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Questions and Answers
What is the average radiation dose reference used for?
What is the average radiation dose reference used for?
What is the effective dose limit for a radiation worker in a single year?
What is the effective dose limit for a radiation worker in a single year?
Which of the following dose limits is applicable to the lens of the eye for radiation exposure?
Which of the following dose limits is applicable to the lens of the eye for radiation exposure?
Which of the following best describes the purpose of dose limits?
Which of the following best describes the purpose of dose limits?
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In which scenario is a direct risk versus benefit assessment typically made?
In which scenario is a direct risk versus benefit assessment typically made?
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What radiation dose limit applies to the skin in occupations with exposure?
What radiation dose limit applies to the skin in occupations with exposure?
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What is the maximum effective dose limit for individuals in the general population under infrequent exposure?
What is the maximum effective dose limit for individuals in the general population under infrequent exposure?
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How is the cumulative dose limit calculated for radiation exposure based on age?
How is the cumulative dose limit calculated for radiation exposure based on age?
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Who is responsible for providing the necessary resources for an ALARA program?
Who is responsible for providing the necessary resources for an ALARA program?
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What does the acronym ALARA stand for?
What does the acronym ALARA stand for?
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Which of the following is NOT one of the basic protective measures to reduce external radiation exposure?
Which of the following is NOT one of the basic protective measures to reduce external radiation exposure?
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What is meant by the term 'reasonable' in the context of the ALARA principle?
What is meant by the term 'reasonable' in the context of the ALARA principle?
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Which action can be taken to optimize radiation protection during radiography?
Which action can be taken to optimize radiation protection during radiography?
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What does the philosophy behind ALARA assume?
What does the philosophy behind ALARA assume?
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Who shares the responsibility for the implementation of the ALARA concept?
Who shares the responsibility for the implementation of the ALARA concept?
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In which scenario is it critical to reduce exposure time in fluoroscopy?
In which scenario is it critical to reduce exposure time in fluoroscopy?
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What is the best timing for radiographic examinations to minimize pregnancy risks in females of childbearing age?
What is the best timing for radiographic examinations to minimize pregnancy risks in females of childbearing age?
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In which circumstances should a radiological request be referred back to the doctor?
In which circumstances should a radiological request be referred back to the doctor?
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What does the ALARA principle stand for in radiation protection?
What does the ALARA principle stand for in radiation protection?
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What is one of the primary objectives of radiation protection?
What is one of the primary objectives of radiation protection?
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Which rule is used to guide the timing of high-dose radiographic examinations to avoid pregnancy risks?
Which rule is used to guide the timing of high-dose radiographic examinations to avoid pregnancy risks?
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What is the term used for the risk of radiation that increases with the amount of exposure, as opposed to having a threshold?
What is the term used for the risk of radiation that increases with the amount of exposure, as opposed to having a threshold?
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What is the recommended approach when high doses of radiation are likely to exceed 10 mGy?
What is the recommended approach when high doses of radiation are likely to exceed 10 mGy?
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Which of the following locations should be avoided when irradiating a female of reproductive capacity?
Which of the following locations should be avoided when irradiating a female of reproductive capacity?
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What is the maximum radiation exposure limit for students under the age of 18 during their educational activities?
What is the maximum radiation exposure limit for students under the age of 18 during their educational activities?
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What are the two critical factors affecting the severity of potential radiation response in utero?
What are the two critical factors affecting the severity of potential radiation response in utero?
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Under which condition is a therapeutic abortion not indicated due to diagnostic x-ray exposure?
Under which condition is a therapeutic abortion not indicated due to diagnostic x-ray exposure?
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What is the typical fetal dose that would rarely exceed after a series of x-ray examinations?
What is the typical fetal dose that would rarely exceed after a series of x-ray examinations?
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What should be done before examining a pregnant patient with x-rays?
What should be done before examining a pregnant patient with x-rays?
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What is the general incidence of congenital abnormalities, which should be taken into account during pregnancy evaluations?
What is the general incidence of congenital abnormalities, which should be taken into account during pregnancy evaluations?
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What is the recommended course of action for patients exposed to radiation below 25 rad?
What is the recommended course of action for patients exposed to radiation below 25 rad?
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What dose of fetal exposure indicates higher risks of latent injury that may justify termination of pregnancy?
What dose of fetal exposure indicates higher risks of latent injury that may justify termination of pregnancy?
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Study Notes
Dose Reference
- Average radiation dose per examination is used as a guide for general practice.
- This helps ensure patient safety and prevent unnecessary high radiation doses.
- This practice also helps prevent negligence from radiology technologists.
Dose Limits
- The effective dose limit is 1 mSv per year.
- In special circumstances, the effective dose limit can be 5 mSv in a single year, but the average over five years must be less than 1 mSv per year.
- The equivalent dose limit to the lens of the eye is 15 mSv per year.
- The equivalent dose limit to the skin is 50 mSv per year.
- Dose limits are designed to prevent deterministic effects and limit stochastic effects.
- Dose limits apply to occupational exposures and not medical exposures.
- The ALARA (As Low As Reasonably Achievable) concept is applied during medical exposures.
Radiation Dose Limits- NCRP vs ICRP
- The NCRP established limits of 50 mSv per year in 1987.
- The ICRP set limits of 20 mSv per year in 1991.
Other Dose Limit Considerations
- The dose limit for skin is 500 mSv per year.
- The dose limit for the eyes is 15 mSv per year.
- The limit for general population exposure is 5 mSv per year for infrequent exposure and 1 mSv per year for frequent exposure, like hospital employees working near radiology.
- Physicists use the 1 mSv per year limit to calculate the thickness of protective barriers.
- Students under 18 are limited to 1 mSv per year during their course of educational activities.
- It is common practice to not accept underage students for radiation technology programs.
Radiation Dose Limits and Pregnancy
- Pregnancy requires particular care and action during diagnostic radiology.
- The severity of potential response to radiation in utero is time and dose related.
- The radiologist and referring doctor can determine the stage of gestation at exposure.
- Options for the patient include continuing the pregnancy to term or terminating the pregnancy.
- A therapeutic abortion is not indicated unless there are other risk factors involved when exposure is below 10 rad.
- Above 25 rad, terminating the pregnancy may be indicated.
- Between 10-25 rad, the time of irradiation and the emotional state of the patient are important considerations.
- Never knowingly examine a pregnant patient with x-rays unless a documented decision is made to do so.
- Discuss the need for the examination with a radiologist before performing x-ray examinations on pregnant patients.
- Determine the patient's menstrual cycle and withhold the exam until any questions about pregnancy are answered.
- The 10-day rule can be a guide, aiming to perform the radiograph before ovulation.
10 Day Rule
- The safest time to x-ray a female of childbearing age is within ten to fourteen days of the onset of menses.
- The 10-day rule is recommended for certain high-dose examinations where the dose to the uterus is likely to exceed 10 mGy.
- High-dose examinations performed within 10 days of the start of the period ensure the patient is not pregnant.
28 Day Rule
- All radiological examinations of female patients of reproductive capacity that place the uterus in or near the primary x-ray beam (between the diaphragm and pubis) should follow the 28 day rule.
- If the patient has missed a period, the request will be referred back to the doctor for discussion.
Objective of Radiation Protection
- Prevent clinically important radiation-induced deterministic effects by adhering to dose limits below threshold levels.
- Limit the risk of stochastic response to a conservative level, taking into account societal needs, values, benefits acquired, and economic considerations.
- The ALARA concept (As Low As Reasonably Achievable) emphasizes that radiation exposure should be kept as low as reasonably achievable with consideration for economic and social factors.
- The continuation of good radiation protection programs and practices traditionally keeps average and individual exposures well below the limit for monitored workers.
- For radiographers and radiologists, the ALARA concept should guide the selection of technical radiographic and fluoroscopic exposure factors for all patient imaging procedures.
- The reason for this concept in radiologic practice is to keep radiation exposure and the consequent dose to the lowest possible level.
Responsibility for Maintaining ALARA
- The employer is responsible for providing the necessary resources and appropriate environment to execute an ALARA program.
- Management should conduct periodic exposure audits to ensure proper lowered radiation exposure practices are being applied.
- Radiation workers with appropriate education and work experience must function with awareness of the rules governing their work situations.
Optimisation of a Practice (ALARA)
- The main goal of the ALARA program is to reduce both external and internal radiation doses to a level that is As Low As Reasonably Achievable.
- ALARA is a philosophy, not a number.
- The three basic protective measures used to reduce external exposure are:
- Minimizing time in a radiation field.
- Maximizing the distance from a radiation source.
- Using shielding.
ALARA Continued
- Assume that any radiation exposure carries some risk.
- ALARA efforts balance the assumed risks of radiation exposure against the benefits of performing the work.
- "Reasonable" in this context means the risk from receiving the exposure is "worth" the net benefit of the activity.
- There should not be any occupational exposure of workers to ionizing radiation without the expectation of an overall benefit from the activity causing the exposure.
- The ALARA concept prevents unnecessary exposure as well as overexposure.
- Implementation of the ALARA concept is the responsibility of all employees.
- The success of the ALARA program depends on each radiological worker's attitude and actions.
Minimize Time
- Exposure = Exposure rate x exposure time.
- Exposure time is reduced during radiography to reduce motion blur and during fluoroscopy to reduce patient and personnel exposure.
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