40 Questions
What is the typical effective dose for a bone scan using Technetium-99m diphosphonates?
5 mSv
What is the purpose of checking the accuracy of the dose calibrator?
To ensure the correct activity of the radionuclide
Which radionuclide is used for tumour imaging and delivers a higher effective dose?
Gallium-67 citrate
What is the typical activity of Technetium-99m MIBI for heart imaging?
400 MBq
Why is it necessary to check and record the activity before administration?
To ensure the correct administration of the radionuclide
What is recommended for patients to minimize their radiation dose?
Drink a good deal of water and empty the bladder frequently
What is the general guideline for female patients who undergo diagnostic examinations with long-lived radionuclides?
Avoid conception for an appropriate period following administration
Why is it important to handle radionuclides with care?
To minimize the risk of internal radiation from accidental ingestion or inhalation
What is a consideration for breastfeeding mothers who undergo diagnostic examinations with radionuclides?
They should seek advice on interrupting breastfeeding
What should be avoided when handling radionuclides?
Contamination of the environment
What is the primary risk associated with radionuclides in a nuclear medicine facility?
Contamination
What is the purpose of separating patients in the waiting area?
To minimize the effect of background radiation
How can departmental layout reduce the effect of background radiation?
By making use of the inverse square law
What is the primary principle of personal protection when handling radionuclides?
Use of distance, shielding, and time
Why should staff only enter areas with radioactivity when necessary?
To minimize exposure to external radiation
Why are syringes protected by heavy metal, tungsten, or lead glass sleeves?
To prevent radiation exposure to the hands
What should be done with syringes before injection?
Vent them into swabs or closed containers
Why are waterproof surgical gloves worn when handling radionuclides?
To prevent accidental ingestion of the radionuclide
What is done to the work surfaces and hands after handling radionuclides?
They are monitored for radioactive contamination
What is done to the air in radiopharmacies?
It is monitored for radioactive contamination
What is the purpose of tissue-weighting factors in calculating the effective dose?
To account for differing organ sensitivities to irradiation
What is the unit of the effective dose?
Sievert (Sv)
What is the typical effective dose range for most nuclear medicine investigations?
Less than 5mSv
What is the process of calculating the effective dose?
Weighting each organ absorbed dose and summing to give the effective dose
What is the purpose of calculating the effective dose?
To determine the risk associated with radiation exposure
What determines the absorbed dose delivered to an organ by the activity within it?
The effective half-life of the activity in the organ and the energy of beta and gamma radiation
What happens to the energy of beta rays in an organ?
Almost all the energy is deposited inside the organ, and very little escapes
What is a key difference between dose delivery in radionuclide examinations and X-ray imaging?
The dose delivered by a radionuclide examination is unaffected by the number of images taken
What happens to the energy of gamma rays in an organ?
Some energy is deposited in the organ, and some leaves it
Why do source organs act as sources of irradiation for other tissues in the body?
Because they act as a source of radiation for other tissues
What is the primary purpose of a SPECT/CT machine?
To perform daily nuclear medicine procedures
What is the most common positron emitter used in PET?
18F
What happens when 18F emits a positron?
It travels 2 mm through the patient
What is the energy of the photons emitted after positron annihilation?
511 keV
What type of detectors are often used in PET cameras?
Scintillation detectors
What material is often used to make PET detectors?
All of the above
What is a desirable property of an ideal PET detector material?
High detection efficiency
What is the purpose of a PET camera?
To image the body using positron-emitting radionuclides
What is a key feature of PET detectors?
They are composed of a very large number of solid scintillation detectors
What is the function of the ring or polygon in a PET camera?
To surround the patient and detect photons
Study Notes
Patient Preparation and Fetal Dose
- Patients should drink plenty of water and empty their bladders frequently to minimize radiation dose to the gonads and pelvic bone marrow.
- Female patients should avoid conception for a certain period after receiving long-lived diagnostic radionuclides.
- Male patients do not need special advice regarding diagnostic examinations.
Handling Radionuclides
- Radionuclides pose external and internal radiation hazards, and contamination of the environment, workplace, and persons must be avoided.
- Accidental ingestion or inhalation of radionuclides or entry through wounds can occur.
- Controlling the spread of radioactive materials is crucial.
Typical Radionuclide Administrations and Doses
- Bone: Technetium-99m diphosphonates (600 MBq, 5 mSv)
- Lung Ventilation: Technetium-99m DTPA aerosol and Krypton-81m gas (80 and 6000 MBq, 0.5 and 0.1 mSv)
- Kidney: Technetium-99m DTPA gluconate and Technetium-99m MAG3 (300 and 100 MBq, 2 and 0.7 mSv)
- Infection: Gallium-67 citrate and Indium-111 leucocytes (150 and 20 MBq, 15 and 7 mSv)
- Tumor: Iodine-123 MIBG (400 MBq, 5 mSv)
- Thyroid: Iodine-123 iodide (20 MBq, 4 mSv)
- Heart: Technetium-99m MIBI and Thallium-201 chloride (400 and 80 MBq, 3 and 18 mSv)
- Brain: Fluorine-18 FDG (400 MBq, 8 mSv)
Dose to the Patient
- The activity administered, fraction taken up by the organ, effective half-life, and energy of beta and gamma radiation affect the absorbed dose.
- The dose to an organ also depends on how much energy escapes from the organ and irradiates other tissues.
Effective Dose to the Body
- The effective dose (E) has the unit sievert (Sv) and is calculated using the differing sensitivities of organs and tissues to irradiation.
- The effective dose is a measure of risk and is unaffected by the number of images taken.
Precautions in Handling Radionuclides
- A nuclear medicine facility should have separate areas for radionuclide preparation and storage, patient injection, waiting, imaging, and temporary waste storage.
- Patients containing radioactivity should be spaced apart in the waiting area.
- Staff should use distance, shielding, and time to minimize radiation exposure.
- Radionuclides are contained in shielded generators or lead pots, and long-handled forceps are used for handling.
Personal Protection
- Lead barriers, heavy metal or lead glass sleeves, and waterproof surgical gloves are used for personal protection.
- Hands and work surfaces are monitored for radioactive contamination, and the air in radiopharmacies is also monitored.
- Staff may be monitored for internal contamination, and swabs are taken from the radiopharmacy workstation to monitor for radioactive and bacterial contamination.
This quiz covers typical radionuclide administrations for adults, including bone, lung ventilation, and lung perfusion imaging, and their corresponding effective doses. It highlights the use of imaging modalities like Technetium-99m and Krypton-81m.
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