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Zusammenfassung Ziele Neben der etablierten Radiojodtherapie werden in Deutschland zunehmend auch Therapien mit Lutetium-177 stationär durchgeführt. All diese Therapien sind bei der Abschätzung der potenziellen Inkorporationsdosis und der Inkorporationsüberwachung des Personals zu berücksichtigen. Dieser Beitrag zeigt die Erfahrungen und Ergebnisse der Inkorporationsüberwachung auf einer nuklearmedizinischen Therapiestation eines Universitätsklinikums. Methoden Personal einer nuklearmedizinischen Therapiestation wurde regelmäßig mittels eines Ganzkörperzählers auf Inkorporation überwacht. Über einen Zeitraum von 12 Monaten erfolgten insgesamt 234 Messungen. Unter Berücksichtigung der im jeweiligen Zeitraum gehandhabten oder applizierten Aktivitäten wurden Inkorporationsfaktoren ermittelt. Ergebnisse In ca. 74 % der Messungen wurde keine Inkorporation festgestellt. In den übrigen Messungen wurde Aktivität erkannt. Bei Annahme von Inkorporation würden sich hieraus maximale Expositionen von weniger als 0,15 mSv effektiver Dosis pro Messung ergeben. Die in dieser Arbeit ermittelten Inkorporationsfaktoren lagen für alle Personengruppen bis auf das Personal der radiochemischen Qualitätskontrolle in einer Größenordnung von 10–7. Für die letztgenannte Personengruppe kann nur eine Obergrenze des Inkorporationsfaktors von 10–5 angegeben werden. Schlussfolgerung Das Inkorporationsrisiko für Personal einer nuklearmedizinischen Therapiestation kann als gering angesehen werden. Ein Inkorporationsfaktor von 10–7 ist für ärztliches Personal, Pflegepersonal, Reinigungspersonal und das Personal, das radiochemische Synthesen durchführt, angemessen.

A multicenter study was conducted to assess the radiation exposure of relatives and caregivers of patients suffering from castration resistant prostate cancer with bone metastases and treated with Ra-223 dichloride in an outpatient setting. As Ra-223 and most of its progeny emit alpha particles, especially the internal exposure of persons in the patient's vicinity had to be evaluated. METHODS The external radiation was measured in distances of 1 m and 2 m. Wipe-tests were taken in the patients' homes to identify significant contaminations and evaluated by liquid scintillation counting. Samples of saliva and sweat were taken and measured using gamma spectrometry. RESULTS The external exposure from the patients measured 10-20min post injection (p. i.) was

In addition to the well-established therapy with iodine-131, treatments with lutetium-177 are increasingly being performed on an inpatient basis in Germany. All of these treatments have be taken into account when assessing the potential internal dose and for incorporation monitoring of personnel. This article describes the experience with and the results of incorporation monitoring of staff of a nuclear medicine ward of a university hospital in Germany.Personnel working in a nuclear medicine ward was regularly measured using a whole body counter. In total, 234 measurements were performed over a period of 12 months. Incorporation factors were determined considering activities handled or applied to patients in the respective time period.In approx. 74 % of measurements, no incorporations was found. In the remaining measurements, activity was detected. Assuming incorporation, the maximum effective dose would be less than 0.15 mSv per measurement. The incorporation factors determined in this work were in the order of magnitude of 10The risk of incorporating radiactivity can be considered low for personnel working in a nuclear medicine ward. An incorporation factor of 10Neben der etablierten Radiojodtherapie werden in Deutschland zunehmend auch Therapien mit Lutetium-177 stationär durchgeführt. All diese Therapien sind bei der Abschätzung der potenziellen Inkorporationsdosis und der Inkorporationsüberwachung des Personals zu berücksichtigen. Dieser Beitrag zeigt die Erfahrungen und Ergebnisse der Inkorporationsüberwachung auf einer nuklearmedizinischen Therapiestation eines Universitätsklinikums.Personal einer nuklearmedizinischen Therapiestation wurde regelmäßig mittels eines Ganzkörperzählers auf Inkorporation überwacht. Über einen Zeitraum von 12 Monaten erfolgten insgesamt 234 Messungen. Unter Berücksichtigung der im jeweiligen Zeitraum gehandhabten oder applizierten Aktivitäten wurden Inkorporationsfaktoren ermittelt.In ca. 74 % der Messungen wurde keine Inkorporation festgestellt. In den übrigen Messungen wurde Aktivität erkannt. Bei Annahme von Inkorporation würden sich hieraus maximale Expositionen von weniger als 0,15 mSv effektiver Dosis pro Messung ergeben. Die in dieser Arbeit ermittelten Inkorporationsfaktoren lagen für alle Personengruppen bis auf das Personal der radiochemischen Qualitätskontrolle in einer Größenordnung von 10Das Inkorporationsrisiko für Personal einer nuklearmedizinischen Therapiestation kann als gering angesehen werden. Ein Inkorporationsfaktor von 10

Purpose Tracer kinetic modeling of tissue time activity curves and the individual input function based on arterial blood sampling and metabolite correction is the gold standard for quantitative characterization of microglia activation by PET with the translocator protein (TSPO) ligand 18F-GE-180. This study tested simplified methods for quantification of 18F-GE-180 PET. Methods Dynamic 18F-GE-180 PET with arterial blood sampling and metabolite correction was performed in five healthy volunteers and 20 liver-transplanted patients. Population-based input function templates were generated by averaging individual input functions normalized to the total area under the input function using a leave-one-out approach. Individual population-based input functions were obtained by scaling the input function template with the individual parent activity concentration of 18F-GE-180 in arterial plasma in a blood sample drawn at 27.5 min or by the individual administered tracer activity, respectively. The total 18F-GE-180 distribution volume (VT) was estimated in 12 regions-of-interest (ROIs) by the invasive Logan plot using the measured or the population-based input functions. Late ROI-to-whole-blood and ROI-to-cerebellum ratio were also computed. Results Correlation with the reference VT (with individually measured input function) was very high for VT with the population-based input function scaled with the blood sample and for the ROI-to-whole-blood ratio (Pearson correlation coefficient = 0.989 ± 0.006 and 0.970 ± 0.005). The correlation was only moderate for VT with the population-based input function scaled with tracer activity dose and for the ROI-to-cerebellum ratio (0.653 ± 0.074 and 0.384 ± 0.177). Reference VT, population-based VT with scaling by the blood sample, and ROI-to-whole-blood ratio were sensitive to the TSPO gene polymorphism. Population-based VT with scaling to the administered tracer activity and the ROI-to-cerebellum ratio failed to detect a polymorphism effect. Conclusion These results support the use of a population-based input function scaled with a single blood sample or the ROI-to-whole-blood ratio at a late time point for simplified quantitative analysis of 18F-GE-180 PET.

The value of interim 18F-FDG PET/CT (iPET)-guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the change-in-SUV max (DSUV max) approach-2 methods to assess early metabolic response to standard chemotherapy in DLBCL. Methods: Of 609 DLBCL patients participating in the PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas trial, iPET scans of 596 patients originally evaluated using the DSUV max method were available for post hoc assessment of the Deauville score. A commonly used definition of an unfavorable iPET result according to the Deauville score is an uptake greater than that of the liver, whereas an unfavorable iPET scan with regard to the ΔSUV max approach is characterized as a relative reduction of the SUV max between baseline and iPET staging of less than or equal to 66%. We investigated the 2 methods' correlation and concordance by Spearman rank correlation coefficient and the agreement in classification, respectively. We further used Kaplan-Meier curves and Cox regression to assess differences in survival between patient subgroups defined by the prespecified cutoffs. Time-dependent receiver-operating-characteristic curve analysis provided information on the methods' respective discrimination performance. Results: Deauville score and DSUV max approach differed in their iPET-based prognosis. The ΔSUV max approach outperformed the Deauville score in terms of discrimination performance-most likely because of a high number of false-positive decisions by the Deauville score. Cutoff-independent discrimination performance remained low for both methods, but cutoff-related analyses showed promising results. Both favored the ΔSUV max approach, for example, for the segregation by iPET response, where the event-free survival hazard ratio was 3.14 (95% confidence interval, 2.22-4.46) for ΔSUV max and 1.70 (95% confidence interval, 1.29-2.24) for the Deauville score. Conclusion: When considering treatment intensification, the currently used Deauville score cutoff of an uptake above that of the liver seems to be inappropriate and associated with potential harm for DLBCL patients. The ΔSUV max criterion of a relative reduction in SUV max of less than or equal to 66% should be considered as an alternative.

Background: In the multimodal breast-conserving curative therapy of some high-risk breast cancer patients, extended external beam radiotherapy (EBRT) not only to the breast but also to the supraclavicular fossa and the internal mammary chain (parasternal region (PSR)) is indicated. We report a dosimetric study on the EBRT of the breast (“B”) and the breast including PSR (“B + PSR”), comparing the supine and the laterally tilted prone patient positions in free breathing. Methods: The planning CT scans of 20 left- and 20 right-sided patients were analyzed. EBRT plans were calculated with 3D conformal EBRT (3D) and with intensity-modulated EBRT (IMRT) for “B” and “B + PSR” in the prone and supine positions. The mean and threshold doses were computed. The quality of EBRT plans was compared with an overall plan assessment factor (OPAF), comprising three subfactors, homogeneity, conformity, and radiogenic exposure of OAR. Results: In the EBRT of “B”, prone positioning significantly reduced the exposure of the OARs “heart” and “ipsilateral lung” and “lymphatic regions”. The OPAF was significantly better in the prone position, regardless of the planning technique or the treated breast side. In the EBRT of “B + PSR”, supine positioning significantly reduced the OAR “heart” exposure but increased the dose to the OARs “ipsilateral lung” and “lymphatic regions”. There were no significant differences for the OPAF, independent of the irradiated breast side. Only the IMRT planning technique increased the chance of a comparatively good EBRT plan. Conclusion: Free breathing prone positioning significantly improves plan quality in the EBRT of the breast but not in the EBRT of the breast + PSR.

The exposure of a pregnant woman to X-rays is an event that can cause uncertainty for all concerned. This review provides guidance on how to assess such a situation and how to determine the dose to the unborn child. In general, the use of X-rays in pregnant women in radiology should be avoided. If possible, alternatives should be used, or examinations postponed to a time after the pregnancy. This review gives a summary of the procedure for determining the radiation exposure of a pregnant woman. Based on the previous report of 2002 and the literature on prenatal radiation exposure published thereafter, the DGMP/DRG report on the procedure for the assessment of prenatal radiation exposure was adapted to the current state of science and technology. Typically, only relatively low radiation exposures of less than 20 mSv occur for the unborn child in X-ray diagnostics in the vast majority of cases. At these dose level the additional risk of damage to the embryo or fetus caused by the radiation is low and therefore only a rough conservative estimate using tabulated values are made. Only in a few types of examination (CT and interventional radiology) higher doses values might occur in the uterus. Instead of dose estimates (step 1 in the two-step model) in these cases the calculation of dose (step 2) are required and further action by the physician may be necessary. During the assessment, it is useful to initially use simple conservative estimation procedures to quickly determine whether a case falls into this large group less than 20 mSv, where there is a very low risk to the unborn child. If this is the case, the pregnant woman should be informed immediately by the doctor who performed the examination/treatment. This avoids a psychological burden on the patient. The DGMP/DRG report suggests a relatively simple, clearly structured procedure with advantages for all parties involved (physician, medical physics experts, MTRA and patient). · The DGMP/DRG report on prenatal radiation exposure describes the procedure for calculating radiation exposures and the associated risks for the unborn child.. · Using the two-step model, only a simple assessment based on the first step is necessary for most prenatal radiation exposures.. · With the given tables it is possible to estimate individual risks for the unborn child taking into account the radiation exposure.. · Only in the rare case that the first estimate results in a uterine dose larger 20 mSv a more accurate calculation is necessary..· Fiebich M, Block A, Borowski M et al. Prenatal radiation exposure in diagnostic and interventional radiology. Fortschr Röntgenstr 2021; 193: 778 - 786. Die Exposition einer Schwangeren mit Röntgenstrahlung ist ein Ereignis, das bei allen Beteiligten Unsicherheit hervorrufen kann. Diese Übersichtsarbeit gibt Hinweise, wie eine derartige Situation zu bewerten ist und wie die Dosis für das ungeborene Kind ermittelt werden kann. Generell gilt, dass die Anwendung von Röntgenstrahlung bei Schwangeren in der Radiologie möglichst vermieden, Alternativen genutzt oder die Anwendung auf einen Zeitpunkt nach der Schwangerschaft verschoben werden sollen. Diese Übersichtsarbeit gibt eine Zusammenfassung der Vorgehensweise zur Bestimmung der Strahlenexposition einer Schwangeren. Auf Basis des Vorgängerberichts von 2002 und der danach publizierten Literatur zur pränatalen Strahlenexposition wurde der DGMP/DRG-Bericht zur Vorgehensweise bei der Bewertung der pränatalen Strahlenexposition dem Stand von Wissenschaft und Technik angepasst. Typischerweise treten in der Röntgendiagnostik in den überwiegend meisten Fällen nur relativ geringe Strahlenexpositionen kleiner als 20 mSv für das Ungeborene auf. Bei diesen Dosen ist das durch die Strahlung erzeugte zusätzliche Risiko für eine Schädigung des Embryos bzw. des Fötus gering und daher erfolgt hier nur eine grobe konservative Abschätzung nach Tabellenwerten. Nur bei wenigen Untersuchungsarten (CT oder interventionelle Radiologie) können höhere Werte der Uterusdosis erreicht werden. Statt der Dosisabschätzungen (Stufe 1 im 2-Stufen-Modell) sind in diesen Fällen Berechnungen (Stufe 2) zur Bestimmung der Dosis erforderlich und ggf. auch weitergehende Handlungen der Ärztin/des Arztes notwendig. Es ist sinnvoll, bei der Bewertung zunächst mit einfachen konservativen Abschätzverfahren schnell festzustellen, ob ein Fall in diese große Gruppe kleiner als 20 mSv fällt, bei der eine sehr geringe Gefährdung des Embryos oder Fötus vorliegt. Ist dies der Fall, so soll die Schwangere von der Ärztin/dem Arzt, die/der die Untersuchung/Behandlung durchgeführt hat, sogleich davon unterrichtet werden. Dies vermeidet eine psychologische Belastung der Patientin. Der DGMP/DRG-Bericht schlägt ein relativ einfaches, klar strukturiertes Vorgehen vor, mit entsprechenden Vorteilen für alle Beteiligten (Arzt, Medizinphysik-Experten, MTRA und Patient). · Der DGMP/DRG-Bericht zur pränatalen Strahlenexposition beschreibt die Vorgehensweise bei der Berechnung der Strahlenexpositionen und der damit verbundenen Risiken für das Ungeborene.. · Dem 2-Stufen-Modell folgend ist für die meisten pränatalen Strahlenexpositionen nur eine einfache Abschätzung nach der ersten Stufe notwendig.. · Anhand von Tabellenwerten ist eine Abschätzung einzelner Risiken für das Ungeborene unter Berücksichtigung der Strahlenexposition möglich.. · Nur im seltenen Fall, dass die erste Abschätzung eine Uterusdosis größer als 20 mSv ergibt, ist eine genauere Berechnung notwendig..· Fiebich M, Block A, Borowski M et al. Prenatal radiation exposure in diagnostic and interventional radiology. Fortschr Röntgenstr 2021; 193: 778 – 786.

Cochlear implantation constitutes a successful therapy of inner ear deafness, with the majority of patients showing good outcomes. There is, however, still some unexplained variability in outcomes with a number of cochlear-implant (CI) users, showing major limitations in speech comprehension. The current study used a multimodal diagnostic approach combining single-photon emission computed tomography (SPECT) and electroencephalography (EEG) to examine the mechanisms underlying speech processing in postlingually deafened CI users (N = 21). In one session, the participants performed a speech discrimination task, during which a 96-channel EEG was recorded and the perfusions marker 99mTc-HMPAO was injected intravenously. The SPECT scan was acquired 1.5 h after injection to measure the cortical activity during the speech task. The second session included a SPECT scan after injection without stimulation at rest. Analysis of EEG and SPECT data showed N400 and P600 event-related potentials (ERPs) particularly evoked by semantic violations in the sentences, and enhanced perfusion in a temporo-frontal network during task compared to rest, involving the auditory cortex bilaterally and Broca’s area. Moreover, higher performance in testing for word recognition and verbal intelligence strongly correlated to the activation in this network during the speech task. However, comparing CI users with lower and higher speech intelligibility [median split with cutoff + 7.6 dB signal-to-noise ratio (SNR) in the Göttinger sentence test] revealed for CI users with higher performance additional activations of parietal and occipital regions and for those with lower performance stronger activation of superior frontal areas. Furthermore, SPECT activity was tightly coupled with EEG and cognitive abilities, as indicated by correlations between (1) cortical activation and the amplitudes in EEG, N400 (temporal and occipital areas)/P600 (parietal and occipital areas) and (2) between cortical activation in left-sided temporal and bilateral occipital/parietal areas and working memory capacity. These results suggest the recruitment of a temporo-frontal network in CI users during speech processing and a close connection between ERP effects and cortical activation in CI users. The observed differences in speech-evoked cortical activation patterns for CI users with higher and lower speech intelligibility suggest distinct processing strategies during speech rehabilitation with CI.

While the importance of the serotonergic system in obsessive compulsive disorder (OCD) is well established, its role in Tourette syndrome (TS) is uncertain. Particularly in TS patients with comorbid OCD (TS + OCD), decreased serotonin transporter (SERT) binding has been suggested. Here, we investigated for the first time SERT binding in TS patients with and without OCD (TS - OCD) compared to both healthy controls (HC) and OCD patients as well as the influence of escitalopram using the potent SERT imaging ligand [

ZusammenfassungFür die Behandlung von Patienten mit symptomatischen Knochenmetastasen bei kastrationsresistentem Prostatakarzinom (mCPRC) ohne bekannte viszerale Metastasen wird ein Medikament mit dem Wirkstoff 223Ra-Dichlorid eingesetzt. Diese Therapie stellt den derzeit einzigen Einsatz eines Alphastrahlers in der klinischen Routinetherapie dar. Dieser Artikel geht auf die Durchführung der 223Ra-Dichlorid-Therapie nebst Dosimetrie ein und beschreibt Anforderungen an den Strahlenschutz, die sich bei der Anwendung von 223Ra-Dichlorid ergeben.

Background 15O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of 15O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered. Results It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p

Ga-68-labeled radiotracers, particularly used for the detection of neuroendocrine tumors by means of Ga-68-DOTA-TATE or -DOTA-TOC or for the diagnosis of prostate cancer by means of Ga-68-labeled antigens (Ga 68-PSMA), become increasingly important. In addition to the high sensitivity and specificity of these radiopharmaceuticals, the short-lived radionuclide Ga-68 offers almost ideal nuclear characteristics for use in PET. Ga-68 is obtained from a germanium-gallium-generator system, so that the availability of Ga-68-labeled radiotracers is independent of an on-site-cyclotron regardless of the short half-life of Ga-68 of about 68minutes. Regarding the disposal of the radioactively contaminated waste from the preparation of the radiopharmaceutical, the eluted Ga-68 has to be considered to be additionally contaminated with its parent nuclide Ge-68. Due to this production-related impurity in combination with the short half-life of Ga-68, the radioactive waste has to be considered to be contaminated with Ge-68 and Ga-68 in radioactive equilibrium (hereafter referred to as Ge-68+). As there are no clearance levels for Ge-68+ given in the German Radiation Protection Ordinance, this work presents a method to calculate the missing value basing on a recommendation of the German Radiation Protection Commission in combination with simple geometric models of practical radiation protection. Regarding the relevant exposure scenarios, a limit value for the unrestricted clearance of Ge-68+ of 0.4 Bq/g was determined.

According to recent studies, the human eye lens is more sensitive to ionising radiation than previously assumed. Therefore, the dose limit for personnel occupationally exposed to ionising radiation will be lowered from currently 150 mSv to 20 mSv per year. Currently, no data base for a reliable estimation of the dose to the lens of the eye is available for nuclear medicine. Furthermore, the dose is usually not monitored. The aim of this work was to determine dose rate constants for the quantity Hp(3), which is supposed to estimate the dose to the lens of the eye. For this, Hp(3)-dosemeters were fixed to an Alderson Phantom at different positions. The dosemeters were exposed to radiation from nuclides typically used in nuclear medicine in their geometries analog to their application in nuclear medicine, e.g. syringe or vial. The results show that the handling of high-energy beta (i.e. electron or positron) emitters may lead to a relevant dose to the lens of the eye. For low-energy beta emitters and gamma emitters, an exceeding of the lowered dose limit seems to be unlikely.

ZusammenfassungDas Aktivimeter ist eines der wichtigsten und am häufigsten eingesetzten Messinstrumente zur Bestimmung der Aktivität in der Nuklearmedizin. Um eine gleichbleibende Qualität der Aktivitätsmessungen zu gewährleisten, ist unter anderem die Konstanzprüfung der Systemlinearität in regelmäßigen Abständen durchzuführen, typischerweise gemessen mit 99mTc. Das aus einem 99Mo/99mTc-Generator gewonnene 99mTc-Eluat enthält eine Molybdän-Verunreinigung. Wird der Molybdän-Verunreinigungsanteil nicht berücksichtigt, so kann die für die Konstanzprüfung erlaubte Toleranzgrenze der Abweichung zum Referenzwert von maximal 5% trotz fehlerfreier Messfunktion des Aktivimeters überschritten werden. Wesentliche Ursachen für diese Verunreinigung sind neben dem reinen Verunreinigungsanteil auch dessen relativer Anstieg in Abhängigkeit von der Gesamtdauer der Messung (hohe Startaktivitäten). Ergebnis: Im Rahmen dieser Arbeit wurde der Einfluss der Molybdän-Verunreinigung auf die Ergebnisse der Konstanzprüfung zur Systemlinearität untersucht und für bestimmte Verunreinigungen die maximalen Startaktivitäten ermittelt, bei denen die systematischen Abweichungen in der Systemlinearität im Rahmen der Konstanzprüfung unter 5% liegen. Schlussfolgerung: Sofern bestimmte Randbedingungen eingehalten werden, kann bei der Auswertung auf eine Korrektur bezüglich der Molybdänverunreinigung verzichtet werden.

ZusammenfassungDiese Handlungsempfehlung soll eine Grundlage für die Qualitätssicherung der Radionuklidtherapie von Knochenmetastasen mit Radium-223 schaffen. Sie wurde interdisziplinär erarbeitet und beschreibt die allgemeine Zielsetzung, Definitionen und klinischen Hintergrundinformationen sowie Indikationen und Kontraindikationen dieser Radionuklidtherapie. Ausgeführt werden die Anforderungen, die an ein Behandlungszentrum gestellt werden, prätherapeutisch notwendige Untersuchungsbefunde sowie Empfehlungen, wie die Behandlung technisch und organisatorisch durchgeführt werden sollte. Ferner finden sich Angaben zur Kontrolle und Nachsorge der therapierten Patienten. Grundsätzlich sollen Behandlung und Nachsorge in Abstimmung und Zusammenarbeit der beteiligten Fachdisziplinen erfolgen.

The alpha-emitting radionuclide Ra-223 is used in nuclear medicine in form of the commercially available radiopharmaceutical "Xofigo". The direct progeny of Ra-223 is Rn-219, a noble gas with a half-life of approx. four seconds, that might be exhaled by patients treated with Ra-223. For assessing the exhalation of Rn-219, a radon monitor calibrated for this isotope is necessary. This work investigates on the response of the commercially available Alphaguard radon monitor to Rn-219 and proposes for the first time a factor for the calculation of the Rn-219-concentration in the instrument's measurement chamber from the instrument reading suitable for estimating patients exhalations.

Background 15O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of 15O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered. Results It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p

Purpose Interim positron emission tomography (PET) using the tracer, [18F]fluorodeoxyglucose, may predict outcomes in patients with aggressive non-Hodgkin lymphomas. We assessed whether PET can guide therapy in patients who are treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). Patients and Methods Newly diagnosed patients received two cycles of CHOP—plus rituximab (R-CHOP) in CD20-positive lymphomas—followed by a PET scan that was evaluated using the ΔSUVmax method. PET-positive patients were randomly assigned to receive six additional cycles of R-CHOP or six blocks of an intensive Burkitt’s lymphoma protocol. PET-negative patients with CD20-positive lymphomas were randomly assigned or allocated to receive four additional cycles of R-CHOP or the same treatment with two additional doses rituximab. The primary end point was event-free survival time as assessed by log-rank test. Results Interim PET was positive in 108 (12.5%) and negative in 754 (87.5%) of 862 patients treated, with statistically significant differences in event-free survival and overall survival. Among PET-positive patients, 52 were randomly assigned to R-CHOP and 56 to the Burkitt protocol, with 2-year event-free survival rates of 42.0% (95% CI, 28.2% to 55.2%) and 31.6% (95% CI, 19.3% to 44.6%), respectively (hazard ratio, 1.501 [95% CI, 0.896 to 2.514]; P = .1229). The Burkitt protocol produced significantly more toxicity. Of 754 PET-negative patients, 255 underwent random assignment (129 to R-CHOP and 126 to R-CHOP with additional rituximab). Event-free survival rates were 76.4% (95% CI, 68.0% to 82.8%) and 73.5% (95% CI, 64.8% to 80.4%), respectively (hazard ratio, 1.048 [95% CI, 0.684 to 1.606]; P = .8305). Outcome prediction by PET was independent of the International Prognostic Index. Results in diffuse large B-cell lymphoma were similar to those in the total group. Conclusion Interim PET predicted survival in patients with aggressive lymphomas treated with R-CHOP. PET-based treatment intensification did not improve outcome.

The chemokine receptor CXCR4 is a promising target for molecular imaging of CXCR4+ cell types, e.g. inflammatory cells, in cardiovascular diseases. We speculated that a specific CXCR4 ligand, [68Ga]pentixafor, along with novel techniques for motion correction, would facilitate the in vivo characterization of CXCR4 expression in small culprit and nonculprit coronary atherosclerotic lesions after acute myocardial infarction by motion-corrected targeted PET/CT. CXCR4 expression was analysed ex vivo in separately obtained arterial wall specimens. [68Ga]Pentixafor PET/CT was performed in 37 patients after stent-based reperfusion for a first acute ST-segment elevation myocardial infarction. List-mode PET data were reconstructed to five different datasets using cardiac and/or respiratory gating. Guided by CT for localization, the PET signals of culprit and various groups of nonculprit coronary lesions were analysed and compared. Ex vivo, CXCR4 was upregulated in atherosclerotic lesions, and mainly colocalized with CD68+ inflammatory cells. In vivo, elevated CXCR4 expression was detected in culprit and nonculprit lesions, and the strongest CXCR4 PET signal (median SUVmax 1.96; interquartile range, IQR, 1.55–2.31) was observed in culprit coronary artery lesions. Stented nonculprit lesions (median SUVmax 1.45, IQR 1.23–1.88; P = 0.048) and hot spots in naive remote coronary segments (median SUVmax 1.34, IQR 1.23–1.74; P = 0.0005) showed significantly lower levels of CXCR4 expression. Dual cardiac/respiratory gating provided the strongest CXCR4 PET signal and the highest lesion detectability. We demonstrated the basic feasibility of motion-corrected targeted PET/CT imaging of CXCR4 expression in coronary artery lesions, which was triggered by vessel wall inflammation but also by stent-induced injury. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of coronary atherosclerotic plaque.

PURPOSE The aims of this study were to gain mechanistic insights into prostate cancer biology using dynamic imaging and to evaluate the usefulness of multiple time-point Ga-prostate-specific membrane antigen (PSMA) I&T PET/CT for the assessment of primary prostate cancer before prostatectomy. METHODS Twenty patients with prostate cancer underwent Ga-PSMA I&T PET/CT before prostatectomy. The PET protocol consisted of early dynamic pelvic imaging, followed by static scans at 60 and 180 minutes postinjection (p.i.). SUVs, time-activity curves, quantitative analysis based on a 2-tissue compartment model, Patlak analysis, histopathology, and Gleason grading were compared between prostate cancer and benign prostate gland. RESULTS Primary tumors were identified on both early dynamic and delayed imaging in 95% of patients. Tracer uptake was significantly higher in prostate cancer compared with benign prostate tissue at any time point (P ≤ 0.0003) and increased over time. Consequently, the tumor-to-nontumor ratio within the prostate gland improved over time (2.8 at 10 minutes vs 17.1 at 180 minutes p.i.). Tracer uptake at both 60 and 180 minutes p.i. was significantly higher in patients with higher Gleason scores (P < 0.01). The influx rate (Ki) was higher in prostate cancer than in reference prostate gland (0.055 [r = 0.998] vs 0.017 [r = 0.996]). CONCLUSIONS Primary prostate cancer is readily identified on early dynamic and static delayed Ga-PSMA ligand PET images. The tumor-to-nontumor ratio in the prostate gland improves over time, supporting a role of delayed imaging for optimal visualization of prostate cancer.

The bone scan index (BSI) was introduced as a quantitative tool for tumor involvement in bone of patients with metastatic prostate cancer (mPCa). The computer-aided diagnosis device for BSI analysis EXINIboneBSI seems to represent technical progress for the quantitative assessment of bone involvement. But it is not yet clear if the automated BSI (aBSI) could contribute to improved evaluation of progression in patients under antiandrogens or chemotherapy in contrast to the visual interpretation and/or conventional biomarkers such as the prostate-specific antigen (PSA). In 49 mPCa patients, bone scans were performed initially and during different therapy courses. Scans were evaluated visually and by the artificial-neural-network-based expert system EXINIboneBSI. Progression of metastatic bone involvement was defined according to the Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria in the visual interpretation. The computer-assisted interpretation was based on different cutoff values in relative changes of the aBSI. Additionally, assessments according to bone scanning were compared to changes in the PSA value as a potential surrogate for treatment response. Using a sensitive cutoff value (5% or 10%) for the relative aBSI increase led to significantly increased progression determination compared to the visual interpretation of bone scans (49% and 43% vs. 27%, p

Clearance monitor systems are used for gross gamma measurements of waste potentially contaminated with radioactivity. These measurements are to make sure that legal requirements, e.g. clearance criteria according to the german radiation protection ordinance, are met. This means that measurement results may overestimate, but must not underestimate the true values. This paper describes a pragmatic way using a calibrated Cs-137 point source to generate a conservative calibration for the clearance monitor system used in the Medizinische Hochschule Hannover (MHH). The most important nuclides used in nuclear medicine are considered. The measurement result reliably overestimates the true value of the activity present in the waste. The calibration is compliant with the demands for conservativity and traceability to national standards.

In this study, alterations in brain perfusion have been investigated in patients with Tourette syndrome (TS) compared with control subjects. In addition, we investigated the effects of deep brain stimulation (DBS) in both globus pallidus internus (GPi) and centromedian-parafascicular/ventralis oralis internus nuclei of the thalamus (CM/Voi) and sham (SHAM) stimulation on cerebral blood flow. In a prospective controlled, randomized, double-blind setting, five severely affected adult patients with TS with predominant motor or vocal tics (mean total tic score on the Yale Global Tic Severity Scale: 39) underwent serial brain perfusion single photon emission computed tomography with (99m)Tc-ECD. Results were compared with data from six age-matched control subjects. All patients were investigated at four different time points: once before DBS implantation (preOP) and three times postoperatively. Postoperative scans were performed in a randomized order, each after 3 months of either GPi, CM/Voi, or SHAM stimulation. At each investigation, patients were injected at rest while awake, but scanned during anesthesia. This procedure ensured that neither anesthesia nor movement artifacts influenced our results. Control subjects were investigated only once at baseline (without DBS or anesthesia). At baseline, cerebral blood flow was significantly reduced in patients with TS (preOP) compared with controls in the central region, frontal, and parietal lobe, specifically in Brodmann areas 1, 4-9, 30, 31, and 40. Significantly increased perfusion was found in the cerebellum. When comparing SHAM stimulation to preOP condition, we found significantly decreased perfusion in basal ganglia and thalamus, but increased perfusion in different parts of the frontal cortex. Compared with SHAM condition both GPi and thalamic stimulation resulted in a significant decrease in cerebral blood flow in basal ganglia and cerebellum, while perfusion in the frontal cortex was significantly increased. Our results provide substantial evidence that, in TS, brain perfusion is altered in the frontal cortex and the cerebellum and that these changes can be reversed by both GPi and CM/Voi DBS.

This document describes the guideline for therapy of bone metastases with radium-223 ((223)Ra) published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften in Germany (AWMF) under the auspices of the Deutsche Gesellschaft für Nuklearmedizin (DGN), Östereichische Gesellschaft für Nuklearmedizin (OGN), and Schweizerische Gesellschaft für Nuklearmedizin (SGNM). This guidance is based on an interdisciplinary consensus. These recommendations are a prerequisite for the quality management in the treatment of patients with bone metastases from prostate cancer using (223)Ra. They are aimed at guiding nuclear medicine specialists in selecting candidates to receive therapy and to deliver the treatment in a safe and effective manner. The document contains background information and definitions. It covers the rationale, indications and contraindications for therapy with (223)Ra. Essential topics are the requirements for institutions performing the therapy, which patient data have to be available prior to performance of therapy, and how treatment has to be carried out technically and organisationally. Moreover, essential elements of follow-up and aftercare are specified. As a matter of principle, the treatment inclusive aftercare has to be realised in close cooperation with the involved medical disciplines.

Der diagnostische Mehrwert durch Kombination von funktioneller und anatomischer Bildgebung ist aus der klinischen Routine nicht mehr wegzudenken. Gleichzeitig sind fur Hybridgerate die organisatorischen und technischen Strahlenschutzaspekte fur die jeweiligen Komponenten in Einklang zu bringen. Im Rahmen der Qualitatskontrolle solcher Hy­bridgerate bilden neben den Anforderungen an die einzelnen Komponenten insbesondere die Genauigkeit der Koregistrierung und die Gute der Skalierung der Absorptionskoeffizienten die zusatzlich zu prufenden Schnittstellen. Fur PET/CT-Systeme sind der Umfang der Konstanzprufungen und deren zeitliche Frequenzen nun erstmals im Entwurf der DIN 6858-1 festgelegt worden. Insbesondere fur die Neuerrichtung von Raumlichkeiten zur Hybridbildgebung ergeben sich aus der Novellierung der Richtlinie ‚Strahlenschutz in der Medizin‘ wachsende Anforderungen an den baulichen Strahlenschutz. Aus erweiterten Anwendungen erwachst zusatzlich ein erhohter Bedarf an spezialisiertem Zubehor – beispielsweise Lagerungshilfen und Lasersysteme zur PET/CT-gestutzten Strahlentherapieplanung. Wird eine separate Nutzung beider beteiligten Komponenten in Betracht gezogen, ist aufgrund der strahlenschutzrechtlichen Anforderungen – z. B. der vorherigen Freigabe der Raumlichkeiten – ein fundiertes Organisationskonzept erforderlich.

Zusammenfassung Die intraarterielle Selektive Interne Radiotherapie (SIRT) mit 90 Y-markierten Mikrospharen ist mittlerweile eine wichtige lokal-ablative Therapieoption fur die Behandlung onkologischer Patienten geworden. Die SIRT stellt gegenwartig einen palliativen Therapieansatz fur die Behandlung von Lebermalignomen dar. Infolge der Art des 90 Y-Zerfalls als β - -Strahler ohne eine begleitende Gammaemission, bedarf es zur Validierung der erzielten Verteilung des Radioembolisates einer Bremsstrahlungsbildgebung. Dieser Artikel demonstriert durch eine Phantommessung diese Art der Bildgebung und zeigt anhand einer Patientenstudie die Vorteile einer posttherapeutischen Schnittbildgebung. Es werden Ansatzpunkte fur weitere Optimierungen der Bremsstrahlungsbildgebung aufgezeigt.

The aim of the study was to estimate the external radiation exposure emitted by the patient to his surroundings after discharge. Being in compliance with legal requirements is especially important when doing multiple therapies. To estimate the effective half-life to be used quite realistically, the individual effective half-lives for 41 patients with 52 therapies were calculated. From the resulting histogram the maximum value was determined to be 100 h. Substituting the physical half-life by this maximum effective half-life results in dose estimates, which are lower but still conservative. In addition, the analysis of dose related parameters for patients who underwent multiple therapies demonstrates that the parameters estimated for the first therapy cannot be transferred to the subsequent ones.

Zusammenfassung PET-Untersuchungen werden heute fast ausschlieslich mit PET/CT-Hybridsystemen durchgefuhrt. Wahrend Abnahme- und Konstanzprufung fur die Einzelkomponenten PET bzw. CT durch entsprechende Vorschriften geregelt sind, fehlen Regelungen fur die Schnittstelle der Hybridgerate. Diese Schnittstelle beinhaltet die Justage beider Gantries und der Liege zueinander sowie die Energieskalierung von Absorptionskoeffizienten von der CT-Energie auf 511 keV. Bis jetzt werden Kontrollmessungen bezuglich der mechanischen Justage (Bestimmungen von Offset-Parametern) nach den Empfehlungen des Herstellers durchgefuhrt typischerweise halbjahrlich. An einem Biograph 16 (Fa. Siemens) wurde die Stabilitat dieser Offsetbestimmungen systematisch durch wochentliche Messungen uber einen Beobachtungszeitraum von zehn Monaten untersucht, erganzt durch Messungen mit einer zusatzlichen Belastung der Liege bis zu 135 kg und bei verschiedenen vertikalen Liegenpositionen. Nach den vorliegenden Ergebnissen beim getesteten Geratetyp kann von uber die Herstellerempfehlung hinausgehenden Konstanzprufungen des Offsets abgesehen werden. Auch die Energieskalierung der Absorptionskoeffizienten ist abhangig von Methodik und Softwareimplementierung und somit nicht Gegenstand der Konstanzprufung. Notwendig hingegen ist die Entwicklung geeigneter Methoden der Abnahmeprufung, sowohl zur Erfassung und Feststellung aller Freiheitsgrade der mechanischen Justage als auch zur Ermittlung der Gute der Absorptionskorrektur der Emissionsdaten.

SummaryIn nuclear medicine therapy the treatment of tumours by radiation exposure from internally deposited labelled antibodies or labelled peptides is currently an active field of investigation. To permit the efficient delivery of high amounts of radiation dose to tumours while limiting the radiation dose to critical organs dosimetry calculations have to be performed. These are relying on scintigraphic data being input to the well known MIRD formalism.This paper focuses on the methods and the difficulties associated with the scintigraphic determination of organ kinetics. The physical properties of the well-known scintigraphic imaging modalities, PET, SPECT and planar scintigraphy, are discussed thereby taking into account the properties of the appropriate radionuclides currently being available for therapy and dosimetry. Several arguments are given and disputed for the limited clinical use of PET and SPECT in dosimetry and the ongoing preference of planar whole-body imaging as the method of choice. The quantitative restrictions still inherent to this method are also discussed in detail. Procedural recommendations are proposed covering all processes related to data acquisition, data correction and data analysis which finally lead to reliable estimations of organ dose.

Since meningiomas show a high expression of somatostatin receptor subtype 2, PET with (68)Ga-DOTATOC was proposed as an additional imaging modality beside CT and MRI for planning radiotherapy. We investigated the input of (68)Ga-DOTATOC-PET/CT on the definition of the "gross tumour volume" (GTV) in meningiomas, in order to assess the potential value of this method.Prior to radiotherapy, 42 patients with meningiomas (26 f, 16 m, mean age 55) underwent MRI and (68)Ga-DOTATOC-PET/CT examinations.operated n = 24, radiotherapy n = 1, operation and radiotherapy n = 8, no treatment n = 9. PET/CT and MRI data were co-registered using a BrainLAB workstation. For comparison, the GTV was defined first under consideration of CT and MRI data, then using PET data.3/42 patients were excluded from the analysis (two with negative PET results, one with an extensive tumour, not precisely delineable by MRI or PET/CT). The average GTV(CT/MRI) was 22(+/-19)cm(3); GTV(PET) was 23(+/-20)cm(3). Additional GTV, obtained as a result of PET was 9(+/-10)cm(3) and was observed in patients with osseous infiltration. In some pre-treated patients there were intratumoural areas (as identified in CT/MRI) without SR-expression (7(+/-11)cm(3)). Common GTV as obtained by both CT/MRI and PET was 15(+/-14)cm(3). The mean bi-directional difference between the GTV(CT/MRI) and GTV(PET) accounted to 16(+/-15)cm(3) (93%, p0.001). In a subgroup of seven patients with multiple meningiomas, PET showed a total of 19 lesions; nine of them were not recognizable by CT or MRI.(68)Ga-DOTATOC-PET enables delineation of SR-positive meningiomas and delivers additional information to both CT and MRI regarding the planning of stereotactic radiotherapy. The acquisition on a PET/CT scanner helps to estimate the relation of PET findings to anatomical structures and is especially useful for detection of osseous infiltration. (68)Ga-DOTATOC-PET also allows detection of additional lesions in patients with multiple meningiomas.

Radioimmunotherapies (RITs) and peptide receptor radiotherapies (PRRTs) with (90)Y-labelled compounds offer promising prospects for tumor treatment in nuclear medicine. However, when preparing and performing these therapies, which require manipulations of high activities of (90)Y (>1 GBq), technicians and physicians may receive high exposures, mainly to the skin of the hands. Even non-occupationally exposed persons, such as caregivers and family members, receive external exposures in the initial period after therapy, arising from the (90)Y in the patient. The local skin doses of the individual staff members, measured during RITs and PRRTs with thermoluminescence detectors fixed with tapes to the fingers, vary considerably. The exposure of staff can exceed the annual permissible dose limit of 500 mSv if radiation protection standards are low. Thus, adequate safety measures are needed. Measurements of the dose rate around patients, made using survey meters with sufficient response to beta particles, indicate that the exposure of caregivers and family members is considerably higher than previously assumed, and was dominated by primary beta radiation instead of bremsstrahlung. Nevertheless, under normal circumstances, the annual dose limits for the public (effective dose: 1 mSv, skin dose: 50 mSv) will be complied with.

Aims High-energy resolution and sensitivity of novel cadmium-zinc-telluride (CZT) detector equipped SPECT systems facilitate simultaneous imaging of multiple isotopes and may enhance the detection of molecular/cellular signals. This may refine the detection of endocarditis. This study was designed to determine the feasibility and diagnostic accuracy of simultaneous imaging of inflammation with 111In-labeled white blood cells (WBCs) and myocardial perfusion with 99mTc-sestamibi, for localization of WBCs relative to the valve plane in suspected endocarditis. Methods and results A dedicated cardiac CZT camera (Discovery 530c, GE Healthcare) was employed. Anthropomorphic thorax phantom studies were followed by clinical studies in 34 patients with suspected infection of native valves ( n = 12) or implants ( n = 22). Simultaneous 111In-WBC/99mTc perfusion imaging was performed, and compared with standard 111In-WBC planar scintigraphy and SPECT-CT. Phantom studies ruled out significant radioisotope crosstalk. Downscatter on 99mTc images was not observed for 111In activity as high as 2.5*99mTc activity. In patients, image quality was superior for CZT imaging vs. conventional SPECT-CT and planar scintigraphy ( P < 0.01). Cadmium-zinc-telluride dual isotope imaging improved reader confidence for detection of inflammatory foci. Diagnostic accuracy based on surgery or Duke Criteria during follow-up was highest for CZT imaging ( P < 0.001). Conclusion Novel CZT SPECT technology improves the accuracy of molecular/cellular cardiac imaging. Simultaneous multi-isotope imaging with 111In and 99mTc is feasible and aids in the workup of suspected endocarditis.

Dose calibrators are one of the most important and most frequently used instruments for the determination of activities in nuclear medicine. For guaranteeing a constant quality of the dose calibrators' measurements, constancy checks including the examination of the system linearity have to be performed regularly, usually measured using 99mTc. The 99mTc eluate extracted from a 99Mo/99mTc generator is contaminated with molybdenum. Not accounting for the molybdenum impurity might lead to an exceed of the tolerance limit of 5% deviation to the reference value for this constancy check. The reason for this effect is the contamination of the 99mTc eluate with 99Mo, whose impact depends on both the amount of the impurity and on the total measurement time (high start activities).In this work, the influence of the molybdenum impurity on the results of the constancy check of the system linearity was investigated and maximum start activities for certain impurities were determined providing that the deviation to the reference values is below 5%.Provided that certain boundary conditions are observed, a correction of the results with respect to the molybdenum contamination is not necessary.

Ga-68-labeled radiotracers, particularly used for the detection of neuroendocrine tumors by means of Ga-68-DOTA-TATE or -DOTA-TOC or for the diagnosis of prostate cancer by means of Ga-68-labeled antigens (Ga 68-PSMA), become increasingly important. In addition to the high sensitivity and specificity of these radiopharmaceuticals, the short-lived radionuclide Ga-68 offers almost ideal nuclear characteristics for use in PET. Ga-68 is obtained from a germanium-gallium-generator system, so that the availability of Ga-68-labeled radiotracers is independent of an on-site-cyclotron regardless of the short half-life of Ga-68 of about 68minutes. Regarding the disposal of the radioactively contaminated waste from the preparation of the radiopharmaceutical, the eluted Ga-68 has to be considered to be additionally contaminated with its parent nuclide Ge-68. Due to this production-related impurity in combination with the short half-life of Ga-68, the radioactive waste has to be considered to be contaminated with Ge-68 and Ga-68 in radioactive equilibrium (hereafter referred to as Ge-68+). As there are no clearance levels for Ge-68+ given in the German Radiation Protection Ordinance, this work presents a method to calculate the missing value basing on a recommendation of the German Radiation Protection Commission in combination with simple geometric models of practical radiation protection. Regarding the relevant exposure scenarios, a limit value for the unrestricted clearance of Ge-68+ of 0.4 Bq/g was determined.

According to recent studies, the human eye lens is more sensitive to ionising radiation than previously assumed. Therefore, the dose limit for personnel occupationally exposed to ionising radiation will be lowered from currently 150 mSv to 20 mSv per year. Currently, no data base for a reliable estimation of the dose to the lens of the eye is available for nuclear medicine. Furthermore, the dose is usually not monitored. The aim of this work was to determine dose rate constants for the quantity H

The human eye lens appears to be more radiosensitive than previously assumed. The reduction of the limit for the dose to the lens of the eye to 20 mSv per year has been passed in the current Euratom Directives (2013). Therefore, in this work the impact of laboratory glasses and X-ray protective goggles was investigated and reciprocal attenuation factors (i.e. transmission factors) for different nuclides (Tc-99m, I-131, Y-90, F-18 and Ga-68) were determined. The radionuclides in typical geometry (syringe, applicator) were positioned at a distance of 50 cm to the eyes of four Alderson-Head-Phantoms. Different dosemeters measuring H p (3) respective H p (0.07) were fixed to the eyes of the phantoms, either behind the glasses or without any protection means, respectively. The mean reciprocal attenuation factors were determined to be between unity for F-18 and I-131 using laboratory glasses (no attenuation effect) and

Considerable progress has been made in the treatment of hearing loss with auditory implants. However, there are still many implanted patients that experience hearing deficiencies, such as limited speech understanding or vanishing perception with continuous stimulation (i.e., abnormal loudness adaptation). The present study aims to identify specific patterns of cerebral cortex activity involved with such deficiencies. We performed O-15-water positron emission tomography (PET) in patients implanted with electrodes within the cochlea, brainstem, or midbrain to investigate the pattern of cortical activation in response to speech or continuous multi-tone stimuli directly inputted into the implant processor that then delivered electrical patterns through those electrodes. Statistical parametric mapping was performed on a single subject basis. Better speech understanding was correlated with a larger extent of bilateral auditory cortex activation. In contrast to speech, the continuous multi-tone stimulus elicited mainly unilateral auditory cortical activity in which greater loudness adaptation corresponded to weaker activation and even deactivation. Interestingly, greater loudness adaptation was correlated with stronger activity within the ventral prefrontal cortex, which could be up-regulated to suppress the irrelevant or aberrant signals into the auditory cortex. The ability to detect these specific cortical patterns and differences across patients and stimuli demonstrates the potential for using PET to diagnose auditory function or dysfunction in implant patients, which in turn could guide the development of appropriate stimulation strategies for improving hearing rehabilitation. Beyond hearing restoration, our study also reveals a potential role of the frontal cortex in suppressing irrelevant or aberrant activity within the auditory cortex, and thus may be relevant for understanding and treating tinnitus.

A sterile inflammation in the cavernous sinus was hypothesized to underlie cluster headache (CH). Neurogenic inflammation is accompanied by the extravasation of plasma proteins in the surrounding tissue. We tested the hypothesis of an inflammatory process in the cavernous sinus in CH patients using 99mTc-human serum albumin (HSA) and single photon emission computed tomography (SPECT). Six patients with episodic CH were enrolled. After baseline imaging, CH attacks were induced by IV injection of nitroglycerin. The patients remained untreated for 20 min. A second SPECT was performed after successful treatment. Region of interest (ROI) analysis was performed on the basis of coregistered MRI/SPECT data. There was no statistical difference between the 99mTc-HSA uptake in the ipsilateral cavernous sinus before and after induction of an acute CH attack. There was no evidence for 99mTc-HSA extravasation in the cavernous sinus during the active episode as compared with the remission phase. Our results do not support the hypothesis of an inflammation in the cavernous sinus.

Bei der Anwendung von 90Y-Zevalin im Rahmen der Radioimmuntherapie ist aus der Sicht des Strahlenschutzes sowohl die s - -Strahlung als auch die daraus resultierende Bremsstrahlung zu berucksichtigen. Ziel der Arbeit war die Ermittlung der Dosisleistung am Patienten, der Strahlenexposition der Angehorigen sowie die Bestimmung der Aktivitatskonzentration im Urin des Patienten. Weiterhin sollte die Hautdosis des Personals bei der Praparation und Applikation von 90Y-Zevalin ermittelt werden. Methode: Insgesamt wurden die Daten von 31 Therapien aus vier Einrichtungen ausgewertet. Bei der Praparation und Applikation wurde die Hautdosis an den Fingern des Chemikers/der MTA, und des Arztes ermittelt. Sofort nach Injektion wurde die durch den Patienten hervorgerufene Dosisleistung gemessen. Bei stationaren Therapien wurde die im Urin des Patienten ausgeschiedene Aktivitat bestimmt. Um die Strahlenexposition der Angehorigen bei ambulanten Therapien zu erfassen, wurden Dosimeter ausgehandigt und uber sieben Tage die Dosis ermittelt. Ergebnisse: Wahrend der Praparation und Applikation wurde die jeweils maximal auftretende Hautdosis bestimmt. Gemittelt uber die Zahl der Personen betrugen die so bestimmten Hautdosen bei der Praparation 6 mSv (n = 7), bei Applikation 3 mSv (n = 8). Die gemessene Dosisleistung lag 2 m vom Patienten entfernt bei 0,4±0,1 µSv/h. Nach 24 h post injectionem (p.i.) waren 3,9±1,4% und nach 48 h p.i. 4,4±1,4% der Aktivitat ausgeschieden, das entspricht 43±18 MBq bzw. 50±20 MBq 90Y. Die Dosis der Angehorigen der Patienten betrug 40±14 µSv. Schlussfolgerungen: Bei der Praparation und Applikation von 90Y-Zevalin sind geeignete Strahlenschutzmasnahmen erforderlich. Fur die Angehorigen des Patienten und das medizinische Pflegepersonal sind keine weitergehenden Strahlenschutzmasnahmen uber die sonst bei nuklearmedizinischen Untersuchungen/ambulanten Behandlungen ublichen hinaus notwendig.

Zusammenfassung Ziel dieser Arbeit war, Methoden auszuarbeiten, mit denen die Nuklidabhangigkeit einer Gamma-Kamera untersucht werden kann und damit zu klaren, ob fur jedes Nuklid, das bei Patientenaufnahmen mit SPECT (Single Photon Emission Computed Tomography) verwendet wird, eine eigene Homogenitatskorrekturmatrix erstellt werden muss. Zwei Verfahren zur Uberprufung der Nuklidabhangigkeit der Gamma-Kamera wurden erarbeitet. Um die Qualitat der Energiekorrektur der Detektoren zu prufen, wird beim ersten Verfahren die inharente Inhomogenitat bestimmt und es werden Aufnahmen mit asymmetrischem Energiefenster erstellt. Beim zweiten Verfahren werden Korrekturmatrizen mittels verschiedener Nuklide erstellt und diese auf Phantomdaten angewendet, die ebenfalls mit verschiedenen Nukliden aufgenommen worden sind. Beide Verfahren brachten bei der Untersuchung einer Doppelkopf-Kamera das gleiche Ergebnis. Bei einem Detektor wurde eine leichte Nuklidabhangigkeit gefunden, die auf eine unzureichende Qualitat der Energiekorrektur zuruckzufuhren war. In diesem Fall sollte fur jedes bei SPECT-Untersuchungen eingesetzte Nuklid eine mit dem gleichen Nuklid aufgenommene Korrekturmatrix verwendet werden. Der andere Detektor arbeitete nuklidunabhangig. Bei diesem war daher die Erstellung einer Korrekturmatrix fur nur ein Nuklid ausreichend.

The aim of this study was to evaluate the cross-calibration of positron emission tomographs and their peripheral devices prior to a multicenter study. The instrumentation of 22 sites (including 24 dedicated PET scanners), including 21 that could be operated in 2D mode and 20 in 3D mode, was investigated according to standardized acquisition and reconstruction protocols, and the cross-calibration was checked against the dose calibrators (22 instruments) and the sample changer (20 instruments). The deviation of the cross-calibration to the dose calibrators was below 5% for 10 of 21 PET scanners (2D mode) and 6 of 20 (3D mode). For 6 (2D mode) and 6 (3D mode) scanners, the corresponding error was up to 10%. In turn, the deviation between dose calibrator and standard was less than 8% for 19 devices, and even less than 5% for 14 devices. In most of the well counters evaluated, the cross-calibration error was less than 10%. Although required in general, the cross-calibration between positron emission tomographs and their peripheral devices becomes even more critical when pooling data in the framework of quantitative clinical multicenter studies.