Dr Adarsh

1. Dr. Adharsh Kumar. M
3rd year resident,
Department ofVascular and endovascular surgery,
Ramaiah medical college, Bangalore

2. Guess
"Don't talkto me about X-rays, I am afraid of them"

3. Introduction
• Radiation is increasingly used for diagnostic and therapeutic
purposes.
• Hazardous to both patient and operator, especially during major
therapeutic procedures.
• Appropriate education  about radiation safety
• Concern of radiation safety increased in recent times because of
evolution of endovascular techniques with our speciality over the
past decade.

4. Hazards of radiation

5. Types of radiation
•Radiation is a form of
energy emitted as
electromagnetic waves or
particles.
Non ionizing
US, MRI , Laser and
microwaves
Doesn’t possess energy to
ionize atoms of absorbing
matter
Ionizing
X-rays , Gamma rays and
beta rays
Contain sufficient energy
to interact with atoms and
produce biologic injury

6. Measurement
• Amount of ionization that radiation produces in air
• measured as roentgen
• wont accurately reflect potential to cause biologic injury.
• Biologic effect depends :
• Total energy of radiation absorbed per unit mass
• Sensitivity of organ
• Actual strength of radiation

7. Quantification of radiation
•Absorbed dose:
• Measure of amount of energy deposited in medium by ionizing
radiation per unit mass of matter and is equal to amount of heat
generated by radiation per tissue weight in specified material.
• SI unit of absorbed dose
• Gy (Gray)
• 1Gy = 1 Joule of energy absorbed / kilogram (J/kg)
• Older term = Radiation absorbed dose (Rad)
• 1Gy = 100 Rad
• 1 Rad = 0.01 J/Kg

8. Quantification of radiation
•Equivalent dose:
• Measure of radiation dose to tissue and takes into account
different degrees of damage by different types of radiation by
introducing a radiation weighing factor (Wr)
• SI unit of Equivalent dose :
• Sv (Sievert)
• Equivalent dose = absorbed dose x Wr (Sv = Gy x Wr)
• OldTerm  Roentgen equivalent man (REM)
• REM = Rad x Wr
• 1 Sv = 100 REM
• Wr  calculated by type of radiation (1: gamma & X-rays , 3-10 :
protons and neutrons )
• For vascular surgical interventions  Sievert & Gray are roughly
equal (Absorbed = equivalent dose)

9. Quantification of radiation
•Effective dose :
• Different tissues and organs have different sensitivity to
radiation
• Takes into account part of body irradiated and volume & type of
radiation exposed
• Done byWeighting equivalent dose by tissue weighting factor
(Wt)
• Often to avoid confusionWr andWt grouped asW (single
weighting factor)
• In medical field , commonly milli grays (mGy) or milli sieverts (mSv)
is used

10. Quantification of radiation

11. Biologic effects of radiation
•Ionizing radiation damages living cells
• Repair themselves
• Die
• Undergo mutation
•Effects on biologic tissue :
• Deterministic effect
• Stochastic effect

12. Deterministic effect (DE)
•Dose dependent :
• cell death
• impairs hair follicles, skin, subcutaneous tissues and lens.
• Higher dose = Greater injury
• Threshold exists, but varies amongst individuals. Often large
doses causes DE (1-2 Sv)
• Symptoms start when significant cells are killed and
subsequent inflammation or fibrosis begins.

13. Deterministic effect (DE)
•Whole body exposure  10-20 Gy high energy radiation
at single time is fatal.
•0.5- 1 Sv  light radiation sickness
•1 Sv  slight blood changes
•2 – 3 Sv  nausea, hair loss , hemorrhage
•Acute dose of 3 Sv  death in 50% within 30 days.

14. Stochastic effect
•Probabilistic effect.
•DNA damage to cells  mutations  cancer & genetic
defects.
•All or none phenomenon.
•No threshold levels . Probability increases as cumulative
radiation exposure increases, but severity is independent
of the dose.
•Theoretically , with doses <100 mSv/year, probabilistic
effect is very low.

15. Stochastic effect
•Type of cancer produced is independent of type of
radiation  Leukemia and other cancers (lungs, breast,
thyroid , skin , GIT)
•Latent period between exposure and cancer
• 2-5 years  leukemia
• 5 yrs  thyroid
• >10 years  other cancers
•Probability of fatal cancer  4 % per 1 Sv of lifetime
dose equivalent

17. Background exposure
•Humans are constantly exposed to naturally
occurring radiation
• Radioactive materials
• Cosmic radiation
•Average annual radiation in US  3mSv/ year.
•Dose increases with higher altitudes.
•Greatest source of domestic radiation :
• Radon gas from decay of radium (2nd most frequent cause of
lung cancer after cigarette smoking)
• Building materials , fuels , televisions, smoke detectors

18. Occupational exposure
•Apart from natural sources,Total
average exposure forAmericans  3.6
mSv/year.
•Pilots exposed to solar radiation are at
higher risk.
•Amount of cosmic radiation doubles
with every 2000 mile increase in
altitude and cosmic radiation is
strongest at the poles.

20. Principles of radiation protection
• ICRP system of protection in medical practice :
• stresses the fundamental principles of justification
• optimization of protection
• dose and risk limits
• Use of radiation in medicine must be Justified  produce more benefit than harm
• Responsibility of the hospital :
• ensure that the radiation equipment is properly maintained to deliver the lowest
possible dose of radiation
• safety instructions and protective measures are available and adopted
• System of reporting and remedial measures be in place when recommended limit is
exceeded
• Special operating procedures available for high-risk paediatric and pregnant workers

21. Safety in diagnostic procedures
•Alternative imaging modality without
ionizing radiation  US and MRI ,
preferred whenever possible.
•Routine X-rays as skull (for minor head
injuries)and chest (done after hospital
admission)  avoided.
•CT :
• commonly used due to wide availability and faster
results
• SpiralCT and Multidetector CT  10-30% more
dosage
• Less essential cases  low dose exam , wider pitch
and partial rotation

22. Safety and EVAR
•CT and aneurysms :
• Automated tube current
modulation used to reduce
radiation exposure in CT after EVAR
• Follow-up needs repeated CT angio
 can reach harmful levels  solid
malignancies , especially in women
and old age
• Contrast enhanced US used
whenever feasible for postop
surveillance.

23. Safety in diagnostic procedures
•3D rotational angio (Dyna CT)  preop
planning, emergencies and detection
of endo leaks  7-8 times less
radiation than a standard CT
•Sometimes, high risk organs are
exposed even if they are not targets of
examination.
• Lens , thyroid , breast  at CT of head and
thorax.
• Gonads  at CT pelvis.
• Damage mainly in old age and women of child
bearing age.
• Efforts made to shield radiosensitive organs
when not examined.

24. Safety and endovascular therapy
• Radiation exposure for operator in modern cath lab  0.05 mSv
• Hands are at main risk:
• 1 min of exposure – 20mSv skin dose
• Transient skin erythema can occur at 2 Sv
• High dose to eyes  cataract formation in posterior pole of eyes.
• Since most pts are old age  deterministic effects are more than
stochastic effects
• 1 min of fluoroscopic time in cath lab = 200-400 chest X-rays.

25. Safety and endovascular therapy
•Emission control :
• Voltage of tube  controls penetration of beam and
contrast
• Current  controls photons produced by tube
• High voltage and less current  reduce radiation
with good image quality
• Large image intensifier requires less radiation dose
• Review last image hold carefully instead of
additional fluoroscopic exposures.
• Use of Magnification  2-3 times more radiation
• Xray field collimation and filters used whenever
feasible  focuses beam and produces clear image

26. Safety and endovascular therapy
•Time :
• Minimise fluoroscopy time
• Refrain continuous activation of beam on switch, do
intermittent short exposures
• Safety measures as timer used(indicates after 5 min
interval)
• To note patient absorbed dose and fluoroscopy time
at end of procedure.
• DSA  high dose rapid sequencing  10 times more
radiation than fluoroscopy and 60% of total personal
doses ; hence use variable frame rates as tailored to
examination.

27. Safety and endovascular therapy
•Distance :
• Raising fluoroscopic table as high as possible image
intensifier as close to patient as possible and tube as far
away as possible
• Amount of scatter radiation decreases with square of
distance from tube (exposure = 1/d2)
• Radiation varies according to angulation of tube
• exposure lowest with detector to patient distance of <5cm,
source to image distance <15cm , 10 cm vertical collimation.
• Ideal to use power injector for contrast materials injection
• Avoid standing in fluoroscopy room when not personally
washed up.

28. Safety and endovascular therapy
•Barriers :
• Needed for controlling both the patient as well as operator
dosages.
• Three types are there 
• Architectural barrier
• Equipment mounted barrier
• Personal protective devices
•Architectural barrier :
• Built into walls of procedure rooms
• Transparent leaded plastic shield  stationery and mobile on
floors

29. • Equipment Barriers:
• Highest scatter exposure is at table level.
• Table side lead shields hanging from table
• Ceiling mounted mobile acrylic shields  reduce doses to brain and eyes by
factor of 20
• Personal protective devices :
• Properly worn Apron essential  0.25mm lead equivalent (96%) and 0.5mm
wrap (attenuates almost 99%). Skirt configuration preferred.
• Lead eye glasses  should have large lenses and side shields
• Thyroid shields
• Protective hand gloves – 0.35 mm lead equivalent  not often worn due to
reduced tactile sensitivity.

30. Safety & endovascular therapy
•Technique :
• Operator should have good knowledge of radiation
safety and operational skills
•Monitoring exposure :
• Monitored by dosimeters – worn at all times  one at waist level and other
at thyroid shield
• Film badge based , thermo-luminescent dosimeters  measures specific
dose over period of time
• Cumulative total dose reaches IRCP limits over 1 year  temporary
withdrawal from radiation work.
• Discussion and informed consent with patient and family before any major
procedure  about high risk of radiation and possible skin reaction
• Doses exposed > 3-5 Gy  follow-up In 1-2 weeks

31. Practical safety points
• Fluoroscopy should be intermittent
• Never use unless operator sees monitor
• Allow only essential persons inside room
• Display ample warning signs at entrances
• Regularly service and calibrate equipment's
• Newer machines and fixed systems are better  less dosing , better image
intensifier , pulsed fluoroscopy , better quality images in less time
• Use radio opaque catheters whenever feasible

32. Safety &
endovascular surgeon
•Many hospitals have modern hybrid suites nowadays
• high resolution screens
• motorized C arm control
• positioning control
• reduces radiation exposure , screening time and contrast used
•Better image quality , no overheating issues.
•Dose absorbed by a vascular surgeon  usually lesser
than cardiologist or interventional radiologists

33. Safety and endovascular surgeon
•Ho and colleagues  extrapolated
data shows “ to reach IRCP annual
dose limits , a vascular surgeon has
to do 2500 aneurysm repairs or 6500
peripheral procedures ”
•Higher exposure  patients with
high body mass index , complex
anatomy, undergoing fenestrated
and branched procedures.

34. Radiation and pregnancy
•Recommended  an occupationally exposed pregnant
women declare pregnancy for purpose of reducing risk to
unborn child.
• Risk highest during organogenesis  first trimester and least
in third trimester
• Diagnostic tests or procedures that involve radiation
exposure  deferred or adequately informed and performed.
• Major adverse events to foetus  abortion, teratogenicity,
mental retardation, intrauterine growth retardation and
induction of cancer.

35. Radiation dosage & pregnancy
• CNS malformations expected if dose exceeds 100 mSv ,
especially between 8-16 weeks of pregnancy  reduction of
intelligence and microcephaly.
• Cancers like leukaemia in children and foetus increases with
prenatal exposure of 10 mSv itself
• Pregnant heath care workers can continue to work as long as
foetal dose is <1 mSv in entire course of pregnancy.
• Nuclear commission guidelines  no more than 5 mSv of
equivalent dose during entire pregnancy / <0.5 mSv/ month.

36. ICRP recommendations
• Department develops a policy that staff wears two dosimeters, one
under apron at waist level and one at collar level above the lead
aprons.
• Hand doses monitored with additional things like ring dosimeter.
• Annual equivalent dose to lens of eyes : 150 mSv
• Annual equivalent dose to hands and feet : 500 mSv
• For pregnant ladies:
• Fetal dose is estimated using a dosimeter placed on mothers abdomen, under
her radiation protective garments.
• Additional dose to embryo, not exceed 1mSv during entire course of pregnancy.

37. ICRP recommendations

38. General Recommendations
•In European union:
•20mSv/year, averaged over defined period of 5 years
•May not exceed 50 mSv in one year
•Germany :
•400mSv life time dose limit
•US :
•<50mSv / year , lifetime limit – 10mSv multiplied by
patient age in years

39. Conclusion
• Get adequate training  Be aware of radiation hazards and safety
strategies especially in this era
• Plan procedures well with all available data and execute with utmost skill,
especially major ones like EVAR
• Wear dosimeters and keep track of individual dose levels
• Minimize fluoroscopy time
• Use collimation
• Position in low scatter area
“ALARA”