Mixed Deck — All RSO Topics Flashcards

An RSO is working with a source of I-131, which has a half-life of approximately 8 days. If the initial activity is 40 mCi, what will the activity be after 24 days?

Answer: 5 mCi

24 days equals 3 half-lives (24/8 = 3), so the activity decreases by half three times: 40 → 20 → 10 → 5 mCi.

A hospital's pathology waste is found to contain a patient's tissue with measurable I-131 activity. This waste should be:

Answer: Managed as radioactive waste with decay-in-storage if activity allows, then disposed per license conditions

Tissue containing I-131 is radioactive waste; given I-131's 8-day half-life, decay-in-storage is practical, and disposal must comply with the license and applicable state/NRC regulations.

Indirect action in radiation biology refers to:

Answer: Radiation ionizing water to produce free radicals that damage DNA

Indirect action involves radiation ionizing water molecules in cells to produce hydroxyl radicals and other reactive species that then diffuse to and damage DNA.

A whole-body counter is used to measure:

Answer: Internally deposited gamma-emitting radionuclides

A whole-body counter uses large-volume gamma detectors positioned around the body to detect and quantify internally deposited gamma-emitting radionuclides in organs and tissues.

Which nuclear process results in the emission of a positron (β+)?

Answer: Beta-plus decay

Beta-plus decay occurs when a proton converts to a neutron inside the nucleus, emitting a positron and a neutrino.

Linear attenuation coefficient (μ) is used to describe photon beam attenuation in matter. Which formula correctly represents the intensity of a narrow photon beam after passing through a thickness x of a material?

Answer: I = I₀ × e^(-μx)

The intensity of a narrow photon beam decreases exponentially as I = I₀ × e^(-μx), where μ is the linear attenuation coefficient and x is the material thickness.

Liquid scintillation waste containing H-3 or C-14 may be disposed of by sanitary sewer only if:

Answer: The activity per liter and total monthly/annual discharge limits in the NRC license are not exceeded

NRC 10 CFR 20.2003 and license conditions specify allowable concentrations and total annual discharge quantities for sewer disposal; both the concentration and total limits must be met.

Under NRC regulations, workers have the right to receive radiation safety training information including:

Answer: The radiation dose they have received and the results of any surveys or monitoring in their work area

10 CFR 19.13 requires licensees to provide workers with their dose records and the results of radiation surveys in their work area upon request, ensuring workers can make informed decisions about their exposure.

An RSO must report a misadministration in nuclear medicine to the NRC when:

Answer: The administered dose exceeds the prescribed dose by defined thresholds (e.g., >20% for therapeutic doses) or involves the wrong patient/radionuclide

NRC 10 CFR 35.3045 defines medical events (misadministrations) based on dose thresholds, wrong patient/radionuclide/route criteria; these require 24-hour verbal and 15-day written notification to the NRC.

The traditional unit of radioactivity is the Curie (Ci). One Curie is defined as:

Answer: 3.7 × 10^10 disintegrations per second

One Curie equals 3.7 × 10^10 disintegrations per second, based on the activity of one gram of radium-226.

How frequently must sealed sources used in industrial radiography be tested for leakage under NRC regulations?

Answer: Every 6 months

NRC regulations (10 CFR 34.27) require that sealed sources used in industrial radiography be tested for leakage at intervals not to exceed 6 months.

Radiation safety interlock systems on irradiators and accelerators serve what primary purpose?

Answer: To prevent personnel access to the radiation field and terminate exposure automatically if an entry is detected

Interlocks are engineered safety features that prevent accidental human entry into the radiation field by terminating the exposure or withdrawing the source when a door or barrier is opened.

The Annual Limit on Intake (ALI) for a radionuclide is defined as the intake that would result in a committed effective dose of:

Answer: 50 mSv (5 rem)

The ALI is the amount of a radionuclide that, if inhaled or ingested, would deliver a committed effective dose equal to the annual occupational limit of 50 mSv (5 rem).

Personnel decontamination following skin contamination should generally begin with:

Answer: Gentle washing with soap and lukewarm water, avoiding skin abrasion that could increase absorption

Gentle soap and water washing removes most surface contamination effectively while intact skin is the best barrier against absorption; abrading the skin can break this barrier and increase the risk of internal contamination.

The primary objective of radiation safety training effectiveness evaluation is to verify that:

Answer: Workers understand radiation hazards and can apply safe work practices in their actual job tasks

Training effectiveness evaluation assesses whether workers have internalized the knowledge and skills to work safely with radiation, not just whether they attended a class or received materials.

Which of the following should be included in a radiation safety audit?

Answer: A review of personnel dosimetry records

A comprehensive radiation safety audit must include a thorough review of personnel dosimetry records. This review verifies that individual radiation exposures are accurately monitored and remain within regulatory limits, and that the overall dosimetry program is effective. It is a critical component for assessing the safety of workers and the overall performance of the radiation safety program.

Which document must be available to radiation workers at all times under 10 CFR 19?

Answer: NRC Form 3, 'Notice to Employees,' posted in the workplace

NRC regulations require that NRC Form 3 (Notice to Employees) be posted in the workplace to inform workers of their rights, including the right to request dose records and report safety concerns.

What is the primary federal agency responsible for regulating the use of radioactive materials in the United States?

Answer: Nuclear Regulatory Commission (NRC)

The Nuclear Regulatory Commission (NRC) is the primary federal agency responsible for regulating the civilian use of radioactive materials in the United States. Its mission is to ensure public health and safety, promote the common defense and security, and protect the environment from radiation hazards. The NRC establishes and enforces regulations for nuclear power plants and other uses of radioactive materials.

An RSO reviewing dosimetry data notices that an embryo/fetus has received 4 mSv during the declared pregnancy. NRC regulations limit fetal dose during the entire gestation period to:

Answer: 5 mSv

NRC regulations (10 CFR 20.1208) limit the dose to an embryo/fetus during the entire gestation period to 5 mSv (500 mrem) once the pregnancy is declared.

Under NRC regulations, which entity is ultimately responsible for ensuring that radioactive waste generated at a licensed facility is properly managed?

Answer: The licensed facility (the licensee)

The NRC licensee retains cradle-to-grave responsibility for radioactive waste generated under its license, even after transferring it to a licensed disposal contractor.