283 - Radiation Oncology Flashcards

1
Q

How does fractionating radiation allow for better cell kill and sparing of normal tissues?

A
  • Spares normal tissue
    • Allows normal tissue to repair itself, re-populate
    • Often, malignant cells do not have these repair mechanisms
  • Better cell kill
    • Reassortment: Allows cells in radio-resistant phase to get to a more sensitive phase before the next tx
    • Reoxygenation: Tumors that are hypoxic don’t respond as well; oxygenation is important for indirect killing (Ionizing radiaton -> free radical generation -> DNA damage)
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2
Q

What is the mechanism by which radiation induces a biologic eent?

A
  • Direct (~1/3 of damage)
    • Ionizing radiation causes DNA breaks
  • Indirect (~2/3 of damage)
    • Ionizing radiation generates free radicals, which cause DNA breaks
    • Oxygen is important for this!
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3
Q

What is brachytherapy?

When is it indicated?

A

Focal delivery of a radioactive isotope via implant for the purpose of cancer therapy

Example: curative therapy in locally advanced cervical cancer

Thank you @Lauren Smith and PJDJ deck!

Vs. external beam = shooting x-rays or gamma rays at the tumor from an external source

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4
Q

What is “gamma knife” radiation?

When is it used?

A

Gama knife = stereotactic radiosurgery. Uses advanced image guidance

Used when there are small, well-defined targets (not for microscopic spread)

Often used for intra-cranial treatment (single fraction)

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