BackgroundIn recent years, Copper-64 (T1/2 = 12.7 h) in the chemical form of copper dichloride ([64Cu]CuCl2) has been identified as a potential agent for PET imaging and radionuclide therapy targeting the human copper transporter 1, which is overexpressed in a variety of cancer cells. Limited human biodistribution and radiation dosimetry data is available for this tracer. The aim of this research was to determine the biodistribution and estimate the radiation dosimetry of [64Cu]CuCl2, using whole-body (WB) PET scans in healthy volunteers. Six healthy volunteers were included in this study (3 women and 3 men, mean age ± SD, 54.3 ± 8.6 years; mean weight ± SD, 77.2 ± 12.4 kg). After intravenous injection of the tracer (4.0 MBq/kg), three consecutive WB emission scans were acquired at 5, 30, and 60 min after injection. Additional scans were acquired at 5, 9, and 24 h post-injection. Low-dose CT scan without contrast was used for anatomic localization and attenuation correction. OLINDA/EXM software was used to calculate human radiation doses using the reference adult model.ResultsThe highest uptake was in the liver, followed by lower and upper large intestine walls, and pancreas, in descending order. Urinary excretion was negligible. The critical organ was liver with a mean absorbed dose of 310 ± 67 μGy/MBq for men and 421 ± 56 μGy/MBq for women, while the mean WB effective doses were 51.2 ± 3.0 and 61.8 ± 5.2 μSv/MBq for men and women, respectively.ConclusionsTo the best of our knowledge, this is the first report on biodistribution and radiation dosimetry of [64Cu]CuCl2 in healthy volunteers. Measured absorbed doses and effective doses are higher than previously reported doses estimated with biodistribution data from patients with prostate cancer, a difference that could be explained not just due to altered biodistribution in cancer patients compared to healthy volunteers but most likely due to the differences in the analysis technique and assumptions in the dose calculation.
Purpose: Characterize a medical linear accelerator using Monte Carlo methods to investigate the precision and exactitude of dose delivery on small animal irradiation, particularly Wistar rat species. Method and Materials: A dedicated 6.0 MV linear accelerator (Novalis®, BrainLAB, Germany) for stereotactic radiosurgery (SRS) was simulated using BEAMnrc. A phase space (PS) data file was generated. The Monte Carlo (MC) calculations were tuned and validated to match depth and off‐axis dose profile data measured using a shielded diode detector (PFD3G, IBA‐dosimetry, Germany) for a 15.0 mm circular collimator. The animal model was based on a computed tomography (CT) scan of a Wistar rat for medullar trauma lesion model. An in‐house mask fixation system compatible with the treatment planning system (TPS) was developed to immobilize the rat. The CT scan images were imported to DOSXYZnrc using ctcreate tool and to the TPS via DICOM network. Dose distribution was calculated by the TPS using 2 non‐coplanar circular (NCAs). The NCAs were simulated using 20 static beams. The MC dose calculations were exported for analysis and compared with TPS dose calculations. On the other hand, absolute dose measurements were performed using the PFD3G inter calibrated using a Farmer type ionization chamber. Results: Absolute dose measurements showed that dose difference between TPS and treatment delivery is less than 4.3% on the selected points. Difference between TPS and MC dose calculations showed an over‐estimation by the TPS up to 15.0%. However, in the spinal cord lesion there is a good agreement between TPS and MC calculated data. Conclusion: Dose delivered by the dedicated linear accelerator is reliable to perform spinal cord irradiation in trauma lesion models. These preliminary results must be improved including an accurate source model of an arc radiation beam instead of the 20 discrete static beams.
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