Radiation hazards in ortho

RADIATION HAZARDS IN
ORTHOPEDIC TRAUMA CARE
PRESENTED BY
DR R NARESH KUMAR
PG IN ORTHOPEDICS
MODERATOR:
DR. M.PARDHASARADHI
ASSISTANT PROFESSOR

 INTRODUCTION
 RADIATION MEASUREMENTS
 RADIATION INJURY
 TERMINOLOGIES
 TYPES OF RADIATION EFFECTS
 FACTORS DETERMINE
BIOLOGICAL EFFECTS OF RADIATION
 RADIATION PROTECTION

RADIATION BIOLOGY
Radiation biology is the study of the effects
of ionizing radiation on living systems.

RADIATION
Radiation, as defined as the emission and
propagation of energy through space or a
substance in the form of waves or
particles.
1. IONIZING RADIATION
2. NON-IONIZING RADIATION

Ionizing Radiation
Ionizing radiation can be defined as radiation that is
capable of producing ions by removing or adding an
electron to an atom.
Ionizing radiation can be classified into two groups:
(1) particulate radiation
(2) electromagnetic radiation.

 In this type, the energy is "packaged" in small
units known as photons or quanta.
 Visible light, radio waves, and x-rays are
different types of EM radiation.
 EM radiation has no mass, is unaffected by
either electrical or magnetic fields, and has a
constant speed in a given medium.
 EM radiation is characterized by wavelength (λ),
frequency (v), and energy per photon (E)
EM RADIATION

 The other general type of radiation consists of small
particles of matter moving through space at a very high
velocity.
 Particle radiation differs from electromagnetic
radiation in that the particles consist of matter and
have mass.
 Particle radiation is generally not used as an imaging
radiation because of its low tissue penetration.
 ex. Electron, alfa particles.
Particulate Radiation

The x-ray tube.
 The tube head consists
of a pair of electrodes.
- A negatively
charged cathode with
include a heater
filaments.
- A positively
charged a node with a
tungsten target.

Steps in x-ray production.
 Filament is heated and gives off cloud of
electrons.
 A large electrical charge is placed in the
cathode/anode space causing the electrons to
race toward the anode.
 When they crush into the anode it causes x-ray
to be given off.

X-ray machine
components.
 The tube head where the x-rays are
generated.
 The control panel which regulate the
strength and amount of the x-rays
produced and trigger the exposure.
 The power supply which provide the
energy to creates the x-rays.

Control panel
Higher kv attract the electrons toward the
anode by greater force.
 They smash the anode harder and produce x-ray
with higher energy and greater tissue penetrating
power.
Increasing mA increase the number of
electrons cloud around the filament. Result in
higher number of x-ray produced per second.

X-ray film composition.
 Polyester base that provide support has bluish
tint.
 Film emulsion is a thin layer of chemicals
coating the base composed of.
- Light sensitive silver halide (mainly Bromide
AgBr) crystals.
- gelatins that keep the silver bromide grains
evenly dispersed.

RADIATION MEASUREMENTS
 International Commission on Radiation Units and Measurement (ICRU) has
established special units for the measurement of radiation.
Such units are used to define four quantities of radiation:
 (1) exposure/air.
 (2) dose/tissue.
 (3) dose equivalent.
 (4)Radioactivity
 At present, two systems are used to define radiation measurements:
(1) The older system is referred to as the traditional system, or standard system.
(2) the newer system is the metric equivalent known as the SI system.

EXPOSURE/AIR
 EXPOSURE;The term exposure refers to the measurement of
ionization in air produced by x-rays.
Standard unit-Roentgen (R)
SI unit -Coulombs per kilogram (C/kg)
One roentgen is equal to the amount of radiation that produces
approximately two billion, or 2.08 × 10 9 , ion pairs in one cubic
centimeter (cc) of air.

DOSE/TISSUE
 Dose can be defined as the amount of energy absorbed by a
tissue.
Standard unit-Radiation absorbed dose (rad)
SI unit -Gray (Gy)

DOSE EQUIVALENT
Different types of radiation have different effects on tissues.The
dose equivalent measurement is used to compare the biologic
effects of different types of radiation.
Standard unit-Roentgen equivalent (in) man (rem)
SI unit -Sievert (Sv)

RADIOACTIVITY
 It is the process by which a nucleus of an unstable atom loses
energy by emitting ionizing radiation.
Standard unit-Curie(Ci)
SI unit -Becquerel(Bq)
 1Curie is =3.7x1010 (37 Billion Bq)disintegrations per second.
 1 Becquerel is = one disintegration per second.
 DPS-The number of subatomic particles (e.g. alpha particles) or
photons (gamma rays) released from the nucleus of a given

The amount of radiation encountered in
daily life ranges in the dimension of
1Gy=1SV=1Joule/kg
100millirems=1mGy=1mSv.

In the radiology dept........
Chest x-ray 0.1mSv
Ct head 1.5 mSv
Ct whole
body
9 - 13 mSv
The dose required to produce radiation
sickness is between 500 - 1000 msv,equivalent
to that amount citizens of Hiroshima were
exposed in 1945.

Regarding thyroid cancer,85% of
papillary carcinomas are radiation
induced
Carcinogenic dose being100 msv
Threshold value per year should not
exceed ,
1. 300 mSv for thyroid,
2. 150 msv for eye, and
3. 500 msv for hand

DURING IM NAILING HAND
RECIEVES  41.7MICROSV
DURING PLIF HAND RECIEVES
117 MICROSV

RADIATION INJURY
 Radiation injury- tissue damage or changes caused by
exposure to ionizing radiation-namely, gamma and x-
rays such high-energy particles as neutrons, electrons,
and positrons.
 In diagnostic radiography, not all x-rays pass through
the patient and reach the x-ray film; some are
absorbed by the patient’s tissues.

Mechanisms of
radiation injury
Two specific mechanisms of radiation
injury are possible:
(1) ionization
(2) free radical formation

IONIZATION
 Ionization is produced through the photoelectric effect or Compton
scatter and results in the formation of a positive atom and a dislodged
negative electron.
 The ejected high-speed electron is set into motion and interacts with
other atoms within the absorbing tissues. The kinetic energy of such
electrons results in further ionization, excitation, or breaking of
molecular bonds, all of which cause chemical changes within the cell
that result in biologic damage

FREE RADICALS FORMATION
 X-ray causes cell damage primarily through the formation of
free radicals. Free radical formation occurs when an x-ray
photon ionizes water, the primary component of living cells.
 Ionization of water results in the production of hydrogen and
hydroxyl free radicals
 A free radical is an uncharged (neutral) atom or molecule that
exists with a single, unpaired electron in its outermost shell.

Direct or Target Action
Theory
 The direct theory of radiation injury suggests that cell
damage results when ionizing radiation directly hits
critical areas, or targets, within the cell.
 For example, if x-ray photons directly strike the DNA
of a cell, critical damage occurs, causing injury to the
irradiated organism.

Indirect Action or Poison
Chemical Theory
 x-ray photons are absorbed by the water within a cell, free
radicals are formed. These free radicals combine to form toxins.
(e.g., H 2 O 2 ), which cause cellular dysfunction and biologic
damage.
 The chances of free radical formation and indirect injury are
great because cells contain 70% to 80% water.

1.latent period
2.Period of injury
3.Recovery period
4.Cumulative effects
Sequence of Radiation Injury

Sequence of Radiation Injury
 Chemical reactions (e.g., ionization, free radical formation) that follow the
absorption of radiation occur rapidly at the molecular level.
 However, varying amounts of time are required for these changes
to alter cells and cellular functions.
 As a result, the observable effects of radiation are not visible immediately
after exposure. Instead, following exposure, a latent period occurs.
 A latent period can be defined as the time that elapses between exposure to
ionizing radiation and the appearance of observable clinical signs.

 After the latent period, a period of injury occurs. A variety of cellular injuries
may result, including cell death, changes in cell function, breaking or clumping
of chromosomes, formation of giant cells, cessation of mitotic activity, and
abnormal mitotic activity.
 The last event in the sequence of radiation injury is the recovery period. Not
all cellular radiation injuries are permanent. With each radiation exposure,
cellular damage is followed by repair. Depending on a number of factors, cells
can repair the damage caused by radiation.
 If effects of radiation exposure are additive, the unrepaired damage accumulates
in the tissues. The cumulative effects of repeated radiation exposure can
lead to health problems (e.g., cancer, cataract formation, birth defects).

Terminologies
LINEAR ENERGY TRANSFER (LET)
RELATIVE BIOLOGIC EFFECTIVENESS(RBE)
LATENT PERIOD
MAXIMUM PERMISSIBLE DOSE
MAXIMUM ACCUMULATED DOSE
TOTAL DOSE
DOSE RATE
MEDIAN LETHAL DOSE

LINEAR ENERGY TRANSFER
(LET)
 Amount of energy is transferred from
ionizing radiation to soft tissue
49

RELATIVE BIOLOGIC
EFFECTIVENESS(RBE)
Biologic response compared
with two types of radiation
50

LATENT PERIOD
 THE TIME LAPSE BETWEEN
EXPOSURE OF THE RADIATION
AND THE APPEARENCE OF THE
EFFECTS
51

MAXIMUM PERMISSIBLE DOSE
 Greatest dose of radiation which is not expected to cause detectable
bodily injury to people at any time during their lifetime.
 The amount of ionizing radiation a person may be exposed
to supposedly without being harmed
 For radiology workers and surgeons this limit for the whole body is
50 mSv.

median lethal dose
 The amount of ionizing radiation that
will kill 50 percent of a population in a
specified time
Abbreviation: LD50

Stochastic effects
 Stochastic effects are those that may develop.Their development
is random and depends on the laws of chance or probability.
Examples of somatic stochastic effects include leukaemia and
certain tumours.
 These damaging effects may be induced when the body is
exposed to any dose of radiation.
 It is therefore assumed that there is no threshold dose, and that
every exposure to ionizing radiation carries with the possibility
of inducing a stochastic effect.
 However, the severity of the damage is not related to the size of
the inducing dose.

Nonstochastic effects (deterministic effects)
 Nonstochastic effects (deterministic effects) are somatic effects
that have a threshold and that increase in severity with
increasing absorbed dose.
 Examples of nonstochastic effects include erythema, loss of hair,
cataract formation, and decreased fertility.
 Compared with stochastic effects,deterministic effects require
larger radiation doses to cause serious impairment of health.

Short-Term Effects
 Following the latent period, effects that are seen within
minutes, days, or weeks are termed short-term effects.
Short-term effects are associated with large amounts of
radiation absorbed in a short time (e.g., exposure to a
nuclear accident or the atomic bomb).
 Acute radiation syndrome (ARS) is a short-term effect
and includes nausea,vomiting, diarrhea, hair loss, and
hemorrhage.

Long-term effects
 Effects that appear after years, decades, or generations
are termed long-term effects.
 Long-term effects are associated with small amounts of
radiation absorbed repeatedly over a long period. Repeated
low levels of radiation exposure are linked to the induction of
cancer, birth abnormalities, and genetic defects.

Somatic and Genetic Effects
 All the cells in the body can be classified as either somatic
or genetic.
 Somatic cells are all the cells in the body except the
reproductive cells.
 The reproductive cells (e.g., ova, sperm) are termed
genetic cells.
 Depending on the type of cell injured by radiation, the
biologic effects of radiation can be classified as somatic or
genetic.

somatic effects
 Somatic effects are seen in the person who has been irradiated.
Radiation injuries that produce changes in somatic cells produce
poor health in the irradiated individual.
 Major somatic effects of radiation exposure include the
induction of cancer, leukemia, and cataracts.
 These changes, however, are not transmitted to future
generations

Genetic effects
 Genetic effects are not seen in the irradiated person but are
passed on to future generations. Radiation injuries that produce
changes in genetic cells do not affect the health of the exposed
individual.
 Instead, the radiation-induced mutations affect the health of the
offspring .
 Genetic damage cannot be repaired.

 Doubling dose: dose of radiation expected to double the
number of genetic mutations in a generation.(or) Amount of
radiation that doubles the incidence of stochastic effects.
Human data from Hiroshima/Nagasaki
suggest somewhat average doubling dose is
1.6 Sv

Effects on the fetus
 The developing fetus is particularly sensitive to the effects of
radiation, especially during the period of organogenesis (2–9
weeks after conception).
 Exposures in the range of 2 to 3 Gy during the first few days
after conception are thought to cause undetectable death of the
embryo.
 The period of maximal sensitivity of the brain is 8 to 15 weeks
after conception.

The major problems are:
1.Congenital abnormalities or death associated with large
doses of radiation
2.Mental retardation associated with low doses of radiation.
As a result, the maximum permissible dose to the abdomen of a
woman who is pregnant is regulated by law.

 INTRODUCTION
 RADIATION MEASUREMENTS
 RADIATION INJURY
 TERMINOLOGIES
 TYPES OF RADIATION EFFECTS
 FACTORS DETERMINE BIOLOGICAL EFFECTS OF RADIATION
 RADIATION PROTECTION

1. Nature of tissue irradiated
2. Area irradiated:
3. Rate of dose
4. Fractionization:
5. Latent period:
6. Age of the patient:
7. Recovery power of the tissue
8. Type of cell:
9. Type of irradiation:
10. Stage of development of the tissue:
11. Tissue threshold:
12. Species and individuals:
13. Oxygenation:
Factors determine biological effects of
radiation

 1. NATURE OF TISSUE IRRADIATED.
i. Radioresponsive.
ii. Radioresistant.
 2. AREA IRRADIATED:
For the same dose, if a smaller area is irradiated, the effect of radiation is
less.
 3. RATE OF DOSE:
Smaller the dose, distributed over a large period of time results in a
smaller or lesser effect of the radiation.

CONT….
 4. FRACTIONIZATION:
Division of the dose, with sufficient gaps, helps in
tissue recovery resulting in lesser effect of the
radiation.
 5. LATENT PERIOD:
This is the period between the time of irradiation
and the appearance of the effect.
 6. AGE OF THE PATIENT:
Younger the patient greater the chances of
recovery.

CONT….
 7. RECOVERY POWER OF THE TISSUE:
Undifferentiated cells have a greater power of recovery.
 8. TYPE OF CELL:
The effect of radiation is seen in the same generation if a somatic cell is effected,
and in case of the genetic cell the effect of radiation will be seen in the next generation.
 9. TYPE OF IRRADIATION:
There are different types of irradiations—low energy, high energy or linear energy
transfer.

CONT…
 11. TISSUE THRESHOLD:
Greater the tissue threshold,lesser the damage seen. This depends on the
amount of radiation absorbed. Somatic changes do not occur until a minimum
of tissue threshold is exceeded. Genetic changes occur with any given dose.
 12. SPECIES AND INDIVIDUALS:
Different species respond differently. The median lethal dose varies in
different species. Similarly in individuals of the same species the response may
be variable. This variation of the Maximum Permissible Dose is approximately
50 percent

 OXYGENATION:
Greater oxygenation of the tissue,chances of recovery are greater, e.g.
hyperbaric oxygen is used to treat osteoradio necrosis.
 The presence of oxygen in a cell acts as a radiosensitizer making the effects of
the radiation more damaging. Tumor cells typically have a lower oxygen
content than normal tissue.
 This condition is known as tumor hypoxia and therefore the oxygen effect acts
to decrease the sensitivity of tumor tissue. Generally it is believed that neutron
irradiation overcomes the effect of tumor hypoxia, although there are
counterarguments.

 BIOLOGICAL EFFECTS
EFFECT ON CELLS
1.DNA
2.CYTOPLASM
3.NUCLEUS
4.CHROMOSOMES
5.PROTEINS
6.CELL DIVISION
7.CELL DEATH
RADIATION EFFECT ON CRITICAL ORGANS
1.SKIN
2.BONE MARROW
3.THYROID
4.GONADAL
5.EYE
EFFECT ON ORAL TISSUES
1.ORAL MUCOSA-MUCOSITIS
2.TASTE BUDS
3.SALVARY GLANDS-XEROSTOMIA
4.TEETH- RADIATION CARIES
5.BONES-OSTEORADIO NECROSIS
EFFECT ON WHOLE BODY
1.ACUTE RADIATION SYNDROME
2.HEMATOPOITIC SYNDROME3.
3.GASTROINTESTINAL SYNDROME
4.CARDIOVASCULAR SYNDROME
5.CENTRAL NERVOUS

 Single strand break can repair
 Double strand break is responsible for
.mutation
.cell death
.carcinogenisis
 Point mutations: Effect of radiation on individual genes is
referred to as point mutation.

 Single strand break can repair
 Double strand break is responsible for
.mutation
.cell death
.carcinogenisis
 Point mutations: Effect of radiation on
individual genes is referred to as point
mutation.

CYTOPLASM
 Increased permeability of plasma
membrane to sodium and potassium ions.
Swelling and disorganization of
mitochondria.
Focal cytoplasmic necrosis.

{
NUCLEUS
Nucleus is more radiosesitive than the
cytoplasm

 Denaturation
 primary structure of the protein is usually not
significantly altered
 secondary and tertiary structures are effected
by breakage of hydrogen or disulfide bonds
 Inactivation of enzymes sometimes occurs.
PROTEINS

Mitochondria demonstrate –
.Increased permeability
.swelling
.Disorganization of the
internal cristae
MITOCHONDRIA

Chromosome Aberrations
If radiation exposure occurs after DNA synthesis (I,e G2 or late
s)only one arm of the effected chromosome is broken
If radiation occurs before DNA synthesis (G1 or early S) both arms
are effected

EFFECTS ON CELL REPLICATION
 Mild dose-mild mitotic delay
 Moderate dose-longer mitotic delay
 Severe dose-profound delay with
incomplete recovery

CELL DEATH
 Reproductive death in a cell population is loss of the capacity
for mitotic division. The three mechanisms of reproductive
death are
 DNA damage,
 Bystander effect
 Apoptosis.

Bystander effect
 It is the phenomenon in which unirradiated(normal)
cells exhibit irradiated effects as a result of signals
received from nearby irradiated cells.
 This bystander effect has been demonstrated for both
α particles and x rays and causes chromosome
aberrations, cell killing, gene mutations, and
carcinogenesis.

APOPTOSIS
 Leaves falling from tree
 Also known as’ programmed cell death’
 Apoptosis is particularly common in hemopoietic
and lymphoid tissues.

EFFECT ON CELLS
1.DNA
2.CYTOPLASM
3.NUCLEUS
4.CHROMOSOMES
5.PROTEINS
6.CELL DIVISION
7.CELL DEATH
RADIATION EFFECT ON CRITICAL ORGA
1.SKIN
2.BONE MARROW
3.THYROID
4.GONADAL
5.EYE
EFFECT ON ORAL TISSUES
2.TASTE BUDS
3.SALVARY GLANDS-XEROSTOMIA
5.BONES-OSTEORADIO NECROSIS

RADIATION EFFECT ON
CRITICAL ORGANS
 In radiography the critical organs receiving scattered radiation include:
 SKIN
 BONE MARROW
 THYROID
 GONADAL
 EYE

Skin:
I. EARLY OR ACUTE
SIGNS:.
• Intolerance to surgical scrub.
• Blunting and leveling of finger
ridges.
• Brittleness and ridging of finger
nails.
.

ii. LATE OR CHRONIC
SIGNS:
• Loosening of hair and epilation.
• Dryness and atrophy of skin, due to
destruction of the sweat glands.
• Progressive pigmentation, telangiectasia
and keratosis.
• Indolent type of ulcerations.
• Possibility of malignant changes in tissue

 All these changes in the skin are due to radiation
trauma to:
1-The blood vessels.
2- Connective tissue.
3- Epithelium.
 Early erythema may appear from a single dose of
about 450 rads.
 With lower doses no erythema occurs.

BONE MARROW
 A maximum dose of 200 R is required for any damage to the
marrow or blood forming organs.
 The primary somatic risk from radiography is leukemia
induction,especially in young individuals.
 This is because at birth all bones contain only red bone marrow.
younger individuals are at a greater risk of developing
leukemia.

 THYROID A dose of 10 R will produce thyroid cancer.
 Eye Cataract of the lens is produced after 500 R of
exposure.

4.CARDIOVASCULAR SYNDROME
5.CENTRAL NERVOUS
EFFECT ON CELLS
1.DNA
2.CYTOPLASM
3.NUCLEUS
4.CHROMOSOMES
5.PROTEINS
6.CELL DIVISION
7.CELL DEATH
RADIATION EFFECT ON
CRITICAL ORGANS
1.SKIN
2.BONE MARROW
3.THYROID
4.GONADAL
5.EYE
EFFECT ON ORAL TISSUE
2.TASTE BUDS
3.SALVARY GLANDS-XEROSTOM
5.BONES-OSTEORADIO NECROSI

RADIATION EFFECT ON
ORAL TISSUES
 ORAL MUCOUS MEBRANE
 TASTE BUDS
 SALIVARY GLANDS
 RADIATION CARIES
 OSTEORADIO NECROSIS
102

Mucositis
 Describes inflammation of oral mucosa resulting from
chemotherapeutic agents or ionizing radiation,Typically
manifests as erythema or ulcerations.
 May be exacerbated by local factors.
 Blood in the mouth
 Sores in mouth,gums and tongue

TASTE BUDS
These are sensitive to radiation and patient
realizes a loss of taste in the second or third
week of radiation therapy.
 . It may take 2 or 3 months or more before your taste
sensations return.
 It is common to have an increased sensitivity to sour and
bitter taste,or to have a “metallic” taste in your mouth
Changes in taste may cause you to lose your appetite.

MANAGEMENT
Research has shown that taking zinc
sulfate during treatment may be
helpful in expediting the return of
taste after irradiation.

SALIVARY GLANDS
Parotid gland is more radio sensitive than the
other glands
Decrease salivary secretion(XEROSTOMIA)
fibrosis
loss of fine vasculature
and simultaneous parenchymal degeneration.

 There is marked decrease in the salivary flow.
• The saliva loses its lubricating properties.
• The mouth becomes dry and tender due to xerostomia.
• The pH of saliva is decreased which may initiate
decalcification of enamel.
• A compensatory hypertrophy of the salivary gland may
take place and the xerostomia may subside after six to twelve
months after therapy.

Acute Radiation Syndrome (ARS) is an acute
illness caused by irradiation of the entire
body (or most of the body) by a high dose of
penetrating radiation in a very short period of
time (usually a matter of minutes)
ACUTE RADIATION SYNDROME

stages of ARS
 PRODROMAL STAGE (N-V-D STAGE): The classic symptoms for this stage are nausea,
vomiting, as well as anorexia and possibly diarrhea (depending on dose), which occur
from minutes to days following exposure. The symptoms may last (episodically) for
minutes up to several days.
 LATENT STAGE: In this stage, the patient looks and feels generally healthy for a few
hours or even up to a few weeks.
 MANIFEST ILLNESS STAGE: In this stage the symptoms depend on the specific
syndrome and last from hours up to several months.
 RECOVERY OR DEATH: Most patients who do not recover will die within several
months of exposure. The recovery process lasts from several weeks up to two years

Bone marrow (hemopoietic)
syndrome:
 (2 to7 Gy) Here severe damage may be caused to the circulatory system.
 The bone marrow being radiosensitive, results in fall in the number of
granulocytes, platelets and erythrocytes.
 Clinically this is manifested as lymphopenia, granulocytopenia and
hemorrhage due to thrombocytopenia and anemia due to depletion of the
erythrocytes.

Gastrointestinal syndrome
(7 to 15 Gy): This causes extensive damage to the
gastrointestinal tract, leading to anorexia, nausea,
vomiting,severe diarrhea and malaise.

Cardiovascular and central nervous
system
syndrome
(more than 50 Gy): This produces death within
one or two days. Individuals show
incordination,disorientation and convulsions
suggestive of extensive damage to the nervous
system.

As Low As Reasonably
Achieved
¨ Implies a balancing of benefit( risk
reduction ) vs cost (financial and
cost)
¨ 1.planning regarding protection in
advance of construction
¨ 2.utilizing all appropriate protective
measures
ALARA

X ray intensity decreases
rapidly with distance from
source ;
conversely , intensity increases
rapidly with closer distance to
source
Inverse square law

1. Distance between x-ray tube and
patient
2. Distance of patient to image
receptor
3. Collimation
4. Fluoroscopic and radiographic
acquisition mode
Factors affecting dose of
exposure

5. Fluoroscopy time
6. Wedge filter
7. Magnification
8. Thickness and composition of
patient
9. X ray beam quality
10. Pulse rate and pulse width for
pulsed fluro
11. And scaterr grid
12. Angulation

n The best configuration during surgery is with
intensifier up and the xray tube down
n This reduces the exposure to team and lens by
3 or more times
n The surgeon should not stand on the xray tube
side , since they will receive scattered radiation
up to 4-8 mSv
X ray tube position

n Standing on the intensifier side
reduces the exposure received by
one tenth
n If the surgeon stands on the xray
tube side,thyroid exposure is 3-
4times higher
n The dose rates to torso from the xray
tube side are 0.53 mSv/min, where as
standing on the intensifier side it is
just 0.02 mSv/min

Factors affecting patient entrance

Grid is placed in front of the image detector
A grid reduces the effect of scatter
( degrading image contrast), but it also
attenuates the primary x-ray beam( both
scatter and primary hit grid strip )
Typically require a 2 times increase in
patient dose rate to compensate for
attenuation
Surface dose rates - grid

Small patients produce less scatter
For smaller patient and small
body parts adequate imaging may
obtained without grid
Consider removing grid for
patients < 20 kg

Confines the xray beam to an area of
the user choice .
Beam limitation to the smallest
possible dimensions by a variable
beam limiting device
Collimation

Thicker tissue masses absorb more
radiation, thus much more radiation
must be needed for larger patients
Risk to skin is greater in larger patients
Needs 2 times more exposure for every 5
cm increase in thickness
Effect of patient size on
dose

 Factor which increases the scattered
radiation to surgeons
 The more we want to magnify the image the
higher the relative entrance has to be, which
increases the scattered radiation
 Placing the pt. as close to the image
intensifier ,reduces the scattered radiation
Intensifier diameter

Which part of the body most
exposed?
In surgeons, its first the hands,
followed closely by eyes ,though
more distant but more sensitive.
The third being thyroid
Specific body exposure

 Google's with 0.15 mm lead equivalent attenuate
radiographic beams by 70%
 Thyroid collar decreases scattered radiation by 2.5 fold
 0.5lead apron used during fluoroscopy attenuate 95% of
scattered radiation, vs 80% for the light weight apron
 Hand and glove protection ranges from 60% - 64% with
52-58 kV.

Folding the lead apron decreases its
efficiency by 20%
Bismuth is more effective in
absorbing scatter radiation than lead
Lead aprons should not be used for
more than 5 years

Eye Protection
 Eye glasses made of plastic, standard glass, photochromic
lenses, and lead-glass lenses reduced the amount of
radiation exposure to the user’s eyes by 0% to 97%,
depending on the x-ray tube potential.
 A lead-acrylic face mask reduced the brain dose by 81%.

Face Protection
 If the operator’s eyes are exposed to radiation, the brain, nose,
cheeks, and mouth also are exposed. Face masks may be used to
protect the entire face of personnel who are exposed to radiation,
most likely in the form of scatter radiation from patients
 Face masks are normally made of acrylic that is impregnated with
lead, and the head piece can be adjusted to fit the user.
Manufacturers also offer antistatic spray and antifog cleaner to keep
the masks clear and comfortable.

Thyroid Protection
 Because of the thyroid’s location fairly close to the skin and
likely within the trajectory of scatter radiation, it is susceptible
to radiation damage that can trigger negative effects
throughout the body.
 If this influential organ is not already protected with a neck
shield attached a lead apron, then a thyroid collar should be
worn.

Hand Protection
 Radio protective gloves could block 15% to 30% of scatter
radiation, but if gloved hands are in the beam’s path, a
fluoroscopy machine will automatically increase the kilovolts
(kV), raising the amount of radiation exposure to medical
personnel and the patient; in these cases, gloves could provide
a false sense of protection and negate their benefit.

Hand Protection
 One study noted that certain types of radiation-
attenuating flexible gloves are prone to produce forward-
scatter and backscatter x-rays, thus reducing their
protective effectiveness. Therefore, they concluded that in
lieu of shielding, time and distance were the best options
personnel had to protect their hands during
interventional radiology and cardiology procedures.

Leg Protection
 Although technologists’ hands may seem closer to the
radiation source during interventional procedures, their legs
and feet may receive an equal or higher amount of radiation.
 One study showed that the mean radiation dose to operators’
legs was between 0.19 and 2.16 mSv per interventional
procedure, while the hands received between 0.04 and 1.25
mSv. This leg exposure dropped to approximately 0.02 mSv
when protection was used.

n Must be worn by persons operating
fluro equipment and medical
personnel required to be present
within 6 ft of the primary beam
during fluro procedures.
n Must be worn such that it is not
shielded by lead aprons or other
shields
n E.g. film badges,tld badges.etc.
Personal dorsimeters

n Certain C-arms have a virtual patient anatomy feature
which helps to select appropriate dose, corresponding
to selected body area
n Selectable dose rate ,according to patient size
n Integrated lasers, help to correctly position the beam to
mark on the body
Technical contribution

n Pulse acquisition , use of pulsed
images and avoidance of
screening will dramatically reduce
radiation exposure
n Correct operating factors:
Low KVP/highmA- high patient
dose rates
High kVp/low mA- low dose rates
with reduced contrast

 Increases the
hardness of x-ray
beam
 Removes non image
producing radiation.
Filtration

Collimation without radiation:
view last hold image and adjust
collimation with graphical overlay on
image
patient positioning without radiation:
position patient via graphical display
showing central beam location and
edges of field on LIH
NEW DEVELOPMENTS IN DOSE
REDUCTION

Automatic beam filtration: adds
filtration to decrease patient
dose based on patient
attenuation

Radiation Protection
 The ICRP set out 3 fundamental principles for an overall system
of radiation protection:
 JUSTIFICATION,
 DOSE LIMITATION, AND
 OPTIMIZATION OF PROTECTION.
.

 Justification refers to the necessity to do more good than harm when
deciding whether radiation use is necessary.
 The ICRP established dose limitations for occupational radiation to
manage workers’ exposure via proper facility design and operation
planning.
 Within the optimization of protection principle are 3 more tenets of
radiation protection: TIME, DISTANCE, AND SHIELDING

Protective Pads
 A drape over or under a patient also can be helpful to reduce scatter
radiation. One such drape is the RADPAD, a lead-free, disposable
bismuth antimony shielding pad. This pad may be disposed of in the
regular trash because it does not contain lead or vinyl.
 Although the RADPAD now is made with bismuth, it is still safe for
regular disposal and the drapes come in a variety of procedure-
specific designs.

Ceiling Suspended or Mounted
Shielding Screens
 Leaded shields can either be acrylic or glass panels that can be suspended from the
ceiling or portable on wheels. These shields absorb up to 90% of the scatter
radiation with the equivalent of 0.50 mm of lead within their plastic or glass.
Because of their effective absorbency, especially in protecting the eyes, shields
should be used in all fluoroscopy suites, even though they may seem like a
hindrance at times.
 Thornton et al found that a ceiling-suspended shield eliminated all detectable
radiation at the eye level of a phantom operator during digital subtraction
angiography, besting the protection provided by lead glasses and scatter radiation-
shielding drapes used either alone or together.

Fetal Dose Limits
 The National Council on Radiation Protection and
Measurements (NCRP) recommends an occupational radiation
fetal dose limit of 5.0 mSv during an entire pregnancy (with a
daily limit of 0.025 mSv), and less than 0.5 mSv per month. The
ICRP recommends less than 1.0 mSv total fetal exposure
during an entire pregnancy. In general, these limits are
achievable with the proper precautions in place.

n Radiation hazard can be reduced
through a variety of ways including
n Proper positioning of x-ray tube
underneath the patient
n When in lateral view ,staying away
from the x-ray tube , keeping the
xray tube at a maximal distance to
the patient.
Summary

n Not overusing magnification
n Considering scattering radiation
during procedures
n Wearing protective clothing
n Maintaining distance from the
source
n Keeping hands away from and
out of the beam

REFERENCES:
 1.Grainger & alisons DIAGNOSTIC RADIOLOGY
Volume 1, chapter 10, radiation protection and patient doses in
diagnostic radiology
 2 The fundamentals of x-ray and radium physics
Chapter 23. protection in radiology- health physics
 3.Indian journal of radiology and imaging .
 4. internet .

Next seminar by
DR K.SURYAVARDHAN
PAEDIATRIC FRACTURES
AROUND ELBOW on 7-09-15

Radiation hazards in ortho

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Radiation hazards in ortho

Similar to Radiation hazards in ortho (20)

Recently uploaded

Recently uploaded (20)

Radiation hazards in ortho