Nuclear Medicine - Radiobiology - Radiation Carcinogenesis

Front 1

Describe undifferentiated cells

Back 1

Precursor cells to cells with more defined function like stem cells. Depopulation of this cell type is dangerous to organism

Front 2

What is a undifferentiated cell that dies in interphase, is radiosensitive that is an exception to the law of Bergonie and Tribondeau

Back 2

Lymphocytes

Front 3

List the 4 main categories of cells related to radiosensitivity from most radiosensitive to least

Back 3

1. VIM Vegetative Intermitotic cells
rapidly dividing, undifferentiated, short lifespan, ex. type A spermatoginia, basal cells of epidermis, intestinal crypt cells
2. DIM Differentiating Intermitotic Cells
actively dividing, but more differentiated than VIM, type B Spermatogonia, myelocytes -->

Hint 3

3. RPM reverting post mitotic cells
not proliferating normally but maintain reproductive integrity: liver, glandular, mature lymphocytes (exception, are radiosensitive)
4. FPM fixed post mitotic cells
no division, highly differentiated, most radioresistant: nerve, muscle RBC's

Front 4

2 Other broad categories of cells?

Back 4

1. Parenchymal; typical of organ or tissue function
2. Stromal; connective tissue, blood vessels

Front 5

What is prodromal syndrome?

Back 5

signs and symptoms shortly after significant radiation exposure (threshold of 50-100 rads)
severe response indicates poor clinical prognosis
what are the 2 categories?

Hint 5

1.At LD50/60: fatigue, vomiting, anorexia
2. Additional signs at lethal dose or higher: Fever, hypotension and immediate diarrhea

Front 6

What follows prodromal syndrome?

Back 6

Latent period
What determines its length?

Hint 6

The higher the dose the shorter the latent period

Front 7

What are the 3 possible outcomes after the latent period and their associated doses?

Back 7

1. Hematopoietic syndrome 400 rads
2. Gastrointestinal syndrome 1000 rads
3. Cerebrovascular syndrome 10,000 rads

Front 8

Symptoms of Hematopoietic syndrome?

Back 8

300-800 rads
sufficient to sterilize actively dividing precursor cells of RBC's, platelets and WBC's
L/D 50/60 for humans is about 325 rads

Front 9

Symptoms of Gastrointestinal syndrome?
(cause of death?)

Back 9

1000 rads (no record of anyone surviving this dose)
nausea, vomiting, prolonged diarrhea, loss of appetite and weight
death within 5-10 days
mostly caused by depopulation of epithelial lining of gastrointestinal tract and intestinal crypt cells

Front 10

Symptoms of Cerebrovascular syndrome?

Back 10

10,000 rads +
death in hours
severe nausea, vomiting, disorientation, loss of coordination, respiratory distress, diarrhea, seizures, coma, death
most likely breakdown of nervous system that leads to death
not readily understood as only a few people have ever received this much radiation

Front 11

What are stochastic effects for radiation carcinogenisis?

Back 11

These are non-threshold effects. late effects on somatic cells of the body. Even very small dosages can eventually cause a malignant change in a cell

Front 12

What are non-stochastic effects for radiation carcinogenesis?

Back 12

Zero chance of occurrence below a certain threshold. Above the threshold severity increases with dose.
What is the other name this is known by?

Hint 12

Deterministic effects

Front 13

Define the following terms:
1. Carcinoma
2. Sarcoma
3. Lymphoma
4. Carcinogen
5. Metastasis

Back 13

1. Carcinoma is cancer arising from epithelial tissue.
2. Sarcoma is arrising from connective tissue.
3. Lymphoma is arising from lymphatic tissue or WBC's
4. Carcinogen is cancer causing agent (chemical, viral or radiation)
5. Metastasis is ability of cancer to spread to other parts of the body where new tumors can grow (most important property of cancer which leads to death of host)

Front 14

What are the 4 areas where cancer cells differ from normal cells?

Back 14

1. Immortalization - don't stop reproducing
2. Loss of contact inhibition - ignore neighboring cell signals (ignore space issues)
3. Lose ability to metastasize - ability to stick together
4. Immature - with each division become less specialized and lose differentiation

Hint 14

IISI

Front 15

What is the tumor called when it has lost all differentiation?

Back 15

anaplastic
what is the grading system for this?

Hint 15

GX - cannot be assessed
G1 - well differentiated
G2 - moderately differentiated
G3 - poor differentiated
G4 - undifferentiated

Front 16

What is the grading system for cancer?

Back 16

TNM System
T- Tumor size - 1-4
N - degree of Node involvement - 0-2
M - extent of Metastasis - 0-2

Front 17

What is the latent period for cancer and what is the general time period?

Back 17

Amount of time between exposure to the carcinogen and development of cancer
Solid tumors - 15 yrs
Leukemias - 7-12 yrs

Front 18

What are some of the problems with establishing risk models for cancer?

Back 18

1. No group of people have been studied sufficiently through a lifetime that have been exposed to large amounts of radiation, except for Japanese WWII A-bomb survivors, which may not be representative of all people
2. Data obtained at high doses are extrapolated to the low doses, which may not be accurate

Front 19

What is the Absolute Risk Model?

Back 19

Risk to contract a certain cancer for an age group, which is measured in cases/million people/rad

Front 20

What is the Relative Risk Model?

Back 20

Indicated increased risk for a person at all ages which increases with age

Front 21

What is Linear vs. Quadratic Risk Models?

Back 21

Linear - risk of cancer is proportional to dose at all levels of dosage
Quadratic - risk increases as dose increases

Front 22

What are the most sensitive tissues in the body to the risk of cancer?

Back 22

Lung, breast and thyroid