Radiation Protection Principles, Shielding, and Transport

Question 1

Material Classification

Non-Radioactive

(10 CFR 71)

Answer 1

If the amount of material is less than 0.002 µCi g^-1, it is not considered radioactive for transportation purposes.

Question 2

Material Classification

Limited Quantity

(10 CFR 71)

Answer 2

If the amount is greater than 0.002 µCi g^-1, but does not exceed 1/1000th of the A₁ or A₂ value, then the material is considered a limited quantity.

Question 3

Material Classification

Type A Quantity

(10 CFR 71)

Answer 3

If the amount is less than or equal to the A₁ or A₂ value, but greater than 1/1000th of the value, then the material requires a Type A package.

Question 4

Material Classification

Type B Quantity

(10 CFR 71)

Answer 4

If the amount is greater than the A₁ or A₂ value, but less than or equal to 3,000 times these values, then the material requires a type B package.

Question 5

Material Classification

Highway Route Controlled Quantity

(10 CFR 71)

Answer 5

The amount is greater than 3,000 times the A₁ or A₂ value, but less than 27,000 curies.

Requirements

• Type B package
• The carrier must have special training.
• State officials must be notified if the material is radioactive waste.

Question 6

What are the three types of shipping containers?

(10 CFR 71)

Answer 6

• Strong Tight Container ⇒ Designed to survive normal transportation handling.
• Type A ⇒ Designed to survive normal transportation handling and minor accidents.
• Type B ⇒ Designed to survive severe accidents.

Question 7

What is an “A” value?

(10 CFR 71 )

Answer 7

The A₁ or A₂ value represents the limit, in curies, permitted to be transported in a Type A package.

Question 8

What are special form radionuclides?

(10 CFR 71)

Answer 8

• Special form radionuclides are usually encapsulated sources which would only pose an external radiation hazard, not a contamination hazard, if the package was ruptured.
• A₁ values

Question 9

What are normal form radionuclides?

(10 CFR 71)

Answer 9

• Normal form radionuclides are usually not securely encapsulated and could yield significant contamination if the package was ruptured.
• These materials could pose an internal hazard to people at the scene of an accident.
• Typically liquids and powders.
• A₂ values

Question 10

What radiation levels apply for a White I label?

• Surface Radiation Levels
• Radiation Levels at 1 m

What is the Transportation Index?

(10 CFR 71)

Answer 10

Surface radiation levels ⇒ Do not exceed 0.5 mrem hr^-1

Radiation levels at 1 meter ⇒ Not applicable

TI ⇒ Not applicable

Question 11

What radiation levels apply for a Yellow II label?

• Surface Radiation Levels
• Radiation Levels at 1 m

What is the Transportation Index?

(10 CFR 71)

Answer 11

Surface radiation levels ⇒ Do not exceed 50 mrem hr^-1 AND

Radiation levels at 1 meter ⇒ Do not exceed 1 mrem hr^-1

TI < 1

Question 12

What radiation levels apply for a Yellow III label?

• Surface Radiation Levels
• Radiation Levels at 1 m

What is the Transportation Index?

(10 CFR 71)

Answer 12

Surface radiation levels exceed 50 mrem hr^-1 OR

Radiation levels at 1 meter exceed 1 mrem hr^-1

TI < 10

Question 13

What is the transport index (TI)?

(10 CFR 71)

Answer 13

The highest radiation level at 1 meter from the surface of the package in mrem hr^-1.

Question 14

What radiation levels apply for a common carrier (open/closed)?

• Surface radiation levels
• Radiation levels at 1 m

(10 CFR 71 )

Answer 14

200 mrem hr^-1 on surface of the package

OR

10 mrem hr^-1 at 1 meter from any surface

Question 15

What radiation levels apply to a contract carrier (exclusive use, closed transport)?

• Package surface
• Vehicle surface
• 2 m from vehicle
• In vehicle cabin

(10 CFR 71)

Answer 15

1000 mrem hr^-1 on package surface

200 mrem hr^-1 on vehicle surface

10 mrem hr^-1 at 2 meters from vehicle

2 mrem hr^-1 in vehicle cabin

Question 16

What radiation limits apply to a contract carrier (exclusive use, open transport)?

• Package surface
• Vehicle surface
• 2 m from vehicle
• In vehicle cabin

Answer 16

200 mrem hr^-1 on package surface

200 mrem hr^-1 on any imaginary surface

10 mrem hr^-1 at 2 meters from any imaginary surface

2 mrem hr^-1 in vehicle cabin

Question 17

DOT classifies radioactive material as hazardous when their specific activity exceeds what values?

Answer 17

Nuclide specific values found in 49 CFR 173

Question 18

What are the limits for removable alpha/beta contamination for packages to be shipped in a non-exclusive use conveyance?

Answer 18

• α ⇒ 24 dpm cm^-2
• β/γ ⇒ 240 dpm cm^-2

Question 19

What is the maximum allowable exposure rate on contact of any external surface of an exclusive use vehicle transporting radioactive material?

Answer 19

• 200 mR hr^-1
• The limit at 2 meters from the surface of the vehicle is 10 mR hr^-1

Question 20

What is the lower limit for specific activity that represents the DOT-regulated radioactive material?

Answer 20

0.002 uCi g^-1

Question 21

For a radioactive materials package shipped via an exclusive use, closed transport, when does removable beta/gamma contamination become unacceptable upon arrival at the consignee’s facility?

Answer 21

• 24,000 dpm
• Regs allow package surface contamination levels up to 100 times the normal limits upon arrival if the package is transported exclusive use

Question 22

What is the maximum transport index for a passenger aircraft?

Answer 22

3

Question 23

What is the maximum exposure rate on contact with a radioactive materials package shipped via exclusive use?

Answer 23

1000 mrem hr^-1

Question 24

State four radiation protection concerns in room preparation for a nuclear medicine patient

Answer 24

• External radiation received by staff
• External radiation received by visitors
• Internal radiation received by family members
• Spread of contamination

Question 25

Describe four specific measures that could be taken in room preparation for a nuclear medicine patient

Answer 25

* Posting sign on door alerting to ongoing radiation therapy to patient in room. * Provide properly labeled vessels with instructions for the collection and processing of all excreta from patient * Providing properly labeled hamper with clear instructions on handling bedding/clothing worn by patient * Installing yellow rope barriers at a specified distance from patient with signs providing appropriate instructions to visitors and staff.

Question 26

What radiation protection measures/controls should be implemented for the protection of hospital staff caring for a nuclear medicine patient?

Answer 26

* Providing training of staff in proper care of a radiation therapy patient. * Informing patient of procedure to be followed to minimize spread of contamination and external radiation received by all persons whom they may contact * Removal of contaminated bed and clothing * Removal of excreta by directly flushing down the toilet (if patient ambulatory) OR immediately as soon as possible if not ambulatory

Question 27

What radiation protection concerns would you have regarding allowing a nuclear medicine patient to resume activities as a radiation worker at a nuclear power facility?

Answer 27

External radiation causing disruptions and problems * Medical isotopes ruing dose of record on personnel dosimetry * Setting off alarms taking away from normal workflow Spread of contamination from internal nuclides leaving the body through normal biological processes

Question 28

List three factors that affect the conversion factor (D_gN) in determining average glandular dose to the breast from mammography.

Answer 28

* Energy quality of incident X-rays * Size and shape of irradiated breast * Density of breast tissue

Question 29

Is it appropriate to use the measurement of H_E in radiotherapy assessment and patient communication?

Answer 29

* Not appropriate * Radiotherapy is applied to selected tissues and cells in order to kill malignant cells. * Often a single organ or tissue is involved and the benefit is considered to far outweigh the risk to the tissue. * The risk factors for healthy tissue may be significantly different that those for diseased or damaged tissues * Additionally, HE is designed for chronic low-level exposures (of populations, not people) compared to the acute doses tailored to the specific care of specific individuals

Question 30

List two disadvantages in the use of H_E in assessing overall patient risk

Answer 30

* Tissue dose distribution can differ significantly among patients of different body sizes and shapes. Therefore, the estimation of patient dose may be in significant error when reference man tissue weighting factors are used. * Tissue dose distribution changes as effective photon energy changes. Depending on the techniques used by a particular technologist for a particular patient, the risk from the estimated H_E value may be different for a given entrance exposure.

Question 31

List five typical quality assurance tests that a medical health physicist would perform on mammographic X-ray equipment.

Answer 31

* Accuracy of kVp * Accuracy of timer * Half-value layer measurement * Linearity and reproducibility of mA * Measurement of representative entrance skin exposure

Question 32

List five recommendations for radiation protections should be implemented when working with beta-emitters?

Answer 32

* Cover surface of the items with sufficient plastic to stop the beta particles * Wear gloves when handling the beta-emitters * Wear protective eye goggles * Have workers check gloves, clothing, and skin for contamination * Have workers wear TLDs to monitor dose to the exposed eyes, skin, and fingers

Question 33

Describe the physical and/or radiological process that creates the three distinct slopes

Answer 33

A ⇒ Absorption of alpha particles and low energy beta particles B ⇒ Absorption principally of high energy beta particles emitted C ⇒ Attenuation of X-ray, bremsstrahlung, and gamma photons

Question 34

Recommend two procedure changes to reduce entrance skin exposure for a diagnostic image. State the effect each change would have on image quality.

Answer 34

Decrease mAs ⇒ Poorer image quality (assuming optimal image quality with current exposure techniques) Increase film speed and/or use image intensifier screens ⇒ better image quality

Question 35

Identify three design characteristics of a general purpose X-ray system and the associate image receptor system which are required to minimize patient dose.

Answer 35

* Film of sufficient speed * Collimation of beam * Required inherent filtration to remove low energy photons

Question 36

What type of radiation do ¹¹C, ¹³N, ¹⁵O, and ¹⁸F emit?

Answer 36

* Either positron emission or electron capture occur with these radionuclides. Therefore they emit positrons and neutrinos. * Characteristic X-rays and gamma-rays are associated with the decay of the atomic and nuclear excited states respectively. * Annihilation photons have an energy of 0.511 MeV and are produced in the surrounding materials when the emitted positrons combine with electrons and undergo positron-negatron annihilation.

Question 37

Identify two health physics concerns which would result from the use of plastic transport lines for ¹¹C, ¹³N, ¹⁵O, and ¹⁸F

Answer 37

* Radiation damage may cause cracking of the lines and release of radionuclides into the room. * Radioactive species such as ¹⁸F may react with the plastic, and the lines could present an external radiation hazard.