Late Effects of Radiation

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Late Effects of Radiation Dr. Sandra Vermeulen,
M.D. Swedish Cancer Institute Northwest Hospital
Gamma Knife Center Seattle, Washington
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Cats Eye Nebula

• The Cats Eye Nebula produces energy that
  is part of the Electromagnetic spectrum
• Located 3,000 light years away from our
  Milky Way Galaxy
• First planetary nebula to be discovered by
  the Hubble telescope
• Nebula are dying stars
• Chemical elements in the nebula emit light
  at very specific wavelength
• - Hydrogen Atoms Red
• - Oxygen Atoms Blue
• - Nitrogen Ions Green

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Our Solar System

• The solar system was made from recycled
  elements originating from a dying star
  (Planetary Nebula)
• In terms of mass
• - 70 Hydrogen
• - 28 Helium
• - 1 Oxygen
• - 1 All Remaining Elements

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C.H.O.N.
Carbon, Hydrogen, Oxygen and Nitrogen are so
common in clouds of gas and dust in space they
are simply referred to by the acronym C.H.O.N.
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Body Mass
Water Weight - 65 H20 Dry Weight - 50
Carbon - 25 Oxygen - 10 Nitrogen - 15
All other elements combined We are made
from the 4 most reactive elements in the Universe
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Radiation Therapy Machines
Radiation Therapy Machines produce energy from
the Electromagnetic Spectrum - Linear
Accelerator - CyberKnife - Gamma Knife
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The Electromagnetic Spectrum

• It is the name given to the group of
  radiation types
• All radiation is a form of energy
• Energy in this example increases from left
  to right
• Energy is defined as ionizing or
  non-ionizing if it is large enough to remove
  electrons from their atoms.

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DNA (DeoxyriboNucleic Acid)

• The effect of radiation on cancer cells is
  due to ionization or damage caused by the
  breakage of chemical bonds in the DNA molecule
• DNA damage prevents the cells from
  replicating
• As long as cancer cells cannot reproduce,
  they cannot grow in size or metastasize

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Dose Equivalent
SIEVERT, (REM, roentgen equivalent man, old term)
is used to compare different types of radiation.
GRAY (RAD, old term) equals radiation-absorbed
dose (in tissue) QF is the quality factor and
accounts for the different degree of damage
produced by equal doses of different radiation
types. QF is 1 for photons (the most commonly
used energy in therapeutic radiation
medicine) SIEVERT GRAY X QF   100 rad 100 cGy
1 Gy 1 Sv (if the QF is 1) 1000 mrad
1000 mGy 1000 mSv
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Exposure to Ionizing Radiation
Source Average Dose
Back ground radiation on earth 2 mSv/year
Crews aboard the space station 80 160 mSv/ 6 months
Although the type of radiation is different, 1
mSv of space irradiation is equivalent to
approximately3 chest x rays (equal to lt 1 Gy)
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Radiation Therapy Planning Session
The goal of radiation therapy is to injure more
cancer cells than normal cellsTo achieve this,
a treatment planning session or simulation is
undertaken prior to actual treatment. Many
variables need to be considered including -
Treatment Type - Field Size - Number of
Treatment Beams - Beam Direction - Beam
Modifiers (Blocks, Wedges, Tissue Compensators)
- Computerized Dosimetery Plan - Patient
Immobilization Device
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Side Effects
The effects of radiation maybe temporary (because
the cell is able to repair it) or permanent (by
injuring the repair mechanism) and become
apparent anywhere from days to weeks to months to
years after exposure. Radiation injury is a
function of radiation type, dose, fraction size,
volume of tissue irradiated and area of the body
exposed
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Whole Brain Irradiation Dose Volume Equivalents
800 cGy/1 fx 2000 cGy/5 fx 3000 cGy/10 fx
3500 cGy/14 fx 4500 cGy/25 fx 50 of
metastases are controlled with these
doses Control with radiosurgery alone or as a
boost is 80-90
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Primary Brain Tumors
Glioblastomas and other astrocytomas do not show
a response above 6000 cGy Treatment is usually
delivered to the partial brain at 180 cGy over
33 fx
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Radiation Side Effects
Acute Side Effect (1-6 months after Treatment) Late Side Effects(6-24 months after Treatment)
Skin Burns Hair Loss Fatigue Occasional Worsening of Neurological Symptoms Headaches Nausea / Vomiting Hearing Loss Dry Eyes Ataxia, Urinary Incontinence Hearing Loss Dry Eyes 10-20 risk of cognitive change, which include memory loss and apathy
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Radiation Treatment Goal
The goal of any radiation treatment is to 1.
Stop 2. Cure 3. Eradicate the growth of the
Cancer which will slow down or prevent worsening
neurological function and eventually death
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Normal Tissue Tolerance To Therapeutic Radiation
Dose expected to give a 5 risk of injury at 5
years
Organ cGy (Volume) Side Effect
Brain 6,000 (1/3) 5,000 (2/3) 4,500 (3/3) InfarctionNecrosis
Optic Nerve 5,000 (no partial volume) Blindness
Lens 1,000 (no partial volume) Cataract
Spinal Cord 4,500 (10 cm) InfarctionNecrosis
Pituitary 4,500 Endocrine Abnormalities Sex HormonesThyroid HormoneCortisol
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Brain Volume
Listed in decreasing order of brain volume
exposed to the effects of ionizing radiation -
Conventional External Beam Irradiation- 3D
- Conformal Radiation Therapy- Intensity
Modulated Radiation Therapy- Stereotactic
Radiosurgery / Stereotactic Radiotherapy
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Medication for Radiation Side Effects
Medications Indications
Decadron Brain Swelling
Anti-Emetics Nausea
Antisiezure Drug Seizures
Hydrocortisone / Aloe Vera Skin Irritation
Antihistamines Otitis
Artificial Tears Eye Dryness
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Question?
Is there anything that can be done for
long-term/chronic side effects such as memory
loss and fatigue?
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Things To Consider / Try To Optimize Brain Health

• Stop smoking
• Treat all other unrelated disease conditions
  aggressively such as, diabetes and infections
• Get adequate rest and exercise
• Eat right/see a dietician
• See a Naturopath
• - Vitamins (anti-oxidants), minerals,
  including omega 3 fatty acids and DHA
  (docosahexaenoic)/EPA (eicosapentaenoic)
• Check for and treat any progressing endocrine
  abnormalities
• - Low thyroid, low levels of estrogens and
  testosterone, low levels of cortisol
• Reduce stress
• - Bio-feedback therapy, psychotherapy, support
  groups
• - Seek Spiritual comfort
• Non-traditional western medicine approach to
  health
• - Yoga, meditation
• Hyperbaric oxygen therapy?

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Question?
Question How do I optimize my Brain Health to
receive the right therapy for my disease
type? Answer Get more than one opinion before
starting treatment.
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Conclusion
We are on the continued quest of study to harness
the benefits of energy produce by the
Electromagnetic Spectrum
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