| 1. |
- Morphis, Michaella, et al.
(författare)
-
Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification : a Monte Carlo study
- 2021
-
Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well as image corrections incorporated in the iterative reconstruction process. These factors can be investigated and optimised using Monte Carlo simulations. This study aimed to evaluate SPECT quantification accuracy for 123I with both the low-energy high resolution (LEHR) and medium-energy (ME) collimators and 131I with the high-energy (HE) collimator. Methods: Simulated SPECT projection images were reconstructed using the OS-EM iterative algorithm, which was optimised for the number of updates, with appropriate corrections for scatter, attenuation and collimator detector response (CDR), including septal scatter and penetration compensation. An appropriate calibration factor (CF) was determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere in water-filled (cold) cylindrical phantom, sphere in air and point-like source), investigated with different volume of interest (VOI) diameters. Recovery curves were constructed from recovery coefficients to correct for partial volume effects (PVEs). The quantitative method was evaluated for spheres in voxel-based digital cylindrical and patient phantoms. Results: The optimal number of OS-EM updates was 60 for all isotope-collimator combinations. The CFpoint with a VOI diameter equal to the physical size plus a 3.0-cm margin was selected, for all isotope-collimator geometries. The spheres’ quantification errors in the voxel-based digital cylindrical and patient phantoms were less than 3.2% and 5.4%, respectively, for all isotope-collimator combinations. Conclusion: The study showed that quantification errors of less than 6.0% could be attained, for all isotope-collimator combinations, if corrections for; scatter, attenuation, CDR (including septal scatter and penetration) and PVEs are performed. 123I LEHR and 123I ME quantification accuracies compared well when appropriate corrections for septal scatter and penetration were applied. This can be useful in departments that perform 123I studies and may not have access to ME collimators.
|
|
| 2. |
- Morphis, Michaella, et al.
(författare)
-
Modelling of energy-dependent spectral resolution for SPECT Monte Carlo simulations using SIMIND
- 2021
-
Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 7:2
-
Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo (MC) modelling techniques have been used extensively in Nuclear Medicine (NM). The theoretical energy resolution relationship (∝1/E−−√), does not accurately predict the gamma camera detector response across all energies. This study aimed to validate the accuracy of an energy resolution model for the SIMIND MC simulation code emulating the Siemens Symbia T16 dual-head gamma camera.MethodsMeasured intrinsic energy resolution data (full width half maximum (FWHM) values), for Ba-133, Lu-177, Am-241, Ga-67, Tc-99m, I-123, I-131 and F-18 sources in air, were used to create a fitted model of the energy response of the gamma camera. Both the fitted and theoretical models were used to simulate intrinsic and extrinsic energy spectra using three different scenarios (source in air; source in simple scatter phantom and a clinical voxel-based digital patient phantom).ResultsThe results showed the theoretical model underestimated the FWHM values at energies above 160.0 keV up to 23.5 keV. In contrast, the fitted model better predicted the measured FWHM values with differences less than 3.3 keV. The I-131 in-scatter energy spectrum simulated with the fitted model better matched the measured energy spectrum. Higher energy photopeaks, (I-123: 528.9 keV and I-131: 636.9 keV) simulated with the fitted model, more accurately resembled the measured photopeaks. The voxel-based digital patient phantom energy spectra, simulated with the fitted and theoretical models, showed the potential impact of an incorrect energy resolution model when simulating isotopes with multiple photopeaks.ConclusionModelling of energy resolution with the proposed fitted model enables the SIMIND user to accurately simulate NM images. A great improvement was seen for high-energy photon emitting isotopes (e.g. I-131), as well as isotopes with multiple photopeaks (e.g. Lu-177, I-131 and Ga-67) in comparison to the theoretical model. This will result in accurate evaluation of radioactivity quantification, which is vital for dosimetric purposes.
|
|
| 3. |
- Morphis, Michaella, et al.
(författare)
-
Validation of a SIMIND Monte Carlo modelled gamma camera for Iodine-123 and Iodine-131 imaging
- 2021
-
Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 7:6
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Monte Carlo (MC) modelling techniques can assess the quantitative accuracy of both planar and SPECT Nuclear Medicine images. It is essential to validate the MC code's capabilities in modelling a specific clinical gamma camera, for radionuclides of interest, before its use as a clinical image simulator. This study aimed to determine if the SIMIND MC code accurately simulates emission images measured with a Siemens Symbia™ T16 SPECT/CT system for I-123 with a LEHR and a ME collimator and for I-131 with a HE collimator. Methods: The static and WB planar validation tests included extrinsic system energy pulse-height distributions (EPHDs), system sensitivity and system spatial resolution in air as well as a scatter medium. The SPECT validation test comprised the sensitivity from a simple geometry of a sphere in a cylindrical water-filled phantom. Results: The system EPHDs compared well, with differences between measured and simulated primary photopeak FWHM values not exceeding 4.6 keV. Measured and simulated planar system sensitivity values displayed percentage differences less than 6.9% and 6.3% for static and WB planar images, respectively. Measured and simulated planar system spatial resolution values in air showed percentage differences not exceeding 6.4% (FWHM) and 10.0% (FWTM), and 5.1% (FWHM) and 5.4% (FWTM) for static and WB planar images, respectively. For static planar system spatial resolution measured and simulated in a scatter medium, percentage differences of FWHM and FWTM values were less than 5.8% and 12.6%, respectively. The maximum percentage difference between the measured and simulated SPECT validation results was 3.6%. Conclusion: The measured and simulated validation results compared well for all isotope-collimator combinations and showed that the SIMIND MC code could be used to accurately simulate static and WB planar and SPECT projection images of the Siemens Symbia™ T16 SPECT/CT for both I-123 and I-131 with their respective collimators.
|
|
| 4. |
- Zimmerman, Brian E, et al.
(författare)
-
Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification : An IAEA phantom study
- 2017
-
Ingår i: Zeitschrift für Medizinische Physik. - : Elsevier BV. - 1876-4436 .- 0939-3889. ; 27:2, s. 98-112
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing 133Ba, which was chosen as a surrogate for 131I. The sources, with nominal volumes of 2, 4, 6 and 23mL, were calibrated for 133Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang's first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multicentre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to about 6% with planar imaging and SPECT (with Chang-AC) and within 2% for SPECT-CT.
|
|
| 5. |
- Stave, Christina, 1957-, et al.
(författare)
-
Hälsa och cykling i staden : en tvärvetenskaplig studie
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Studien visar att ett tvärvetenskapligt angreppssätt kan ge ett större djup i förståelsen för de komplexa samband som är aktuella vid planering av transportinfrastruktur. Redan vid planeringen framkom att de olika disciplinerna har olika behov vad gäller förberedelsetid för planering, mätutrustning och mätplatser, vilket tydliggjorde att stort behov av tid och kommunikation inom forskargruppen. Pilotstudiens resultat visade att de som valde cykelbanan inne i parken hade upplevelsen av grönskan, välbefinnande, och mindre stress större betydelse. Den yttre cykelbana betraktades som ”autostradan”, den var snabbare, utan gående och med få avbrott. De delar av hälsan som handlar om upplevelser av grönska och mental balans tycks prioriteras av färre cyklister. Risker för exponering av luftföroreningar och buller tycktes inte vara stor och övervägde inte snabbhet och framkomlighet för de flesta. Det behövs vägval för cyklister som ger en mindre exponering för luftföreningar och buller samt att vidare studera de variabler som påverkar valet i den aktuella situationen. Denna pilotstudie visar dock att det finns goda möjligheter att förbättra den positiva hälsoeffekten genom att utforma miljön kring cykelvägarna så att mental hälsa och balans samt exponering för miljörisker minimeras. För att få med de många faktorer som påverkar cyklisters val av färdväg samt planläggning av infrastruktur för cyklister behövs tvärvetenskapliga studieupplägg.
|
|
| 6. |
- Bergman, Karl
(författare)
-
Staden, pesten, renhållning och modernitet, Karlskrona 1710-1712
- 2011
-
Ingår i: Karolinska förbundets årsbok. - : Karolinska förbundet. - 0348-9833. ; , s. 7-71
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study concerns the plague that hit Karlskrona and the navy alike in 1710, and which would come to threaten the navy’s very existence. Its theoretical basis is the Foucaultian field of research on disease and disease control as a part of a shift in the balance of power, for it demonstrates that it was doctors, not priests, who stood at the Admiralty leadership’s right hand as advisors and experts. Religious rhetoric, as an explanatory model, was indeed in evidence, but played a subordinate role. The subsequent systemization centred on a belief in human – or rather learned doctors’ – powers of observation and ability to draw conclusions. Categorization, separation, and control were the key-words in the process. Against this was the populace’s grass-roots, religiously inspired behaviour; behaviour that in their rulers’ eyes was a threat to the natural order and had to be suppressed. Doctors with their ‘science’ and the military with their brute power made for a powerful combination in the struggle against what they saw as disorder. On the heels of this battle against the plague, the navy furthermore appeared in the guise of the defender of fundamental ‘welfare’, to use a modern expression. At the peak of the crisis, the naval base was the lone institution able to offer the promise of food and medicine. The first basic hospitals also began to take shape. The issue is studied as one of many possible ‘tracks’ or steps in a Swedish modernization process.
|
|
| 7. |
|
|
| 8. |
- Forsberg, Bertil, professor, 1956-, et al.
(författare)
-
Coronanedstängningens betydelse för luftföroreningshalter, beräknade hälsokonsekvenser och registrerade uttag av astmaläkemedel i Stockholmsområdet
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nedstängningen av samhällen på grund av pandemin våren 2020 skedde tämligen globalt, varför åtföljande förändringar av utsläpp både lokalt och på långt avstånd kan ha påverkat luftkvaliteten i Stockholm. Denna rapport redovisar tre delstudier: en analys av hur föroreningshalterna i Stockholmsområdet påverkades av den inledande nedstängningen av samhället, en hälsokonsekvensberäkning av vilka hälsoeffekter en sådan förändring av halterna antas medföra, samt en epidemiologisk tidsseriestudie av sambanden mellan registrerat dagligt antal utköp av astmamediciner och halter av luftföroreningar under den inledande nedstängningen och före/efter denna period.Vi har i detta projekt använt två metoder, spridningsmodellering med emissionsdata respektive regressionsanalys med mätdata, för att beräkna hur främst kväveoxidhalterna påverkades av minskade emissioner lokalt, samt hur bl.a halterna av kvävedioxid och ozon i staden avvek ifrån förväntade värden efter hänsyn till meteorologins inverkan på halterna.Spridningsberäkningarna visade att halterna av kvävedioxid minskade med 0,7 μg/m3 under mars-juli till följd av minskad lokal trafik. Utifrån sammanvägningar av publicerade epidemiologiska samband skulle detta leda till cirka 2 dödsfall färre i 9 kommuner med totalt drygt 1,5 miljoner invånare, medan besök och inläggningar på sjukhus för andningsorganen förväntas minska med drygt 24 fall genom minskade lokala utsläpp.Den väderjusterade minskningen av totala NO2 halterna var 2,8 μg/m3, vilket skulle förväntas leda till ungefär 97 färre besök och inläggningar på sjukhus för andningsorganen under samma 5 månader. Men eftersom minskade utsläpp av kväveoxider även följdes av en oväntat stor väderjusterad ökning av marknära ozon förväntas för vissa hälsoutfall en nettoökning av antalet fall, exempelvis av patienter med problem i andningsorganen.Eftersom utköp av förskrivna läkemedel inte kräver att man besöker sjukvården, inte ens att man besöker ett apotek, studerades dagligt antal utköp av astmaläkemedel i relation till variationer i luftföroreningshalterna. Trots en inledande hamstringsvåg med efterföljande svacka i utköp under maj och lägre uppmätta halter av kväveoxider (NOx) och partiklar <10 mikrometer (PM10) än normalt, fanns sammantaget även under april-juli 2020 en statistiskt säkerställd effekt av PM10 och NOx på dagligt antal utköp. När relativa riskökningen per 10 μg/m3 jämförs mellan denna nedstängningsperiod och övrig studieperiod kan konstateras att ökningen av utköp per haltökning var högre under april-juli 2020. För hela perioden 2018 - 2021 visade en meta-skattning över 21 kommuner i Stockholms län på 2,6 procent ökning i uttag av lång- och korttidsverkande astmaläkemedel per 10 μg/m3 ökning av PM10 (medelvärde för samma dygn och det föregående).
|
|
| 9. |
- Fasth, Anders, 1945
(författare)
-
Osteopetros - när skelettet är hårt som sten men skört som glas
- 2019
-
Ingår i: Barnläkaren. - 1651-0534. ; 2019:4, s. 26-27
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Kan det vara en slump att jag befinner mig i Petra, Jordanien när inbjudan att skriva om osteopetros dimper ner i mail-korgen? Petra, Petrus, petrifierad, osteopetros. Allt syftar på sten eller klippa. Petrus en klippa bland lärjungarna och Petra, staden uthuggen direkt i berget. Osteopetros är således uttytt ben som blir till sten. Ett annat namn är marmorbensjuka
|
|
| 10. |
-
Crime, Victimization and Vulnerability in Malmö
- 2019. - 1
-
Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Malmö and its inhabitants are living in a historical era and in a changing environment – in a city that has grown with 43 percent since 1990. Crime, Victimization and Vulnerability in Malmö presents a selection of current research, and the impact that crime, victimization and vulnerability have had on Malmö since the early 2000s.Crime, Victimization and Vulnerability in Malmö addresses topics such as gun and explo-sive violence, arson, offender characteristics, hate crime and victimological aspects. The book also discusses the link between crime and substance abuse, presents a crime victim study of EU citizens, and invites readers to listen in on a conversation between a criminolo-gist and an active-duty police officer. Finally, a psychiatrist reflects on how society’s inte-raction with people with antisocial problems has changed over time.The book has a clear link to Malmö, but can be used to understand crime, victimization and vulnerability in other places. Readers are encouraged to reflect critically on crime, victimization and vulnerability, and on how these are portrayed both in the media and in the book itself. The hope is that this book will contribute to the discussion on Malmö’s crime, victimization and vulnerability and that it will inspire thoughts, questions and curiosity about criminology as a subject.
|
|
