Fluoroscopy Credentialing
William Robeson, Radiation Safety Officer
North Shore University Hospital
Radiology/Radiation Safety Office
(516) 562- 3895
Presentation created by: Miyuki Yoshida-Hay
Objectives
The Joint Commission accreditation requires
physicians who use or operate fluoroscopic x-ray
systems be properly credentialed. This training shall
include radiation safety, management of fluoroscopic
radiation and operation of fluoroscopic x-ray
system(s) used by the physician. Training in radiation
safety and fluoroscopic radiation management is in
addition to any clinical training or qualifications
required to perform the specific clinical diagnostic or
therapeutic procedures for which the fluoroscopic
systems are used.
Credentialing Requirements
The hospital requires documentation of appropriate training
before granting fluoroscopic privileges.
In order to become credentialed, a physician must do the
following:
– View this powerpoint presentation
– Complete the self-assessment quiz
– Upon completing the training, each physician will need to
complete an attestation. The attestation certificate is
available for printing.
– Present this certificate to the department chairperson for
recording the successful completion of the fluoroscopy
safety requirement.
It is up to the each department to establish other training and
education requirements needed to obtain fluoroscopy
privileges.
TOPICS
X-ray Production
Units of Radiation Exposure and Absorbed Dose
Dose Equivalent and Effective Dose Equivalent
Mobile C-arms
Factors Influencing Fluoroscopy Exposure Rate
Sources of Radiation Exposure
Radiation Protection
Personnel Monitoring
Basic Radiation Biology
Example of a Skin Injury from Fluoroscopy
Radiation and Pregnancy
Summary
X-ray Production
X-rays are produced in an x-ray tube when electrons are
accelerated through a high voltage (50,000 – 150,000 volts or
50 - 150 kVp) and allowed to hit a target composed of high
atomic number materials such as tungsten.
X-ray Production (cont.)
Electrons are released from an electrically heated filament and are
accelerated to the target by the high voltage. This flow of electrons
from the filament to the target is known as the tube current (mA).
Fluoroscopy is usually performed using 2 to 6 (mA) and an
accelerating voltage of 75 to 125 kVp.
The amount of x-rays produced is determined by the tube current
(mA) and the high voltage (kVp). X-ray production is directly
proportional to the tube current therefore doubling the tube current
(mA) doubles the # of x-rays produced at a particular kVp.
However, x-ray production increases more rapidly with kVp than mA
therefore increasing the kVp by 15% is equivalent to doubling the
mA.
NOTE: Higher kVp values also provides a more penetrating
x-ray beam
Units of Radiation Exposure & Absorbed Dose
Exposure
– The quantity of x-rays or
gamma radiation required to
produce an amount of
ionization (electric charge) in
air at standard temperature
and pressure
– Units: Roentgen (R)
– 1R = 2.58x10-4 C/kg
(coulombs/kilogram)
– Usually expressed in terms
of exposure rate: i.e., R/hr or
fluoroscopy output
measured as R/min.
Absorbed Dose
– The amount of ionizing
radiation energy absorbed
per unit mass of tissue.
– Units: rad (radiation absorbed dose)
1 rad = 0.01 Joules/kg
1 rad = 0.01 Gray
– For x-rays used in
fluoroscopy an exposure of
1R results in an absorbed
dose of approximately 1 rad.
Dose Equivalent and Effective Dose Equivalent
Dose Equivalent
– Used to account for differences in the biological effectiveness of
different types of ionizing radiation.
– Defined as (the absorbed dose) x (radiation quality factor) specific to the
type of radiation to which an individual was exposed.
– Units: rem (roentgen equivalent in man)
or Sievert (Sv): 1 Sv = 100 rem
– For diagnostic medical x-rays the quality factor is 1, therefore an
absorbed dose of 1 rad is equal to a dose equivalent of 1 rem
Effective Dose Equivalent (EDE)
– The risk of potential health effects when only part of the body is
irradiated is smaller than when the whole body is exposed.
– The EDE is a calculation of risk to an individual posed by a partial body
irradiation.
– The EDE is also used to estimate the equivalent whole body exposure
for fluoroscopy staff wearing protective aprons for comparison to annual
personnel dose limits for radiation exposure
Mobile C-arms
Moved around ORs to visualize anatomy during
surgery
Metallic c-arm contains x-ray tube at one end and
image receptor at the other
An associated unit contains the display
Factors Influencing Fluoroscopy
Exposure Rate
Modern fluoroscopy units produce images with an image
intensifier (II) which brightens the image level sufficiently
so that the image may be displayed on a TV screen.
Fluoroscopy units are usually operated in an automatic
brightness control (ABC) mode.
These units will automatically adjust the brightness by
first increasing the kVp to increase x-ray penetration and
then adjusts the mA to increase intensity.
Note: Exposure to a thick patient will be greater than to a thin
patient and also abdominal fluoro will require a greater exposure
than a chest fluoro due to increased thickness and tissue density in
the abdomen.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 1: The image intensifier input should
be positioned as close to the patient as practicable.
This results in a lower patient dose and sharper image.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 2: Use the exposure pedal as
sparingly as possible.
Radiation exposure during fluoroscopy is also directly proportional to the
length of time the unit is activated by the foot pedal. Depression of the
foot pedal determines the length of exposure. The fluoroscopy time is an
important determinant of patient and staff radiation dose. Fluoroscopy
units are equipped with a timer and an alarm which sounds at the end of
5 minutes. The alarm serves as a reminder of the elapsed time.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 3: Use “last-image” hold and
pulsed fluoro whenever possible.
Most modern fluoro units are equipped with “last-image” hold, which
stores the last fluoro image and allows viewing without having to expose
the patient again. Many fluoro units also offer a “pulsed fluoro mode”, in
which the x-ray beam is pulsed rapidly on and off and results in a lower
radiation dose without significantly degrading the appearance of the
image on the display.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 4: Use the smallest field of view
practicable.
Radiation exposure also depends on x-ray field size and keeping the x-ray field
as small as possible (by using collimators) which will decrease the dose to
BOTH the patient and staff in the fluoroscopy suite. Restricting the field size not
only decreases radiation dose but will also produce a better image. The
contrast in the image between various tissue types will be greater for the
smallest field of view that encompasses the desired anatomy.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 5: High dose or detail modes
should be used only sparingly.
Many fluoro units will have various dose modes, such as low dose,
medium dose and high dose mode.
It is important to recognize that fluoroscopic image quality can be
adversely affected by too few x-rays in the image; the image is noisy for
low dose. More tissue contrast is produced by the “high dose” mode
which will improve the image quality at the expense however of
increased patient dose.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 6: Magnification should be used
only when necessary.
Fluoroscopy units are capable of using different magnification modes.
Image resolution is improved with magnification but field size is reduced
and patient radiation dose is increased. Patient dose is minimized by
using the lowest magnification (largest field size) appropriate for the
image procedure being performed.
Under Normal mode, there is little magnification with
the whole beam used to generate a bright image.
Under Mag 1 mode, a smaller beam area is projected to
the same II output. The resulting object size is larger,
but the image is dimmer due to the less beam input.
The ABC system senses the brightness loss and either
boosts machine X-ray output, increases tube voltage, or
a combination of both.
6 inch mag FOV increases dose by a factor of 4 over non-mag image
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
Recommendation # 7: For C-arm type fluoroscopy
units the patient should be positioned as far from the
x-ray tube as practicable to minimize patient entrance
dose. To reduce personnel exposure the x-ray tube
should be positioned beneath the patient.
In the case of portable C-Arm systems, eliminating the air gap
between the I-I and the patient ensures that the table top is as far
away as possible from the X-ray tube, minimizing radiation
exposure to the patient’s skin.
Note: The separator cone should always be utilized before
commencing fluoroscopy on portable C-arm systems, as depicted
below on the image at right.
Factors Influencing Fluoroscopy
Exposure Rate (cont.)
In conventional under-table x-ray tube fluoroscopic units, the x-ray tube
is located at a fixed distance from the patient’s skin.
In C-arm fluoroscopy, where the distance between the x-ray tube and
image intensifier is fixed, the patient can be positioned in close proximity
to the x-ray tube which increases the entrance skin dose and reduces
image sharpness.
It is preferable to locate the C-arm x-ray tube underneath the patient.
Since the radiation transmitted through the patient is typically only 5 –
10 % of the entrance dose, inadvertent exposure to the operator hand
on the exit side of the patient will result in a smaller dose compared to
the dose to the hand on the entrance side of the patient. Also the
amount of scatter radiation the operator is exposed to on the beam exit
side of the patient is significantly less than on the beam entrance side.
X-ray
tube
X-ray
tube
Sorenson, 2000.
Note: The benefit is exaggerated - some operator dose occurs on the image
intensifier (I-I) side.
Sorenson, 2000.
Care should be taken whenever the image view angle is changed during the
procedure (e.g, changing from an ANT to a steep LAO).
The I-I is often moved away from the patient while changing X-ray tube position.
Large air gaps can result if the table or I-I height remains unadjusted.
Sources of Radiation Exposure
DIRECT EXPOSURE
– Entrance Skin Exposure (ESE) rates (where the x-rays enter the
patient) are limited to less than 10 R/minute
(NOTE: At ESE rates of 10 R/min, 30 minutes of fluoroscopy can
deliver 300 R in skin dose.)
– ESE rates for typical fluoroscopy procedures are usually less than 5
R/min.
– On some machines an operator can deliberately choose a setting
that will increase the output. The use of higher radiation rates or
"boost" modes are useful in situations requiring high video image
resolution. ESE of up to 20 R/min is permitted for short duration.
Special operator reminders, such as audible alarms, are activated
during "boost" modes.
Sources of Radiation Exposure
SCATTER EXPOSURE TO
PERSONNEL
– Most of the radiation exposure
received by the operator or other
personnel in the fluoroscopy suite
is due to scatter radiation from the
patient.
– The operator will be exposed to a
dose rate of approximately one
one-thousandth (1/1000) of the
ESE rate at a distance of 1 meter
from the center of the fluoroscopy
field.
Sorenson, 2000.
Sources of Radiation Exposure
Factors which increase the dose from scatter
radiation:
– Large patients which will cause the automatic
brightness control (ABC) to adjust the kVp and mA to
higher values causing greater amounts of scatter
radiation.
– A large x-ray field, a result of not restricting field size will
increase scatter radiation
– The length of time the fluoroscopy unit is on. Complex
interventional cases will require greater procedure time,
increasing dose to both the patient and operator
Sources of Radiation Exposure
Other sources of exposure to the operator
may be associated with the following:
– A small percentage of exposure to the operator may
be due to leakage radiation through the x-ray tube
housing.
– C-arm operators should be aware that the shielding
built in to “fixed” fluoroscopy systems is not available
for protection against backscatter. This may be of
greater concern if the C-arm is rotated out of the
normal vertical plane.
Radiation Protection
The three most productive means of reducing
radiation dose is:
– Time:
Minimize time spent in the radiation field.
Use of “last-image-hold” and pulse fluoro features
are technical advantages in reducing the total time
x-rays are produced
– Distance: Radiation dose rates increase or decrease
according to the inverse square law
Ex: Double your distance from the source and
decrease your exposure by a factor of 4
– Shielding: Use of lead garments, lead gloves, thyroid
shields, leaded eyeglasses, lead drapes and
clear leaded glass barriers between the patient
and operator
PPE and Radiation Monitoring
Sorenson, 2000.
Personnel Monitoring
Even when radiation protection techniques and
engineering controls are in place to reduce personnel
exposure, individual dose monitoring is required.
Various types of dosimeters are available (i.e., film
badges, thermo-luminescent (TLD) and opticallystimulated luminescent (OSL) badges).
Badges are assigned to an individual and must never be
shared.
A badge designed to measure the whole body (torso
including head) should be worn at the collar – OUTSIDE
the lead apron.
Monthly Investigational Levels (mrems)
Level I
Level II
Body Badge (DDE)
50
150
Collar Badge
150
450
Eye (LDE)
150
450
Ring/Wrist (SDE)
or Extremity
500
1,500
DDE = Deep Dose Equivalent
LDE = Lens Dose Equivalent
SDE = Shallow Dose Equivalent
Monthly Investigational Levels
Level I: Each incident will be noted on the personnel
badge report by the Radiation Safety Office. A
notification letter is sent to the employee.
Level II: The Radiation Safety Office will investigate
each such incident. A report will be generated and the
results of each investigation will be presented to the
hospital radiation safety committee.
Physicians performing fluoroscopy that receive Level II
collar badge readings will get a notification letter that
includes their effective dose.
Personnel Monitoring (cont.)
The effective dose equivalent (EDE) may be
calculated in the following manner:
– A two-badge system (waist and collar badges) is used to calculate
an individual’s EDE by taking into account the protective factor of
the lead apron. In this situation, one badge is worn OUTSIDE the
lead apron (collar) and a second badge is worn UNDERNEATH the
lead apron (waist). The EDE is calculated as follows:
EDE = [1.5 x (waist)] + [0.04 x (collar)]
– A one-badge system (collar badge ONLY) is where one badge is
worn on the OUTSIDE of the lead apron. The EDE is calculated as
follows:
EDE = [0.3 x (collar)]
Personnel Monitoring
(cont.)
Dosimeters must be promptly turned in and exchanged each month
to give accurate assessments.
Badge reports are reviewed by the Radiation Safety Office.
Notification letters are sent to individuals who exceed monthly
“Level I” exposure limits. Investigational letters are sent to those
who exceed monthly “Level II” exposures limits. A written response
to the letter is required, which includes an acknowledgement and
an explanation of the Level II exposure, if known. The letter is to be
returned to the Radiation Safety Office within one week of receipt.
Copies of badge reports (3 months) must be posted in each
department for individuals to review.
Badges are susceptible to heat and moisture damage. Badges not
in use should be stored in a cool, dry place, away from any sources
of radiation. Do not take dosimeters home or travel on a plane with
a dosimeter or wear a dosimeter during a medical radiological
procedure.
OCCUPATIONAL DOSE LIMITS
(NRC)
RADIATION WORKERS
ANNUAL LIMIT
Whole Body
Lens of the Eye
Skin, extremities
5,000 mrem
15,000 mrem
50,000 mrem
Embryo/Fetus
500 mrem gestation
50 mrem/month
For hospital radiation workers, annual doses rarely exceed
10 % of these values.
Basic Radiation Biology
X-rays from fluoroscopy interact with biological materials
by transferring their energy to an electron which
subsequently interacts with the target molecule to
produce an ion or a free radical.
Indirect action is the creation of free radicals from
interactions with water molecules. Free radicals may
then chemically interact with biologically sensitive
molecules (DNA, RNA, proteins) causing damage
Direct action is the interaction of ionizing radiation with
biologically sensitive molecules such as DNA causing
direct destruction or mutation
Since water molecules are much more numerous than
biologically sensitive molecules, indirect action is the
most common form of biological damage.
Basic Radiation Biology (cont.)
Cells can sustain a variable amount of radiation
and still repair themselves from sub-lethal
damage.
Continuous high intensity radiation will produce
greater damage than an equivalent fractionated
(multiple smaller) dose since fractionation allows
for cell repair.
Basic Radiation Biology (cont.)
A given organ’s response to radiation depends on:
–
–
–
–
–
Total dose
Dose rate
Fractionated scheme
Volume of irradiated tissue
Inherent tissue radiation sensitivity
A large total dose, high dose rate and small fractionated
schedule (which is all possible in fluoroscopy) will cause
a greater degree of damage.
Major concern in fluoroscopy is the possibility of acute,
direct or deterministic, radiation damage which manifests
as a skin injury. The severity of skin injury is dosedependent; more dose means more severe symptoms
FDA Specification of Radiation-Induced Skin Injuries
Threshold Dose
Typical Fluoro-On Time in Minutes
Skin Effect
rem
Sv
Normal mode @
10 R/min
High Dose mode @
20 R/min
Time to
Onset
Early Transient
Erythema
200
2
20 minutes
10 minutes
Hours
Temporary
Epilation
300
3
30 minutes
15 minutes
20 days
Basal Cell
Erythema
600
6
60 minutes
30 minutes
10 days
Permanent
Epilation
700
7
70 minutes
35 minutes
20 days
Dry
Desquamation
1000
10
100 minutes
50 minutes
30 days
Note that the time to expression of symptoms is long enough that the patient
may no longer be in the hospital when symptoms appear. The physician
performing the fluoroscopy cannot discern the damage by observing the patient
immediately following the procedure.
Basic Radiation Biology (cont.)
These threshold doses to cause an effect cannot
be considered exact due to many variables such as
individual biological response, age, characteristics
of the individual exposed and the area exposed.
A patient may exceed the threshold dose without
showing symptoms. This may be due to:
– The x-ray beam may not have been concentrated on a
single area of the skin for the entire time and because 10
R/min or 20 R/min are maximum outputs for very thick
patients.
Example of a Skin Injury from
Fluoroscopy
This case, patient A is that of a 40year-old male who underwent
coronary angiography, coronary
angioplasty and a second
angiography procedure due to
complications, followed by a
coronary artery by-pass graft, all on
March 29, 1990. The area of injury
six to eight weeks following the
procedures. The injury was
described as "turning red about one
month after the procedure and
peeling a week later."
Example of a Skin Injury from
Fluoroscopy (cont.)
In mid-May 1990, it
had the appearance of
a second-degree burn.
The condition in late
summer 1990, exact
date unknown, with
the appearance of a
healed burn, except
for a small ulcerated
area present near the
center.
Example of a Skin Injury from
Fluoroscopy (cont.)
Skin
breakdown
continued
over the
following
months with
progressive
necrosis.
Example of a Skin Injury from
Fluoroscopy (cont.)
The injury eventually
required a skin graft.
The magnitude of the
skin dose received by
this patient is not known.
However, from the
nature of the injury, it is
probable that the dose
exceeded 20 Gy.
Wagner LK, Eifel PJ, Geise RA. Potential
Biological Effects Following High X-ray Dose
Interventional Procedures. JVIR 1994; 5:71-8
Deterministic Effects
Threshold dose below which no effect is observed
Severity increases with dose
Examples: skin erythema, dermatitis, desquamation
cataracts
Stochastic Effects
Incidence increases with dose
No dose threshold assumed
Basis for ALARA principle of radiation protection
Example: cancer
Pregnancy and Radiation
The decision to perform a radiological procedure on a
patient who may be pregnant is a medical decision and
shall be made by a physician in consultation with the
patient. If the procedure is to be performed, the
physician must explain the risks to the patient, provide
informed consent and the appropriate consent form shall
be signed.
Shielding shall be used to shield the abdomen from
radiation provided it does not interfere with the
procedure.
Every attempt must be made to minimize direct exposure
to the fetus according to the principles described in this
presentation.
Medical emergency radiological procedures however
take precedence over pregnancy status.
Principles for Fluoroscopy
PAUSE to properly plan and prepare for study
 Activate dose saving features of equipment
 No exposures unless necessary
 Depress last image hold and last image grab instead
 PULSE at lowest possible rate
PAUSE:
Clinical indication, appropriateness of study, questions to be answered,
unusual anatomy or prior surgery, and type of study to be performed
should be clarified as much as possible. Explain procedure, risks and
required immobilization to patient &/or parents, a cooperative and helpful
patient &/or parent can greatly shorten study and exposure. Ensure that
fluoroscopic protective lead barriers on the tower unit are in place and
place upper and lower lead shields under the patient as appropriate.
PULSE
COLLIMATE / NO MAGNIFICATION: Bring the image intensifier tower as close
as possible to the patient. Preset the collimators to the likely field of view
and position the unit over the anatomic location of interest prior to
beginning fluoroscopy
STEP LIGHTLY: Step lightly on the fluoroscopy pedal. Hand or foot controls,
intermittent visualization only as needed. Most images obtained during the
study can be screen saves without any additional radiation. If more detail is
needed some images can be camera spots with no need for cine or
cassette film images.
FLUOROSCOPY TIME: Check fluoroscopic time used, document time/dose
information as per the policy of hospital/ department
Radiation Safety Officer
Any institution that uses radiation for diagnostic
and/or therapeutic purposes must name a
radiation expert as their Radiation Safety Officer
(RSO). This individual is responsible for the
day-to-day safe use of radiation at the
institution.
Find out who is the RSO at your facility and
don’t hesitate to contact the Radiation Safety
Officer with any questions you may have.
Quiz
1.
2.
3.
Which parameter effects the penetration of an x-ray beam through
a patient?
a) kVp
b) mA
c) Both
Automatic brightness control (ABC) _______ the quantity of
radiation for large patients
a) Increases
b) Decreases
c) Has no effect
Correct fluoroscopy technique requires which of the following to be
close to the patient:
a) X-ray tube
b) Image intensifier
c) Does not matter
Quiz
4.
Which of the following reduces patient dose?
a) Last image hold
b) Pulsed fluoroscopy
c) Both of the above
5.
Which of the following is better technique to reduce patient
dose?
a) Use of collimation
b) Use of magnification mode
c) Neither has an effect on dose
6.
For c-arm fluoroscopy, which is better?
a) Position x-ray tube under table
b) Position x-ray tube over table
c) It does not matter
Quiz
7.
When wearing a single radiation badge during a fluoroscopy
procedure, it must be worn:
a) Attached to the thyroid collar
b) Underneath the lead apron at the waist
c) There is no need for radiation badges in fluoroscopy
8.
The biggest concern for patients receiving high dose fluoroscopy is:
a) Skin damage
b) Cancer induction
c) Both concerns are equal
9.
Fluoroscopy procedures should never be performed on a pregnant
woman.
a) True
b) False
Quiz
10. The most productive means of reducing radiation exposure during
fluoroscopy is:
a) Wearing lead garments
b) Reducing fluoroscopy time
c) Both of the above
Answers
1
2
3
4
5
a
a
b
c
a
6
7
8
9
10
a
a
a
b
c
PHYSICIAN ATTESTATION (Fluoroscopy Credentialing)
I have read the material on radiation safety and fluoroscopy and understand the operation
and radiation safety features of the fluoroscopic units that I will use.
Print Name __________________________
Signature_________________________________ Date________________
Hospital Affiliation: _______________________ Dept__________________
The information presented in this training document is designed to give a practitioner a
basic knowledge of radiation safety principles as they apply to the use of fluoroscopy. The
practitioner in addition must have knowledge and experience in the use of the specific
radiographic systems that they will perform procedures with.
This attestation must be presented to and filed with the department chairman who
privileges physicians to perform specific fluoroscopic procedures. The responsibility for
delineation of clinical privileges ultimately lies with the department chairman.
This certificate expires two (2) years from the date above.