late effects of radiation dr. sandra vermeulen, m.d. swedish cancer institute northwest hospital...
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Late Effects of RadiationDr. Sandra Vermeulen, M.D.
Swedish Cancer Institute
Northwest Hospital Gamma Knife Center
Seattle, Washington
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• 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
Cat’s Eye Nebula
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• 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
Our Solar System
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C.H.O.N.
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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.
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
Body Mass
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Radiation Therapy Machines produce energy from the Electromagnetic Spectrum
- Linear Accelerator
- CyberKnife
- Gamma Knife
Radiation Therapy Machines
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• 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.
The Electromagnetic Spectrum
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• 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
DNA (DeoxyriboNucleic Acid)
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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
Dose Equivalent
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Exposure to Ionizing Radiation
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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 approximately
3 chest x rays (equal to < 1 Gy)
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
Radiation Therapy Planning Session
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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
Side Effects
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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%
Whole Brain Irradiation Dose Volume Equivalents
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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
Primary Brain Tumors
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Radiation Side Effects
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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
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
Radiation Treatment Goal
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Normal Tissue Tolerance To Therapeutic Radiation
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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
Lens1,000 (no partial volume) Cataract
Spinal Cord4,500 (10 cm) Infarction
Necrosis
Pituitary
4,500 Endocrine Abnormalities Sex HormonesThyroid HormoneCortisol
Dose expected to give a 5% risk of injury at 5 years
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
Brain Volume
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Medication for Radiation Side Effects
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Medications Indications
Decadron Brain Swelling
Anti-Emetics Nausea
Antisiezure Drug Seizures
Hydrocortisone / Aloe Vera
Skin Irritation
Antihistamines Otitis
Artificial Tears Eye Dryness
Is there anything that can be done for long-term/chronic side effects
such as memory loss and fatigue?
Question?
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• 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?
Things To Consider / Try To Optimize Brain Health
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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.
Question?
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We are on the continued quest of study to harness
the benefits of energy produce by
the Electromagnetic Spectrum
Conclusion
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