Rad Bio - ... (Unit 1-3)

Tissue Reactions

Biologic somatic effects of ionizing radiation that can be directly related to the dose received; can be early or late.

Cataract

Opacity of the eye that results in partial or complete loss of vision.

Radiation-induced cataracts in humans follow what type of relationship?

Threshold nonlinear dose-response

Single dose of ____ can induce the formation of cataracts.

2 Gyt

Occupational dose of ______ over time is required to induce cataracts and this is extremely rare.

10 Gyt

Atrophy

A destructive response in biologic tissue where significant cell death leads to shrinkage of organs and tissues.

Atrophy may involve:

Parenchymal Cells

Parenchymal Cells

Specific cells of a gland or organ, contained in and supported by the connective tissue framework.

Fibrosis

Abnormal formation of thick, fibrous tissue.

Radiation-induced __________ can develop as a late effect of radiation therapy.

Fibrosis

Infertility

Fertility is uncertain/impaired; may require intervention.

Sterility

Cannot conceive, intervention has no effect.

Oogonia

Immature female sex cells that mature to ova.

Spermatogonia

Immature male sex cells that mature to sperm.

Gonadal dose at _______ = temporary infertility is likely.

2 Gyt

Gonadal dose at ________ = sterility.

5 Gyt

Most x-ray exams deliver fetal doses of <0.02 Gy which do not cause ______________________.

Embryologic Effects

Spontaneous abortion may occur at radiation doses:

Stochastic (aka Probabilistic) Effects

• Non-threshold, randomly occurring biologic somatic changes.

• Probability of occurrence increase with each radiation exposure.

While early tissue effects increase with severity, stochastic increases with __________________.

Probability (incidence)

Carcinogenesis

Formation of a cancer.

___________ is the most significant late stochastic effect caused by exposure to ionizing radiation.

Cancer

In humans, radiation induced cancer may take _______ to develop.

5+ years

Leukemia

Type of cancer that affects the blood-forming tissues in the body, particularly the bone marrow and blood.

A stochastic effect increases in __________ but not ___________ as the dose increases.

Which of the following radiation exposure outcomes exhibit a non-linear threshold dose-response relationship?

• Gastrointestinal Disorders

• Leukemia

• Cancer

• Epilation

• Organ Atrophy

• Genetic Effects

• Erythema

National Council on Radiation Protection and Measurements (NCRP)

US nongovernmental, nonprofit, private corporation that makes guidelines for radiation protection.

Nuclear Regulatory Commission (NRC)

Federal agency that primarily oversees the nuclear energy industry; but also has the authority to enforce medical radiation protection standards.

NRC mandates that a _____________________ and a ____________________ be established for the medical facilities.

• Radiation Safety Committee (RSC)

• Radiation Safety Officer (RSO)

RSO is responsible for: (4)

• Developing a radiation safety program.

• Ensuring radiation practices adequately protect staff from unnecessary exposure.

• Reviewing and maintaining radiation-monitoring records for all personnel.

• Provide counseling/training.

Requirements for X-Ray Equipment

1. Positive Beam Limitation (PBL)

2. Filtration

3. Duplication

4. Collimation for Fluoro Spot Films

5. “Beam On” Indicators

6. Manual Backup Timers for AEC

The RSO is responsible for: (select all that apply)

• Developing a radiation safety program.

• Ensuring facility’s operation radiation practices adequately protect staff.

• Reviewing and maintaining radiation monitoring records for all personnel.

• Provide counseling/training for individuals with a high incidence of repeat x-ray exams.

ALARA

As low as reasonably achievable

EfD Limiting System

Current method for controlling the risk of biologic damage to radiation workers and the general public from radiation exposure.

Effective Dose Limit (EDL)

Dose of ionizing radiation that results in a negligible (small) risk.

Occupational Risk

Potential for death or overall poorer quality of life.

Effective (EfD)

Effective dose annual limits are used for while body and whole-body cumulative.

Equivalent (EqD)

Equivalent dose annual limits for tissues and organs (more localized).

Equivalent vs Effective Dose

Equivalent dose accounts for the absorbed dose to a specific/localized area while effective dose accounts for the risk to the entire organism.

Which of the following is equal to the annual dose limit of the lens of the eye belonging to a radiation worker?

Radiation Hormesis

Hypothesis that a positive effect exists for specific populations that are continuously exposure to moderately higher levels of radiation.

Which of the following statements is incorrect?

• Public effective dose limit = 1 mSv/yr

• Occupational effective dose limit = 5 mSv/yr

• Occupational lens of the eye limit = 150 mSv/yr

• Public Equivalent dose limit of the hands = 50 mSv/yr