radiationoncology

Question 1

what are the 3 main treatment options for cancer

Answer 1

surgery, medical therapy, and radiation therapy never forget the nccn.org

Question 2

what are the 4 basic patterns of spread

Answer 2

local growth tumor itself enlarges over time, local extension tumor invades adjacent organs affects the n stage, lymph node metasteses, hematogenous metastases affects m stage

Question 3

what cancers are RT with chemo used instead of surgery

Answer 3

anal cancers chemo, limited stage small cell lung cancer chemo, esophageal chemo without surgery, stage 3b NSCLC chemor and RT

Question 4

when is RT used as an adjuvant treatment

Answer 4

breast cancer, skin cancer, prostate cancer, uterine/endometrial cancer.

Question 5

when is RT used as a neoadjucant

Answer 5

esophagectomy, rectal, pancreatic , extremity sarcoma only RT no chemo

Question 6

what cancers get the least amount of treatments and the most

Answer 6

Prostate 44 treatments m-f bone 1-10 fractions.

Question 7

what are the 4 r’s of radiation therapy

Answer 7

repair small doses allow repair, redistribution allows the cells to move into the most sensitive phase, reoxygenation allow inner hypoxic tumor cells to get a greater exposure to o2 over time, repopulation delivery continuous daily blows prevents repopulation and thriving.

Question 8

what are the 2 ways that radation is generated

Answer 8

radioactive source brachytherapy seeds that give a halo effect for prostate cancers, or linear accelerator photons or particles electrons for skin and protons no exit dose.

Question 9

what phase are the cells radiosensitive and what phase are they resistant

Answer 9

M/G2 sensitive S resistant

Question 10

what is the therapeutic ratio

Answer 10

TCP over NTCP tumor over normal what dose will kill what.

Question 11

what is the role of Oxygen in radation therapy

Answer 11

helps with the double strand breaks, hypoxic cells are resistant needs the hydroxide ions.

Question 12

what are the fractionation schedules

Answer 12

Standard 180-200 cGy 1x day pallative 300 daily, hyperfractionantion 120=150 2x daily, hypofractionation 800-2200 for 1-3 fractions

Question 13

what is the 5 levels of treament coplexity

Answer 13

non planned, 2d plan scan but no normal tissue, 3dcrt angel of treatment hits tumor and as little normal structure as possible using a computer dose volume histogram has leakage outside the lines, IMRT plan different portions of the treatment fields get different doses of the radiation,SRS/SBRT super high doses convergence of beams to kill the tumor cells in one swoop.

Question 14

what is GTV

Answer 14

gross demonstabe extent of tumor visible tumor

Question 15

what is CTV

Answer 15

margin on GTV to account for tissue with presumed tumor /typical site of spread

Question 16

what is ITV

Answer 16

CVT + internal margin for movement of the body

Question 17

what is PTV

Answer 17

CVT or ITV+ setup margin for patient movement and setup uncertainties

Question 18

what is OAR

Answer 18

organ at risk/critical structure

Question 19

fusion when planning when is it used

Answer 19

MRI brain PET lung head and neck always a CT

Question 20

when would you use electrons or photons

Answer 20

electrons shallow and superficial but photons skin sparing everything deep.

Question 21

what is the difference between steroscopic and cone beam IGRT

Answer 21

when you shift based on bone for steroscopicx ray and soft tissue ct for cone