UNIT 4: Management of Patient Radiation Dose

Question 1

Voluntary motion

Answer 1

Voluntary motion would, under normal circumstances, be expected to be controlled by the patient. Inability to exercise such control may be attributed to:
• The patient’s advanced age
• Breathing problems or irregularities
• Increased anxiety
• Physical discomfort
• Fear of the examination
• Fear of unfavorable prognosis
• Mental instability

Question 2

Involuntary motion

Answer 2

Caused by muscle groups such as those associated with the digestive organs or the heart, cannot be willfully controlled. Other clinical manifestations also cause involuntary motion. These include:
• Chills
• Tremors such as those experienced by patients with Parkinson’s disease
• Muscle spasms
• Pain
• Active withdrawal

Question 3

Remote Room

Answer 3

Room where personnel set up the patient then leave the room before imaging

Question 4

Artifacts

Answer 4

unwanted densities in the image that are not part of the patient’s anatomy and may negatively affect the ability of a radiologist to interpret the image correctly

Question 5

Mean marrow dose

Answer 5

-The average radiation dose to the entire active bone marrow
-Ex: if in the course of performing a specific radiographic procedure, 25% of the active bone marrow were in the useful beam and received an average absorbed dose of 0.8 mGyt, the mean marrow dose would be 0.2 mGyt

Question 6

Fluoroscopic guided positioning (FGP)

Answer 6

the practice of using fluoroscopy to determine the exact location of the central ray before taking a radiographic exposure

Question 7

Position of the American College of Radiology (ACR) on Abdominal Radiologic Examinations of Female Patients

Answer 7

-The primary professional organization of radiologists in the United States
-“Abdominal radiological examinations that have been requested after full consideration of the clinical status of a patient, including the possibility of pregnancy, need not be postponed or selectively scheduled.”

Question 8

Last menstrual period (LMP)

Answer 8

Whenever a female patient of childbearing age is to have an x-ray examination, it is essential that beforehand the radiographer carefully question the patient regarding any possibility of pregnancy. Part of this questioning involves asking the patient for the date of her last menstrual period.

Question 9

What is the conversion between cm and inches?

Answer 9

1 inch = 2.54cm

To convert cm to inches, divide your cm figure by 2.54cm

Question 10

Identify the benefit of effective communication:

Answer 10

This type of dialog alleviates the patient’s uneasiness and increases the likelihood of full cooperation and successful completion of the procedure

Question 11

Good communication can lead to:

Answer 11

• Encourages reduction in anxiety and emotional stress
• Enhances the professional image of the radiographer as a person who cares about the patient’s well-being
• Increases the chance for successful completion of the x-ray examination, thereby reducing the potential of repeat exposures resulting from poor communication

Question 12

When a radiographer takes time to explain a procedure, address and answer questions truthfully, what might this create?

Answer 12

This creates a sense of trust between the patient and the radiographer and encourages any further discourse

Question 13

How can the radiographer reduce/eliminate voluntary motion during radiography?

Answer 13

Gain the cooperation of the patient or adequately immobilize that individual during
the radiographic exposure

Question 14

How can the radiographer reduce/ eliminate involuntary motion during radiography?

Answer 14

Decreasing the exposure time with an appropriate increase in milliamperes (mA) to maintain sufficient milliampere-seconds (mAs) for useful radiographic brightness and using very-high-speed imaging receptors

Question 15

Which body parts should be shielded from the radiographic beam when possible?

Answer 15

• Lens of the eye
• Breasts
• Thyroid gland

Question 16

Explain how/ when gonadal shielding should be applied

Answer 16

-American Association of Physicists in Medicine (AAPM) stated that patient gonadal shielding and fetal shielding during diagnostic imaging procedures should be discontinued as routine practice. Use proper Collimation instead.

-Specific area shielding: Radiosensitive organs and tissues may be selectively guarded against the primary beam during a diagnostic radiographic examination. Shields for the lens of the eye are the contact type and are positioned directly on the patient.

Question 17

What is the ratio between exposure to female versus male gonads during pelvic-region radiography?

Answer 17

female gonads receive about three times more exposure than males

Question 18

Identify and briefly describe the basic types of gonadal shielding available

Answer 18

• Flat contact shields- Uncontoured lead strip or lead-impregnated material 1 mm thick placed directly over the patient’s reproductive organs to provide protection from exposure to ionizing radiation
• Shadow shields- A shield of radiopaque material suspended from above the radiographic beam-defining system; these shields are positioned at some distance above the patient to cast a radiation protection shadow in the primary beam over the area spanned by the patient’s reproductive organs
• Shaped contact shields- A cup-shaped radiopaque shield, containing 1 mm of lead that is contoured to enclose the scrotum and penis to protect the male reproductive organs from exposure to ionizing radiation.
• Clear lead shields- Transparent lead acrylic material that has been impregnated with approximately 30% lead by weight. It is used for viewing windows and pull-down or roll-away x-ray room shielding.

Question 19

How should flat contact shields be applied during fluoroscopic exams?

Answer 19

under the patient because the tube is under the radiographic table

Question 20

Discuss the radiation protection technique(s) that should be employed when performing a scoliosis series on an adolescent female

Answer 20

PA projection with a clear lead shadow shield to reduce exposure to the patient’s breasts

Question 21

Identify the characteristics of a high quality digital image

Answer 21

-Sufficient brightness/density
-Subject contrast to differentiate structures
-Maximum spatial resolution
-Minimal distortion

Question 22

Why is standardizing technique charts so important in the digital imaging age?

Answer 22

It creates a quality diagnostic image with minimal patient exposure. Neglecting to use such technique charts necessitates estimating the technical exposure factors, which may result in:
• Poor-quality images
• Repeat examinations
• Additional and unnecessary exposure to the patient

Question 23

Who should establish the standardize technique charts?

Answer 23

The Radiology departments

Question 24

How is optimal contrast achieved on the digital image?

Answer 24

With adequate penetration from the correct kVp. As long as the part is adequately penetrated, increasing kVp by 15% with a corresponding decrease in mAs reduces patient exposure significantly while yielding satisfactory image quality.

Question 25

Explain how AEC can minimize patient exposure. What are its limitations?

Answer 25

It ends the radiation when a predetermined amount of radiation is received by an arrangement of sensors. Automatic exposure systems are designed to produce an acceptable diagnostic image while limiting the total amount of radiation exposure to the patient.

Question 26

Describe the air gap technique, the rationale for its use in radiography, and its limitations.

Answer 26

An alternative procedure to use in place of a radiographic grid for reducing scattered radiation during specific examinations. This technique works by using an increased object-to-image receptor distance (OID). Less scatter radiation at the detector decreases image blurring and thereby improves radiographic image contrast.

•IR 4 – 6” behind patient
•Requires 10-12’ SID to reduce magnification

· reduces scatter radiation
· scattered x- less likely to strike the IR.
· not effective over 90 kVp

Question 27

What is the difference between a repeat image and an additional image?

Answer 27

A repeat image is an image that must be performed more than once because of human or mechanical error during the production of the initial image. An additional image is an image recommended by the radiologist for obtaining additional diagnostic information.

The radiographer should, from the beginning of the examination:
• Correctly position the patient
• Select the appropriate technical radiographic exposure factors that will ensure the production of optimal quality images

Question 28

What is/ are the benefit(s) of having a repeat analysis program?

Answer 28

-In digital imaging, overexposed or underexposed images can be adjusted by computer to appear technically acceptable. With CR or DR, it is necessary to develop a policy whereby the digital files that correspond to retaken images can be recovered for analysis, since this would not happen automatically.

• Provides valuable information for process improvement
• Helps minimize patient exposure
• Improves the overall performance of the department

Question 29

Identify reasons for unacceptable images

Answer 29

•Patient mispositioning
•Incorrect centering of the radiographic beam
•Patient motion during the radiographic exposure
•Incorrect collimation of the radiographic beam
•Presence of external foreign bodies
•Postprocessing artifacts

Question 30

Describe the concept of “unnecessary radiologic procedures” and how these might contribute to the “collective risk” of radiation exposure

Answer 30

Some traditional radiographic examinations are very often casually performed in the absence of definite medical indications. This practice unnecessarily exposes the patient to radiation even though there is virtually no useful medical information gained from the procedure

Question 31

Identify the means that may be used to figure the amount of radiation received by a patient from diagnostic imaging

Answer 31

1. Entrance skin exposure (ESE) includes skin and glandular (commonly used because it’s simplest to determine)
2. Bone marrow dose
3. Gonadal dose

Question 32

Explain how skin dose may be directly measured

Answer 32

using well-documented multiplication factors

Question 33

Differentiate between the gonadal dose and the genetically significant dose

Answer 33

-Genetically significant dose (GSD) is used to assess the overall impact of a gonadal dose on a populace. GSD is defined as the equivalent dose (EqD) to the reproductive organs that, if received by every human in a large population group, would be expected to bring about an identical gross genetic injury to that total population

-gonadal dose: dose for one person
-genetically significant dose: genetic consequences for an entire population

Question 34

How can the bone marrow dose be accurately measured?

Answer 34

-mean marrow dose, which is defined as “the average radiation dose to the entire active bone marrow.”

-Example: if in the course of performing a specific radiographic procedure, 25% of the active bone marrow were in the useful beam and received an average absorbed dose of 0.8 mGyt, the mean marrow dose would be 0.2 mGyt. Because multiple bony areas span the entire body, the radiation dose absorbed by the organ that is called “bone marrow” cannot be measured accurately by a direct method; it can only be estimated.

Question 35

Identify the arguments for & against utilizing FGP ( Fluoroscopic guided positioning) in clinical practice?

Answer 35

The ASRT recognizes that the routine use of fluoroscopy to ensure proper positioning before making an exposure is an unethical practice that increases patient dose unnecessarily and should never be used in place of appropriate skills required of a competent radiologic technologist. Even though the ASRT does not condone FGP, some imaging facilities continue to allow RTs to use fluoroscopy as a positioning aid because they believe that it:
• Is faster than having a repeat exposure
• Reduces the number of repeat exposures
• Provides less radiation exposure to the patient

Question 36

When does the NCRP recommend abdominal radiographs be performed on women of childbearing age to minimize the risk of radiating an embryo?

Answer 36

abdominal examinations should be performed during the first few days after the onset of menses(period)

Question 37

How can the radiographer help avoid exposure to an embryo?

Answer 37

carefully question the patient regarding any possibility of pregnancy (request pregnancy test if needed)

Question 38

Describe the process and list the individuals involved to determine the EqD received by an embryo as a result of a radiographic procedure during an unknown pregnancy

Answer 38

-Process: The first step in the process is to list the specifics of the x-ray examination in as much detail as possible. A useful form can be developed to assist in this process. Request the radiation dose received from the patient’s x-ray list details about the x-ray exam in detail.
-Individuals involved: the medical physicist, radiologist, or radiation safety officer

Question 39

When might it be appropriate to image a known pregnant patient?

Answer 39

when the physician believes it’s in the best interest of the pregnant patient

Question 40

What practices should the radiographer implement to minimize exposure to the embryo/ fetus?

Answer 40

Selecting the smallest technical exposure factors that will still yield a diagnostically acceptable image for the examination and by precisely collimating the radiographic beam to include only the anatomic area of interest. When the patient’s lower abdomen and pelvic regions do not have to be included in the area to be irradiated, they should be protected with a lead apron or other suitable protective shield

Question 41

Why should radiographing children be viewed as “special considerations”?

Answer 41

Children are much more vulnerable to the late effects of radiation than are adults.
Because children have a greater life expectancy, they may easily survive long enough to develop late effects like leukemia or another radiogenic malignancy such as lung or thyroid cancer

Question 42

Identify the most common challenge when imaging children

Answer 42

Patient motion

Question 43

What techniques can the radiographer employ to reduce motion in pediatric patients?

Answer 43

employ very short exposure times by selecting a high mA (400 mA or greater) station and using effective immobilization techniques

Question 44

When might the radiographer forgo the gonadal shield during pediatric imaging?Why?

Answer 44

-When it’s more than 2 cm from the edge of the FOV
-The patient dose is caused more by internal scatter

Question 45

Image Gently

Answer 45

The goal of this campaign is to change long-established practice by raising awareness about methods for lowering radiation dose during pediatric medical imaging examinations

Question 46

Image Wisely

Answer 46

This campaign promotes lowering the amount of radiation used in medically necessary imaging procedures and eliminating unnecessary procedures in adult medical imaging

Question 47

CARES Committee

Answer 47

CARES’ purpose is for all stakeholders to educate the profession regarding the AAPM gonadal shielding position statement. It is of the utmost importance that the shield is not to any degree located within the collimated area of exposure because if AEC is used, it will not allow the exposure to terminate because it attempts to penetrate the lead shield

Question 48

Biggest reason for image repeats

Answer 48

Positioning of the patient

Question 49

Unnecessary Radiologic Procedures

Answer 49

•A chest x-ray examination automatically scheduled on admission to the hospital
•A chest x-ray examination as part of a preemployment physical
•Lumbar spine examinations as part of a preemployment physical
•Chest x-ray examination or other unjustified x-ray examination as part of a routine health checkup
•Chest x-ray examination for mass screening for tuberculosis (TB)
•Whole-body computed tomography (CT) screening

Question 50

Skin dose is

Answer 50

used in radiation safety terminology to refer to the dose to the epidermis, the most
superficial layer of the skin

Question 51

Thermoluminescent dosimeters (TLDs)

Answer 51

are the sensing devices most often used to determine skin dose directly

Question 52

A review of the literature emphasized the following guidelines:

Answer 52

• No diagnostic procedure using ionizing radiation should be conducted unless its benefit outweighs its risk
• Exposures should be kept ALARA, with the procedure optimized to reduce radiation hazards
• The ESE dose level specified in regulations must not be exceeded
• To maintain ALARA and follow the ASRT position statement and the ARRT code of ethics, technologists must not use FGP positioning of patients

Question 53

In fluoroscopy, how is the amount of radiation that a patient receives usually estimated?

Answer 53

By measuring the radiation exposure rate at the tabletop and multiplying this by the fluoroscopy time

Question 54

When should gonadal shielding be applied during a radiographic exam?

Answer 54

When the gonadal organs are within approximately 2 inches of the properly collimated beam and outside the area of interest

Question 55

A dose used to measure the effects of gonadal radiation exposure in the offspring of those exposed is called the:

Answer 55

genetically significant dose

Question 56

What effect does a repeat image have on the radiation dose received by the patient?

Answer 56

The patient’s skin and possibly the gonads, if they were in the included imaged area, receive a double radiation dose