Radbio

Question 1

Histology of skin cancers

Answer 1

Basal, SCC, Melanoma

Question 2

Histology of H and N

Answer 2

SCC

Question 3

Histology of CNS

Answer 3

Astrocytomas

Question 4

Histology of Breast

Answer 4

Intraductal Carcinoma

Question 5

Histology of Hodgkins Disease

Answer 5

Lymphoma

Question 6

Histology of Lung

Answer 6

Non Small Cell Carcinoma, Small Cell Carcinoma

Question 7

Histology of Esophagus

Answer 7

Upper 2/3 = SCC;

Lower 1/2 = Adenocarcinoma

Question 8

Histology of Stomach

Answer 8

Adenocarcinoma

Question 9

Histology of Colorectal

Answer 9

Adenocarcinoma

Question 10

Histology of prostate

Answer 10

Adenocarcinoma

Question 11

Histology of Renal

Answer 11

Adenocarcinoma

Question 12

Histology of Bladder

Answer 12

Transitional Cell

Question 13

Histology of Testicular

Answer 13

Germ Cell (seminoma/non-seminoma)

Question 14

Histology of Cervix

Answer 14

SCC

Question 15

Histology of Endometrium

Answer 15

Adenocarcinoma

Question 16

Histology of Ovary

Answer 16

Epithelial

Question 17

Histology of Vulva

Answer 17

SCC

Question 18

Law of Bernie and Tribondeau:

Answer 18

Radiosensitivity varies with:

1. Cell proliferation - more rapidly dividing are more sensitive
2. Future Cell Division - more dividing futures are more sensitive
3. Differentiation - undifferentiated are more sensitive

Question 19

At what exposure does Cerebrovascular Radiation Syndrome take place?

Answer 19

> 10,000 rads

Question 20

At what exposure does Gastrointestinal Radiation Syndrome take place?

Answer 20

500-1200 rads

Question 21

At what exposure does Hematopoitic (bone marrow) Radiation Syndrome take place?

Answer 21

200-800 rads

Question 22

What is LD 50/30 and 50/60, and what is the exposure for each

Answer 22

Lethal Dose - 50% of people will die within 30 days - 450 rads; 50% within 60 days - 350 rads

Question 23

Define the four R’s of Radiotherapy for fractionation

Answer 23

1. Repair - normal cells have capacity to repair themselves
2. Repopulation - normal and cancer cells repopulate between fractions
3. Reoxygenation - tumors cells are allowed time to reoxygenate between fractions (making them more sensitive)
4. Redistribution - tumor cells may reassert themselves between fx’s to areas of adequate vascular supply

Question 24

Most radiosensitive step of Cell Cycle

Answer 24

Mitosis

Question 25

Most radioresistant step of Cell Cycle

Answer 25

Late S

Question 26

Stochastic Effect

Answer 26

No Threshold - not characterized by severity buy by incidence (you either get it or don't get it) ex. cancer, leukemia

Question 27

Non-Stochastic (Deterministic)

Answer 27

Threshold dose - Severity is based on increasing exposure. | ex. erythema, cataracts

Question 28

Radiation safety goals regarding Stochastic and Non-stochastic effect:

Answer 28

Want to eliminate Non-stochastic, and reduce stochastic (only way to eliminate is to stop using radiation)

Question 29

Define Somatic Effects

Answer 29

Observable, ie. cataracts, or blood changes

Question 30

Define Teratogenic Effects

Answer 30

Effects on fetus

Question 31

Define BED mathematically

Answer 31

``` BED = n x d x RE *n = # of fractions; d = dose ```

Question 32

Define RE (relative effectiveness) mathematically

Answer 32

RE = (1 + d / (alpha/beta)) | *alpha/beta ratio

Question 33

What is responsible for the Direct Cell Kill component, and what does it include?

Answer 33

Alpha; DNA double stand breaks and Non-repairable component

Question 34

What is responsible for the Indirect Cell Kill component, and what does it include?

Answer 34

Beta; DNA single Stand breaks and potentially repairable component

Question 35

What is RBE normalized to?

Answer 35

250kVp

Question 36

As LET increases, RBE ______

Answer 36

increases

Question 37

What is OER and define mathematically

Answer 37

Oxygen Enhancement Ratio; | OER = dose w/o oxygen to cause Biological Effect / dose w/ oxygen to cause Same Effect

Question 38

What is the OER for a 250 kvp X-ray?

Answer 38

2.5

Question 39

DVH y-axis and x-axis

Answer 39

Y-axis: % volume or Vol (cc) | X-axis: % dose or Dose (Gy)

Question 40

Max dose constraints are given to serial or parallel structures?

Answer 40

Serial

Question 41

% volume-dose constraints are given to serial or parallel structures?

Answer 41

Parallel

Question 42

Define X and Y axis of NTCP (Normal Tissue Complication Probability)

Answer 42

Y-axis: complication | X-axis: dose

Question 43

Define Y and X axis of TCP (Tumor Control Probability)

Answer 43

Y-axis: Tumor Control | X-axis: Dose

Question 44

Therapeutic Ratio

Answer 44

Ratio of tumor response for a fixed level of normal-tissue damage