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Assisting with Diagnostic Imaging
Chapter 50
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Learning Objectives
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Define, spell, and pronounce the terms listed
in the vocabulary.
Apply critical thinking skills in performing
patient assessment and care.
Identify the principal components of an x-ray
machine.
Describe the cassette and film image receptor
system, and explain its function in radiography.
Recognize the precautions to be taken when
unloading, loading, and processing radiograph
film and cassettes.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Learning Objectives
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Distinguish among the three body planes, and use
these terms correctly when discussing
radiographic positions.
Identify anteroposterior (AP), posteroanterior (PA),
lateral, oblique, and axial radiographic projections.
Compare and contrast radiography and
fluoroscopy, and give examples of appropriate
applications of each.
List and describe imaging modalities that do not
involve x-rays.
Explain patient preparation guidelines for typical
diagnostic imaging examinations.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Learning Objectives
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Outline the general procedure for assisting
with an x-ray examination.
Summarize guidelines for scheduling
multiple diagnostic procedures.
Apply patient education principles when
providing instructions for preparation for
diagnostic procedures.
Describe the health risks associated with low
doses of x-ray exposure such as those used
in radiography.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Learning Objectives
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Summarize the steps to ensure that patients
receive the least possible exposure during
x-ray procedures.
Describe precautions to ensure the safety of
equipment operators and staff during x-ray
procedures.
Explain the legal responsibilities associated
with x-ray procedures and the administrative
management of diagnostic images.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Radiography
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Process of recording of x-ray images or radiographs.
X-rays are produced in a vacuum tube, creating a
radiation field that can penetrate most substances and
form an image on film.
Radiopaque—substance that is not easily penetrated
by radiation and so appears light on the radiograph
(bone).
Radiolucent—substance that is easily penetrated (air,
soft tissue) and so appears dark on the radiograph.
Latent image—invisible changes in exposed film that
become visible when the film is processed.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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X-Ray
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Principal Exposure Factors
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Milliamperage (mA)—electrical control setting
that determines how rapidly the radiation is
produced
Exposure time (seconds)—duration of the
patient’s x-ray exposure
Kilovoltage (kVp)—electrical control setting that
determines the penetrating power of the x-ray
beam
Source-to-image distance (SID)—distance
between the x-ray tube and film or other image
receptor
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Chest X-Ray
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Radiographic Equipment
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Principal components of the x-ray machine are:
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X-ray tube, which is the source of radiation in its
barrel-shaped protective housing
Collimator mounted beneath the housing, which varies the
radiation field size
Tube support, suspended from ceiling or attached to tube
stand, which provides support and mobility for the tube
Adjustable radiographic table
Bucky, which moves the grid device to prevent scatter
radiation
Within the grid device is the cassette tray, which holds the
x-ray film
Control console, in the control booth, where the operator
selects exposure settings and takes the x-ray film
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Radiographic Equipment
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Image Receptor Systems
Cassette—holds film during the x-ray examination
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Rigid structure protects film from light and houses
intensifying screens
Intensifying screens—one front and back of the film
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Coated with phosphors—to give off light when exposed to
x-rays
Used to reduce the amount of radiation exposure needed
to get the x-ray image
Keep clean and avoid touching to prevent damage and
x-ray artifacts
Film—sensitive to light emitted by intensifying screens
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Handling Cassettes
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Cassettes are unloaded and reloaded in the
darkroom under safelight illumination only.
Ensure that the door is locked, your hands are
clean and dry, and the film is not creased,
bent, or scraped in loading and unloading.
Reload the cassette with only one fresh film,
and latch securely.
Keep the loading bench clean to prevent dirt
from getting into the cassette.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Film Identification
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Record the identity of the patient in the image
and the date and location of the examination.
Serious errors in diagnosis and treatment
might occur if films are not correctly identified.
Type identification information on a card that is
inserted into a photographic printer in the
darkroom. The printer stamps the information
on the film after it is removed from the cassette
and before it is processed.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Film Identification
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Fluoroscopy
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Enables the radiologist to view x-ray images in
motion.
Most fluoroscopy units can also take “spot
films.”
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x-ray films taken during the procedure that record
the fluoroscope image
Typical fluoroscopic studies are UGI series and
LGI series.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Anatomic Locations and Positions
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Anatomic position
Anterior
Cephalic
Caudal
Distal
External
Inferior
Internal
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Medial
Lateral
Palmar
Plantar
Posterior
Proximal
Superior
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Patient Positions
 Prone
 Dorsal
recumbent
 Lateral recumbent
 Ventral recumbent
 Supine
 Upright
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Body Planes
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Sagittal plane
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Coronal or frontal
plane
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Midsagittal plane
Midcoronal plane
Transverse plane
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Radiographic Projections
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Indicates the position of the body part in
relation to the film and x-ray tube
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Anteroposterior (AP)
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Posteroanterior (PA)
From Hunkele MM: Radiography essentials for
limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
20
Radiographic Projections
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Lateral projection—sagittal plane of the body
is parallel to the film
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
21
Radiographic Projections
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Oblique projection—body rotated so projection
is neither frontal nor lateral
From Hunkele MM: Radiography essentials for limited practice, ed 2, Philadelphia, 2006, Saunders.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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X-Ray Studies Using Contrast Media
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Contrast media—radiopaque substances (barium
sulfate and iodine compounds) that enhance
visualization of soft tissues
Used in the following studies:
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UGI series (barium swallow)—patient swallows barium
sulfate suspension to diagnose ulcers, tumors, and other
abnormalities of the esophagus, stomach, and
duodenum
 LGI series (barium enema)—fills the colon and helps
diagnose polyps, tumors, and diverticulosis
 Intravenous urogram—IVU (intravenous water-soluble
iodine) - identifies kidney stones, tumors, and other
abnormalities of the urinary tract
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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X-Ray Studies Using Contrast Media
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Arthrogram (iodine compound)—injected into
joint capsules; image of the soft-tissue
components of joints
Myelography—injection of iodine compounds into
the spinal canal to visualize spinal tumors and
herniated intervertebral disks
Angiography—iodine into blood vessel
• Arteriograms—pictures of specific arteries
• Venograms—studies of veins
• Embolization—therapeutic techniques that decrease or
stop blood flow to control hemorrhage, cut off blood
supply to a tumor, or reduce blood loss during surgery
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Computed Tomography (CT)
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Computerized x-ray imaging that provides axial
(slices of views in the transverse plane) and
three-dimensional scans.
Noninvasive but may cause patient apprehension.
Patient lies on a movable table with a circular
gantry that rotates the x-ray tube around the
patient to get images.
Contrast medium improves imaging.
Used to visualize the brain, abdomen, spine,
joints, chest, blood vessels, and so on.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Computed Tomography (CT)
Courtesy GE Healthcare, a division of General Electric Company.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Magnetic Resonance Imaging (MRI)
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Noninvasive procedure that does not use radiation.
Uses a strong magnetic field and radiofrequency
pulses to create computer images of bones and soft
tissue in multiple planes.
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Excellent imaging of nervous system
Soft tissue of joints
Hazardous for patients with artificial heart valves, pacemakers,
IUDs, metal fragments in skin, orthopedic pins, and so on
Patient lies on table, which moves into gantry (5 to
8 feet long) that holds the magnet and radiofrequency
coil.
Open gantry designs are better for large or
claustrophobic patients but do not provide high-quality
images.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Sonography
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Sonography (diagnostic ultrasound)
demonstrates soft tissues by using
high-frequency sound waves.
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Transducer sends high-frequency sound waves
through tissue
 Moved over surface of body, and real-time image
is examined
 Used for fetal, gallbladder, breast, heart imaging
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
28
Nuclear Medicine and PET
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Nuclear medicine – demonstrate function of
tissues by mapping radiation after radioactive
tracers are ingested or injected
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Does not provide clear anatomic images but gives
information about tissue function
Abnormal tissues – tracer is metabolized at a
different rate
Examples: thallium scan; bone, brain, thyroid scans
PET and SPECT-– tracers are mapped to
diagnose or assess cancer, heart disease,
lungs, and brain
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DEXA Scan
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Dual Energy X-ray Absortiometry – evaluates
bone density levels
Decrease in bone density is diagnostic proof of
osteoporosis
Osteopenia – bone density loss: indicates risk of
developing osteoporosis over time
Evaluates bone density of the hip – the greater
the mineral density of the bone, the longer the
x-ray image is transmitted, the higher the test
number that is recorded
Density results are compared with standard bone
density tables to determine the presence and/or
level of demineralization
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Patient Recommendations for DEXA
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Women with multiple risk factors for
osteoporosis
Women with long-term estrogen deficiencies
Individuals taking steroids for an extended
period of time
Individuals on osteoporosis medications to
evaluate the effectiveness of treatment
Patients with unexplained fractures and/or
deformities of the vertebra
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
31
Scheduling Diagnostic Imaging
Procedures
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Multiple diagnostic procedures must be scheduled
in a sequence so they do not interfere with one
another.
Recommended sequence order:
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4.
5.
6.
X-ray studies not requiring contrast media and those
using iodine uptake
Fiberoptic studies before those using barium contrast
(colonoscopy before LGI series)
X-rays of urinary tract
X-rays of biliary system
LGI series (barium enema)
UGI series (barium swallow)
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
32
Patient Preparation for Radiography
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Procedure explained to patient, and consent form
signed.
Preparation for chest x-ray examination: undress to
the waist and put on gown; remove all metal objects.
Patient stands at an upright film holder.
UGI series—patient must fast; no water, chewing
gum, or smoking for at least 8 hours before
examination.
LGI series—extensive bowel cleansing; low-residue
or clear liquid diet, forced fluids, cathartics,
suppository, and low-volume enema.
Table 50-3
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
33
Critical Thinking Application
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Mrs. Pellegrini, a 62-year-old diabetic patient,
calls Metro Urgicenter at 8:30 am to confirm
her 10:00 am appointment for an outpatient
imaging procedure that requires fasting.
On speaking with her, Sara discovers
Mrs. Pellegrini has already taken her morning
insulin. Should Mrs. Pellegrini keep her
appointment or be rescheduled? Why or
why not?
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Critical Thinking Application
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Dr. Roberts, a physician at Metro Urgicenter, has
scheduled Mr. Tillman for a barium enema, and
David asks Sara to provide preparation
instructions for the procedure to Mr. Tillman.
What information should Sara obtain from
Mr. Tillman to determine whether the usual bowel
preparation is appropriate? If Sara thinks the
usual preparation might be too harsh for
Mr. Tillman, how should she explain her concern
to David and Dr. Roberts? Who should decide
whether to implement a variation in
protocol—Sara, David, or someone else?
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
35
Radiation Exposure
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Most cellular effects are short-lived.
Sometimes DNA changes occur because of cellular
damage.
Cell sensitivity to radiation exposure is dependent on:
–
age
– differentiation
– metabolic rate
– mitotic rate
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Sensitive cells include blood and bone marrow; skin;
mucosal lining of mouth, nose, and GI tract; thyroid
gland; breast; fetal tissue. Cells in children are
sensitive. Nerve and bone cells are less sensitive.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
36
Effects of Radiation Exposure
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Somatic—occur to the body of the person
exposed
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Low-dose exposure causes long-term effects
Causes increased risk of:
• Cataracts
• Carcinogenesis—skin, thyroid, breast, leukemia
• Shortened life span
• During pregnancy—abortions, congenital defects, genetic
abnormalities
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Genetic—mutations in the hereditary material of
reproductive cells
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May be passed on to future generations
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
37
Pediatric Guidelines
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Provide age-appropriate explanations about the
procedure
Inform parents about the procedure
Provide written instructions about examination
preparation
Permitting parents in x-ray room is up to the facility
Use commercial immobilization devices when
possible
Parent should help maintain positioning when
needed; parent must wear appropriate lead shield
equipment
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
38
Radiation Protection
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Personnel Safety
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Scatter radiation present during x-ray examination
Only time hazard exists is during x-ray examination
Wear lead apron, gloves, and so on
Avoid direct exposure from the primary x-ray beam
Stand well behind the protective lead barrier of
control booth
Close x-ray room door during exposure
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
39
Radiation Protection
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Personnel Safety Continued
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Exposure increases when assisting with
fluoroscopy and using mobile x-ray units
• Dose decreased when time of exposure is minimized
• Increase distance between you and x-ray machine
• Use lead shields—goggles, thyroid shields, and so on
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
40
Personnel Monitoring
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Dosimeter—badge worn that monitors radiation
exposure
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Wear around collar and outside of lead apron
OSL type more accurate
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41
OSL Dosimeter
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
42
Personnel Monitoring
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Monitoring laboratories provide the badges, process
and report results, and keep permanent records of
radiation exposure for each person.
Monthly monitoring recommended for fluoroscopy
workers; quarterly if control booth protection is
consistently used.
Employers required to provide radiation exposure
history to all employees.
Effective Dose Equivalent (EDE) calculates upper
limit of safe occupational exposure (5 rem/year).
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
43
Patient Protection
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Avoid errors.
Avoid repeat exposures because of careless errors.
Collimate.
Use highest kilovolts (kVp) of energy and lowest
milliamperage (mA) to produce best picture.
Use at least 40 inches of source-to-image distance
(SID).
Use fastest films and screens to get a high-quality
image.
Provide shields.
Warn all women of childbearing age of potential risks.
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
44
Critical Thinking Application

Ingrid White is gowned and ready for a
lumbar spine x-ray examination and Sara
asks Ingrid whether there is any possibility
that she might be pregnant. Ingrid confides
that she and her husband have been trying to
conceive for several months, and she is not
sure whether she is currently pregnant. What
should Sara do?
Copyright © 2011, 2007, 2003, 1999 by Saunders, an imprint of Elsevier Inc. All rights reserved.
45
Critical Thinking Application
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One of the new medical assistants at Metro
Urgicenter, Carla O’Neal, tells Sara she is not
qualified to practice radiography in the office’s
jurisdiction. David has instructed her to
position a patient and set up the equipment
for an x-ray examination. When Carla stated
that she was not yet qualified to practice
radiography, David replied, “Don’t worry. I’ll
come by in a few minutes and make the
exposure.” What should Sara and Carla do
about this?
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46