Fluoroscopy Safety
Robert Metzger, Ph.D.
Introduction
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On September 9th, 1994, the FDA issued an advisory for facilities that
use fluoroscopy for invasive procedures. Recommendations….
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Appropriate credentials and training for physicians performing
fluoroscopy
Operators be trained and understand system operation, and
implications of radiation exposure for each mode of operation
Physicians be educated in assessing risks and benefits on a
case-by-case basis for patients
Patients be counseled regarding the symptoms and risks of large
radiation exposures
Physicians justify and limit use of high dose rate modes of
operation
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Who Can Perform Fluoroscopy and
Associated Radiography?
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Most states have regulations regarding the operation of radiation
producing equipment and these regulations vary from state to state.
However, the fact is that many physicians who use fluoroscopy have
essentially no training in this area.
In some states, it may be illegal for an untrained person to operate an
x-ray machine even under the direct orders of a physician.
What should an operator
know?
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How to operate the machine
How to properly position the patient
How to minimize the use of radiation
How the radiation is distributed in the room
How to control the factors that optimize image quality (kVp, mA etc.)
How to control factors that reduce radiation levels (collimation)
How to properly use shielding devices and personnel monitoring
devices
What an operator should
know
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Two professionals trained in specific aspects of fluoroscopy are the
radiological technologist and medical physicist

Physician is ultimately responsible for assuring that the x-rays are
safely and properly applied and that appropriate radiation protection
measures are followed

Nurses or physician assistants should be trained in its safe and
proper operation if asked to operate x-ray equipment
Skin Injuries
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During the application of x-rays, the patient has no sensation of
temperature rise in the skin, even if the patient is fully conscious and
even for all but the most massive doses of radiation
Chronic exposure to low doses can also result in gradual erosion
of tissue
Small doses from modern equipment might induce cancer, but the
frequency of induction would be too low to detect a direct
relationship with x-rays
Potential Effects in Skin in
Fluoroscopy
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays. 1996.
Skin Injuries – Case Reports
Three weeks post rf cardiac catheter ablation
Ischemic dermal necrosis 5 months post procedure
Exposed to 20 minutes fluoro with elbow 2025 cm from focal spot. Note circular pattern
coinciding with x-ray beamport
Suggesting that the 18 Gy threshold was passed
during the procedure
c.f. Koenig TR, et al. Skin Injuries from Fluoroscopically Guided Procedures:
Part 1, Characteristics of Radiation Injury. AJR 2001, 177, pp. 3-11.
Skin Injuries – Case Reports
Skin Injuries – Case Reports
Deep ulceration with exposure of the humerus at 6.5 months post-procedure
Some radiation ulcers never heal completely, but break down intermittently. Progression
of the ulcer may ensue and can be extensive, exposing deep tissues such as tendons,
muscles or bones.
c.f. Koenig TR, et al. Skin Injuries from Fluoroscopically Guided Procedures:
Part 1, Characteristics of Radiation Injury. AJR 2001, 177, pp. 3-11.
Skin Injuries – Case Reports
Three transjugular intrahepatic portosystemic
shunt placements within a week
Non-healing deep tissue necrotic ulcer with
exposure of deep tissues, including spinous
processes of vertebra at 22 mos.
Injuries that are advanced to this stage require surgical
excision and grafting.
At 23 months, musculocutaneous skin grafting was
performed. Disfigurement is permanent.
c.f. Koenig TR, et al. Skin Injuries from Fluoroscopically Guided Procedures:
Part 1, Characteristics of Radiation Injury. AJR 2001, 177, pp. 3-11.
Radiation Injuries of the
Skin
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Many articles in literature about skin injuries (see Koenig manuscript)
Some case reports teach us two important lessons:
 Radiation dermatitis is delayed, from weeks to years after the exposure
 Several procedures can result in very high cumulative doses to the
same area if the skin
 A conscientious effort should be made to avoid prolonged exposure to
the same area of the skin
 Documentation of certain conditions will help physicians if future
procedures are needed
 A careful record identifying the location of the exposed skin will alert
other physicians about the need to avoid irradiation of the same area
 A record of the estimated skin dose is also helpful
Controlling Image Quality, Dose,
and Dose Rate
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The following ten factors are the principal determinants of image
quality, radiation dose rate and total radiation dose to the patient and
to personnel during fluoroscopy → “the Ten Commandments”
 patient size
 tube current (mA) and kVp
 proximity of the x-ray tube to the patient
 proximity of the II to the patient
 image magnification
 x-ray field collimation and use of a grid
 shielding and position of personnel relative to patient and
equipment
 beam-on time
Commandment #1:
Patient Size
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Keep in mind that dose rates are greater and dose accumulates
quicker for larger patients
Commandment #2: Tube
Current (mA)
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Keep the tube current as low as possible
Commandment #3: Tube
Kilovoltage (kVp)
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Keep the kVp as high as possible to achieve the appropriate
compromise between image quality and low patient dose
Commandment #4:
Proximity of x-ray tube
to patient
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Keep the x-ray tube at the maximal “reasonable” distance from the
patient
Commandment #5:
Proximity of the Image
Intensifier to the Patient
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Keep the image intensifier as close to the patient as possible
 To optimize image quality and reduce radiation dose
 Optimize image quality  distortion of anatomy and image blur
decreases
 Radiation Dose decrease  x-ray intensity required to produce a
bright image (automatic brightness control) decreases
Commandment #6:
Image Magnification
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Don’t overuse the magnification mode of operation
 Magnification can be achieved in 2 ways:
 magnification option on the image intensifier
 geometric magnification
(#6) Magnification
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Magnification options of the image intensifier
 This is achieved by making the x-ray field smaller and displaying
the smaller field over the full viewing area of the monitor
 The mode of least magnification (largest field) usually delivers
the lowest dose rate
 Sometimes the dose rate does not change with magnification but
frequently, the dose rate increases with magnification
 To optimize overall radiation management, use the lowest level
of magnification consistent with the goals of the procedure and
reduce the irradiated volume of the patient by employing narrow
collimation
(#6) Magnification
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Geometric Magnification
 Achieved by increasing the distance between the patient and the
image intensifier (contrary to dose reduction method)
 Geometric magnification can be used with isocentric systems
 Dose typically increases with the square of the magnification
 i.e., if magnification increases by 2x, dose rate goes up by 4x
 Maximum dose rates in this configuration may exceed 10 R/min
(legal entrance exposure limit)
 this is because compliance dose rates are tested under
conditions of least geometric magnification (patient closest to
image intensifier)
Again, the minimum magnification consistent with the goals of the
procedure should be used to manage radiation properly
Commandment #7: the
Grid
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Remove the grid during procedures on small patients, thin body
parts or when the image intensifier cannot be placed close to the
patient
Commandment #8: X-ray field
Collimation
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Always use tight collimation
Commandment #9: Distance
Shielding
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Personnel must wear protective aprons, use shielding, monitor their
doses, and know how to position themselves and the imaging
equipment for minimum dose
(#9) Shielding and Distance
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The principal source of radiation for the patient is the x-ray tube
(#9) Shielding and Distance
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The principal source of radiation for the operator and other
personnel is scatter from the patient
(#9) Shielding and Distance
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One of the most important means
by which personnel can reduce
dose to themselves is by using
shielding and properly positioning
themselves relative to the patient
and the fluoroscopic equipment
All personnel who are not
positioned behind a radiation
barrier must wear a lead apron
during a procedure
(#9) Shielding and Distance
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Lead aprons
 lead equivalency: 0.25 mm to 0.50 mm
 0.25 mm: absorbs > 90% of scatter
 0.35 - 0.50 mm: absorbs 95 - 99% of scatter (but heavier)
Lead aprons should be properly stored on a hanger when not in use
Aprons should be checked annually for holes, cracks or other forms
of deterioration
x-ray
(#9) Shielding and Distance
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Aprons do not protect the thyroid gland or the eyes.
 Thyroid shields and leaded glass can be used
 Leaded glass attenuates 30%-70% depending on the content of
lead in glass
 Protective gloves of 0.5 mm lead of greater should be worn if
hands are going to be near the primary beam (false sense of
protection)
Protection of a
Physician’s Hands
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Dermal atrophy of the forearm and hands were observed in
physician who performed fluoroscopy for years Convinced some
physicians to wear special radiation-attenuating surgical gloves or
hand shields Such devices are not likely to protect hands if placed
fully into the beam The automatic brightness control (ABC) detect
the reduction in brightness due to the attenuation by the gloves and
boost the radiation output to penetrate the “protective” gear
Protective hand gear can be relied on only to protect against
radiation outside the field of view of the ABC
Protection of
Physician’s Hands
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To protect hands during fluoroscopy, it is recommended:
 Keep hands out of and away from the x-ray field when the beam
is on unless physician control of invasive devices is requires for
patient care during fluoroscopy
 Work on the exit-beam side of the patient whenever possible
 x-ray tube should be below table for vertical orientations
 for oblique and lateral projections, stand on the side of the
patient where the image intensifier is located
 for adult abdomen, exit radiation is only about 1% the
intensity of the entrance radiation
 extra care must be exercised in situations where physician
must work on the x-ray tube side of the patient
Protection of
Physician’s Hands
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To protect hands during fluoroscopy, it is recommended to:
 wear a ring badge to measure your hand exposure monthly
 ring monitors dose only at the base of the finger
 dose at the finger tips may be significantly higher
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
(#9) Shielding and Distance
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All personnel who perform
fluoroscopic procedures are
required to wear a radiation
monitoring device, usually a film
badge
 Personnel potentially exposed
to 10% of the occupational
annual limit (50 mGy or 5000
mrem) need a radiation badge
It is recommended that personnel
wear their badges anteriorly on
their collar outside of lead apron
Badge readings are monitored by
the radiation safety office (RSO)
(#9) Distance
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Radiation Dose to personnel can be significantly reduced by
increasing their distance from the radiation source
Inverse-square law: the dose rate drops significantly as the distance
from the source increases
Given:
Exposure
Rate at 2 ft
= 90 mR/hr.
(#9) Distance
3 ft
2 ft
1 ft
1 ft
2 ft
3 ft
2 ft
4 ft
6 ft
 D1 
E2  E1  
 D2 
2
Exposure Rate at 4 ft = (90 mR/hr)(2ft/4ft)2 = 22.5 mR/hr.
Exposure Rate at 6 ft = (90 mR/hr)(2ft/6ft)2 = 10 mR/hr.
(#9) Radiation at 1 Meter From
Patient
About 0.1% of patient entrance radiation exposure reaches 1 meter from
patient
1m
x-ray
100%
0.1%
The NCRP recommends that personnel stand at least 2 meters
from the x-ray tube, whenever possible. (6 feet = 1.82 m)
(#9) C-Arm Fluoroscopy
Shielding
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With the C-arm oriented vertically, the x-ray tube should be located
beneath the patient with the II above
In a lateral or oblique orientation, the x-ray tube should be
positioned opposite the area where the operator and other
personnel are working
In other words, the operator and II should be located on the same
side of the patient
 This orientation takes advantage of the patient as a protective
shield
(#9) The Separator Device (or
Spacer Cone)
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The FDA requires that fluoroscopic x-ray machines be designed so that the
patient’s skin is at least a specified fixed distance from the X-ray source
The purpose of this regulation is to prevent the dangerous situation in which
the intense beam emerging from the x-ray source is too close to the
patient’s skin
To provide flexibility for some procedures, the FDA permits machines to be
designed with removable spacers
For Dx procedures, the device is to remain attached to the x-ray source
For modern machines fixed in room, this distance is 38 cm
For mobile machines, this distance is 30 cm
For “special surgical procedures” the device may be removed and the minimum
distance can be as short as 20 cm (potentially dangerous)
(#9) The Separator Device (or
Spacer Cone)
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
Commandment #10: Beam OnTime
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Keep beam-on time to an absolute minimum! - The Golden Rule
Control over beam on-time is almost always the most important aspect of
radiation management It is essential practice to disengage fluoroscopic
exposure when the image on the monitor is not being used
Absentmindedly leaving the x-rays on while viewing other factors
associated with the procedure, such as direct observation of the patient
or communication with other personnel in the room, must be strictly
avoided
Fluoroscopic Timer
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A 5-minute cumulative timer is required on all fluoroscopic units to
remind the operator audibly of each 5-minute time interval and to
allow the technologist to keep track of the total amount of fluoro time
for the exam
Good Vs. Bad Geometry:
Patient Dose and the Position
of the Fluoroscope
the Good
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
the Bad
Good Vs. Bad Geometry:
Patient Dose and the Position
of the Fluoroscope
the Ugly
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
even Uglier
Good Vs. Bad Geometry:
Summary
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Differences in geometry of as little as a few centimeters can have a major
impact on dose to a patient’s skin
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
Good Vs. Bad Geometry:
Patient Dose and Physician
Height
No invasive devices present
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
Invasive devices present
Good Vs. Bad Geometry:
Patient Dose and Physician
Height
30% dose reduction
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
Good Vs. Bad Geometry:
Patient Dose and Invasive
Devices
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In many invasive procedures, syringes, catheters, or other devices may be
protruding from the patient With the patient prone on the procedure table,
some distance must be maintained between the patient and the image
intensifier to provide adequate working space In oblique orientations it is
necessary to move the image intensifier to a position that avoids collisions
with the patient and the invasive devices This may place severe constraint
on how far the x-ray tube can be positioned from the patient For larger
patients, the port of the x-ray tube may actually come into contact with the
patient’s skin Extreme caution is advised in these situations to reduce the
potential of inducing skin burns
Good Vs. Bad Geometry: Invasive
Devices and Personnel vs. Patient
Dose
c.f. Wagner and Archer. Minimizing Risks from
Fluoroscopic X-rays – Supplement 1. 1997.
Good vs. Bad Geometry:
Recommendations on Managing
Risks from Geometry
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Attach the separator cone to the port if at all possible
Move the x-ray tube away from the skin as far as practicable
Move the image intensifier as close to the patient as possible
Keep the beam-on time of the study as short as possible
If the image contrast is not affected, remove the grid
Routinely keep hands away from the imaged area and outside the housing
of the image intensifier
Use collimation to control image quality and reduce scatter
Monitor hand dose
Step back from the patient before engaging fluoroscopy
Use a transparent shield for the head and neck if the x-ray tube is above the
patient
Have assistants use extra shielding or stand well back from the patient if
tube is above patient
Good vs. Bad Geometry: Where
Do Stand When Using a C-Arm?
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When using lateral and oblique projections, the scatter radiation and the
primary beam are least intense on the exit beam side (image intensifier
side) of the patient
 For example, in the lateral orientation scatter is about 3 to 10x greater
on the x-ray tube side than on the image intensifier side, depending on
patient size and section of body irradiated
In many situations, it is required that the physician work on the x-ray tube
side
 For example, cardiologists work in a bi-plane configuration and stand
next to the laterally projecting x-ray tube located on the right side of the
patient, left side of cardiologist exposed
 lead aprons and ceiling suspended radiation shields should be used to
reduce exposure to the head and neck
 radiation badge should be worn on the left side
Cataracts
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Cataracts are a potential risk for patients undergoing high-dose
interventional procedures in the head
The threshold for radiation-induced cataract is about 1 Gy
To reduce the potential for cataracts:
 for lateral orientation of the tube, the eyes can be shielded on the
lateral side by using tight collimation to shield a large portion of
the orbit that is closest to the x-ray tube
 the frontal view should be performed with the x-ray tube posterior
to the head and the image intensifier anterior. This ensures that
the eyes receive only the much reduced exit beam dose and not
the much higher entrance dose
http://www.optometry.co.uk/articles/20010406/brown.pdf
Thoracic Fluoroscopy in Women
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Breast cancer has been induced in women who
underwent thoracic fluoroscopic evaluation for the
treatment of tuberculosis
These women, for the most part, were positioned
with their breasts facing the x-ray tube
This might occur with today’s procedures if the xray c-arm is oriented for an oblique view through
the thorax, perhaps to view the spine
 breast could get exposed to high x-ray
intensities
It may be reasonable to turn the c-arm over so
that the x-ray tube is above the back of the prone
patient
 breast would receive only the reduced exit
dose
Position the beam so that the breast is not in
direct line with the x-rays or consider using tape
or bandages to move some of the breast out of
the direct x-ray beam
http://www.xray.hmc.psu.edu/rci/ss1/ss1_4.html
Dose Reduction by Heavy
Filtration
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Some modern fluoroscopy units now provide options for heavy x-ray
beam filtration under some conditions (e.g., Philips ‘Spectrabeam’)
 this filtration more effectively removes non-penetrating, doseenhancing, low-energy x-rays than does conventional filtration
 this results in reduced patient x-ray exposure
 this heavy filtration typically consists of thin plates of copper
inserted at the window of the x-ray source
To be effective, the tube current must be set very high
The physician should be aware that the equipment has this special
feature and know when it is engaged so that unnecessary concerns
over high tube currents can be avoided
Other Factors
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Use modes of operation such as pulsed fluoro (30, 15, 7.5 and 3.75
pulses per second) which reduce dose dramatically over continuous
fluoro techniques
Try to avoid long exposure time to same skin area
Don’t allow any extraneous body parts in the beam
Real-time dose monitoring is now standard on most newer
fluoroscopic/angio/interventional systems
Try to avoid high skin dose modes of operation such as cine, highlevel control if possible
Conclusions
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Be smart about radiation and use common sense
Keep the beam-on time to a minimum
Consciously and conscientiously practice ALARA
Apply the risk-reducing factors (“the Ten Commandments”)
discussed herein for the patient’s safety as well as your own