What is the radiation dose for a PET/CT (Positron Emission Tomography/Computed Tomography) scan with Dotatate (Somatostatin analog) for the chest, abdomen, and pelvis with and without contrast?

From the Guidelines

The radiation dose in a PET/CT DOTATATE scan of the chest, abdomen, and pelvis with and without contrast typically ranges from 14-25 millisieverts (mSv) total. This includes approximately 7-10 mSv from the CT portion and 7-15 mSv from the radiotracer (68Ga-DOTATATE) injection, as supported by recent studies on radiation exposure in medical imaging 1. The radiation exposure is necessary because the DOTATATE radiotracer specifically binds to somatostatin receptors, making it excellent for detecting neuroendocrine tumors and their metastases. The CT portion provides anatomical information while the PET component shows functional activity of these receptors. While this dose is higher than conventional imaging, the clinical benefit typically outweighs the radiation risk for patients with suspected or known neuroendocrine tumors. Some key points to consider when evaluating the radiation dose include:

• Patient size: larger patients may require higher doses of radiotracer and/or CT contrast to achieve adequate image quality 1
• Specific protocol used: different protocols may use varying amounts of radiotracer and/or CT contrast, affecting the total radiation dose
• Equipment at the imaging facility: newer equipment may be able to achieve higher quality images with lower radiation doses It's also important to note that the actual dose can vary based on these factors, and the radiation dose from the CT portion can be optimized with respect to the diagnostic question, as highlighted in recent guidelines on tumour imaging 1.

From the FDA Drug Label

1. 6 Radiation Dosimetry Estimated radiation absorbed doses per injected activity for organs and tissues of adult patients following an intravenous administration of copper Cu 64 dotatate injection are shown in Table 1. Table 1. Estimated radiation absorbed dose per injected activity in selected organs with copper Cu 64 dotatate injection

• Mean of 5 patients. Target OrganMean *absorbed dose (mGy/MBq) Adrenals 0. 137 Brain 0.013 Breasts 0.013 Gallbladder wall 0.040 Lower large intestine wall 0.043 Small intestine 0.066 Stomach wall 0.019 Upper large intestine wall 0.022 Heart wall 0.019 Kidneys 0.139 Liver 0.161 Lungs 0.017 Muscle 0.019 Ovaries 0.019 Pancreas 0.093 Red marrow 0.027 Osteogenic cells 0.034 Skin 0.012 Spleen 0.115 Testes 0.014 Thymus 0.015 Thyroid 0.014 Urinary bladder wall 0.037 Uterus 0.

The recommended amount of radioactivity to be administered for PET imaging is 148 MBq (4 mCi).

• The estimated radiation absorbed doses per injected activity for organs and tissues of adult patients are shown in Table 1.
• The radiation dose for a PET/CT scan of the chest, abdomen, and pelvis is not explicitly stated, but the estimated radiation absorbed doses for selected organs are provided in Table 1 2.
• To estimate the total radiation dose, the dose from the CT scan should also be considered, in addition to the dose from the Dotatate.
• However, the exact radiation dose for this specific scan cannot be determined from the provided information.

From the Research

Radiation Dose in PET/CT Scans

• The average radiation dose for a PET/CT scan can range from 13.45 to 31.91 mSv, depending on the CT protocol used 3.
• A study found that the mean effective dose from a PET/CT scan with a diagnostic quality CT was 24.4 ± 4.3 mSv, while a scan with a standard registration CT had a mean effective dose of 14 ± 1.3 mSv 4.
• The CT component of a PET/CT scan can contribute up to 42% of the overall effective radiation dose, with the PET component contributing around 38% 5.

Radiation Dose in Chest, Abdomen, and Pelvis CT Scans

• A study found that the mean effective dose for a chest, abdomen, and pelvis CT scan was 22.4 ± 5.9 mSv per procedure 6.
• The radiation dose per procedure was found to be higher compared to previous studies, highlighting the need for optimization of patient radiation doses 6.

Cumulative Radiation Dose from Recurrent PET-CT Examinations

• There is a concern about the cumulative radiation doses from repeated PET-CT examinations, with some patients receiving a cumulative effective radiation dose of ≥100 mSv 7.
• The use of a dose tracking system can help facilitate surveys on patient cumulative doses and implementation of justification for PET-CT examinations and utilization of dose reduction measures 7.

Factors Affecting Radiation Dose

• Patient-specific parameters, such as organ mass, can optimize patient dosimetry and assist in the justification of risk and optimization of PET/CT acquisition parameters 4.
• The use of different CT protocols and techniques can significantly affect the radiation dose, with some protocols resulting in higher doses than others 3.