German physicist

- in 1895 produced and detected electromagnetic radiation in a wavelength range known as x-rays

- achievement that earned him the first Noble Prize in Physics

- Radiographs/CT: examinations involve X-ray

- Nuclear scans: examinations involve radionuclides

- Sonograms: examinations involve sound waves

- MRI: examinations involve magnets and radiowaves

- Plain "films": digital images on high resolution monitors

- High levels are used to kill tumor cells

- All levels of ionizing radiation are associated with possible risk of carcinogenesis

- Risk during pregnancy depend on gestational age

- Radiation dose is cumulative

- Children are more sensitive than adults

Guiding Philosophy in Medical Radiation Use:

ALARA

Air --------0.001

Lung ----0.32

Fat ------0.91

Muscle --1.00

Bone ---1.85

Lead ----11.35

The thicker a structure is, the more of the x-ray beam it will absorb. As a result, thicker structures will appear whiter on radiographs than thinner structures of the same compostion

Plain "Films"

(Digital images on high resolution monitors)

Advantages

- Fast

- Relatively inexpensive

- Available everywhere

Plain "Films"

(Digital images on high resolution monitors)

Disadvantages

- Uses ionizing radiation

- Limited information regarding soft tissues

- Cannot see through bones

- Identify the patient: patient name and/or number, even if the film came out of the "right" folder

- When the image was taken: dates and times

- Are these the proper images

- Are the images technically adequate

- Are they properly labeled

- Exposure

- Development/ display

- Positioning

- Proper contrast

- Artifacts (movement, interference)

- Real time x-ray beam activated by stepping on a switch

- Patient lies on table and moving x-ray beam is used to watch at real time

- Contrast agents can be added to delineate area of interest

- Potentially significant radiation exposure to patient and operator

Intravenous Pyelogram

(IVP)

Computed Tomography

(CT)

Advantages

- Fast

- Allows deep structures to be visualized in fine detail

- Widely available

- Can facilitate interventional procedure

- Allows multi-planar imaging

Computed Tomography

(CT)

Disadvantages

- Accumulated radiation dose

- Often requires contrast enhancement with risks

(nephrotoxicity & anaphylaxis)

- Some weight limitations by table

Ultrasound

Advantages

- Portable, inexpensive equipment

- Cheaper than other cross-sectional imaging techniques

- Real time

- Can facilitate interventional procedures

- Allows multi-planar imaging

- Good at deciding cystic vs. solid

Ultrasound

Disadvantages

- Doesn't show function, only anatomy

- Difficult with obese patients

- Hard to see deep structures

- Can't see through bone or air

- Looks like weather map to untrained eye

Nuclear Medicine

Advantages

- Excellent at delineating function

- Specific label to target diseased area

- Can treat patients with theraputic doses

Nuclear Medicine

Disadvantages

- Patient is radioactive till total decayed

- Images not as detailed

- Availability of isotope

Magnetic Resonance

(MR)

Advantages

- Excellent soft-tissue characterization

- Allows multi-planar imaging

- No radiation

Magnetic Resonance

(MR)

Disadvantages

- Gadolinium contrast agent can be problematic

- Claustrophobia sometimes a concern

- Pacemakers, certain implants and metals cannot be in the field

- Not available everywhere

- Lengthy and expensive exams

Antero-Posterior (AP)

Lateral

Posterior-Anterior (PA)