Transcript Document

Late Effects of Radiation
Dr. Sandra Vermeulen, M.D.
Swedish Cancer Institute
Northwest Hospital Gamma Knife Center
Seattle, Washington
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Cat’s Eye Nebula
• The Cat’s 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
Back ground radiation
on earth
Crews aboard the
space station
Average Dose
2 mSv/year
80 – 160 mSv/ 6 months
Although the type of radiation is different, 1 mSv of
space irradiation is equivalent to approximately
3 chest x rays (equal to < 1 Gy)
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Radiation Therapy Planning Session
The goal of radiation therapy is to injure more cancer cells than
normal cells
To 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
• Ataxia,
• Hair Loss
• Urinary Incontinence
• Fatigue
• Hearing Loss
• Occasional Worsening of
Neurological Symptoms
• Dry Eyes
• Headaches
• Nausea / Vomiting
• Hearing Loss
• Dry Eyes
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• 10-20% risk of cognitive change, which
include memory loss and apathy
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)
Infarction
Necrosis
Optic Nerve
5,000 (no partial volume)
Blindness
1,000 (no partial volume)
Cataract
4,500 (10 cm)
Infarction
Necrosis
4,500
Endocrine Abnormalities
Sex Hormones
Thyroid Hormone
Cortisol
Lens
Spinal Cord
Pituitary
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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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