Digital Imaging and Radiology

1
Digital Imaging and Radiology
2
Traditional x-rays

• Use electromagnetic waves to make pictures

3

• New imaging techniques use computers to generate
  pictures of internal body organs

4
Computers can make pictures using mathematical
information
5
Newer Technologies

• Computerized tomography is a diagnostic procedure
  that uses special x-ray equipment to obtain cross
  sectional pictures of the body.
• The CT computer displays these pictures as
  detailed images of organs, bones, and other
  tissues.
• In cancer, CT is used to detect a tumor, provide
  information about the extent of the disease, help
  plan treatment, and determine whether the cancer
  is responding to treatment

6

• A CT scan uses slightly more radiation than a
  chest x-ray, but the benefits generally outweigh
  the risks
• During a CT scan, the person lies very still on a
  table. The table slowly passes through the center
  of a large x-ray machine. The person might hear
  whirring sounds during the procedure. People may
  be asked to hold their breath at times, to
  prevent blurring of the pictures.
• Often, a contrast agent, or dye, may be given
  by mouth or injected into a vein before the CT
  scan is done. The contrast dye can highlight
  specific areas inside the body, resulting in a
  clearer picture.

7
Magnetic Resonance Imaging (MRI)

• MR imaging uses a powerful magnetic field, radio
  waves and a computer to produce detailed pictures
  of organs, soft tissues, bone and virtually all
  other internal body structures. The images can
  then be examined on a computer monitor or
  printed. MRI does not use ionizing radiation
  (x-rays).

8

• In most cases, an MRI exam is safe for patients
  with metal implants, except for a few types.
  People with the following implants cannot be
  scanned and should not enter the MRI area
• internal (implanted) defibrillator
• cochlear (ear) implant
• clips used on brain aneurysms

9
Positron Emission Tomography

• A PET scan, unlike a normal X-ray, can detect
  cancer before organ or gland enlargement occurs.
  Here a normal X-ray of the chest (left) is
  compared with a PET scan of the chest producing
  normal results (top right) and a PET scan
  revealing cancer that's spread to the lymph nodes
  (bottom right).

10
Advantages of digital imaging

• No developing process
• Copies are as good as originals
• Viewed on computer screen
• Can be transmitted over telephone lines
• Less radiation
• More flexible
• Can be highlighted or enhanced

11

• X-rays are most frequently used in orthopedics
  and dentistry
• As with many of mankind's monumental discoveries,
  X-ray technology was invented completely by
  accident. In 1895, a German physicist named
  Wilhelm Roentgen made the discovery while
  experimenting with electron beams in a gas
  discharge tube. Roentgen noticed that a
  fluorescent screen in his lab started to glow
  when the electron beam was turned on. This
  response in itself wasn't so surprising --
  fluorescent material normally glows in reaction
  to electromagnetic radiation -- but Roentgen's
  tube was surrounded by heavy black cardboard.
  Roentgen assumed this would have blocked most of
  the radiation.

12

• Roentgen placed various objects between the tube
  and the screen, and the screen still glowed.
• Finally, he put his hand in front of the tube,
  and saw the silhouette of his bones projected
  onto the fluorescent screen. Immediately after
  discovering X-rays themselves, he had discovered
  their most beneficial application

13
Mammography is a traditional x-ray

• Mammography is a low-powered x-ray technique that
  captures a picture of the internal structure of
  the breast. Additional angles and magnified views
  are taken of suspicious areas.
• A mammogram may help in the diagnosis of breast
  problems, including cancer.
• It is recommended a woman have a baseline
  mammogram
• at age 40, followed by a
• mammogram every couple of
• years until age 50.
• After 50, a woman should
• have a mammogram every year.

14
Ultrasound can distinguish between cysts and
tumors

• It is used along with mammograms
• Does not use radiation but high frequency sound
  waves

15
Computer Tomography

• Uses x-rays and digital technology to produce a
  cross-sectional image of the body. (Enhanced CTs
  use dye)

16
Magnetic Resonance Imaging

• Produces images of soft tissue within the body
• The image is produced by a computer with a
  magnetic field that is 25,000 times stronger than
  the earths magnetic field

17
Positron Emission Tomography (PET)

• Scans can be two or three dimensional
• Used in the study of Alzheimers and Parkinsons
  disease
• They produce pictures of activity and function

18
Interventional Radiology

• Treats an ever-widening range of conditions
  inside the body from outside the body by
  inserting various small instruments or tools,
  such as catheters or wires, with the use of
  various x-ray and imaging techniques (i.e., CT
  scanners, MRI scanners, ultrasound scanners).
• Interventional radiology offers an alternative
  to the surgical treatment of many conditions and
  can eliminate the need for hospitalization, in
  some cases
• Surgical biopsies have now been replaced with
  needle biopsies

19
Stereotactic Radiosurgery

• Stereotactic radiosurgery (SRS) treats brain
  disorders with a precise delivery of a single,
  high dose of radiation in a one-day session.
  Focused radiation beams are delivered to a
  specific area of the brain to treat
  abnormalities, tumors or functional disorders.
• Is the very precise delivery of radiation to a
  brain tumor with sparing of the surrounding
  normal brain.

20
Stereotactic Radiosurgery cont.

• Uses a gamma knife which is a painless device
• The gamma knife uses multiple beams of radiation
  converging in three dimensions to focus precisely
  on a small volume, such as a tumor, permitting
  intense doses of radiation to be delivered to
  that volume safely.

21
Focused ultrasound surgery

• Uses sound waves which create a powerful
  ultrasonic beam
• High-intensity ultrasound energy focused on a
  small target volume raises the tissue temperature
  high enough to destroy it. This is similar to the
  manner in which sunlight focused by a magnifying
  glass can create sufficient heat to start a fire.
  The use of heat to destroy tissue is called
  thermal ablation