radiation hazards in ortho

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RADIATION HAZARDS IN ORTHOPEDIC TRAUMA CARE

PRESENTED BY DR R NARESH KUMAR PG IN ORTHOPEDICSMODERATOR: DR. M.PARDHASARADHI ASSISTANT PROFESSOR

INTRODUCTIONRADIATION MEASUREMENTSRADIATION INJURYTERMINOLOGIESTYPES OF RADIATION EFFECTSFACTORS DETERMINE BIOLOGICAL EFFECTS OF RADIATIONRADIATION PROTECTION

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

RADIATIONRadiation, as defined as the emission and propagation of energy through space or a substance in the form of waves or particles. IONIZING RADIATIONNON-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 (), 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

Particulate radiation

How x-rays are produced

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 panelHigher 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)RadioactivityAt 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)

RADIOACTIVITYIt 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 atom over one second

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-ray0.1mSv Ct head1.5 mSv Ct whole body9 - 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 inducedCarcinogenic dose being100 msvThreshold value per year should not exceed , 300 mSv for thyroid, 150 msv for eye, and 500 msv for hand

DURING IM NAILING HAND RECIEVES 41.7MICROSV

DURING PLIF HAND RECIEVES 117 MICROSV


RADIATION INJURYRadiation 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 patients tissues.

Mechanisms of radiation injury Two specific mechanisms of radiation injury are possible: ionizationfree radical formation

IONIZATIONIonization 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 FORMATIONX-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.

Theories of Radiation Injury

Direct or Target Action TheoryThe 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 InjuryChemical 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).


TerminologiesLINEAR ENERGY TRANSFER (LET)RELATIVE BIOLOGIC EFFECTIVENESS(RBE)LATENT PERIODMAXIMUM PERMISSIBLE DOSE MAXIMUM ACCUMULATED DOSETOTAL DOSEDOSE RATEMEDIAN LETHAL DOSE

LINEAR ENERGY TRANSFER (LET)Amount of energy is transferred from ionizing radiation to soft tissue49

RELATIVE BIOLOGIC EFFECTIVENESS(RBE)Biologic response compared with two types of radiation50

LATENT PERIODTHE TIME LAPSE BETWEEN EXPOSURE OF THE RADIATION AND THE APPEARENCE OF THE EFFECTS51

MAXIMUM PERMISSIBLE DOSEGreatest 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 EffectsFollowing 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 effectsEffects 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 EffectsAll 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 effectsSomatic 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 effectsGenetic 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 (29 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.


1. Nature of tissue irradiated2. Area irradiated:3. Rate of dose4. Fractionization: 5. Latent period: 6. Age of the patient: 7. Recovery power of the tissue8. 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 irradiationslow energy, high energy or linear energy transfer.

CONT11. 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 EFFECTSEFFECT ON CELLS1.DNA2.CYTOPLASM3.NUCLEUS4.CHROMOSOMES5.PROTEINS6.CELL DIVISION7.CELL DEATH

RADIATION EFFECT ON CRITICAL ORGANS1.SKIN2.BONE MARROW3.THYROID4.GONADAL5.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 BODY1.ACUTE RADIATION SYNDROME2.HEMATOPOITIC SYNDROME3.3.GASTROINTESTINAL SYNDROME4.CARDIOVASCULAR SYNDROME5.CENTRAL NERVOUS

Single strand break can repairDouble strand break is responsible for .mutation .cell death .carcinogenisisPoint mutations: Effect of radiation on individual genes is referred to as point mutation.

Single strand break can repairDouble strand break is responsible for .mutation .cell death .carcinogenisisPoint 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.

NUCLEUSNucleus is more radiosesitive than the cytoplasm

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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

CHROMOSOMEScell cycle:

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

EXAMPLES OF MUTATIONS

EFFECTS ON CELL REPLICATIONMild dose-mild mitotic delayModerate dose-longer mitotic delaySevere dose-profound delay with incomplete recovery

CELL DEATHReproductive death in a cell population is loss of the capacity for mitotic division. The three mechanisms of reproductive death areDNA damage, Bystander effectApoptosis.

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 particles and x rays and causes chromosome aberrations, cell killing, gene mutations, and carcinogenesis.

APOPTOSIS

Leaves falling from treeAlso known as programmed cell deathApoptosis is particularly common in hemopoietic and lymphoid tissues.

BIOLOGICAL EFFECTSEFFECT ON CELLS1.DNA2.CYTOPLASM3.NUCLEUS4.CHROMOSOMES5.PROTEINS6.CELL DIVISION7.CELL DEATH



EFFECT ON WHOLE BODY1.ACUTE RADIATION SYNDROME2.HEMATOPOITIC SYNDROME3.3.GASTROINTESTINAL SYNDROME4.CARDIOVASCULAR SYNDROME5.CENTRAL NERVOUS

RADIATION EFFECT ON CRITICAL ORGANSIn radiography the critical organs receiving scattered radiation include:SKINBONE MARROWTHYROIDGONADALEYE

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 MARROWA 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.

EFFECT ON WHOLE BODY

1.ACUTE RADIATION SYNDROME2.HEMATOPOITIC SYNDROME3.3.GASTROINTESTINAL SYNDROME4.CARDIOVASCULAR SYNDROME5.CENTRAL NERVOUS

BIOLOGICAL EFFECTS

EFFECT ON CELLS1.DNA2.CYTOPLASM3.NUCLEUS4.CHROMOSOMES5.PROTEINS6.CELL DIVISION7.CELL DEATH



RADIATION EFFECT ON ORAL TISSUESORAL MUCOUS MEBRANETASTE BUDSSALIVARY GLANDSRADIATION CARIESOSTEORADIO NECROSIS102

MucositisDescribes 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 mouthSores 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 mouthChanges 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 glandsDecrease salivary secretion(XEROSTOMIA)fibrosis loss of fine vasculatureand 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 ARSPRODROMAL 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

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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 systemsyndrome(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 AchievedImplies a balancing of benefit( risk reduction ) vs cost (financial and cost)1.planning regarding protection in advance of construction2.utilizing all appropriate protective measures

ALARA

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

Distance between x-ray tube and patientDistance of patient to image receptorCollimationFluoroscopic and radiographic acquisition modeFactors affecting dose of exposure

5. Fluoroscopy time6. Wedge filter7. Magnification8. Thickness and composition of patient9. X ray beam quality10. Pulse rate and pulse width for pulsed fluro11. And scaterr grid12. Angulation

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

Standing on the intensifier side reduces the exposure received by one tenthIf the surgeon stands on the xray tube side,thyroid exposure is 3- 4times higherThe 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 scatterFor smaller patient and small body parts adequate imaging may obtained without gridConsider 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 deviceCollimation

Thicker tissue masses absorb more radiation, thus much more radiation must be needed for larger patientsRisk to skin is greater in larger patientsNeeds 2 times more exposure for every 5 cm increase in thicknessEffect of patient size on dose

Factor which increases the scattered radiation to surgeonsThe more we want to magnify the image the higher the relative entrance has to be, which increases the scattered radiationPlacing 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 thyroidSpecific body exposure

Google's with 0.15 mm lead equivalent attenuate radiographic beams by 70% Thyroid collar decreases scattered radiation by 2.5 fold0.5lead apron used during fluoroscopy attenuate 95% of scattered radiation, vs 80% for the light weight apronHand 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 ProtectionEye glasses made of plastic, standard glass, photochromic lenses, and lead-glass lenses reduced the amount of radiation exposure to the users eyes by 0% to 97%, depending on the x-ray tube potential. A lead-acrylic face mask reduced the brain dose by 81%.

Face ProtectionIf the operators 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 ProtectionBecause of the thyroids 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 ProtectionRadio protective gloves could block 15% to 30% of scatter radiation, but if gloved hands are in the beams 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 ProtectionOne 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 ProtectionAlthough 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.

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.Must be worn such that it is not shielded by lead aprons or other shieldsE.g. film badges,tld badges.etc.Personal dorsimeters

Certain C-arms have a virtual patient anatomy feature which helps to select appropriate dose, corresponding to selected body area

Selectable dose rate ,according to patient sizeIntegrated lasers, help to correctly position the beam to mark on the bodyTechnical contribution

Pulse acquisition , use of pulsed images and avoidance of screening will dramatically reduce radiation exposureCorrect operating factors: Low KVP/highmA- high patient dose ratesHigh 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 ProtectionThe 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 PadsA 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 ScreensLeaded 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 LimitsThe 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.

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

Not overusing magnificationConsidering scattering radiation during proceduresWearing protective clothingMaintaining distance from the sourceKeeping 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 .

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radiation hazards in ortho

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