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  • 1
    Online Resource
    Online Resource
    Bedeutung der Dosimetrie aus Sicht des Nuklearmediziners
    Georg Thieme Verlag KG ; 2023
    In:  Angewandte Nuklearmedizin Vol. 46, No. 01 ( 2023-03), p. 65-68
    Details
    In: Angewandte Nuklearmedizin, Georg Thieme Verlag KG, Vol. 46, No. 01 ( 2023-03), p. 65-68
    Abstract: Auch wenn bei der Radionuklidtherapie die individuelle Dosimetrie unter Mitwirkung des Medizin-Physik-Experten in der Strahlenschutzverordnung (StrSchV) festgeschrieben ist, bestehen unterschiedliche Auffassungen über das Ausmaß der Datenerfassung und auch technische Limitationen im Hinblick auf eine valide Bildgebung zur Bestimmung der Biokinetik. Dabei ist für die klinische Anwendung stets eine einfache und robuste Approximation zu bevorzugen. Für wissenschaftliche Fragestellungen und für die Berücksichtigung der biologisch effektiven Dosis bedarf es jedoch valider Algorithmen, insbesondere für die Kombination interner und externer Radiotherapie. Die Anwendung von Alphastrahlern mit geringen Aktivitätsmengen und geringer Emissionswahrscheinlichkeit von Gammastrahlung zur Bilderzeugung zwingt jedoch teilweise, auf Standardaktivitätsmengen auszuweichen oder sich an Wirkung und Nebenwirkung analog zu anderer onkologischer Systemtherapie zu orientieren.
    Type of Medium: Online Resource
    ISSN: 2749-7445 , 2749-7453
    URL: Article
    DOI: 10.1055/a-1802-8633
    Language: German
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2023
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  • 2
    Online Resource
    Online Resource
    Bildgebung, Kinetik, Quantifizierung
    Georg Thieme Verlag KG ; 2023
    In:  Angewandte Nuklearmedizin Vol. 46, No. 01 ( 2023-03), p. 13-19
    Details
    In: Angewandte Nuklearmedizin, Georg Thieme Verlag KG, Vol. 46, No. 01 ( 2023-03), p. 13-19
    Abstract: Nuklearmedizinische tomografische Verfahren wie die Positronen-Emissions-Tomografie (PET) und Single-Photonen-Emissions-Computertomografie (SPECT) werden in einem quantitativen Setting genutzt (z. B. die PET) bzw. sind, wie im Fall der SPECT, aufgrund der Erfordernisse nuklearmedizinischer Therapien an eine bildbasierte Dosimetrie, als quantitative bildgebende Modalität zu etablieren. Für die quantitative Analyse der bereitgestellten Bilddaten existieren unterschiedliche Konzepte. Ausgehend von der Quantifizierung dynamischer Aufnahmen mittels der Zeitaktivitätskurve wird für die kinetische Modellierung die Patlak-Methode vorgestellt. Verschiedene Methoden zur Auswertung statischer PET-Messungen, wie der Standardized Uptake Value (SUV) und das Standardized Uptake Ratio (SUR), werden diskutiert. Für die SPECT werden exemplarisch verschiedene methodische Entwicklungen auf dem Weg zur quantitativen Modalität adressiert.
    Type of Medium: Online Resource
    ISSN: 2749-7445 , 2749-7453
    URL: Article
    DOI: 10.1055/a-1802-8602
    Language: German
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    Radiation doses from low-dose CT scans in SPECT/CT and PET/CT examinations: A survey in Germany
    Georg Thieme Verlag KG ; 2022
    In:  Nuklearmedizin - NuclearMedicine Vol. 61, No. 04 ( 2022-08), p. 294-300
    Details
    In: Nuklearmedizin - NuclearMedicine, Georg Thieme Verlag KG, Vol. 61, No. 04 ( 2022-08), p. 294-300
    Abstract: Aim Recently, dose reference levels (DRLs) have been defined in Germany for auxiliary low-dose CT scans in hybrid SPECT/CT and PET/CT examinations, based on data from 2016/17. Here, another survey from 2020 was evaluated and compared with the new DRLs as well as with similar surveys from foreign countries. Methods The survey, which had already been conducted in the Nordic countries, queried for various examinations including the following values: patient weight and height, volume CT dose index (CTDIvol), dose length product (DLP). For each examination, statistical parameters such as the third quartile (Q3) were determined from all submitted CTDIvol and DLP values. Additionally, for examinations comprising datasets from at least 10 systems, the third quartile (Q3-Med) of the respective median values of each system was calculated. Q3 and Q3-Med were compared with the newly published DRLs from Germany and values from similar studies from other countries. Results Data from 15 SPECT/CT and 13 PET/CT systems from 15 nuclear medicine departments were collected. For the following examinations datasets from more than 10 systems were submitted: SPECT lung VQ, SPECT bone, SPECT & PET cardiac, PET brain, PET oncology. Especially for examinations of the thorax and heart, the new DRLs are very strict compared to this study. The CTDIvol values for examinations of the head were lower in this study than the DRLs prescribe now. Conclusions For certain examination types, there is a need for dose optimization at some clinics and devices in order to take into account the new DRLs in Germany in the future.
    Type of Medium: Online Resource
    ISSN: 0029-5566 , 2567-6407
    URL: Article
    DOI: 10.1055/a-1759-3900
    Language: English
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2022
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  • 4
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    Online Resource
    Induction and rejoining of DNA double-strand breaks in the lymphocytes of prostate cancer patients after radium-223 treatment as assessed by the γH2AX foci assay
    Georg Thieme Verlag KG ; 2019
    In:  Nuklearmedizin Vol. 58, No. 05 ( 2019-09), p. 387-394
    Details
    In: Nuklearmedizin, Georg Thieme Verlag KG, Vol. 58, No. 05 ( 2019-09), p. 387-394
    Abstract: Aim The aim of this study is to assess if the number of radiation-induced double strand breaks (DSB) in lymphocytes of prostate cancer patients is affected after repeated Ra-223 therapies. In addition, we investigated the repair of ex vivo induced DSB to investigate the repair proficiency in patient’s lymphocytes over the therapy course. Methods Before each of six therapy cycles, blood samples were obtained from seventeen patients. After separation of lymphocytes, the cells were subjected to immunofluorescence staining for detection of DSB-marking γH2AX foci. The number of foci per cell per patient sample was determined for each cycle (X1-X6, baseline foci per cell). Additionally, appropriate samples were exposed ex vivo to an X-ray dose of 1 Gy. The number of γH2AX foci per cell were analyzed after 0.5 h, 2 h and 24 h of recovery. Results Patient-specific linear regression of the baseline foci per cell over the therapy cycles revealed no significant slopes in the regression lines. Likewise, the mean baseline foci per cell of all patients for cycles X2-X6 was not significantly elevated in comparison to the pre-therapeutic value (X1). The differences between the percentages of residual DSB and cycles were not significant, both at 2 h and 24 h repair time. Consideration of the X6/X1 ratios of both the number of lymphocytes and the amount of residual damage at 24 h indicated a significant correlation. Conclusion Our findings indicate that the number of γH2AX foci per cell was not changed in dependence on the Ra-223 therapy cycles. The ability of patient’s lymphocytes to repair ex vivo induced DSB remained unaffected throughout the entire therapy course.
    Type of Medium: Online Resource
    ISSN: 0029-5566 , 2567-6407
    URL: Article
    DOI: 10.1055/a-0974-3767
    Language: English
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2019
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  • 5
    Online Resource
    Online Resource
    PET Rekonstruktionen – Harmonisierung, alte und neue Ansätze
    Georg Thieme Verlag KG ; 2022
    In:  Angewandte Nuklearmedizin Vol. 45, No. 03 ( 2022-09), p. 204-209
    Details
    In: Angewandte Nuklearmedizin, Georg Thieme Verlag KG, Vol. 45, No. 03 ( 2022-09), p. 204-209
    Abstract: Nach einer einführenden Erklärung der Funktionsweise der Positronen-Emissions-Tomografie (PET) Diagnostik werden Inhalt und Ziel der Rekonstruktion von PET-Daten vorgestellt. Es wird dargelegt, welche physikalischen Prozesse die PET-Bildgebung beeinflussen und wie diese im Rahmen der Rekonstruktion von PET-Daten korrigiert werden können. Dazu gehören Korrekturen für zufällige, gestreute und absorbierte Photonen sowie Korrekturen für Totzeiteffekte des Detektors. Die beiden gängigsten PET-Rekonstruktionsverfahren, die gefilterte Rückprojektion (Filtered Back Projection, FBP) und der iterative Rekonstruktionsalgorithmus, werden erklärt und die jeweiligen Vor- und Nachteile dargelegt. Auf zwei Beispiele der iterativen Rekonstruktionsmethode wird detaillierter eingegangen: das Verfahren der Maximum Likelihood Expectation Maximization (MLEM) und die aktuell in der klinischen PET-Bildgebung am häufigsten angewendete Methode der Ordered Subsets Expectation Maximization (OSEM) Rekonstruktion. Weiterhin werden verschiedene Möglichkeiten der Reduktion von Bildrauschen bei iterativen Rekonstruktionen vorgestellt, wie beispielsweise die Bayesian Penalized Likelihood (BPL) Methode. Es wird auf technische Neuerungen hinsichtlich der Gerätetechnik und der Software von PET-Geräten eingegangen. Time of Flight (ToF) Messung und Point Spread Function (PSF) Modellierungen im Rahmen der Rekonstruktion werden erklärt und deren Vor- und Nachteile dargestellt. Abschließend werden neue Möglichkeiten der datengestützten Bewegungskorrektur (data-driven motion correction) und Ansätze mittels künstlicher Intelligenz aufgegriffen.
    Type of Medium: Online Resource
    ISSN: 2749-7445 , 2749-7453
    URL: Article
    DOI: 10.1055/a-1715-5239
    Language: German
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2022
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  • 6
    Online Resource
    Online Resource
    68Ga-RM2 PET in PSMA- positive and -negative prostate cancer patients
    Georg Thieme Verlag KG ; 2019
    In:  Nuklearmedizin Vol. 58, No. 05 ( 2019-09), p. 352-362
    Details
    In: Nuklearmedizin, Georg Thieme Verlag KG, Vol. 58, No. 05 ( 2019-09), p. 352-362
    Abstract: Aim 68Ga-PSMA-11 is the gold standard for molecular imaging of prostate cancer. However, recurrent tumor manifestations or metastases cannot be detected in every case. Therefore, we investigated if there is an additive value of the gastrin-releasing peptide receptor (GRP-R) ligand 68Ga-RM2 compared to the well-established 68Ga-PSMA-11 in patients with (Group 1) and without (Group 2) pathologic PSMA-expression in different tumor stages. Patients and Methods Sixteen men (median age: 74 years, range 50–80 years) with prostate cancer in different stages who had a recent negative (n = 8) or pathologic (n = 8) PSMA PET underwent a subsequent 68Ga-RM2 PET. Both examinations were analyzed qualitatively and quantitatively and compared in terms of pathologic and physiologic tracer distribution. Results None of the PSMA-negative patients showed any pathological RM2-accumulation. Pathologic PSMA-uptake was observed in 8 patients of whom 5 had pathologic RM2-uptake. The number of patients with a local recurrence was equal in both scans (n = 3). Bone metastases and lymph node metastases were detected in less patients in RM2 PET compared to PSMA PET (n = 4 vs. 7 and n = 2 vs. 5, respectively). In one patient, PSMA-positive liver metastases were not detected in RM2. RM2 PET revealed two additional lesions indicative for bone metastases in two patients with multiple PSMA-positive bone metastases, which had no therapeutic consequence. Conclusion At least in our small and heterogeneous patient population, 68Ga-RM2 showed no clinically relevant, additional benefit compared to 68Ga-PSMA-11 PET.
    Type of Medium: Online Resource
    ISSN: 0029-5566 , 2567-6407
    URL: Article
    DOI: 10.1055/a-0990-8898
    Language: English
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2019
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  • 7
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    Online Resource
    Comparison of 68Ga- and fluorescence-labeled microspheres for measurement of relative pulmonary perfusion in anesthetized pigs
    Georg Thieme Verlag KG ; 2018
    In:  Nuklearmedizin - NuclearMedicine Vol. 57, No. 03 ( 2018-06), p. 100-107
    Details
    In: Nuklearmedizin - NuclearMedicine, Georg Thieme Verlag KG, Vol. 57, No. 03 ( 2018-06), p. 100-107
    Abstract: Aim: We compared 68Gallium (68Ga)- and fluorescence-labeled microspheres for measurement of pulmonary perfusion distribution in anesthetized pigs without lung injury. Methods: In two mechanically ventilated pigs, the distribution of pulmonary perfusion was marked in vivo with 68Ga- and fluorescence-labeled microspheres in supine and prone position. After each injection, the distribution of 68Ga-labeled microspheres was measured in vivo with positron emission tomography/ computed tomography (PET/CT) in the position in which microspheres were injected and vice versa. The distribution of fluorescence-labeled microspheres was measured ex vivo. Perfusion distributions were compared between methods and postures within four lung regions and along the ventro-dorsal gradient. After each injection of 68Ga-labeled microspheres, changes in ventro-dorsal perfusion gradients induced by repositioning were compared for volume- and mass-normalized PET/CT measurements. Results: Regional and gradient analyses of in vivo and ex vivo measurements, respectively, consistently revealed higher pulmonary perfusion in dorsal than ventral regions in supine positioned animals. Both methods showed more pronounced perfusion gradients in supine compared to prone position. Changes in animal position were associated with alterations in the ventro-dorsal perfusion gradient when volume-, but not mass-normalization was conducted for PET/CT data. Conclusions: Ex vivo fluorescence- and in vivo 68Ga-labeled microspheres measurements revealed similar perfusion distributions. Mass-normalized perfusion measurements by 68Ga-labeled microspheres and PET/CT were not affected by positioning artifacts.
    Type of Medium: Online Resource
    ISSN: 0029-5566 , 2567-6407
    URL: Article
    DOI: 10.3413/Nukmed-0970-18-04
    Language: English
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2018
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