Radiation Safety Test 1

Caution Radioactive Material

Used when material exceeds 10× quantity in Part 20, Appendix C

Example: hot lab or radioactive material storage area

Workers likely to receive >100 mrem/year must be instructed on:

• Storage, transfer, and use of radioactive material

• Precautions to minimize exposure

• Responsibility to report unsafe conditions or violations

• Right to request radiation exposure reports

• Awareness of other workers in restricted areas

Title 10 CFR

Code of Federal Regulations

19, 20, 30, 35, 71

Authorized User Training

Must complete 700 hours of training and experience and:

• Pass an examination

OR

• Complete 700 hours including:

  • 80 hours classroom/lab training

  • Supervised work under an AU

  • Written attestation confirming competency

Authorized user scope (Part 35)

Use of radiopharmaceuticals is limited by AU training and facility license

• 35.100: Uptake, dilution, excretion (no written directive)

• 35.200: Imaging/localization (no written directive)

• 35.300: Unsealed therapy (written directive required; includes I-131 thresholds)

• 35.400: Manual brachytherapy

• 35.1000: Other uses (e.g., Y-90 SIRT, specific authorization required)

19

Notice to workers

20

Standards for Protection against radiation

30

Rules of general applicability to domestic licensing of byproduct material

35

Medical use of byproduct material (AU)

71

Packaging and Transportation of Radioactive materials

White I

Surface: 0.5 mR/hr

1 meter (TI): Background

Yellow II

Surface: 50 mR/hr

1 meter (TI): 1 mR/hr

Yellow III

Surface: 200 mR/hr

1 meter (TI): 10 mR/hr

Area survey trigger levels

Not specified by NRC

Rule of thumb:

Unrestricted: <0.2 mrem/hr

Restricted: >5 mrem/hr

Types of surveys

Personnel, after spills, periodic area surveys & wipes, leak tests of sealed sources

Wipe test limits (dpm/100 cm²)

Higher energy (I-131, In-111, Sm-153, I-123, Sr-89)

• Restricted: 2,000

• Unrestricted: 200

Lower energy (Tc-99m, Co-57, Tl-201)

• Restricted: 20,000

• Unrestricted: 2,000

Sealed sources – inventory

Semiannual; record radionuclide, model #, serial #, location, and who performed inventory

RAM license

Permit issued by NRC (or agreement state) to possess and use radioactive material; specifies isotopes, activity limits, authorized users, and permitted activities (use, storage, transport, disposal)

Leak tests – when required?

Before first use (unless done within 6 months before transfer); then every ≤6 months

Leak test action level

0.005 µCi (185 Bq) contamination → remove from service and report within 5 days

What do we not have to leak test?

Do not have to leak test sources with a half life of <30 days, with gases only, anything containing less than 100 uCi (however, still have to do inventory)

Tests of well counter

Well counter efficiency

Efficiency = cpm/dpm

FWHM (Full Width at Half Maximum)

Measures energy resolution of the detector

Constancy

Checks that the system gives consistent readings over time

Minimum detectable activity (MDA)

Lowest activity that can be detected above background

Chi-square test

Evaluates counting statistics; checks if variation is within expected limits

Why do you need efficiency for wipes?

Efficiency = how many decays the detector actually sees.

If efficiency is 25%, the detector only sees 1 out of 4 decays.

So 500 cpm ÷ 0.25 = 2000 dpm.

cpm = what you measure; dpm = true activity, so efficiency is needed to find the real value

RSO

Oversees radiation safety program and ensures compliance with regulations

• 5+ years health physics experience (3 years applied)

• OR 2 years supervised medical physics experience

• AND one of the following:

  • Board certification

  • OR 200 hrs didactic + 1 year under RSO + preceptor sign-off

  • OR listed as Authorized User (AU)

Radiation Safety committee (RSC)

-Group that oversees the radiation safety program; includes RSO, medical physicists, and hospital leadership; reviews policies and ensures compliance

-Meet Quarterly

Part 19 notices to workers & inspections

-What is mandated to be posted in the department

• NRC Form 3 (Notice to Workers)

• Copy of the RAM license

• Operating procedures

• Amendments to document

• Notices of violations

Minor spill steps

• Notify others

• Wear gloves/PPE

• Contain and clean spill

• Survey area

• Dispose of waste properly

Major spill steps

• Notify others and evacuate area

• Prevent spread (restrict access)

• Remove contaminated clothing

• Call RSO immediately

• Survey and decontaminate under supervision

Surveys frequency

Performed as reasonable under the circumstances; frequency not specified by NRC

Wipes Frequency

Done after spills and periodically (to check contamination)

Calibration of Survey Meter

Calibrate before first use, annually (by physicist), and after repairs; must read within ±20% of true value; range 0.1–1000 mR/hr

Caution Radiation Area

5 mrem (0.05 mSv) in 1 hour at 30 cm

Example: near injected patient or imaging room

Caution High Radiation Area

100 mrem (1 mSv) in 1 hour at 30 cm

Example: therapy room or high activity source area

Very High Radiation Area

500 rad (5 Gy) in 1 hour at 1 meter

Example: reactor or extreme radiation source area

Spill procedure (major vs minor) and steps

a. What is the difference?

What is mandated to be on a label – vial, syringe, shield?

Steps for receiving a package; time frame

Monitor within 3 hours of receipt (or within 3 hours of next working day if after hours); wear gloves; visually inspect for damage; survey at 1 meter then surface; perform wipe test; verify contents

Release into atmosphere

Gases such as Xenon

Comply with concentrations in part 20, Appendix B

When to notify NRC (package issues)

200 mR/hr at surface or >10 mR/hr at 1 meter; removable contamination >22 dpm/cm²; possible loss of contents (e.g., package components came loose)

Immediate NRC notification (5× annual limit)

• TEDE ≥ 25 rem (0.25 Sv)

• Lens dose ≥ 75 rem (0.75 Sv)

• Shallow dose ≥ 250 rad (2.5 Gy)

Written report:

• Required within 30 days (in addition to above notifications)

• For doses exceeding limits (adults, minors, embryo/fetus, public, air concentrations)

TEDE (Total Effective Dose Equivalent) = Sum of external (DDE) and internal dose; represents total whole-body radiation dose

Reportable Event

• Dose differs from prescribed by >5 rem effective dose equivalent, >50 rem organ, or >50 rem skin

• Total dose delivered differs from prescribed by ≥20%

• Dose exceeds 5 rem EDE, 50 rem organ, or 50 rem skin due to:
  

  • wrong radioactive drug

  • wrong route

  • wrong individual

Medical Event Reporting

Notify the NRC by telephone no later than the next calendar day

Written report within 15 days

Notification of the referring physician and individual involved within 24 hours

Written report to referring physician within 15 days OF DISCOVERY OF EVENT

Reports of Theft

-Immediately if >1000 times quantity in appendix C

-Within in 30 days if >10 times quantity in appendix C

Written Directive

Must be dated and signed by an authorized user before:

• I-131 sodium iodide >1.11 MBq (30 µCi)

• Any therapeutic dose of unsealed byproduct material

• Any therapeutic dose of radiation from byproduct material

If delay would harm patient:

• Oral directive allowed

• Must be documented ASAP

• Written directive required within 48 hours

Report if dose to nursing child:

• 5 rem (0.05 Sv)

• OR causes unintended permanent functional damage

• Notify NRC by phone no later than next calendar day

• Written report within 15 days

24 hour NRC notification (1× annual limit)

• TEDE > 5 rem (0.05 Sv)

• Lens dose > 15 rem (0.15 Sv)

• Shallow dose > 50 rem (0.5 Sv)

Written report:

• Required within 30 days (in addition to above notifications)

• For doses exceeding limits (adults, minors, embryo/fetus, public, air concentrations)

TEDE (Total Effective Dose Equivalent) = Sum of external (DDE) and internal dose; represents total whole-body radiation dose

Release into sanitary sewage

Does not include patient excreta; material must be water soluble; quantity based on volume; must meet concentration limits in Table 3, Appendix B, Part 20; total release ≤1 Ci (37 GBq) per year

Decay in Storage

For materials with physical half-life <120 days; before disposal, survey at surface, material must measure background, and remove radiation labels before disposal

Transfer to authorized recipient

Central Radiopharmacy

Examples: unused doses

Manufacturer

Examples: Generator

Radioactive material waste site

Example: Lu-177m from Lutathera

DDE (Deep Dose Equivalent)

Whole body dose (1 cm depth); annual limit: 5 rem

LDE (Lens Dose Equivalent)

Lens of the eye dose; annual limit: 15 rem

SDE (Shallow Dose Equivalent)

Skin/extremity dose (0.007 cm depth); annual limit: 50 rem

Pregnant worker limit

Embryo/fetus dose; 0.5 rem total during pregnancy (~0.05 rem/month) 10 month gestation period

Public / minor limit

Dose to general public or minors; 0.1 rem per year

ALARA I

Investigational level; 10% of annual limit (0.5 rem)

ALARA II

Investigational level; 30% of annual limit (1.5 rem)

What records are kept for 3 years?

• Surveys

• Audits and other reviews

• Instrument calibrations

• Dosage records

• Leak tests & inventory

• Decay in storage (35.92)

• Mo-99 concentration

• Receipt, transfer, disposal

• Written directives

What records are kept for 5 years?

• Actions taken by licensee’s management

• Radiation protection program changes

What needs to be on a package label?

Prior to disposal, what must be done to that label?

• Radiation symbol

• “Caution Radioactive Material”

• Radionuclide

• Activity

• Transport label (White I / Yellow II / Yellow III)

• Transport Index (TI)

Remove or deface the radioactive label before placing in an unrestricted area

What is mandated to be on a label – vial, syringe, shield?

• Radiation symbol

• “Caution Radioactive Material”

• Radionuclide

• Quantity of radioactivity

• Date/time

Label the shield if the vial/syringe label is not visible

NRC vs agreement states & letter of intent states

NRC (Nuclear Regulatory Commission)

Regulates byproduct, source, and special nuclear material; oversees reactors and sets radiation safety standards

Examples of NRC states: Idaho, Montana, South Dakota, Delaware, Missouri

Agreement States

States that regulate radioactive materials themselves under NRC agreement; must be at least as strict as NRC; NRC still oversees reactors

Examples: Texas, California, Florida, New York, Illinois

Letter of Intent States

States planning to become agreement states; governor submits intent to NRC

Examples: Indiana, West Virginia, Connecticut

FDA (Food and Drug Administration)

Regulates radiopharmaceuticals and medical devices used in imaging

The Joint Commission

Accredits healthcare facilities and ensures safety and quality standards

ICRP (International Commission on Radiological Protection)

International, non-governmental organization that provides radiation protection recommendations

NCRP (National Council on Radiation Protection and Measurements)

US-based organization that provides radiation safety guidelines and dose recommendations

DOT (Department of Transportation)

Regulates packaging and transport of radioactive materials

Film badge

Photographic film dosimeter with filters; measures exposure to different radiation types (uses filters to differentiate radiation by penetration)

Benefit: can estimate type/energy of radiation

Drawback: cannot detect <0.2 mSv and less durable

OSL (Optically Stimulated Luminescence)

Aluminum oxide detector stimulated by laser to measure dose; unique filter patterns help determine radiation type and whether exposure was static contamination or dynamic while worn

Benefit: can be reanalyzed and detects radiation type; sensitive (minimum reading 1 mrem)

Drawback: signal decreases with repeated rereading

TLD (Thermoluminescent Dosimeter)

Lithium fluoride crystal emits light when heated; often used for ring badges and can be worn in wet or dry conditions

Benefit: tissue equivalent, reliable, useful for extremity monitoring

Drawback: minimum reportable dose is 10 mrem and it is not reread like OSL

Internal exposure

Radiation inside the body (ingested/inhaled); difficult to quantify due to biologic half-life, physical half-life, and distribution

External exposure

Radiation from outside the body; easier to measure and monitor

Effective Dose

Effective dose (E)

Sv or rem

-Radiation exposure may occur to whole body or individual organs

-Different organs are considered due to their radiosensitivity and potential damage

-This nonuniformity of exposure is accounted for in Effective dose by using tissue weighting factors (WT)

More sensitive = gonads, bone marrow, colon

Less sensitive = skin, salivary glands, brain, bone surface

Effective dose = Σ (equivalent dose × Wₜ)

{ Σ (sigma) Means “sum of”, calculate each tissues dose, then add them all together }

Equivalent Dose (HT)

Sv or rem

-Effects of radiation depend not only on the amount of energy absorbed but also Linear energy transfer (LET)

-Biological damaged caused by the same dose of different types of radiation may be different if they have different LET

-To account for this difference we have weighting factors (WR) for each type of radiation

-Used for exposure reports from personnel monitoring

-HT = absorbed dose x weighting factor (Q or WR)

-WR x-rays, gamma, beta = 1 WR alpha = 20

Activity

Bq or Ci

Measurement of spontaneous transformation in nuclear decay

Exposure

Roentgen

The measure of ionization of air when exposed to ionizing radiation

-Only talking about photons and air as the medium

Kerma

Gy or rad

Kinetic energy released to matter

-Measurement of energy transferred from radiation to matter

Dose aka absorbed dose

Gy or rad

The amount of energy absorbed per unit mass of the medium at the point of interest.

-Measurement of energy transferred from radiation to matter

-Not necessarily the same as absorbed dose, but often the two are equivalent (1 Gy= 1 Sv)

Direct vs indirect radiation damage

Direct- Radiation deposits energy directly into DNA, causes strand breaks

Indirect- Radiation interacts with water to produce free radicals, which then damage DNA

Rad safety principles

ALARA

As low as reasonably achievable; minimize radiation using time, distance, and shielding

Image Gently

Reduce radiation dose in children; use child-appropriate imaging protocols

Image Wisely

Avoid unnecessary radiation; use appropriate imaging and lowest effective dose