Radiation Awareness and Safety programme

K.K.D.RAMESHPHYSCIST & RSO

.

What is Radiation?

What is Radiation? Radiation is energy that comes from a source and

travels through space and may be able to penetrate through various materials and causes ionization . Two types of Radiationa)Photons(In-Direct Ion), e.g. X-rays & ɤ-raysb)Particles(Direct Ion), e.g. Electron, Proton, Neutron

Penetrating power of radiation

Penetrating power of radiation

Is Radiation Visible?

No

Can Radiation be Sensed?

No

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Is there RADIATION in this room?

INTRODUCTIONSources of Radiation1. Earth2. Cosmic Radiation3. Medical Exposure-Diagnostic ,Thearpy-

xrays, gamma rays, Electrons, protons, Neutrons

Radiation - We live with

Natural Radiation: Cosmic rays, radiation within our body, in food we eat, water we drink, house

we live in, lawn, building material etc.

Human Body: K-40, Ra-226, Ra-228e.g. a man with 70 kg wt. 140 gm of K

140 x 0.012%=0.0168 gm of K-40

0.1 Ci of K-4028,000 photons emitted/min (T1/2 of K-40 = 1.3 billion yrs)

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Introduction to Radiation Protection in Diagnostic Radiology

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Is there RADIATION in

this room?

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DO WE NEED

RADIATION

PROTECTION?

Yes...

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We live with1-3 mSv

Can kill4000 mSv

Radiation

Where to stop, where is the safe point?What are the effects of radiation?

Low-Level Radiation Effects

• Low level radiation

< Dose required to produce acute radiation syndrome-x

Dose limits recommended by the standards

Ex: Thorium in Kerala beach

• The NCRP defines two general categories for harmful

effects of radiation

Stochastic effects – The probability of occurrence increases with increasing absorbed dose

– The severity dose not depend on the magnitude of the absorbed dose

– e.g. development of a cancer- genetic effect

– No threshold dose

Non- Stochastic effect(Deterministic)

Increase in severity with increasing absorbed dose

Damage to increasing number of cells and tissues

e.g. organ atrophy, fibrosis, cataracts, blood changes,

sperm counts

Possible to set threshold dose

Introduction to Radiation Protection in Diagnostic Radiology 19

Dose

Deterministic effects

Cataract infertilityerythemaepilation

CancerGeneticProb dose

500 mSv cataract 150 mSv for sterility (temporary-males)2500 mSv for ovarian

Eff

ect

OBJECTIVES OF RADIATION PROTECTION

• PREVENTION of deterministic(Non-Stochastic ) effect

• LIMITING the probability of Probabilistic effect (stochastic effect)

Features of some epidemiological studies of radiation-induced cancer risks

Introduction to Radiation Protection in Diagnostic Radiology 21

Life Span Study Massachusetts Children in (LSS) of Ankylosing tuberculosis patients Israel irradiated Japanese atomic Spondylitis given chest for ringworm UK National Registry for bomb survivors Study (ASS) fluoroscopies of the scalp Radiation Workers Parameter (Shimizu et al) (Weiss et al) (Boice et al) (Ron et al) (Kendall et al)

Population 75991 14109 2573 10834 95217 size (with DS86 doses) Period of 5-55 years Up to over Up to over 50 years Up to 32 years Up to 40 years follow-up following exposure 50 years (mean 25.2 (mean 30 years) (mean 26 years) years)

Ranges of: (a) ages at All Virtually all Under 15 to over 40 0-15 years 18-64 years exposure 15 years (b) sexes Similar numbers of 83.5% male Female Similar number of 92% male males and females males and females © ethnic Japanese Western (UK) Western (N. American) African and Asian Western (UK) groups

Setting in War Medical:ther- Medical:diagnostic Medical:therapy Occupational which apy for non- for non-malignant exposure malignant disease was received disease

Basic principles of radiation protection

• Justification of practice

• Optimization of protection

• Individual dose limits

Justification(Patient)

Whether this test is Justified ?

If Patient already had chest x-ray 2 days back, and again Rx X-ray is not Justified.

If The same diagnosis can be found with Ultrasound/MRI- then CT is not Justified.

Justification(Patient)

Using same KV, mAs of Adults-- for kids-is not Justified.

Unnecessary repetition due to Unplanned/Untrained –is not Justified.

.

OPTIMIZATION(Patient)

• Optimized

Using the collimator setting-only to Area of Interest-during X-ray

• Non-optimized

For taking Chest X-ray opening the collimator which covers Eyes, thyroid

For pelvic X-ray examination in kids-- not covering Gonads

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OPTIMIZATION principle (Patient)

To what extent OPTIMIZATION ? Over-stretching OPTIMIZA …………………… TION

Optimization Should not lead to Repitition-Again more Radiation dose.

Optimization(Patient)The ALARA philosophy

As low as reasonably

achievable

Individual Dose Limit(Patient)

• As Patient is getting benefit from radiation there is no dose limit for patient , but we have to consider ALARA (As Low As Reasonably Achievable)

Justification(Public & Radiation Worker)

• Involve the persons who ever aged • Age to work as a Radiation worker is >18• Display pluck cards with Radiation symbols in

Radiation zone

Optimization(Public& Radiation Worker)

• ALARA (As Low as Reasonable Achivable)

Three basic factors • Time• Distance• Shielding

• Risk Vs Benefit

Dose Limit

• Dose Limit for Public is 1msv/year(In special circumstances effective dose averaged over a 5 year period <1msv/year )

• Dose Limit for Trainee Effective dose < 6msv/year

• Dose Limit for Radiation worker is 20msv/year

Cumulative dose over a block of 5yrs shall not exceed 100msv

The effective dose in any calendar year during a 5yrs Block shall not exceed 30msv.

In a calendar year equivalent dose for Lens of the eye < 150 msv

Skin, the hand & Feet < 500msv

In case of radiation worker pregnancy ,equivalent dose to the abdomen (Lower trunk) < 2msv

Radiation Safety

AERB (Atomic Energy Regulatory Board) is competent Authority of Radiation safety for

• Patient and Public• Staff

Radiation Safety-Patient

Site specific Protocols for KV, mAs settings.

Good Equipment –Digital X-ray rather than film based.

Digital equipment gives less dose-if optimized

If Same settings are used as of film –Digital beauty is not utilized.

Digital X-ray gives good Picture Quality for low dose settings –giving less dose to patient than film.

Radiation Safety-Patient contd.,

.

In angiography rotate the tube over the body to avoid exposure -Over single area of skin-Avoid skin burns.

Coronary angioplasty twice in a day followed by bypass graft because of complication. Dose 20 Gy (ICRP 85)

Radiation Safety-Public

• IF YOU THINK THERE IS ANY POSSIBILITY THAT YOU ARE PREGNANT, PLEASE TELL IT TO THE RADIOGRAPHER (RADIOLOGICAL TECHNOLOGIST) OR THE RADIOLOGIST, BEFORE THE X RAY EXAMINATION IS PERFORMED".

Radiation Safety-Public

• X-ray room design according to AERB norms• Lead aprons for Patient attendees-who are with patient during the

examination.• Purchase of AERB RECOMMENDED X-ray units

Radiation Safety -Staff

• Use of Lead Aprons, • Mobile Lead barriers ,• Thyroid collars, • Lead googles • where ever• appropraite

Basic methods of protection against exposure to ionizing radiation

Three basic factors• Time• Distance• Shielding

Time

Exposure rate =10mGy/h

X Time = Total dose

1 hour = 10 mGy

2 hours = 20 mGy

Distance

Inverse square law

150 mSv/h0.06 mSv/h

d=50cm

Shielding photons

Internal exposure

Ingestion / Absorption

Protective clothing and hand washing

How do we measure the Radiation Dose received by Radiation worker?

By using personnel monitoring devices.• 1.Film badge• 2.TLD badge• 3.Pocket dosimeter-Direct reading dosimeter

Film badge

plastic filter metal filters open windows

open window

detects beta, gamma, X Ray

TLD badge

• TLD badge is the most commonly used personnel monitoring device.

• The Radiation dose is measured by heating the TLD hence the name-Thermo Luminescent dosimeter-When heated it emits

Light proportional

to radiation absorbed

TLD Badge

• The Material used in TLD badge –CaSo4:Dy-teflon TLD discs.

• It has open window• 1.6mm thick plastic filter• 1mm Al+ 1mm Cu combined filter.

TLD Badge

• These filters help in ascertaining type and energy of incident radiation.

• TLD badge can give dose received due to X-rays, gamma rays and energetic beta rays.

• Worn at chest level is a measure of whole body dose.

TLD Badge

• Wrist badge and finger badges available• To monitor dose to wrist and finger-Especially used in Brachytherapy -

Manual After loading technique

Will TLD badge protect us from Radiation

• No• It tells how much dose is received by a Radiation worker.

Where should TLD be worn with Lead Apron?

• The dosimeter should be worn under the apron for estimating the effective. One dosimeter worn under the apron will yield a reasonable estimate of effective dose for most instances

• In case of high workload (interventional radiology) an additional dosimeter outside the apron should be considered.

3.Pocket dosimeter-Direct reading dosimeter

ANNUAL FATALITY RATES FROM ACCIDENTS IN DIFFERENT OCCUPATIONS PER 10,000 WORKERS

• TRADE 0.5• MANUFACTURING 0.6• SERVICE 0.7• GOVERNMENT 0.9• TRANSPORTATION AND UTILITIES 2.7• CONSTRUCTION 3.9• AGRICULTURE 4.6• MINING, QUARRYING 6.0 • ALL INDUSTRIES 1.1• RADIATION INDUSTRIES 0.3

THANKS FOR ATTENTION