TY - JOUR A1 - Dickson, John A1 - Eberlein, Uta A1 - Lassmann, Michael T1 - The effect of modern PET technology and techniques on the EANM paediatric dosage card JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - Aim Recent advancements in PET technology have brought with it significant improvements in PET performance and image quality. In particular, the extension of the axial field of view of PET systems, and the introduction of semiconductor technology into the PET detector, initially for PET/MR, and more recently available long-field-of-view PET/CT systems (≥ 25 cm) have brought a step change improvement in the sensitivity of PET scanners. Given the requirement to limit paediatric doses, this increase in sensitivity is extremely welcome for the imaging of children and young people. This is even more relevant with PET/MR, where the lack of CT exposures brings further dose reduction benefits to this population. In this short article, we give some details around the benefits around new PET technology including PET/MR and its implications on the EANM paediatric dosage card. Material and methods Reflecting on EANM adult guidance on injected activities, and making reference to bed overlap and the concept of MBq.min bed\(^{-1}\) kg\(^{-1}\), we use published data on image quality from PET/MR systems to update the paediatric dosage card for PET/MR and extended axial field of view (≥ 25 cm) PET/CT systems. However, this communication does not cover the expansion of paediatric dosing for the half-body and total-body scanners that have recently come to market. Results In analogy to the existing EANM dosage card, new parameters for the EANM paediatric dosage card were developed (class B, baseline value: 10.7 MBq, minimum recommended activity 10 MBq). The recommended administered activities for the systems considered in this communication range from 11 MBq [\(^{18}\)F]FDG for a child with a weight of 3 kg to 149 MBq [\(^{18}\)F]FDG for a paediatric patient weight of 68 kg, assuming a scan of 3 min per bed position. The mean effective dose over all ages (1 year and older) is 2.85 mSv. Conclusion With this, recommendations for paediatric dosing are given for systems that have not been considered previously. KW - PET KW - PET/MR systems KW - EANM dosage card Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265624 SN - 1619-7089 VL - 49 IS - 6 ER - TY - JOUR A1 - Göring, Lukas A1 - Schumann, Sarah A1 - Müller, Jessica A1 - Buck, Andreas K. A1 - Port, Matthias A1 - Lassmann, Michael A1 - Scherthan, Harry A1 - Eberlein, Uta T1 - Repair of a-particle-induced DNA damage in peripheral blood mononuclear cells after internal ex vivo irradiation with \(^{223}\)Ra JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - Purpose As α-emitters for radiopharmaceutical therapies are administered systemically by intravenous injection, blood will be irradiated by α-particles that induce clustered DNA double-strand breaks (DSBs). Here, we investigated the induction and repair of DSB damage in peripheral blood mononuclear cells (PBMCs) as a function of the absorbed dose to the blood following internal ex vivo irradiation with [\(^{223}\)Ra]RaCl2. Methods Blood samples of ten volunteers were irradiated by adding [\(^{223}\)Ra]RaCl2 solution with different activity concentrations resulting in absorbed doses to the blood of 3 mGy, 25 mGy, 50 mGy and 100 mGy. PBMCs were isolated, divided in three parts and either fixed directly (d-samples) or after 4 h or 24 h culture. After immunostaining, the induced γ-H2AX α-tracks were counted. The time-dependent decrease in α-track frequency was described with a model assuming a repair rate R and a fraction of non-repairable damage Q. Results For 25 mGy, 50 mGy and 100 mGy, the numbers of α-tracks were significantly increased compared to baseline at all time points. Compared to the corresponding d-samples, the α-track frequency decreased significantly after 4 h and after 24 h. The repair rates R were (0.24 ± 0.05) h−1 for 25 mGy, (0.16 ± 0.04) h−1 for 50 mGy and (0.13 ± 0.02) h−1 for 100 mGy, suggesting faster repair at lower absorbed doses, while Q-values were similar. Conclusion The results obtained suggest that induction and repair of the DSB damage depend on the absorbed dose to the blood. Repair rates were similar to what has been observed for irradiation with low linear energy transfer. KW - DSB damage KW - irradiation KW - α-Particle KW - γ-H2AX KW - repair Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-324557 VL - 49 IS - 12 ER - TY - JOUR A1 - Aerts, An A1 - Eberlein, Uta A1 - Holm, Sören A1 - Hustinx, Roland A1 - Konijnenberg, Mark A1 - Strigari, Lidia A1 - van Leeuwen, Fijs W. B. A1 - Glatting, Gerhard A1 - Lassmann, Michael T1 - EANM position paper on the role of radiobiology in nuclear medicine JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - With an increasing variety of radiopharmaceuticals for diagnostic or therapeutic nuclear medicine as valuable diagnostic or treatment option, radiobiology plays an important role in supporting optimizations. This comprises particularly safety and efficacy of radionuclide therapies, specifically tailored to each patient. As absorbed dose rates and absorbed dose distributions in space and time are very different between external irradiation and systemic radionuclide exposure, distinct radiation-induced biological responses are expected in nuclear medicine, which need to be explored. This calls for a dedicated nuclear medicine radiobiology. Radiobiology findings and absorbed dose measurements will enable an improved estimation and prediction of efficacy and adverse effects. Moreover, a better understanding on the fundamental biological mechanisms underlying tumor and normal tissue responses will help to identify predictive and prognostic biomarkers as well as biomarkers for treatment follow-up. In addition, radiobiology can form the basis for the development of radiosensitizing strategies and radioprotectant agents. Thus, EANM believes that, beyond in vitro and preclinical evaluations, radiobiology will bring important added value to clinical studies and to clinical teams. Therefore, EANM strongly supports active collaboration between radiochemists, radiopharmacists, radiobiologists, medical physicists, and physicians to foster research toward precision nuclear medicine. KW - radionuclide therapy KW - radiobiology KW - dosimetry KW - biodosimetry KW - biomarkers Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265595 VL - 48 IS - 11 ER - TY - JOUR A1 - Schumann, Sarah A1 - Eberlein, Uta A1 - Muhtadi, Razan A1 - Lassmann, Michael A1 - Scherthan, Harry T1 - DNA damage in leukocytes after internal ex-vivo irradiation of blood with the α-emitter Ra-223 JF - Scientific Reports N2 - Irradiation with high linear energy transfer α-emitters, like the clinically used Ra-223 dichloride, severely damages cells and induces complex DNA damage including closely spaced double-strand breaks (DSBs). As the hematopoietic system is an organ-at-risk for the treatment, knowledge about Ra-223-induced DNA damage in blood leukocytes is highly desirable. Therefore, 36 blood samples from six healthy volunteers were exposed ex-vivo (in solution) to different concentrations of Ra-223. Absorbed doses to the blood were calculated assuming local energy deposition of all α- and β-particles of the decay, ranging from 0 to 142 mGy. γ-H2AX + 53BP1 co-staining and analysis was performed in leukocytes isolated from the irradiated blood samples. For DNA damage quantification, leukocyte samples were screened for occurrence of α-induced DNA damage tracks and small γ-H2AX + 53BP1 DSB foci. This revealed a linear relationship between the frequency of α-induced γ-H2AX damage tracks and the absorbed dose to the blood, while the frequency of small γ-H2AX + 53BP1 DSB foci indicative of β-irradiation was similar to baseline values, being in agreement with a negligible β-contribution (3.7%) to the total absorbed dose to the blood. Our calibration curve will contribute to the biodosimetry of Ra-223-treated patients and early after incorporation of α-emitters. KW - alpha particles KW - blood KW - DNA Breaks KW - double-stranded KW - gamma rays KW - healthy volunteers KW - humans KW - leukocytes KW - radiation effects KW - radium Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175596 VL - 8 IS - 2286 ER - TY - JOUR A1 - Schumann, Sarah A1 - Scherthan, Harry A1 - Frank, Torsten A1 - Lapa, Constantin A1 - Müller, Jessica A1 - Seifert, Simone A1 - Lassmann, Michael A1 - Eberlein, Uta T1 - DNA Damage in Blood Leukocytes of Prostate Cancer Patients Undergoing PET/CT Examinations with [\(^{68}\)Ga]Ga-PSMA I&T JF - Cancers N2 - The aim was to investigate the induction and repair of radiation-induced DNA double-strand breaks (DSBs) as a function of the absorbed dose to the blood of patients undergoing PET/CT examinations with [68Ga]Ga-PSMA. Blood samples were collected from 15 patients before and at four time points after [68Ga]Ga-PSMA administration, both before and after the PET/CT scan. Absorbed doses to the blood were calculated. In addition, blood samples with/without contrast agent from five volunteers were irradiated ex vivo by CT while measuring the absorbed dose. Leukocytes were isolated, fixed, and stained for co-localizing γ-H2AX+53BP1 DSB foci that were enumerated manually. In vivo, a significant increase in γ-H2AX+53BP1 foci compared to baseline was observed at all time points after administration, although the absorbed dose to the blood by 68Ga was below 4 mGy. Ex vivo, the increase in radiation-induced foci depended on the absorbed dose and the presence of contrast agent, which could have caused a dose enhancement. The CT-dose contribution for the patients was estimated at about 12 mGy using the ex vivo calibration. The additional number of DSB foci induced by CT, however, was comparable to the one induced by 68Ga. The significantly increased foci numbers after [68Ga]Ga-PSMA administration may suggest a possible low-dose hypersensitivity. KW - DNA double-strand breaks KW - γ-H2AX KW - 53BP1 KW - nuclear medicine KW - dosimetry KW - Ga-68 KW - PSMA KW - PET/CT KW - contrast agent KW - prostate cancer Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-200585 SN - 2072-6694 VL - 12 IS - 2 ER - TY - JOUR A1 - Schuhmann, Sarah A1 - Eberlein, Uta A1 - Müller, Jessica A1 - Scherthan, Harry A1 - Lassmann, Michael T1 - Correlation of the absorbed dose to the blood and DNA damage in leukocytes after internal ex-vivo irradiation of blood samples with Ra-224 JF - EJNMMI Research N2 - Background: Irradiation with α-particles creates densely packed damage tracks along particle trajectories in exposed cells, including complex DNA damage and closely spaced double-strand breaks (DSBs) in hit nuclei. Here, we investigated the correlation of the absorbed dose to the blood and the number of α-induced DNA damage tracks elicited in human blood leukocytes after ex-vivo in-solution exposure with Ra-224. The aim was to compare the data to previously published data on Ra-223 and to investigate differences in DNA damage induction between the two radium isotopes. Results: Blood samples from three healthy volunteers were exposed ex-vivo to six different concentrations of Ra-224 dichloride. Absorbed doses to the blood were calculated assuming local energy deposition of all α- and β-particles of the Ra-224 decay chain, ranging from 0 to 127 mGy. γ-H2AX + 53BP1 DNA damage co-staining and analysis was performed on ethanol-fixed leukocytes isolated from the irradiated blood samples. For damage quantification, α-induced DNA damage tracks and small γ-H2AX + 53BP1 DSB foci were enumerated in the exposed leukocytes. This revealed a linear relationship between the frequency of α-induced γ-H2AX damage tracks and the absorbed dose to the blood, while the frequency of small γ-H2AX + 53BP1 DSB foci indicative of β-irradiation was similar to baseline values. Conclusions: Our data provide a first estimation of the DNA damage induced by Ra-224 in peripheral blood mononuclear cells. A comparison with our previously published Ra-223 data suggests that there is no difference in the induction of radiation-induced DNA damage between the two radium isotopes due to their similar decay properties. KW - 53BP1 KW - DNA damage KW - γ-H2AX KW - biological dosimetry KW - absorbed dose to the blood KW - α-emitter KW - Ra-224 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176593 VL - 8 IS - 77 ER - TY - JOUR A1 - Lassmann, Michael A1 - Eberlein, Uta T1 - Comparing absorbed doses and radiation risk of the α-emitting bone-seekers [\(^{223}\)Ra]RaCl\(_2\) and [\(^{224}\)Ra]RaCl\(_2\) JF - Frontiers in Medicine N2 - [\(^{223}\)Ra]RaCl\(_2\) and [\(^{224}\)Ra]RaCl\(_2\) are bone seekers, emitting high LET, and short range (< 100 μm) alpha-particles. Both radionuclides show similar decay properties; the total alpha energies are comparable (\(^{223}\)Ra: ≈28 MeV, \(^{224}\)Ra: ≈26 MeV). [\(^{224}\)Ra]RaCl\(_2\) has been used from the mid-1940s until 1990 for treating different bone and joint diseases with activities of up to approximately 50 MBq [\(^{224}\)Ra]RaCl\(_2\). In 2013 [\(^{223}\)Ra]RaCl\(_2\) obtained marketing authorization by the FDA and by the European Union for the treatment of metastatic prostate cancer with an activity to administer of 0.055 MBq per kg body weight for six cycles. For intravenous injections in humans a model calculation using the biokinetic model of ICRP67 shows a ratio of organ absorbed dose coefficients (\(^{224}\)Ra:\(^{223}\)Ra) between 0.37 (liver) and 0.97 except for the kidneys (2.27) and blood (1.57). For the red marrow as primary organ-at-risk, the ratio is 0.57. The differences are mainly caused be the differing half-lives of the decay products of both radium isotopes. Both radionuclides show comparable DNA damage patterns in peripheral blood mononuclear cells after internal ex-vivo irradiation. Data on the long-term radiation-associated side effects are only available for treatment with [\(^{224}\)Ra]RaCl\(_2\). Two epidemiological studies followed two patient groups treated with [\(^{224}\)Ra]RaCl\(_2\) for more than 25 years. One of them was the “Spiess study”, a cohort of 899 juvenile patients who received several injections of [\(^{224}\)Ra]RaCl\(_2\) with a mean specific activity of 0.66 MBq/kg. Another patient group of ankylosing spondylitis patients was treated with 10 repeated intravenous injections of [\(^{224}\)Ra]RaCl\(_2\), 1 MBq each, 1 week apart. In total 1,471 of these patients were followed-up in the “Wick study”. In both studies, an increased cancer mortality by leukemia and solid cancers was observed. Similar considerations on long-term effects likely apply to [\(^{223}\)Ra]RaCl\(_2\) as well since the biokinetics are similar and the absorbed doses in the same range. However, this increased risk will most likely not be observed due to the much shorter life expectancy of prostate cancer patients treated with [\(^{223}\)Ra]RaCl\(_2\). KW - dosimetry KW - biodosimetry KW - 224Ra KW - 223Ra KW - epidemiology Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301509 SN - 2296-858X VL - 9 ER - TY - JOUR A1 - Eberlein, Uta A1 - Peper, Michel A1 - Fernández, Maria A1 - Lassmann, Michael A1 - Scherthan, Harry T1 - Calibration of the \(\gamma\)-H2AX DNA double strand break focus assay for internal radiation exposure of blood lymphocytes JF - PLoS ONE N2 - DNA double strand break (DSB) formation induced by ionizing radiation exposure is indicated by the DSB biomarkers \(\gamma\)-H2AX and 53BP1. Knowledge about DSB foci formation in-vitro after internal irradiation of whole blood samples with radionuclides in solution will help us to gain detailed insights about dose-response relationships in patients after molecular radiotherapy (MRT). Therefore, we studied the induction of radiation-induced co-localizing \(\gamma\)-H2AX and 53BP1 foci as surrogate markers for DSBs in-vitro, and correlated the obtained foci per cell values with the in-vitro absorbed doses to the blood for the two most frequently used radionuclides in MRT (I-131 and Lu-177). This approach led to an in-vitro calibration curve. Overall, 55 blood samples of three healthy volunteers were analyzed. For each experiment several vials containing a mixture of whole blood and radioactive solutions with different concentrations of isotonic NaCl-diluted radionuclides with known activities were prepared. Leukocytes were recovered by density centrifugation after incubation and constant blending for 1 h at 37°C. After ethanol fixation they were subjected to two-color immunofluorescence staining and the average frequencies of the co-localizing \(\gamma\)-H2AX and 53BP1 foci/nucleus were determined using a fluorescence microscope equipped with a red/green double band pass filter. The exact activity was determined in parallel in each blood sample by calibrated germanium detector measurements. The absorbed dose rates to the blood per nuclear disintegrations occurring in 1 ml of blood were calculated for both isotopes by a Monte Carlo simulation. The measured blood doses in our samples ranged from 6 to 95 mGy. A linear relationship was found between the number of DSB-marking foci/nucleus and the absorbed dose to the blood for both radionuclides studied. There were only minor nuclide-specific intra-and inter-subject deviations. KW - in vivo formation KW - chromatin mobility KW - phosphorylation KW - repair KW - 53BP1 KW - damage KW - radioiodine therapy KW - thyroid cancer KW - histone H2AX KW - dose response Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148697 VL - 10 IS - 4 ER - TY - JOUR A1 - Eberlein, Uta A1 - Bröer, Jörn Hendrik A1 - Vandevoorde, Charlot A1 - Santos, Paula A1 - Bardiès, Manuel A1 - Bacher, Klaus A1 - Nosske, Dietmar A1 - Lassmann, Michael T1 - Biokinetics and dosimetry of commonly used radiopharmaceuticals in diagnostic nuclear medicine – a review JF - European Journal of Nuclear Medicine and Molecular Imaging N2 - Purpose The impact on patients’ health of radiopharmaceuticals in nuclear medicine diagnostics has not until now been evaluated systematically in a European context. Therefore, as part of the EU-funded Project PEDDOSE.NET (www.​peddose.​net), we review and summarize the current knowledge on biokinetics and dosimetry of commonly used diagnostic radiopharmaceuticals. Methods A detailed literature search on published biokinetic and dosimetric data was performed mostly via PubMed (www.​ncbi.​nlm.​nih.​gov/​pubmed). In principle the criteria for inclusion of data followed the EANM Dosimetry Committee guidance document on good clinical reporting. Results Data on dosimetry and biokinetics can be difficult to find, are scattered in various journals and, especially in paediatric nuclear medicine, are very scarce. The data collection and calculation methods vary with respect to the time-points, bladder voiding, dose assessment after the last data point and the way the effective dose was calculated. In many studies the number of subjects included for obtaining biokinetic and dosimetry data was fewer than ten, and some of the biokinetic data were acquired more than 20 years ago. Conclusion It would be of interest to generate new data on biokinetics and dosimetry in diagnostic nuclear medicine using state-of-the-art equipment and more uniform dosimetry protocols. For easier public access to dosimetry data for diagnostic radiopharmaceuticals, a database containing these data should be created and maintained. KW - Dosimetry KW - Biokinetics KW - Diagnostic radiopharmaceuticals KW - Effective dose Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133846 VL - 38 IS - 12 ER - TY - JOUR A1 - Beykan, Seval A1 - Dam, Jan S. A1 - Eberlein, Uta A1 - Kaufmann, Jens A1 - Kjærgaard, Benedict A1 - Jødal, Lars A1 - Bouterfa, Hakim A1 - Bejot, Romain A1 - Lassmann, Michael A1 - Jensen, Svend Borup T1 - \(^{177}\)Lu-OPS201 targeting somatostatin receptors: in vivo biodistribution and dosimetry in a pig model JF - EJNMMI Research N2 - Background \(^{177}\)Lu is used in peptide receptor radionuclide therapies for the treatment of neuroendocrine tumors. Based on the recent literature, SST2 antagonists are superior to agonists in tumor uptake. The compound OPS201 is the novel somatostatin antagonist showing the highest SST2 affinity. The aim of this study was to measure the in vivo biodistribution and dosimetry of \(^{177}\)Lu-OPS201 in five anesthetized Danish Landrace pigs as an appropriate substitute for humans to quantitatively assess the absorbed doses for future clinical applications. Results \(^{177}\)Lu-OPS201 was obtained with a specific activity ranging from 10 to 17 MBq/μg. Prior to administration, the radiochemical purity was measured as s > 99.7 % in all cases. After injection, fast clearance of the compound from the blood stream was observed. Less than 5 % of the injected activity was presented in blood 10 min after injection. A series of SPECT/CT and whole-body scans conducted until 10 days after intravenous injection showed uptake mostly in the liver, spine, and kidneys. There was no visible uptake in the spleen. Blood samples were taken to determine the time-activity curve in the blood. Time-activity curves and time-integrated activity coefficients were calculated for the organs showing visible uptake. Based on these data, the absorbed organ dose coefficients for a 70-kg patient were calculated with OLINDA/EXM. For humans after an injection of 5 GBq \(^{177}\)Lu-OPS201, the highest predicted absorbed doses are obtained for the kidneys (13.7 Gy), the osteogenic cells (3.9 Gy), the urinary bladder wall (1.8 Gy), and the liver (1.0 Gy). No metabolites of 177Lu-OPS201 were found by radio HPLC analysis. None of the absorbed doses calculated will exceed organ toxicity levels. Conclusions The \(^{177}\)Lu-OPS201 was well tolerated and caused no abnormal physiological or behavioral signs. In vivo distributions and absorbed doses of pigs are comparable to those observed in other publications. According to the biodistribution data in pigs, presented in this work, the expected radiation exposure in humans will be within the acceptable range. KW - lutetium-177 KW - JR11 KW - antagonist KW - dosimetry KW - neuroendocrine tumor (NET) KW - OPS201 KW - pig model KW - PRRT Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-146888 VL - 6 IS - 50 ER -