RESUMO
PURPOSE: PET/CT with 68Ga-labelled prostate-specific membrane antigen (PSMA)-ligands has been proven to establish a promising imaging modality in the work-up of prostate cancer (PC) patients with biochemical relapse. Despite a high overall detection rate, the visualisation of local recurrence may be hampered by high physiologic tracer accumulation in the urinary bladder on whole body imaging, usually starting 60 min after injection. This study sought to verify whether early dynamic 68Ga-PSMA-11 (HBED-CC)PET/CT can differentiate pathologic PC-related tracer uptake from physiologic tracer accumulation in the urinary bladder. METHODS: Eighty consecutive PC patients referred to 68Ga -PSMA-11 PET/CT were included in this retrospective analysis (biochemical relapse: n = 64; primary staging: n = 8; evaluation of therapy response/restaging: n = 8). In addition to whole-body PET/CT acquisition 60 min post injection early dynamic imaging of the pelvis in the first 8 min after tracer injection was performed. SUVmax of pathologic lesions was calculated and time-activity curves were generated and compared to those of urinary bladder and areas of physiologic tracer uptake. RESULTS: A total of 55 lesions consistent with malignancy on 60 min whole body imaging exhibited also pathologic 68Ga-PSMA-11 uptake during early dynamic imaging (prostatic bed/prostate gland: n = 27; lymph nodes: n = 12; bone: n = 16). All pathologic lesions showed tracer uptake within the first 3 min, whereas urinary bladder activity was absent within the first 3 min of dynamic imaging in all patients. Suvmax was significantly higher in PC lesions in the first 6 min compared to urinary bladder accumulation (p < 0.001). In the subgroup of PC patients with biochemical relapse the detection rate of local recurrence could be increased from 20.3 to 29.7%. CONCLUSIONS: Early dynamic imaging in 68Ga-PSMA-11 PET/CT reliably enables the differentiation of pathologic tracer uptake in PC lesions from physiologic bladder accumulation. Performance of early dynamic imaging in addition to whole body imaging 60 min after tracer injection might improve the detection rate of local recurrence in PC patients with biochemical relapse referred for 68Ga-PSMA-11 PET/CT.
Assuntos
Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Neoplasias da Próstata/diagnóstico por imagem , Bexiga Urinária/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Transporte Biológico , Ácido Edético/análogos & derivados , Isótopos de Gálio , Radioisótopos de Gálio , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Oligopeptídeos , Compostos Organometálicos/metabolismo , Prostatectomia , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Neoplasias da Próstata/cirurgia , Estudos Retrospectivos , Fatores de Tempo , Bexiga Urinária/metabolismoRESUMO
PURPOSE: To determine the value of (68)Ga-DOTA-TOC and (18)F-FDG PET/CT for initial and follow-up evaluation of patients with neuroendocrine tumour (NET) treated with peptide receptor radionuclide therapy (PRRT). METHODS: We evaluated 66 patients who had histologically proven NET and underwent both PRRT and three combined (68)Ga-DOTA-TOC and (18)F-FDG PET/CT studies. (68)Ga-DOTA-TOC PET/CT was performed before PRRT, 3 months after completion of PRRT and after a further 6 - 9 months. (18)F-FDG PET/CT was done within 2 months of (68)Ga-DOTA-TOC PET/CT. Follow-up ranged from 11.8 to 80.0 months (mean 34.5 months). RESULTS: All patients were (68)Ga-DOTA-TOC PET-positive initially and at follow-up after the first full PRRT cycle. Overall, 62 of the 198 (18)F-FDG PET studies (31 %) were true-positive in 38 of the 66 patients (58 %). Of the 66 patients, 28 (5 grade 1, 23 grade 2) were (18)F-FDG-negative initially and during follow-up (group 1), 24 (5 grade 1, 13 grade 2, 6 grade 3) were (18)F-FDG-positive initially and during follow-up (group 2), 9 patients (2 grade 1, 6 grade 2, 1 grade 3) were (18)F-FDG-negative initially but (18)F-FDG-positive during follow-up (group 3), and 5 patients (all grade 2) were (18)F-FDG-positive initially but (18)F-FDG-negative during follow-up (group 4).(18)F-FDG PET showed more and/or larger metastases than (68)Ga-DOTA-TOC PET in five patients of group 2 and four patients of group 3, all with progressive disease. In three patients with progressive disease who died during follow-up tumour SUVmax increased by 41 - 82 % from the first to the last follow-up investigation. CONCLUSION: In NET patients, the presence of (18)F-FDG-positive tumours correlates strongly with a higher risk of progression. Initially, patients with (18)F-FDG-negative NET may show (18)F-FDG-positive tumours during follow-up. Also patients with grade 1 and grade 2 NET may have (18)F-FDG-positive tumours. Therefore, (18)F-FDG PET/CT is a complementary tool to (68)Ga-DOTA-TOC PET/CT with clinical relevance for molecular investigation.
Assuntos
Fluordesoxiglucose F18 , Tumores Neuroendócrinos/diagnóstico por imagem , Tumores Neuroendócrinos/radioterapia , Octreotida/análogos & derivados , Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Receptores de Somatostatina/uso terapêutico , Adulto , Idoso , Transporte Biológico , Feminino , Fluordesoxiglucose F18/metabolismo , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Tumores Neuroendócrinos/metabolismo , Tumores Neuroendócrinos/patologia , Octreotida/metabolismo , Compostos Organometálicos/metabolismo , Estudos RetrospectivosRESUMO
Physiologically increased pancreatic uptake at the head/uncinate process is observed in more than one-third of patients after injection of one of the three (68)Ga-labelled octreotide-based peptides used for somatostatin (sst) receptor (r) imaging. There are minor differences between these (68)Ga-sstr-binding peptides in the imaging setting. On (68)Ga-sstr-imaging the physiological uptake can be diffuse or focal and usually remains stable over time. Differences in the maximal standardised uptake values (SUVmax) reported for the normal pancreas as well as for pancreatic neuroendocrine tumour (PNET) lesions may be related to several factors, including (a) differences in the peptide binding affinities as well as differences in sstr subtype expression of pancreatic α- and ß-cells, and heterogeneity / density of tumour cells, (b) differences in scanner resolution, image reconstruction techniques and acquisition protocols, (c) mostly retrospective study designs, (d) mixed patient populations, or (e) interference with medications such as treatment with long-acting sst analogues. The major limitation in most of the studies lies in the lack of histopathological confirmation of abnormal findings. There is a significant overlap between the calculated SUVmax-values for physiological pancreas and PNET-lesions of the head/uncinate process that do not favour the use of quantitative parameters in the clinical setting. Anecdotal long-term follow-up studies have even indicated that increased uptake in the head/uncinate process still can turn out to be malignant over years of follow up. SUVmax-data for the pancreatic body and tail are limited. Therefore, any visible focal tracer uptake in the pancreas must be considered as suspicious for malignancy irrespective of quantitative parameters. In general, sstr-PET/CT has significant implications for the management of NET patients leading to a change in treatment decision in about one-third of patients. Therefore, follow-up with (68)Ga-sstr-PET/CT is mandatory in the clinical setting if uptake in the head/uncinate process is observed.
Assuntos
Radioisótopos de Gálio/farmacocinética , Tumores Neuroendócrinos/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/normas , Receptores de Somatostatina/metabolismo , Biomarcadores Tumorais/metabolismo , Medicina Baseada em Evidências , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Imagem Molecular/métodos , Tumores Neuroendócrinos/metabolismo , Tumores Neuroendócrinos/cirurgia , Octreotida/farmacocinética , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/cirurgia , Guias de Prática Clínica como Assunto , Compostos Radiofarmacêuticos/farmacocinética , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Signal abnormalities of the substantia nigra and the olfactory tract detected either by diffusion tensor imaging, including measurements of mean diffusivity, a parameter of brain tissue integrity, and fractional anisotropy, a parameter of neuronal fibre integrity, or transcranial sonography, were recently reported in the early stages of Parkinson's disease. In this study, changes in the nigral and olfactory diffusion tensor signal, as well as nigral echogenicity, were correlated with clinical scales of motor disability, odour function and putaminal dopamine storage capacity measured with 6-[(18)F] fluorolevodopa positron emission tomography in early and advanced stages of Parkinson's disease. Diffusion tensor imaging, transcranial sonography and positron emission tomography were performed on 16 patients with Parkinson's disease (mean disease duration 3.7 ± 3.7 years, Hoehn and Yahr stage 1 to 4) and 14 age-matched healthy control subjects. Odour function was measured by the standardized Sniffin' Sticks Test. Mean putaminal 6-[(18)F] fluorolevodopa influx constant, mean nigral echogenicity, mean diffusivity and fractional anisotropy values of the substantia nigra and the olfactory tract were identified by region of interest analysis. When compared with the healthy control group, the Parkinson's disease group showed significant signal changes in the caudate and putamen by 6-[(18)F] fluorolevodopa positron emission tomography, in the substantia nigra by transcranial sonography, mean diffusivity and fractional anisotropy (P < 0.001, P < 0.01, P < 0.05, respectively) and in the olfactory tract by mean diffusivity (P < 0.05). Regional mean diffusivity values of the substantia nigra and the olfactory tract correlated significantly with putaminal 6-[(18)F] fluorolevodopa uptake (r = -0.52, P < 0.05 and r = -0.71, P < 0.01). Significant correlations were also found between nigral mean diffusivity values and the Unified Parkinson's Disease Rating Scale motor score (r = -0.48, P < 0.01) and between mean putaminal 6-[(18)F] fluorolevodopa uptake and the total odour score (r = 0.58; P < 0.05) as well as the Unified Parkinson's Disease Rating Scale motor score (r = -0.53, P < 0.05). This study reports a significant association between increased mean diffusivity signal and decreased 6-[(18)F] fluorolevodopa uptake, indicating that microstructural degradation of the substantia nigra and the olfactory tract parallels progression of putaminal dopaminergic dysfunction in Parkinson's disease. Since increases in nigral mean diffusivity signal also correlated with motor dysfunction, diffusion tensor imaging may serve as a surrogate marker for disease progression in future studies of putative disease modifying therapies.
Assuntos
Gânglios da Base/patologia , Dopamina/metabolismo , Neurônios Dopaminérgicos/patologia , Condutos Olfatórios/patologia , Doença de Parkinson/patologia , Substância Negra/patologia , Idoso , Anisotropia , Gânglios da Base/fisiopatologia , Corpo Estriado/fisiopatologia , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Condutos Olfatórios/metabolismo , Condutos Olfatórios/fisiopatologia , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/fisiopatologia , Tomografia por Emissão de Pósitrons/métodos , Putamen/patologia , Putamen/fisiopatologia , Substância Negra/fisiopatologiaRESUMO
PURPOSE: The aim of this study was to evaluate the impact of (68)Ga-labelled DOTA(0)-lanreotide ((68)Ga-DOTA-LAN) on the diagnostic assessment of neuroendocrine tumour (NET) patients with low to moderate uptake on planar somatostatin receptor (SSTR) scintigraphy or (68)Ga-labelled DOTA(0),Tyr(3)-octreotide ((68)Ga-DOTA-TOC) positron emission tomography (PET). METHODS: Fifty-three patients with histologically confirmed NET and clinical signs of progressive disease, who had not qualified for peptide receptor radionuclide therapy (PRRT) on planar SSTR scintigraphy or (68)Ga-DOTA-TOC PET (n = 38) due to lack of tracer uptake, underwent (68)Ga-DOTA-LAN PET to evaluate a treatment option with (90)Y-labelled lanreotide according to the MAURITIUS trial. The included patients received 150 ± 30 MBq of each radiopharmaceutical intravenously. PET scans were acquired 60-90 min after intravenous bolus injection. Image results from both PET scans were compared head to head, focusing on the intensity of tracer uptake in terms of treatment decision. CT was used for morphologic correlation of tumour lesions. To further evaluate the binding affinities of each tracer, quantitative and qualitative values were calculated for target lesions. RESULTS: (68)Ga-DOTA-LAN and (68)Ga-DOTA-TOC both showed equivalent findings in 24/38 patients when fused PET/CT images were interpreted. The sensitivity, specificity and accuracy of (68)Ga-DOTA-LAN in comparison to CT were 0.63, 0.5 and 0.62 (n = 53; p < 0.0001) and for (68)Ga-DOTA-TOC in comparison to CT 0.78, 0.5 and 0.76 (n = 38; p < 0.013), respectively. (68)Ga-DOTA-TOC showed a significantly higher maximum standardized uptake value (SUV(max)) regarding the primary tumour in 25 patients (p < 0.003) and regarding the liver in 30 patients (p < 0.009) compared to (68)Ga-DOTA-LAN. Corresponding values of both PET scans for tumour and liver did not show any significant correlation. (68)Ga-DOTA-TOC revealed more tumour sites than (68)Ga-DOTA-LAN (106 vs 53). The tumour to background ratios for tumour and liver calculated from SUV(max) measurements were significantly higher for (68)Ga-DOTA-TOC than (68)Ga-DOTA-LAN (p < 0.02). CONCLUSION: (68)Ga-DOTA-TOC PET imaging is an established imaging procedure for accurate staging of NET patients. (68)Ga-DOTA-LAN should only be considered as a PET tracer of second choice in patients with no pathologic tracer uptake on (68)Ga-DOTA-TOC PET. In these patients, (68)Ga-DOTA-LAN PET can provide valuable information when evaluating PRRT as the treatment option, as a broader spectrum of human SSTR subtypes can be detected.
Assuntos
Compostos Heterocíclicos com 1 Anel , Tumores Neuroendócrinos/diagnóstico por imagem , Tumores Neuroendócrinos/metabolismo , Octreotida/análogos & derivados , Compostos Organometálicos , Peptídeos Cíclicos , Tomografia por Emissão de Pósitrons/métodos , Receptores de Somatostatina/metabolismo , Somatostatina/análogos & derivados , Adulto , Idoso , Idoso de 80 Anos ou mais , Transporte Biológico , Feminino , Compostos Heterocíclicos com 1 Anel/metabolismo , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Octreotida/metabolismo , Compostos Organometálicos/metabolismo , Peptídeos Cíclicos/metabolismo , Estudos Retrospectivos , Somatostatina/metabolismo , Adulto JovemRESUMO
PET/CT with the new 68Ga-labeled minigastrin analog DOTA-dGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1-Nal-NH2 (68Ga-DOTA-MGS5) was performed on patients with advanced medullary thyroid cancer (MTC) to evaluate cholecystokinin-2 receptor expression status. Methods: Six patients with advanced MTC underwent PET/CT with 68Ga-DOTA-MGS5. From the images acquired 1 and 2 h after injection, preliminary data on the biodistribution and tumor-targeting properties were evaluated in a retrospective analysis. Results: In total, 87 lesions with increased radiotracer uptake considered malignant were detected (2 local recurrences, 8 lymph node lesions, 27 liver lesions, and 50 bone lesions). In general, radiotracer accumulation in lesions was higher at 2 h than at 1 h after injection (mean SUVmax, 7.2 vs. 6.0, respectively; mean SUVmean, 4.4 vs. 3.6, respectively). Conclusion: The preliminary results clearly demonstrate the potential of 68Ga-DOTA-MGS5 PET/CT in detecting local recurrence and metastases in patients with advanced MTC.
Assuntos
Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Neoplasias da Glândula Tireoide , Humanos , Receptor de Colecistocinina B/metabolismo , Radioisótopos de Gálio/química , Distribuição Tecidual , Estudos Retrospectivos , Compostos Radiofarmacêuticos , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/metabolismoRESUMO
PURPOSE: To assess dose levels in routine nuclear medicine (NUC) procedures in Austria as a prior to a legislative update of the National Diagnostic Reference Levels (NDRL). METHOD: As part of a nationwide survey of common NUC-examinations between June 2019 and November 2019, data sets were collected from 33 Austrian hospitals with NUC equipment. All hospitals were asked to report the NUC imaging devices in use (model, type, year of manufacture, detector material, collimators), the standard protocol parameters for selected examinations (standard activity, collimator, average acquisition time, reconstruction type, use of time-of-flight) and to report data from 10 representative examinations (e.g. injected activity, weight), incl. the most common NUC-examinations for planar imaging/SPECT and PET. Median/mean values for injected activity were calculated and compared to current Austrian and international NDRL. A Pearson correlation coefficient was computed comparing different variables. RESULTS: In total, all 33 hospitals (100% response rate) reported data for this study for 60 SPECT devices, 21 PET/CT devices and 23 scintigraphy devices. Fixed activity values for scintigraphy/SPECT and PET were employed by about 90% and 56% of the hospitals, respectively. The most widely performed examinations for scintigraphy/SPECT are bone imaging, thyroid imaging, renal imaging (with MAG3/EC) and lung perfusion imaging (in 88% of the hospitals) and F-18 FDG-PET studies for oncology indications (in 100% of the hospitals). Significant correlations were found for patient weight and injected activity (scintigraphy/SPECT), use of iterative reconstruction and injected activity (PET) as well as size of field-of-view and injected activity (PET). CONCLUSIONS: The reported injected activity levels were comparable to those in other countries. However, for procedures for which NDRL exist, deviations in injected activities of >20% compared to the NDRL were found. These deviations are assumed to result mainly from advances in technology but also from deviations between NDRL and prescribed activities as given in the information leaflets of the radiopharmaceuticals.
Assuntos
Medicina Nuclear , Adulto , Áustria , Níveis de Referência de Diagnóstico , Fluordesoxiglucose F18 , Humanos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Compostos Radiofarmacêuticos , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
PURPOSE: The purpose of this study was to develop an observer-independent algorithm for the correct classification of dopamine transporter SPECT images as Parkinson's disease (PD), multiple system atrophy parkinson variant (MSA-P), progressive supranuclear palsy (PSP) or normal. METHODS: A total of 60 subjects with clinically probable PD (n = 15), MSA-P (n = 15) and PSP (n = 15), and 15 age-matched healthy volunteers, were studied with the dopamine transporter ligand [(123)I]ß-CIT. Parametric images of the specific-to-nondisplaceable equilibrium partition coefficient (BP(ND)) were generated. Following a voxel-wise ANOVA, cut-off values were calculated from the voxel values of the resulting six post-hoc t-test maps. The percentages of the volume of an individual BP(ND) image remaining below and above the cut-off values were determined. The higher percentage of image volume from all six cut-off matrices was used to classify an individual's image. For validation, the algorithm was compared to a conventional region of interest analysis. RESULTS: The predictive diagnostic accuracy of the algorithm in the correct assignment of a [(123)I]ß-CIT SPECT image was 83.3% and increased to 93.3% on merging the MSA-P and PSP groups. In contrast the multinomial logistic regression of mean region of interest values of the caudate, putamen and midbrain revealed a diagnostic accuracy of 71.7%. CONCLUSION: In contrast to a rater-driven approach, this novel method was superior in classifying [(123)I]ß-CIT-SPECT images as one of four diagnostic entities. In combination with the investigator-driven visual assessment of SPECT images, this clinical decision support tool would help to improve the diagnostic yield of [(123)I]ß-CIT SPECT in patients presenting with parkinsonism at their initial visit.
Assuntos
Cocaína/análogos & derivados , Processamento de Imagem Assistida por Computador/métodos , Transtornos Parkinsonianos/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Idoso , Algoritmos , Análise de Variância , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Estudos de Casos e Controles , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atrofia de Múltiplos Sistemas/diagnóstico por imagem , Atrofia de Múltiplos Sistemas/metabolismo , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/metabolismo , Transtornos Parkinsonianos/metabolismo , Análise de Regressão , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Paralisia Supranuclear Progressiva/diagnóstico por imagem , Paralisia Supranuclear Progressiva/metabolismoRESUMO
PURPOSE: (68)Ga-DOTA-Tyr(3)-octreotide positron emission tomography ((68)Ga-DOTA-TOC PET) has proven to be superior to (111)In-DTPA-D-Phe(1)-octreotide ((111)In-octreotide) planar scintigraphy and SPECT imaging in neuroendocrine tumours (NETs). Because of these promising results, we compared the accuracy of (123)I-metaiodobenzylguanidine ((123)I-MIBG) imaging with PET in the diagnosis and staging of metastatic phaeochromocytoma and neuroblastoma, referring to radiological imaging as reference standard. METHODS: Three male and eight female patients (age range 3 to 68 years) with biochemically and histologically proven disease were included in this study. Three male and three female patients were suffering from phaeochromocytoma, and five female patients from neuroblastoma. Comparative evaluation included morphological imaging with CT or MRI, functional imaging with (68)Ga-DOTA-TOC PET and (123)I-MIBG imaging. Imaging results were analysed on a per-patient and on a per-lesion basis. RESULTS: On a per-patient basis, both (68)Ga-DOTA-TOC and (123)I-MIBG showed a sensitivity of 100%, when compared with anatomical imaging. In phaeochromocytoma patients, on a per-lesion basis, the sensitivity of (68)Ga-DOTA-TOC was 91.7% and that of (123)I-MIBG was 63.3%. In neuroblastoma patients, on a per-lesion basis, the sensitivity of (68)Ga-DOTA-TOC was 97.2% and that of (123)I-MIBG was 90.7%. Overall, in this patient cohort, (68)Ga-DOTA-TOC PET identified 257 lesions, anatomical imaging identified 216 lesions, and (123)I-MIBG identified only 184 lesions. In this patient group, the overall sensitivity of (68)Ga-DOTA-TOC PET on a lesion basis was 94.4% (McNemar p<0.0001) and that of (123)I-MIBG was 76.9% (McNemar p<0.0001). CONCLUSION: Our analysis in this relatively small patient cohort indicates that (68)Ga-DOTA-TOC PET may be superior to (123)I-MIBG gamma-scintigraphy and even to the reference CT/MRI technique in providing particularly valuable information for pretherapeutic staging of phaeochromocytoma and neuroblastoma.
Assuntos
3-Iodobenzilguanidina , Neuroblastoma/diagnóstico por imagem , Octreotida/análogos & derivados , Compostos Organometálicos , Feocromocitoma/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Adolescente , Neoplasias das Glândulas Suprarrenais/diagnóstico por imagem , Neoplasias das Glândulas Suprarrenais/patologia , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estadiamento de Neoplasias , Neuroblastoma/patologia , Feocromocitoma/patologia , Tomografia por Emissão de Pósitrons/normas , Padrões de Referência , Estudos Retrospectivos , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X , Adulto JovemRESUMO
PURPOSE: As radionuclide therapy is gaining importance in palliative treatment of patients suffering from neuroendocrine tumour (NET) as well as castration resistant prostate cancer (CRPC), the radiation protection of patients, staff, family members and the general public is of increasing interest. Here, we determine patient discharge dates according to European guidelines. METHODS: In 40 patients with NET and 25 patients with CRPC organ and tumour doses based on the MIRD concept were calculated from data obtained during the first therapy cycle. Planar whole body images were recorded at 0.5, 4, 20, 68 und 92 h postinjection. Residence times were calculated from the respective time-activity-curves based on the conjugated view method. Residence times for critical organs were fitted into the commercially available OLINDA software to calculate the organ doses. The doses of tumours and salivary glands were calculated via their self-irradiation by approximation with spheres of equivalent volume. Kidney volumes were gained by organ segmentation, volumes of all other organs were estimated by means of OLINDA and hence were lean body mass corrected. Out of the whole body curves reference points for patient discharge were estimated. RESULTS: In patients with NET discharge dates could be properly estimated from dosimetric data, which is not only crucial for radiation protection, but also makes therapy planning easier. For 177Lu-PSMA-617 ligand therapy it is difficult to seriously estimate a generalized discharge date due to large interpatient variation resulting from different tumor loads and heavy pre-treatment. CONCLUSION: Patient release is predictable for 177Lu-DOTATATE therapy but not for 177Lu-PSMA ligand therapy.