrointestinal tract.
It is derived from mineral barites. Barium sulphate preparations are not water soluble and are rarely associated with any contrast reactions.