Radbio Flashcards
Histology of skin cancers
Basal, SCC, Melanoma
Histology of H and N
SCC
Histology of CNS
Astrocytomas
Histology of Breast
Intraductal Carcinoma
Histology of Hodgkins Disease
Lymphoma
Histology of Lung
Non Small Cell Carcinoma, Small Cell Carcinoma
Histology of Esophagus
Upper 2/3 = SCC;
Lower 1/2 = Adenocarcinoma
Histology of Stomach
Adenocarcinoma
Histology of Colorectal
Adenocarcinoma
Histology of prostate
Adenocarcinoma
Histology of Renal
Adenocarcinoma
Histology of Bladder
Transitional Cell
Histology of Testicular
Germ Cell (seminoma/non-seminoma)
Histology of Cervix
SCC
Histology of Endometrium
Adenocarcinoma
Histology of Ovary
Epithelial
Histology of Vulva
SCC
Law of Bernie and Tribondeau:
Radiosensitivity varies with:
- Cell proliferation - more rapidly dividing are more sensitive
- Future Cell Division - more dividing futures are more sensitive
- Differentiation - undifferentiated are more sensitive
At what exposure does Cerebrovascular Radiation Syndrome take place?
> 10,000 rads
At what exposure does Gastrointestinal Radiation Syndrome take place?
500-1200 rads
At what exposure does Hematopoitic (bone marrow) Radiation Syndrome take place?
200-800 rads
What is LD 50/30 and 50/60, and what is the exposure for each
Lethal Dose - 50% of people will die within 30 days - 450 rads; 50% within 60 days - 350 rads
Define the four R’s of Radiotherapy for fractionation
- Repair - normal cells have capacity to repair themselves
- Repopulation - normal and cancer cells repopulate between fractions
- Reoxygenation - tumors cells are allowed time to reoxygenate between fractions (making them more sensitive)
- Redistribution - tumor cells may reassert themselves between fx’s to areas of adequate vascular supply
Most radiosensitive step of Cell Cycle
Mitosis
Most radioresistant step of Cell Cycle
Late S
Stochastic Effect
No Threshold - not characterized by severity buy by incidence (you either get it or don’t get it)
ex. cancer, leukemia
Non-Stochastic (Deterministic)
Threshold dose - Severity is based on increasing exposure.
ex. erythema, cataracts
Radiation safety goals regarding Stochastic and Non-stochastic effect:
Want to eliminate Non-stochastic, and reduce stochastic (only way to eliminate is to stop using radiation)
Define Somatic Effects
Observable, ie. cataracts, or blood changes
Define Teratogenic Effects
Effects on fetus
Define BED mathematically
BED = n x d x RE *n = # of fractions; d = dose
Define RE (relative effectiveness) mathematically
RE = (1 + d / (alpha/beta))
*alpha/beta ratio
What is responsible for the Direct Cell Kill component, and what does it include?
Alpha; DNA double stand breaks and Non-repairable component
What is responsible for the Indirect Cell Kill component, and what does it include?
Beta; DNA single Stand breaks and potentially repairable component
What is RBE normalized to?
250kVp
As LET increases, RBE ______
increases
What is OER and define mathematically
Oxygen Enhancement Ratio;
OER = dose w/o oxygen to cause Biological Effect / dose w/ oxygen to cause Same Effect
What is the OER for a 250 kvp X-ray?
2.5
DVH y-axis and x-axis
Y-axis: % volume or Vol (cc)
X-axis: % dose or Dose (Gy)
Max dose constraints are given to serial or parallel structures?
Serial
% volume-dose constraints are given to serial or parallel structures?
Parallel
Define X and Y axis of NTCP (Normal Tissue Complication Probability)
Y-axis: complication
X-axis: dose
Define Y and X axis of TCP (Tumor Control Probability)
Y-axis: Tumor Control
X-axis: Dose
Therapeutic Ratio
Ratio of tumor response for a fixed level of normal-tissue damage
