UNIT 4: Management of Imaging Personnel Dose and Radioisotopes

Question 1

Primary radiation

Answer 1

emerges directly from the x-ray tube collimator and moves without deflection toward a wall, door, viewing window, and so on. Because of this property, primary radiation, also is known as direct radiation. (Unattenuated beam)

Question 2

Secondary radiation

Answer 2

radiation that has been deflected from the primary beam. Leakage from the tube housing (photons that pass through the housing) and scatter (primarily from the patient) make up the secondary radiation

Question 3

Workload (W)

Answer 3

the radiation output weighted time that the unit is delivering radiation during the week

Question 4

Attenuation

Answer 4

the reduction of the intensity of an x-ray beam as it goes through matter

Question 5

Controlled area

Answer 5

a region adjacent to a wall of an x-ray room is to be used only by occupationally exposed personnel (e.g., radiographers)

Question 6

Uncontrolled area

Answer 6

a nearby hall or corridor that is open to and frequented by the general public

Question 7

Radiation area

Answer 7

an area in which radiation exposures may exceed 0.05 mSv (5 mrem) in 1 hour at 30 cm from a source

Question 8

Isotopes

Answer 8

Atoms with the same number of protons but different numbers of neutrons

Question 9

Radioisotopes

Answer 9

• Isotopes that spontaneously balance their arrangement to achieve a lower energy state.
• Unstable nuclear configuration (too many protons or neutrons)

A few have too many protons for stability, whereas others have too many neutrons, and some are just formed in higher energy states. Because of this, such isotopes spontaneously undergo processes or transformations either to rectify their unbalanced arrangement or to achieve a lower state of energy, or both. All atoms whose nuclei behave in this manner are referred to as radioisotopes.

Question 10

Brachytherapy

Answer 10

radiation that can be delivered more advantageously by infusion or implantation of certain radioisotopes

Question 11

What is the recommended annual occupational effective dose limit from the NCRP? (provide answer using traditional and SI units)
What is/ is not included in this measurement?

Answer 11

-50 millisievert (mSv) or 5 Rem
-does not include personal medical exposure that an employee may receive or the background exposure that all people receive

Question 12

Differentiate between the lifetime effective dose and the cumulative effective dose limit

Answer 12

-Cumulative effective dose (CumEfD): A radiation worker’s lifetime EfD must be limited to their age in years times 10 mSv. This limit pertains to the whole body.
-Lifetime effective dose: Dose in millisieverts that does not exceed 10 times the occupationally exposed person’s age in years, or for the dose in rem, the age of the person

Question 13

What is the rationale that supports radiation workers to receive a larger equivalent dose than the general public?

Answer 13

The workforce in radiation-related jobs is small when compared with the population as a whole. Therefore, the expectation of any measurable increase in disease in the population, in individuals, or impact upon the gene pool is negligible.

Question 14

What practices can radiographers employ to support the ALARA principle?

Answer 14

• The principles of time, distance, and shielding
• Adequately collimating the radiographic beam

Question 15

Describe how the patient may be a source of scattered radiation?

Answer 15

The patient becomes a source of scattered radiation as a consequence of the Compton interaction process. The radiation deflects off of the patient, causing scatter that can hit the x-ray tech or anyone nearby.

Question 16

What poses the greatest occupational hazard in diagnostic imaging? What can the radiographer do to lessen their risk?

Answer 16

-Scattered radiation
-Beam constraint devices, such as automatic collimation, or positive beam limitation, restrict the dimensions of the radiographic beam so that its margins do not extend beyond the image receptor. This reduction in beam size decreases the number of x-ray photons available to undergo Compton scatter.

Question 17

How does filtration of the x-ray beam benefit the radiographer?

Answer 17

Removes nonuseful low energy photons from the beam so in return this reduces scatter radiation to the radiographer

Question 18

Identify two types of secondary radiation

Answer 18

scatter and leakage radiation

Question 19

What is the minimum lead equivalent required for aprons?

Answer 19

0.25mm

Question 20

What are the pros/cons when deciding which thickness of lead equivalent the radiographer should utilize for their aprons?

Answer 20

-Heavier aprons offer more protection but are heavier and cause strain on the back
-Lighter aprons offer less protection but are lighter

Question 21

When should a wrap around apron be utilized?

Answer 21

If any personnel could have the posterior surface of their body turned toward the x ray source during a radiologic procedure

Question 22

What thickness of lead equivalent for aprons is recommended?

Answer 22

0.5mm

Question 23

The correct way to store lead aprons is to:

Answer 23

Lead aprons should be hung on racks or draped over a bar designed for storage

Question 24

The incorrect way to store lead aprons is to _______________________________________. Why?

Answer 24

-be folded or crunched up in any fashion
-Because this will lead to cracks or breaks in the lead impregnated material, thereby compromising the device’s effectiveness for protection from radiation

Question 25

Describe the requirements to ensure the integrity of the lead aprons

Answer 25

all aprons be inspected annually for cracks or other defects either by fluoroscopy or by imaging the apparel with a high kVp technique

Question 26

Physical Attributes of Protective Lead Aprons: PERCENTAGE X-RAY ATTENUATION Table

Answer 26

(Table shows in percentages)

Question 27

During which exams might the radiographer utilize the 0.5mm lead equivalent lead vs. 1 mm lead equivalent?

Answer 27

-With .5mm lead: low kvp exams -With 1 mm: high kVp exams

Question 28

Variations of Lead (Equivalent) Thickness of Aprons: Required Thickness

Question 29

Minimum Lead Requirements of Accessory Devices: Neck & Thyroid Shield

Answer 29

0.5mm

Question 30

Minimum Lead Requirements of Accessory Devices: Eye glasses

Answer 30

0.35-0.5 mm

Question 31

How can technical exposure factors contribute to the radiographer’s cumulative effective dose?

Answer 31

For lower kVps, more mA is needed to secure a high-quality image, and therefore more significant amounts of low-energy photons are present. These characteristics of the x-ray beam lend themselves to the production of increased large-angle scatter radiation. Conversely, higher kVp techniques: • Increase the mean energy of the photons comprising the radiographic beam, leading to a decrease in large angle scatter • Require lower incident photon beam intensity (i.e., lower milliampere-seconds [mAs]) Therefore, with higher selected kVp values, less side-scattered radiation is available to strike imaging personnel, and the potential EqD is reduced.

Question 32

T or F: higher selected kVp values means less side scattered radiation is available to strike imaging personnel, and the potential EqD is reduced

Answer 32

True

Question 33

What is the primary reason repeat images occur in digital imaging?

Answer 33

Mispositioning

Question 34

How should immobilization be implemented for patients who need to be restrained?

Answer 34

Mechanical restraining devices should be used to immobilize the patient whenever possible. If mechanical means of restraint are not feasible, nonoccupationally exposed persons, wearing appropriate protective apparel, are to perform this function. These individuals should be positioned so that their lead-protected torsos are not struck by the primary, or direct, beam.

Question 35

What absolute limitations must the radiographer be aware regarding patient immobilization?

Answer 35

Pregnant women should never assist in holding a patient during an exposure

Question 36

What is the first thing a pregnant radiographer should consider doing? This act is voluntary or mandatory?

Answer 36

-Inform her supervisor -Voluntary

Question 37

What is the facility’s responsibility when there is a pregnant radiographer?

Answer 37

The facility, through its radiation safety officer: • Provides essential counseling • Furnishes an appropriate additional radiation dosimeter for monitoring of any possible radiation exposure to the embryo-fetus

Question 38

How should fetal monitoring be carried out during the pregnancy?

Answer 38

worn at the waist level during all radiation procedures. When a protective lead apron is used, the dosimeter should be worn at waist level beneath the apron

Question 39

What type of shielding is available for pregnant radiographers?

Answer 39

Specially designed maternity protective aprons consist of **0.5 mm lead equivalent over their entire length and width.** They have an **extra 1 mm lead equivalent protective panel that runs transversely across the width of the apron** to provide added safety for the embryo-fetus.

Question 40

Identify and discuss how the work schedule should be implemented when a radiographer declares her pregnancy

Answer 40

the declared pregnant radiographer does not necessarily need to be reassigned to a lower radiation exposure position as a direct consequence of a declared pregnancy

Question 41

What is the relationship between time and radiation dose to the radiographer?

Answer 41

The amount of radiation a worker receives at a particular location is **directly proportional** to the length of time the individual is in the path of ionizing radiation

Question 42

How can the radiographer minimize their time of exposure during a fluoroscopic procedure?

Answer 42

be present in a fluoroscopy room only when needed to perform appropriate patient care and to fulfill the duties associated with the procedure

Question 43

What is the relationship between distance and exposure to the radiographer? How can this relationship be mathematically expressed?

Answer 43

-**Inversely proportional**, with distance, imaging personnel will receive significantly less radiation exposure by standing farther away from a source of radiation -Inverse square law

Question 44

What materials may be used as structural protective barriers?

Answer 44

• Lead • Concrete

Question 45

What is the purpose of a primary protective barrier? Where are they located?

Answer 45

-To prevent direct, or unscattered, radiation from reaching personnel or members of the general public on the other side of the barrier - located perpendicular to the undeflected line of travel of the x-ray beam

Question 46

Describe the common design of a primary protective barrier when an x-ray beam reaches 120 kVp

Answer 46

• Contains of 1.6 mm (1/16 inch) lead • Extends 2.1 m upward from the floor of the x-ray room, when the x-ray tube is 1.5 to 2.1 m from the wall in question

Question 47

Identify sources of secondary radiation

Answer 47

Leakage from the tube housing (photons that pass through the housing) and scatter (primarily from the patient)

Question 48

What is the purpose of a secondary protective barrier and where can they be found?

Answer 48

-Protects against leakage and scatter radiation -Any wall or barrier that is never struck by the primary x-ray beam is classified as a secondary barrier. This does not mean that secondary radiation cannot strike primary barriers as well. **A secondary barrier should overlap the primary protective barrier by approximately 1.3 cm (1/2 inch).**

Question 49

Describe the common design of secondary protective barriers

Answer 49

the secondary barrier consists of 0.8 mm (1/32 inch) of lead

Question 50

Types of Protective barriers

Answer 50

Question 51

What is the maximum allowable exposure a radiographer can receive in the control booth in a week?

Answer 51

1 mSv (100 mrem)

Question 52

In a well-designed facility, approximately how much exposure might the radiographer receive in the control booth?

Answer 52

0.02 mSv (2 mrem)

Question 53

If you are assisting with a fluoroscopic procedure, what practices can you employ to reduce your occupational exposure during the exam?

Answer 53

• Adequate beam collimation • Adequate filtration • Control of technical exposure factors • Appropriate source-to-skin distance • Diagnostic-type protective x-ray tube housing • Cumulative timing device (5 minute timer) - Bucky slot cover (0.25mm lead) - Curtain (0.25mm lead)

Question 54

Table to help you understand how the following should be used to minimize occupational dose during fluoro exams

Answer 54

Question 55

How long should the cord be to the exposure switch on a portable (mobile) x-ray machine?

Answer 55

Must be long enough to permit the radiographer to stand at least 2 m from the: • Patient • X-ray tube • Useful beam

Question 56

Where is the best place for the radiographer to stand in relation to the patient during mobile radiography? Why?

Answer 56

a right angle (90 degrees) to the x-ray beam–scattering object (the patient)

Question 57

When working in the OR during fluoroscopic exams, what practices can the radiographer employ to minimize their dose?

Answer 57

Staying on the side of the patient that is away from the x ray tube (so by the image intensifier)

Question 58

What type of protective shielding should the radiographer use in the OR?

Answer 58

0.5 mm lead apron. A neck and thyroid shield of 0.5 mm lead equivalent should also be worn.

Question 59

Describe the practices a radiographer should implement to reduce patient & personnel dose during fluoro procedures in the OR

Answer 59

reverse the C-arm to place the x-ray tube under the table and the image intensifier over the table

Question 60

What are the negative aspects of utilizing “mag mode” during fluoro procedures in the OR?

Answer 60

requires higher mA, which produces additional radiation exposure

Question 61

How can last image hold reduce patient dose?

Answer 61

no need to expose the patient again to review patient position

Question 62

How can changing the beam entry location reduce patient dose?

Answer 62

reduce the total dose to any one area of skin

Question 63

How can continuous vs pulsed mode fluoroscopy reduce pt dose?

Answer 63

Reducing the use of continuous fluoroscopic mode relative to the pulsed mode of operation

Question 64

How can utilizing 15 imaging frames/ second vs. 30 imaging frames/ second reduce pt dose?

Answer 64

15 frames/ sec reduces exposure

Question 65

Which NCRP limit should interventional physicians be mindful of and how can they protect themselves from reaching this limit?

Answer 65

-An annual EqD limit to localized areas of the skin and hands of 500 mSv (50 rem) -Protective gloves

Question 66

Primary, Scatter, Leakage Radiation

Answer 66

Question 67

What unit of measure is associated with workload?

Answer 67

workload (W)=mA-min/week

Question 68

What technical exposure factor(s) is/ are associated with workload?

Answer 68

mA and S (Seconds)

Question 69

Discuss the Inverse Square Law (ISL), how it relates to radiation protection of personnel and barrier shielding requirements.

Answer 69

The intensity of the x-ray lessens as the distance increases. More distance means less shielding requirements.

Question 70

Inverse Square Law Equation

Answer 70

Question 71

What protective barrier / shielding should be implemented if primary or secondary radiation is never directed at a particular wall or structure?

Answer 71

existing construction is sufficient

Question 72

What parts of the x-ray room will not be exposed to radiation?

Answer 72

Most structures in a diagnostic x-ray suite are struck by radiation to some degree

Question 73

What type of protective barrier/ shielding should be used if no one will ever be present on the other side of the wall of an x-ray room?

Answer 73

Existing construction

Question 74

Identify and explain the rationale for the maximum allowable equivalent dose for the following areas: ● Controlled area: ● Uncontrolled area:

Answer 74

● Controlled area: used only by occupationally exposed personnel (e.g., radiographers). 1000 µSv or 1 mSv. ● Uncontrolled area: a nearby hall or corridor that is open to and frequented by the general public. 20 microsieverts (20 µSv or 2 mrem).

Question 75

How does identification of a controlled or uncontrolled area affect the shielding design of an imaging department?

Answer 75

Controlled area requires more shielding

Question 76

Briefly summarize how the protection planner determines how much lead/ shielding should be used on a primary barrier

Answer 76

Is the barrier primary or secondary? Is the area beyond the barrier controlled or uncontrolled?

Question 77

If a primary barrier is likely to receive secondary and/ or leakage radiation, how does the shielding design of the x-ray room need to be adjusted?

Answer 77

no additional shielding against secondary radiation is needed for areas already protected against primary radiation

Question 78

What assumptions are made when designing shielding for an area that receives scatter radiation?

Answer 78

1. The energy of the scatter radiation is conservatively considered to be equal to that of the primary radiation. 2. The intensity of radiation scattered at 90 degrees at a distance of 1 m from its source is reduced by a factor of 1000 relative to the primary radiation for a field size of 400 cm2

Question 79

What is the maximum limit allowed regarding leakage radiation?

Answer 79

cannot exceed 100 millitoentgens (mR) per hour or 0.88 milligray (mGy) air kerma per hour

Question 80

What requirements do some states employ regarding “beam-on” signage?

Answer 80

Warning lights that are stand out near the door to the examination room from any corridor. The sign should read “x-ray beam on” or the equivalent and be self-illuminating whenever the x-ray equipment is energized.

Question 81

Where might someone find radiation warning signs?

Answer 81

-On the door to CT and interventional x-ray rooms -Linear accelerator treatment rooms -Storage areas for radioactive materials

Question 82

If radiation exposures exceed those in diagnostic radiology, give examples of “special” signage someone may come across and in which departments these might be located?

Answer 82

-High Radiation -Very High Radiation -Airborne Radioactivity -Radioactive Materials -Departments these might be located: Radiation Oncology and Nuclear Medicine

Question 83

What happens if an isotope is “unstable”?

Answer 83

Undergoes changes and becomes radioactive (produces radiation)

Question 84

Where can a radiographer reference the procedures to dispose of radioactive materials?

Answer 84

radiation safety program of the institution

Question 85

Identify the practices personnel should use when handling & disposing of radioactive materials.

Answer 85

-Must wear gloves if the isotopes are in liquid form -Be equipped with personnel dosimeters (whole body and extremity, the latter in the case of close handling) -Follow the cardinal rules of radiation protection (time, distance, and shielding) where applicable -No solid encapsulated radioactive source is ever to be touched directly by hand. Instead, long tongs, which add distance as a safety measure, should be used.

Question 86

Where should leftover radioactive materials be placed and how should they be labeled?

Answer 86

-A residual isotope is to be returned to its shielded container -That container should then be labeled with how much activity remains and the current date

Question 87

How should radioactive contaminated items be handled, stored, and disposed of?

Answer 87

Any contaminated items are to be placed in a sealed plastic bag that is labeled with the name of the radioisotope and the current date. After this is done, all involved personnel are to be checked with the survey meter to ensure that they have not been contaminated. Then the remaining isotope (if it is not to be returned to its supplier) and the packaged contaminated items are to be placed into a secure, shielded, and posted storage area where they must be held for a period of 10 half-lives before being suitable for disposal in ordinary trash.

Question 88

In what modalities might a radiographer most likely encounter radioisotopes/ radioactive materials?

Answer 88

Nuclear medicine, PET/CT, Radiation therapy

Question 89

During an emergency situations, what is the dose limit for individuals engaged in: ● Nonlifesaving activities? ● Lifesaving activities?

Answer 89

● Nonlifesaving activities: 50 mSv (5 rem) ● Lifesaving activities: 250 mSv

Question 90

Which organization has outlined dose limits for lifesaving and non-lifesaving events?

Answer 90

Environmental Protection Agency (EPA)

Question 91

Contrast how patients suffering from surface contamination vs. internal contamination should/ might be managed by medical personnel

Answer 91

-For surface contamination, the clothing of individuals who have been contaminated should be placed in plastic containers and set aside for later evaluation. Removal of surface contamination involves removal of the patient’s clothing and the use of a shower to cleanse the skin. **Personnel should wear gowns, masks, and gloves when working with the patient** -For internal contamination: • Dilute contaminants with fluids -IV and/ or Oral • Administer medications to block absorption in the GI tract(emetics, charcoal, laxatives)

Question 92

EfD limit allowed for individual members of the general population not occupationally exposed. That limit is:

Answer 92

• 1 mSv (100 mrem) for continuous or frequent exposures from artificial sources other than medical irradiation and natural background radiation • 5 mSv (500 mrem) for infrequent annual exposure

Question 93

CumEfD limits do not include:

Answer 93

• Radiation exposure from natural background radiation • Exposure acquired as a consequence of a worker’s undergoing medical imaging procedures

Question 94

CumEfD limits do include the possibility of

Answer 94

• Internal exposure • External exposure

Question 95

Is patient scatter greater at entrance or exit

Answer 95

Entrance

Question 96

Diagnostic imaging personnel are potentially subjected to the highest occupational exposure during:

Answer 96

• Fluoroscopy: fixed and mobile • Mobile radiography • Special procedures • Interventional surgery

Question 97

Radioactive decay

Answer 97

• Unstable isotopes undergo changes to stabilize • Half life

Question 98

What unit of measure is used for Use Factor

Answer 98

U

Question 99

What unit of measure is used for Occupancy Factor

Answer 99

T

Question 100

Most common isotope used in nuclear medicine

Answer 100

TC-99

Question 101

The _________ of a radioisotope is the amount of time needed for its radioactivity to be reduced to one-half its original value.

Answer 101

Half life

Question 102

Which radioactive material is the most concerning for occupational exposure?

Answer 102

Fluorine - 18