Modern Medical Technology

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Modern Medical Technology

• X-rays

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History

• Discovered by Wilhelm Conrad Roentgen in 1895
• Was awarded the first Nobel prize in physics in
  1901 for his discovery.

http//www.xray.hmc.psu.edu/rci/centennial.html
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History of X-rays in Medicine

• Physicians used X-rays to observe
• Bullets, bones, kidney stones, organs
• Began looking for curative effects for diseases
  such as
• Tuberculosis, cancer, lupus

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History of X-rays in Medicine

• January 12, 1896 Emile Grubb treated a woman
  with recurrent breast cancer

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Other Historical uses of X-rays

• X-ray epilation
• Bone protraits
• Investigational work

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Dangers of X-rays

• Feburary, 1896 Dean of Vanderbilt University
  hair fell a few weeks after he agreed to let the
  physics professor perform a X-ray of his skull.
• Death of Clarence Dally began a debate about
  whether or not X-rays were harmless.

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Side Effects of X-rays

• Redness
• Numbness
• Epilation
• Infection
• Pain
• Nausea and vomitting

• Decrease in blood cells
• Temporary sterility
• DNA damage
• Death

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Ionizing Radiation

• High energy forms of radiation that cause
  electrons to be ejected from atoms in a cell
  leaving behind free radicals (ionized atoms with
  unpaired electrons).
• Free radicals are highly reactive.

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Units of Ionizing Radiation

• Amount of ionization is proportional to amount
  of energy deposited.
• Radiation dose unit (rad) 0.01 Joule/kg
• SI unit Gray (Gy) 1 J/kg 100 rad
• Energy needed for one ionization is lt 10-18 J

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Relevant Biological Effectiveness (RBE)

• Roentgen equivalent man (rem) rad x RBE
• SI unit Sievert (Sv) Gy x RBE 100 rem

• Examples
• Type RBE
• X-rays 1
• g rays 1
• Heavy ions 10-20

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Biological Effects of Ionizing Radiation

• Interference with cell reproduction
• Destruction of cells function or destruction of
  cell itself

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Doses of Radiation

• Low dose lt 10 rem
• Moderate dose 10 to 100 rem
• High dose gt 100 rem

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Immediate Effects of Radiation

• Dose in rem
• 0-10
• 10-100
• 35, 50
• 100-200
• 200-500
• 450
• 500-2000
• gt2000

• Effect
• No observable effect
• Slight to moderate decrease in WBC
• Temp. sterility (35 for women 50 for men)
• Sig. decrease in blood cells
• Nausea, vomitting, hair loss, some deaths
• Lethal to 50 in 30 days if untreated
• Limited survival
• Fatal within hours collapse of CNS

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Long Term Effects

• Cumulative
• Radiation-induced cancer
• Life-time risk is only 0.03
• 20 of all deaths are due to cancer

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BERT (Background Equivalent Radiation Time

• Dental X-ray
• 0.06 mSv 1 week of background exposure
• Lower GI series
• 6 mSv 2 years of background exposure

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Therapeutic Uses

• Radiation therapy for cancer
• Rapidly dividing cells are more sensitive to
  radiation.
• Radiopharmaceuticals