This document summarizes techniques to reduce radiation dose in diagnostic radiology, including fluoroscopy. It discusses using the smallest x-ray field, increasing distance between the patient and x-ray source, using filters, grids, and intensifying screens. It also covers automatic processing, avoiding unnecessary repeat images, and techniques to reduce dose in fluoroscopy like intermittent exposure, removal of grids, and last image hold. The document emphasizes training operators and using radiation only when necessary to obtain diagnostic information.

1. Supervising Faculty:
Dr. Vishal Gupta,
Professor
Mentor:
Dr. Amit Mishra,
Senior Resident
Presented By:
Dr. Tarun Goyal,
PG 1
School Of Medical Sciences
and Research, Greater Noida,

2. Conventional Radiography is the use of X-Rays to visualize the
internal structures of a patient. X-Rays are a form of electromagnetic
radiation, produced by an X-Ray tube. The X-Rays are passed
through the body and captured behind the patient by a detector;
film sensitive to X-Rays or a digital detector.
Fluoroscopy is an imaging modality that uses X-Rays to allow
real-time visualization of body structures. During fluoroscopy, X-Ray
beams are continually emitted and captured on a screen, producing
a real-time, dynamic image. This allows for dynamic assessment of
anatomy and function.

3. History Talks About It….
• 1895: Discovery of X-Rays by Roentgen
• 1896: First biological effects in the form of skin
burns, hair loss were noticed
• 1911: Leukemia in 5 radiation workers
• 1915: British Roentgen Society introduced
proposal for radiation protection
• 1927: First observations on mutations by X-Rays in
Drosophila- fruit fly

4. UNIT EQUIVALENT
REM (Roentgen Equivalent
Man)
REM = RAD x Q Factor
Sievert (Sv) 1 Sv = 100 rem
Sv = Gy x Q
RAD (radiation absorbed
dose
1 RAD = 100
erg/gram
Gray (Gy) 1 Gy = 100 rad
Curie (Ci) 1 Ci = 37 billion dps = 37
billion Bq
Becquerel's (Bq) 1 Bq = 27 picoCi
Disintegrations per second
(dps)
1 dps = 1 Bq

5. OBJECTIVE OF REDUCTION OF DOSE……
ALARA
PRINCIPLE
(As Low As
Reasonably
Achievable)
WITH LEAST
POSSIBLE
DOSE OF
RADIATION
TRY TO GET A
DEATILED,
SHARP
IMAGE

6. Reduction of Patient Dose in
Diagnostic Radiology
• Avoidance of unnecessary dose
• Size of X-ray Field
• Distance from the Focal Spot to the Skin or Image Receptor
• Total Filtration in the X-ray Beam
• Grids
• Standby Radiation
• Control of Irradiating and Recording of Irradiating Time
• Intensifying Screen and Radiographic Films
• Radiographic Film Processing
• Reduction in Number of Repeat Irradiations
• Fluoroscopy

7.  Basic principle of as low as reasonably achievable’,
economic and social factors being taken into account should
always apply.
 No excuse for X-Ray examination to be carried out again
and again with unnecessarily high doses.
 Factors leading to reduction of radiation include the
elimination of radiation not contributing to the formation
of the useful image and the correct choice of a sensitive
image receptor suitable for the diagnostic requirements of
a particular case.

8. It is necessary to:
1. Reduce the absorbed doses received by tissues in the
region of the body under examination to the minimum
compatible with obtaining the necessary information for
the particular patient
2. Limits as far as is practicable the irradiation of other parts
of the body.
3. Reduce the frequency of unnecessary repeat irradiation.
4. If another modality without involving radiation can be
used for assessment of disease with comparable accuracy
it should be preferred over X-Rays.

9. • Use of the smallest practicable
x-ray field and it’s accurate
positioning on the patient.
• It reduces the total radiation
energy delivered to the patient
and therefore the mass of the
skin and internal tissues
irradiated.
• Beam limiting devices such as
collimators and beam restrictors
are available which automatically
restrict the x-ray beam to the size
of the radiographic cassette
employed in the x-ray equipment.

10.  Simply moving the x-ray
source further from the patient
the exposure is decreased by
virtue of the inverse square law.
 However, to obtain a desired
radiographic image, the amount
of radiation striking the image
receptor must be the same no
matter at what distance the
source is positioned. The mAs
must be increased accordingly
to maintain a constant
exposure.
The objective of greater SSD's is to
obtain the "skin sparing" effect

11. Two related advantages of SSD are:
1. The "unsharpness" of the image is reduced due to a smaller
penumbra at the larger SSD
2. The magnification of the image at the image receptor is
reduced which is desirable for most diagnostic procedures
since the radiographer wants to see pathology of actual size
for proper comparison to other internal structures.
 Radiography and fluoroscopy with mobile x-ray equipment,
the focal spot-to-skin distance should not be less than 30cm
whereas in stationary distance should not be less than 45cm.
longer focal spot-to-image receptor distances have clinical
advantages; Photofluorography and radiography of the chest
should be performed with a focal spot-to-image receptor
distance of at least 120cm.

12. Typical Exposure Pattern (Depth Dose Curves)
for an X-Ray Beam Passing through a Patient's
Body
Factors That Affect Patient Exposure in a
Radiographic Procedure
As the x-ray beam progresses through the body, it undergoes attenuation. The rate
of attenuation (or penetration) is determined by the photon-energy spectrum (KV
and filtration) and the type of tissue (fat, muscle, bone) through which the beam
passes.

13. • Absorbs the low
energy beam
which otherwise
would be
absorbed mostly
in the patient and
add little value to
the diagnostic
information on
the image.

14. Inherent Filters Added Filters / Compound
Filters.
1. Abortion of low energy photons
by the X-Ray tube components
itself
2. Glass Housing, Metal enclosure
and assembly oil are
responsible.
3. It is measured in ALUMINIUM
EQUIVQLENT which lies
between 0.5 to 1.00mm
4. Disadvantage is that it causes a
significant reduction in the
image contrast.
1. Any beam absorber which is
placed in the path of the X-Ray
beam, this absorber absorbs the
low or high energy photons.
2. Always use added filters
mostly in a group of Aluminum,
13 ( facing patient) + Copper, 29
(facing tube).
3. Patient radiation dose as well as
the image contrast is reduced.
4. Disadvantage is that it increases
the tube loading.

15. Grids are placed between the
patient and the x-ray film to
reduce the scattered radiation.
Consists of Lead Interspacing
aligned with geometry of X-Ray
beam particular for the tube.
The interspaces between lead
strips are made up of Al.
Grids were invented by Dr.
GUSTAVE BUCKY in 1913
The overall reduction of
absorbed dose in the skin of the
patient facing the x-ray tube,
from the combined use of
carbon fiber in patient supports,
anti-scatter grids and
radiographic cassettes, is in the
range of about 30% to more than
50%.

16. Ratio of the incident
radiation falling on the
grid to the transmitted
radiation passing through
the grid.
It indicates how much
we should increase or
decrease the factors
when doing X-Rays with
or without grid.

17. Radiation emitted from the x-ray
tube when the exposure switch or
timer is not activated shall not
exceed a rate of 0.03 mili
roentgens in one minute at 5
centimeters from any accessible
surface of the diagnostic source
assembly
Radiation discharged through
the X-Ray tube will not exceed
100 mR in 1 hour at 100 cm
from the x-ray source.
Applies to any capacitor
energy storage in
diagnostic X-Ray system
with full open Beam
Limiting Device.

18. • Operating switches should be constructed in a way that they
can be terminated manually whenever needed.
• In fluoroscopy, operator should be aware of the irradiation
time, hence it should be fitted with integrated timer which
terminates the irradiation after a pre-set time has elapsed
with an alarm.
• The recording of irradiation time in fluoroscopy is useful in
reminding operators that they should keep fluoroscopy time
to a minimum.

19. They contain high-efficiency phosphorescent materials,
such as rare earth, barium and tantalum, require less
radiation than conventional intensifying screens to
produce radiographs with similar image quality
USING INTENSIFYING SCREENS REDUCES THE DOSE
REQUIRED FOR AN EXAMINATION, WHICH CAN RESULT IN
SHORTER EXPOSURE TIMES AND HENCE LESS MOVEMENT
UNSHARPNESS.

20. Correct processing techniques are necessary to give
reproducible radiographs of optimum diagnostic value
with minimum dose to the patient.
Improper processing techniques can easily result in a
doubling of the dose required to produce a satisfactory
radiograph.
With automatic processing, QUALITY CONTROL is
particularly important.

21. Quality control should be carried out daily by use of film strips
exposed in sensitometer shortly before their processing. The
density and contrast of the film strips should then be quantitatively
evaluated.
It is desirable that radiographers see all their radiographs
immediately after processing so that they can recognize any faults
in technique, equipment or processing and can correct any errors.
AUTOMATIC FILM PROCESSING has got
advantages over the Manual one as it :
• provides compact size films
• faster
• more consistent
• time and temperature controlled
• produce dry radiograph immediately

22. X-Ray should be repeated until the new radiograph will
give added information which was not available on the
previous radiograph.
The major cause of retaken identified in most of these
studies was either errors in POSITIONING the patient or
radiographs that were TOO DARK or TOO LIGHT.
Use of a reference list of technical factors (i.e. kVp and
mAs based on patient size and shape) is strongly
recommended as an aid to proper irradiation.

23. The principal difficulty is the relative positions of the
x-ray tube and the radiographic film, particularly
when an anti-scatter grid was used, which leads to
unnecessary repeat of the X-Rays and thus
radiation.
Fluoroscopy should not be carried out with mobile x-
ray equipment unless an image intensifier is
employed.

24. Absorbed dose in breast tissue during mammography
should be kept as low as reasonably achievable without
sacrificing necessary diagnostic information
Mammography should be carried out with dedicated
mammography x-ray equipment and not with conventional
x-ray equipment intended for use at higher x-ray tube
voltages.
Under no circumstance should the total permanent filtration
be less than 0.03mm of molybdenum for screen-film
mammography.

25. Fluoroscopy should be carried out only if the required information
cannot be obtained by radiography alone.
The absorbed dose rate at the point of the entrance surface of the
patient should not exceed 50 mGy per minute and should be
typically much lower.
Direct fluoroscopy delivers higher doses to the patient than
fluoroscopy with image intensification and produces images of
lower quality, hence should be avoided.
With a properly operating image intensifier, the absorbed dose
rates can be reduced to about one-third of those in direct
fluoroscopy.

26. Dose Reduction Technique
Intermittent Fluoroscopy:
It is keeping the X-Rays on only a few seconds at a time, long enough to
view the current catheter position. It reduce total fluoroscopic times
considerably
Removal of Grid
Grid increase the dose to the patient and staff by a factor of two or more
although improves quality of the image .
Last Image Hold and Electronic Collimation
It allows the last image to be digitally “frozen” on the monitor after x-ray
exposure is terminated and thus is a dose-saving feature since it allows
physicians to contemplate the last image and plan the next move without
additional radiation exposure in an interventional procedure.
Electronic collimation, which overlays a collimator blade on the last image
hold so that one can adjust field dimensions without exposing the patient.

27. Dose Spreading
Some reduction of maximum skin dose can be achieved by
periodically rotating the fluoroscope about a center within the
anatomy of interest.
This method tends to spread the maximum dose over a broader
area of the patient’s skin so that no single region receives the
entire dose.

28. Adjustment of Beam Quality
Beam energy primarily depends on the peak kilovoltage
selected and the amount of filtration in the beam.
For a fixed receptor entrance exposure, the skin entrance
dose varies inversely with the kilovolt peak, more
precisely as (kVp)3.
Substantial reductions in skin dose are also achieved by
inserting appropriate metal filters (aluminum, copper, or
other materials) into the beam at the collimator.

29. Image Magnification
There are two basic ways to magnify the image in
fluoroscopy: Geometric and Electronic.
Geometric magnification takes advantage of the
diverging x-ray beam to project a smaller region in the
patient to a larger area on the image intensifier.
Most modern fluoroscopes can also magnify the image
electronically within the image intensifier. Usually, dose
increases with greater electronic magnification.
One rule of thumb is that the radiation dose to the
patient increases by the square of the ratio of the image
intensifier diameters

30. Effect of Electronic magnification on entrance skin dose.
The radiation dose increases by the square of the ratio of
the image intensifier diameters.
(arb = arbitrary, Mag = magnification)

31. Dose Level Settings
A typical configuration by one manufacturer is to provide
three settings: low, medium, and high—with the dose being
half or twice the medium level at the low and high settings,
respectively.
Mostly, the medium mode should be used.
The low dose setting tends to produce a very noisy image,
and the high dose setting should be used rarely when
viewing very low contrast information since the image noise
is diminished or in a very thick patient.
Also the mode is adjusted according to the built of the
patient as desired. (patient may be too lean or too thick
sometimes….)

32. Training of Fluoroscopic Operators
With the dramatic increase in fluoroscopy use in
medicine and advances in technology, it becomes
critical for fluoroscopy users to have specialized
training in proper use of radiation.
It is necessary to develop procedures for
managing safe use of radiation to ensure that
both patients and personnel are not exposed to
excessive radiation levels

33. X-Ray beam is emitted as a series of short
pulses rather than continuously.
Images may be acquired at 15 frames per
second rather than the usual 30 frames per
second. Pulsed fluoroscopy can also be
performed at even lower frame rates (e.g., 7.5
or 3 frames per second) at the expense of a
“choppy” display when imaging rapidly moving
regions like the heart.

34. One would expect a 50% dose reduction when
going from 30 to 15 frames per second, but,
because of increased milliamperage, the actual
dose savings are 25%–28%; this increase in
milliamperage is done to reduce the noise.
Pulsed fluoroscopy has a great advantage as
long as the radiation exposure is lower at lower
frame rates. If the tube current is set too high to
achieve better-quality images, the entire
advantage of pulsed operation is defeated and
there may be no actual dose savings.

35. Effect of pulsed fluoroscopy on entrance skin dose. For
example, by switching from continuous fluoroscopy (Cont
Fluoro) mode to 15 pulses per second, dose savings of nearly
22% are achieved

36. PotentialEffectsof Fluoroscopic Exposures
on the ReactionoftheSkin

37. 1. Christensen’s Physics Of Diagnostic Radiology, 4th
Edition
2. Grainger & Allison’s Diagnostic Radiology, 6th
Edition
3. www.pubs.rsna.org
4. www.radiopaedia.org
5. www.radiologyassistant.nl