Radiation Safety With Positron Emission Tomography and Computed Tomography
Section snippets
PET/CT Shielding Requirements
PET/CT is most commonly performed with 18F-FDG, which has a half-life of 109.8 minutes. Fluorine-18 is a positron-emitting radionuclide that leads to an annihilation reaction of a positron and electron, producing two 511 keV photons. The 511 keV annihilation photons are much more highly penetrating than other diagnostic radiations.9 Therefore, a greater amount of lead is required for shielding in PET/CT suites compared with traditional diagnostic radiology or nuclear medicine examination rooms.
Radiation Exposure to PET/CT Technologists and Personnel
The radiation doses received by PET/CT technologists may be higher than those received by diagnostic radiology technologists or by general nuclear medicine technologists who do not perform PET/CT.15 There are several factors that lead to an increased risk of occupational exposure for PET/CT technologists, and these are predominantly related to the PET portion of the examination. The 511 keV photons from 18F-FDG have uniquely high energy and penetration. For comparison, the γ ray constant (which
Radiation Exposure to Non-PET/CT Staff and the Public
After injection of a radiopharmaceutical, the patient becomes a radiation source and should be placed in a designated uptake room with a nearby patient-only toilet. Typically, a PET/CT is performed 1 hour after injection. The patient should rest quietly and comfortably in a darkened room for this hour to minimize muscle activity during the uptake period. The main consideration for not returning the patient to the waiting room is the promotion of peaceful inactivity on the part of the patient
Radiation Exposure to Patients
Although most PET/CT studies are performed on patients who already have cancer, the issue of radiation safety is still pertinent. Patients with cancer often undergo multiple PET/CT examinations over the course of several years, and the long-term survival of cancer patients is increasing.19
Radiation dose to the patient from a PET/CT scan is equal to the sum of the combined dose from the PET and the CT components of the scan. The radiation dose of the FDG PET component of the scan has been
Pregnant Patients
There is limited data regarding the use of PET/CT in pregnant patients. A combined PET/CT results in a relatively high radiation dose to an embryo.24 This is a function of 18F-FDG uptake as well as the CT dose, which varies depending on the scan parameters. Every female patient referred for PET/CT should be carefully screened for pregnancy, and the study is usually canceled if there is a question of pregnancy. There may be instances in which the benefits of a PET/CT would outweigh the risks to
Lactating Patients
Given the increasing use of PET/CT, it is not uncommon for a currently breastfeeding woman to be referred for PET/CT. Lactating patients demonstrate significantly increased uptake of radiotracer in their breasts compared with nonlactating patients.27 This is predominantly because of uptake of 18F-FDG by active glandular tissue. A relatively low level of radiotracer is excreted into the actual breast milk.28 Consequently, the main source of radiation exposure for a nursing infant would be close
Pediatric Patients
PET/CT has proven utility in pediatric oncology and can significantly change clinical management in many pediatric malignancies.29 Concern over the radiation dose to pediatric patients undergoing CT examinations has heightened in recent years, and increased awareness and education has led to significant improvements in this regard.30, 31 PET/CT faces similar concerns given the ever-increasing number of pediatric patients referred for examinations. Both the CT and the PET portions of the
Summary
PET/CT has become an indispensable modality in clinical imaging, particularly in the management of oncology patients, and is becoming the study of choice for many indications.36, 4 PET/CT is accurate and quick, and is becoming increasingly available in various practice settings.37 The use of 18F-FDG, a positron-emitting radionuclide, poses special hazards in a PET/CT facility. The radiation exposure to patients undergoing PET/CT is of concern as the dose is a combination of internal and
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Decorated bacteria and the application in drug delivery
2022, Advanced Drug Delivery ReviewsCitation Excerpt :Ultrasonic imaging encounters deficient contrast and resolution, while magnetic resonance imaging technology suffers from a shortage of insufficient sensitivity. Although positron emission computed tomography (PET) imaging is the most advanced imaging technology, potential radiation safety concerns regarding the leakage of harmful radionuclides cannot be ignored [146]. Meticulous design of probes that conform to the requirements of clinical application is central to the development of molecular imaging techniques.
Estimation of patient effective doses in PET/CT- <sup>18</sup>F-Sodium Fluoride examinations
2021, Applied Radiation and IsotopesCitation Excerpt :Even though most patients undergoing PET/CT examinations suffer from malignant tumors, patients' protection against unnecessary radiation exposure still of prime concern. Cancer patients usually undergo several PET/CT procedures during their management and follow-ups, and nowadays, patients have a longer survival rate and a high curable rate (Devine& Mawlawi, 2010). Table 1 shows the patient's population information as well as the image acquisition parameters.
Significant dose reduction is feasible in FDG PET/CT protocols without compromising diagnostic quality
2018, Physica MedicaCitation Excerpt :For the PET component the amount of radiotracer activity can be reduced while for the CT component several acquisition parameters can be modified (reduction in voltage, current time product or tube rotation speed or increase in helical pitch). However, a reduction in patient exposure will affect the image quality and may compromise clinical evaluation of the PET/CT study [3]. A proper PET/CT procedure should achieve the clinical purpose while maintaining radiation dose as low as reasonably achievable (ALARA) [4].
Breast Cancer
2017, PET/CT in Cancer: An Interdisciplinary Approach to Individualized ImagingRadiological staging in pregnant patients with cancer
2016, ESMO OpenCitation Excerpt :While PET and scintigraphy alone cause only minor radiation exposure of the fetus, PET/CT exposes the fetus to a relatively high radiation dose due to the combination of two imaging methods involving ionising radiation. Therefore, PET/CT should be postponed until after completion of pregnancy.153 PET/MRI is a reasonable alternative to eliminate the ionising radiation from CT, which could be considered for the staging of lymphoma, for example.54
Contrast media, radionuclides and diagnostics
2015, Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment: Third Edition