Radiation Oncology Flashcards
What are the 3 top cancers?
Men: Prostate, Lung, colon
Women: Breast, lung, colon
Deaths: Lung, Breast/prostate, colon
What are clinical applications of radiation therapy?
Definitive therapy: W/chemo/sx, gross/microscopic dz
Palliative therapy: Pain relief, symptomatic brain metastases, Improve function
Oncologic emergencies: SPINAL CORD COMPRESSION, superior vena cava syndrome, gynecological bleeding
What is the mechanism of action of radiation?
Direct DNA damage from ejected electron
Indirect Damage from formation of ROS or free radical. Main mechanism.
when are cells most susceptile to radiation?
G2 or M phase
NOT liver,
What are the types of radiation?
external: Machine
Brachytherapy - radioactive feed inserted into body.
What are the 3 main types of external beam radiation?
Photons
Electrons
Protons/Carbon
What are the diff ways to do External Beam Ratiation?
Standard 3D conformal: with the big machine that shoots the correct dose/shape at your tumor.
Intensity Modulated Radiation: using many angles to target organ more precisely
Stereotactic radiosurgery: Using superfocused radiation to give high doses to kill tumor and minimize tissue death. Missing is a big problem
What is cyberknife?
very accurate. robot for car assembly is used to seek out a metal marker that you place in order to seek and find the tumor. this means it is accurate even as the patient breathes.
What is gamma knife?
very high dose given in a single fraction. most accurate. Brain cancer.
What is proton therapy?
X rays pass through all the way. P
Protons have little dose when they enter, then have a peak then stop so no exit wound.
Peds is the main appilcation.
adult CNS tumors
Lung, head/neck, Prostate
Decreases chance that they will have secondary cancer
Explain Brachytherapy
Perminant or temp implants.
High dose, but cant go everywhere. Typically iodine
Inject seeds into prostate or wherever and they emit over time. Can shape well depending on how you dose. focused radiation. no spreading
What are the steps of getting radiated?
Consultation
Simulation: Get fitted for a mold on face/body to ensure accuracy. do a ct.
Contouring: Draw out tumor and normal tissues on scan. also accounting for microscopic movement of the tumor cells.
Planning: ppl take the drawings and calculate doses and angles and whatnot. back and forth. takes about a week.
Quality Assurance:
Set-Up: same position
Delivery:
Follow Up:
How do you know how much to deliver?
Measured in Gray
Dose depends on type of cancer.
What is fractionation?
Give 2 gray a day typically in order to take advantage of attacking tumor and not normal tissue. Tumor cells haev a hard time regrouping and are more susceptible
What is the diff between definitive and Palliative radiation?
Definitive is more aggressive in terms of dose or treatment
Palliative is typically short course and the goal is to impact a certain side effect or symptom.
