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Normal variations of coeliac and hepatic artery blood supply to the liver as identified on multidetector computed tomography (MDCT) studies at Groote Schuur Hospital, Western Cape Province, South Africa between 2018 and 2019Muzenda, Vengesai 16 February 2021 (has links)
Background: Variant anatomy of the coeliac axis and hepatic arterial system is not uncommon and with the evolution of new minimally invasive surgical techniques and endovascular hepatic therapies, the interventional radiologist should have a good knowledge of the normal and variant anatomy to optimize treatment and minimise iatrogenic liver injuries. Objectives: To analyse, describe and illustrate the prevalence of the normal and variant anatomy of the coeliac axis and hepatic arterial system. Methods: A total of 300 MDCT angiography studies performed during a two-year period at Groote Schuur Hospital, Western Cape Province, South Africa were retrospectively reviewed to assess for the normal and variant anatomy of the coeliac axis and hepatic arterial system. Results: The CA and HA variations were analysed as per criteria by Uflacker's and modified Michel's respectively. The normal CA was seen in 88.3% (n=265). Most common variant anatomy was the hepatosplenic trunk seen in 2% (n=6). The remaining 3% (n=9) of patients were unclassified. Normal HA was seen in 55% (n=165). The most common variant anatomy was the accessory LHA seen in 12.7% (n=38). Classified HA variant anatomy was 30.7% and the remaining 14.3 % were unclassified. Double hepatic artery (2.7%) and CHA trifurcations (5.3%) were very common variants. Novel variants such as CHA off the SMA in combination with another variant in the form of accessory LHA (0.7%; n=2), combined double hepatic artery with an accessory LHA (0.3%; n=1) as well as accessory LGA off the PHA (0.3%; n=1) were identified. Conclusion: Variant coeliac axis and hepatic arterial anatomy is very common. Our population study demonstrated a greater prevalence of an accessory LHA than that reported in the literature. Although the rest of the variant frequencies were comparable to literature studies cited, novel hitherto undescribed variants were identified which the radiologist and hepatic surgeons need to be aware of. Two such variants were a persistent communication between SMA and CHA, and an accessory left gastric artery off the PHA.
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Factors influencing pneumothorax rates of transthoracic CT-guided lung biopsies in a Tertiary centre in Cape Town, South AfricaRichards-Edwards, William H 15 September 2021 (has links)
Background: Histological sampling of pulmonary lesions is important in diagnosis of lung carcinoma and affects subsequent decisions on specific management. Transthoracic CT-guided lung biopsy is considered an effective option to obtain tissue with low rates of complications, with pneumothorax being the most common. Objectives: To determine the pneumothorax rate of transthoracic CT-guided lung biopsies of focal lung lesions at Groote Schuur Hospital, and assess how procedural, patient and lesion factors influence these results. Methods: A retrospective review of 237 CT-guided lung biopsies performed over a 24-month period. Patient's CT, biopsy reports and post-procedure x-rays were reviewed. The relationship between pneumothorax rates and categorical demographic and clinical variables was analysed with Cochran's trend test. Mann-Whitney U tests were used to assess differences in continuous variables. Factors influencing pneumothorax rates of transthoracic CT-guided lung biopsies in a Tertiary Centre in Cape Town, South Africa. Results: Pneumothorax occurred in 43 (18.1%) of the 237 biopsies. A chest drain was required in 7 of 43 pneumothoraces (16%; 3% overall). Risk factors that were significantly associated with pneumothorax rate include pleural-lesion distance (p<0.001), smaller lesion size (p=0.002), smaller needle gauge (p=0.012) and perilesional emphysema (p=0.011). Patient age, sex, position, lesion location and level of experience of the performing radiologist had no significant influence on the pneumothorax rate. Conclusion: Our post-procedure pneumothorax rate is within the acceptable range when compared to other institutions. Pleural-lesion distance, lesion size, smaller needle gauge and presence of perilesional emphysema were the most significant risk factors influencing pneumothorax rate. Knowledge of these findings may be applicable in pre-procedure planning to reduce complications and useful to local referring clinicians and patients.
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The utility of abdominal ultrasound in the diagnosis of paediatric abdominal tuberculosis: a single centre reviewSood, Vishesh 01 March 2021 (has links)
Background: Childhood tuberculosis (TB) is a common disease worldwide, with an increased propensity for severe, disseminated disease in settings with a high burden of concomitant HIV infection. Ultrasound is commonly used in diagnosing abdominal TB, however the indications for its use are unclear and often vary amongst clinicians. Objective: In this study, we describe the findings of ultrasound examinations performed for suspected abdominal TB at a tertiary children's hospital and examine the variability in reporting patterns amongst radiologists performing these imaging investigations. Materials and methods: Ultrasound studies performed for “suspected abdominal TB” between 01 January 2013 – 31 December 2018 were reviewed. In studies reported as suggestive of abdominal TB, evidence of microbiologically confirmed disease was sought. Subsequently, a selection of images from these studies were independently reviewed by three paediatric radiologists to determine their level of agreement when interpreting imaging findings. Results: During the study period 1093 studies were performed for suspected abdominal TB, of which 166 (15%) had abnormal features suggestive of TB. Forty-seven percent of these patients (78/166) had microbiologically confirmed disease. The commonest reported features were lymphadenopathy, 77% (128/166) and splenic microabscesses, 55% (92/166) for which substantial inter-reader agreement was documented, Fleiss' kappa = 0.64 and 0.66 respectively. There was moderate inter-reader agreement in the diagnosis of abdominal TB among radiologists (Fleiss' kappa=0.47). Conclusion: Caution is advised when basing clinical decisions on ultrasound studies performed for suspected abdominal TB, as imaging features are non-specific and there is considerable variability in interpretation of studies among reporting radiologists.
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Measurements of the complex permittivity of dielectric reference liquids and human tissuesJenkins, Sharon January 1991 (has links)
No description available.
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The influence of DNA damage, DNA repair and chromatin structure on radiosensitivityRoos, Wynand Paul 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The factors which control radiosensitivity are of vital importance for the
understanding of cell inactivation and for cancer therapy. Cell cycle blocks, total
induced DNA damage, DNA repair, apoptosis and chromatin structure are likely
to playa role in the responses leading to cell death.
I have examined aspects of irradiation-induced G2/M blocks in DNA damage
and repair. In HT29, L132 and ATs4 cells the total amount of induced DNA
damage by isodoses of 4.5 Gy, 5 Gy and 2 Gy was found to be 14 %, 14 % and
12 % respectively. Most of the DNA repair was completed before the G2/M
maximum and only 3 % of DNA damage remains to be restored in the G2/M
block.
The radiosensitivity in eleven cell lines was found to range from SF2 of 0.02 to
0.61. By FADU assay the undamaged DNA at 5 Gy was found to range from
56% to 93%. The initial DNA damage and radiosensitivity were highly correlated
(r2=0. 81). After 5 Gy irradiation and 12 hours repair two groups of cell lines
emerged. The group 1 cell lines restored undamaged DNA to a level ranging
from 94 % to 98 %. The group 2 cell lines restored the undamaged DNA to a
level ranging from 77 % to 82 %. No correlation was seen between residual
DNA damage remaining after 12 hours repair and radiosensitivity.
In CHO-K1 cells chromatin condensation induced by Nocodazole was found to
marginally increase the radiosensitivity as shown by the change of the mean
inactivation dose (D) from 4.446 to 4.376 Gy. Nocodazole also increased the initial DNA damage, induced by 5 Gy, from 7 % to 13 %. In xrs1 cells these
conditions increased the radiosensitivity from D of 1.209 to 0.7836 Gy and the
initial DNA damage from 43 % to 57 %. Disruption of chromatin structure with a
hypertonic medium was found to increase radiosensitivity in CHO-K1 cells from
D of 4.446 to 3.092 Gy and the initial DNA damage from 7 % to 15 %. In xrs1
cells these conditions caused radiosensitivity to decrease from D of 1.209 to
1.609 Gy and the initial DNA damage from 43 % to 36 %.
Repair inhibition by Wortmannin increased the radiosensitivity in CHO-K1 from
a D of 5.914 Gy in DMSO controls to a D 3.043 Gy. In xrs1 cells repair inhibition
had no effect on radiosensitivity. Significant inhibition of repair was seen in
CHO-K1 at 2 hours (p<0.0001) and at 20 hours (p=0.0095). No inhibition of
repair was seen in xrs1 cells at 2 hours (p=0.6082) or 20 hours (p=0.6069).
While DNA repair must be allocated to the post-irradiation period, the G2/M
block seen in p53 mutants reaches a maximum only 12 hours post-irradiation
when most of the repair is completed. As the G2/M block resolves and cells reenter
cycle 28 hours after the G2 maximum it appears that repair processes
cannot be the only reason for the G2IM cell cycle arrest. At low doses of
irradiation initial DNA damage correlates with radiosensitivity. This suggests
that the initial DNA damage is a determinant for radiosensitivity. Repair of DNA
double-strand breaks by the non-homologous end joining (NHEJ) mechanism,
identified by inhibition with Wortmannin, was shown to influence residual DNA
damage and cell survival. Both the initial DNA damage and DNA repair were
found to be influenced by chromatin structure. Chromatin structure was modulated by high salt and by Nocodazole, and has heen identified as a
parameter which influences radiosensitivity. / AFRIKAANSE OPSOMMING: Die faktore wat betrokke is in die meganisme van stralings-sensitisering is van
hoogs belang vir die begrip van sel inaktiveering en kanker terapie. Sel siklus
blokke, totale geïnduseerde DNS skade, DNS herstel, apoptose en chromatien
struktuur is moontlike rol vertolkers in die sellulêre response wat ly tot seldood.
Ek het die aspekte van stralings-geïnduseerde G2/M blokke in DNS skade en
DNS herstelondersoek. Die hoeveelheid geïnduseerde DNS skade, deur
ooreenstemmende stralings-dosisse, in HT29, L132 en ATs4 selle is 14 %, 14
% en 12 %. Meeste van die DNS herstel is klaar voordat die G2/M maksimum
beryk word en net 3 % DNS skade blyoor om herstel te word in die G2/M blok.
Die stralings-sensitiwiteit in elf sel lyne varieer tussen 'n SF2 van 0.02 en 0.61.
Deur die gebruik van die FADU metode is gevind dat die onbeskadigde DNS na
5 Gy bestraling varieer tussen 56 % en 93 %. Die totale geïnduseerde DNS
skade en stralings-sensitiwiteit was hoogs gekorreleer (r2=0.81). Na 5 Gy
bestraling en 12 ure herstel kan die sel lyne in twee groepe gegroepeer word.
Die groep 1 sellyne herstel die onbeskadigde DNS terug na 'n vlak wat varieer
tussen 94 % en 98 %. Die groep 2 sel lyne herstel die onbeskadigde DNS terug
tot op 'n vlak wat varieer tussen 77 % en 82 %. Geen korrelasie is gesien
tussen oorblywende DNS skade en stralings-sensitiwiteit na 12 ure herstel nie.
In die CHO-K1 sel lyn, chromatien kompaksie geïnduseer deur Nocodazole,
vererger die stralings- sensitiwiteit soos gesien deur die gemiddelde
inaktiveerings dosis (D) wat verlaag het van 4.446 tot 4.376. Nocodazole het
ook die totale DNS skade verhoog van 7 % tot 13 %. Onder dieselfde kondisies, in die xrs1 sel lyn, is 'n verergering van stralings-sensitiwiteit (D) gesien van
1.209 tot 0.7836 en verhoog ONS skade van 43 % tot 57 %. Die ontwrigting van
die chromatien struktuur deur die gebruik van hipertoniese medium het die
stralings-sensitiwiteit (D) vererger in CHO-K1 selle van 4.446 tot 3.092. Die
totale ONS skade is verhoog van 7 % tot 15 %. Onder dieselfde kondisies, in
die xrs1 sellyn, verbeter die stralings-sensitiwiteit (D) van 1.209 tot 1.609 en die
totale ONS skade verminder van 43 % tot 36 %. ONS herstel inaktiveering in die
teenwoordigheid van Wortmannin het die stralings-sensitiwiteit (D) in CHO-K1
selle vererger van 5.914 in DMSO verwysings kondisies tot 3.043. Die ONS
herstel inaktiveering in xrs1 selle het geen uitwerking gehaat op stralingssensitiwiteit
nie. Noemenswaardige inaktiveering van ONS herstel is gesien in
CHO-K1 selle na 2 ure (p<0.0001) en na 20 ure (p=0.0095). Geen inaktiveering
is gesien in xrs1 selle na 2 ure (p=0.6082) of na 20 ure (p=0.6069) nie.
TerwylONS herstel moet plaasvind na die bestralings periode, beryk die G2/M
blok in p53 gemuteerde selle sy maksimum 12 ure na bestraling terwyl meeste
van die ONS herstel alreeds voltooi is. Aangesien die G2/M blok eers 28 ure
later begin sirkuleer moet die G2/M blok nog 'n funksie vervul anders as ONS
herstel. By lae dosisse van bestraling korreleer die totale geïnduseerde ONS
skade met stralings-sensitiwiteit. Dit dui daarop dat die totale ONS skade 'n
bepalende faktor moet wees in stralings-sensitiwiteit. Die herstel van ONS
skade deur die nie-homoloë eindpunt samevoeging (NHES) meganisme,
geïdentifiseer deur inaktiveering deur Wortmann in, het 'n invloed op
oorblywende ONS skade en sellulêre oorlewing. Beide die totale ONS skade en
ONS herstel was beïnvloed deur die chromatien struktuur. Chromatien struktuur was gemoduleer deur hoë sout konsentrasies en deur Nocodazole, en is
geïdentifiseer as a belangrike parameter wat stralings-sensitiwiteit beïnvloed.
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Tuned aperture computed tomography (TACT) : an investigation on the factors associated with its image quality for caries detectionDe Abreu, Murillo Jose Nunes 03 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The purpose of this investigation was to explore the multiple variables involved in TACT®
image generation in an attempt to optimize this imaging modality for the diagnostic task of
primary dental caries detection. The work is divided in seven phases in which the variables are
evaluated individually. Teeth from the study samples were mounted in dental stone and imaged
with a solid state digital radiography sensor. As a requisite of TACT® imaging, multiple images
of the teeth were acquired from different projection angles. These resulting basis images were
then used to generate TACT® slices. Variables tested in the investigation included the number of
iterative restorations to which the slices were submitted, the number of basis images, the angle
formed between the basis images, the two- and three-dimensional distribution of the basis
projections in space, and the method through which the slices were reconstructed. For all phases,
observers were asked to assess the presence or absence of primary caries in the teeth imaged
using the TACT® slices treated with the different variables. Finally, to determine whether the
best combination of variables produced a significant improvement in diagnostic performance, a
comparison with conventional digital radiography images was carried out. No statistically
significant differences were found in caries detection between TACT® slices submitted to
different numbers of iterative restorations, reconstructed from basis images bearing different
angular disparities, spatial distributions (in both two and three dimensions), or through different
reconstruction methods. A statistically significant difference was detected between TACT® slices
reconstructed from different numbers of basis projections. The final comparison showed that
TACT® was not statistically superior to conventional digital radiography for the task of caries
detection. The results of this investigation suggest that, although TACT® has been shown to be
useful in many tasks performed in dentistry, its application in caries detection is not essential
inasmuch as there are modalities that are simpler, more practical, less expensive, and that submit
the patient to smaller radiation doses.
Keywords: TACT, tomosynthesis, image reconstruction, digital radiography, caries detection,
ROC analysis, analysis of variance / AFRIKAANSE OPSOMMING: Die doel van hierdie proefskrif was om die veelvuldige veranderlikes wat betrokke is by
gewysigde spleet rekenaartomografie (Tuned Aperture Computed Tomography (TACT)) te
ondersoek in 'n poging om die beeldingsmodaliteit te optimaliseer in die diagnostiese opsporing
van primere karies. Die proefskrif bestaan uit 'n ekstensiewe literatuur oorsig en word in 7
fases aangebied waarin die veranderlikes individueel geevalueer word. Tande is in gips ingebed
en radiografiese opnames is gemaak met behulp van 'n digitale radiografiese sensor. As 'n
voorvereiste vir TACT beelding is veelvuldige beelde uit verskillende projeksiehoeke van die
tande gemaak. Die resulterende basisbeelde is dan gebruik om TACT snitte te produseer.
Veranderlikes wat in die proefskrif getoets is, sluit die volgende in: 'n aantal herhalende
herstellings waaraan die snitte blootgestel is, die aantal basisbeelde, die hoek gevorm tussen die
basisbeelde, die 2 en 3 dimensionele verspeiding van die basis projeksies in die ruimte en die
metodes waardeur die snitte gerekonstrueer is. In aIle fases is waarnemers gevra om die
teenwoordigheid of afwesigheid van primere karies te evalueer wat met TACT afgeneem is met
in ag neming van die verskillende veranderlikes. Ten slotte, om te bepaal of die beste
kombinasie van veranderlikes 'n aansienlike verbetering in diagnostiese prestasies sou meebring,
is 'n vergelyking met konvensionele digitale radiografiese beelding uitgevoer. Geen statistiese
beduidende verskille is waargeneem in die opsporing van karies tussen TACT snitte wat
blootgestel is aan verskillende aantal herhalende herstellings, rekonstruksie van basis beelding
met verskillende hoek veranderinge, ruimtelike verspreiding (beide 2 en 3 dimensioneel) of deur
verskillende rekonstruksie metodes nie. 'n Statistiese beduidende verskil is waargeneem tussen
TACT snitte wat van 'n verskeidenheid basis projeksies gerekonstrueer is. Die finale
vergelyking het aangetoon dat TACT nie statisties beter is as konvensionele radiografie in die
opsporing van karies nie.
Die resultate van hierdie proefskrif het getoon dat alhoewel TACT bruikbaar is in vele
prosedures wat in die tandheelkunde uitgevoer word, is die toepassing daarvan in die diagnose
van karies nie noodsaaklik nie, omdat daar in die tandheelkunde modaliteite beskikbaar is, wat
meer eenvoudig, meer prakties en goedkoper is, met 'n laer stralingsdosis vir die pasient.
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Extended Cr-51 RBC combined with Tc-99m RBC for the detection and localisation of occult GIT bleedingModebe, Emmanuel Obinna 04 1900 (has links)
Thesis (MMed)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Background
Occult blood loss from the gastrointestinal tract (GIT), causing iron deficiency often with anaemia, can be diagnostically and therapeutically challenging. This is because the endoscopic and radiologic tests may be negative due to the slow, chronic and intermittent nature of the gastrointestinal bleeding, making timing key in detection and localisation of the bleed. These limitations can be approached using two different radioactive isotopes. Firstly, we tested the sensitivity of extending Cr-51 RBC for 21 days relative to 5 days to detect GIT bleeding and its use to optimise timing of a Tc-99m RBC study for GIT blood loss localisation. Finally, we tested if the information provided by the Tc-99m RBC study aided gastroenterologic intervention for anatomical localisation of a lesion.
Method
In this retrospective review, after obtaining institutional and ethics committee approval, records of patients referred for evaluation of possible GIT blood loss were reviewed. In each; daily appearance of radiochromium in stool was measured in the whole body counter. In those cases exceeding 50 ml/day, a technetium-99m (Tc-99m) localization study was performed. These studies were correlated with clinical findings.
Results
A total of 59 Cr-51 RBC studies were carried out in 36 females and 21 males (n = 57). In 32 (54%) the radiochromium results were positive with 75% of the bleeding incidences occurring after 5 days of stool collection. Of 17 cases in whom Tc-99m RBC imaging studies were performed, 14 (82%) were positive with specific anatomical sites successfully defined in twelve. In all patients with blood loss of >100 ml/24h, Tc-99m RBC were positive and localised. Ten of the 17 Tc-99m RBC studies were further investigated and half diagnosed with small-bowel angiodysplasia.
Conclusion
This sequential twin isotope method is practical in revealing otherwise silent intestinal haemorrhage. Although it has good patient acceptability and clinical as well as diagnostic utility in management, further studies are required to clearly establish a cut-off level of blood loss for performing imaging studies and the impact of the findings on the overall patient management. / AFRIKAANSE OPSOMMING: Agtergrond
Die evaluasie van okkulte bloedverlies uit die gastro-intestinale kanaal (GIT), met gevolglike ystertekort anemie, kan diagnosties en terapeuties uitdagend wees. Dit is omdat endoskopiese en radiologiese ondersoeke negatief mag wees as gevolg van die stadige, chroniese en intermitterende aard van die gastro-intestinale bloeding, wat die presiese tydstip van opsporing en lokalisering van die bloeding krities belangrik maak. Hierdie beperkings kan aangespreek word deur twee verskillende radioaktiewe isotope te gebruik.
Eerstens is die sensitiwiteit van die verlenging van die Cr-51 RBS studie tot 21 dae in plaas van 5 dae om die GIT bloeding op te spoor, getoets, asook die gebruik daarvan om die optimale tyd vir ‘n Tc-99m RBS studie om die GIT bloedverlies te lokaliseer, vas te stel.
Laastens is getoets of die inligting van die Tc-99m RBS studie wel bygedra het tot die gastroenterologiese ingreep om die letsel anatomies te lokaliseer. Metode
Na institusionele en etiese komitee toestemming is inligting van pasiënte wat vir die evaluering van ‘n moontlike GI bloedverlies verwys is, in hierdie retrospektiewe oorsig nagegaan. Die daaglikse voorkoms van radioaktiewe chroom in stoelgangmonsters is in ‘n heelliggaamteller gemeet. In gevalle waar dit 50 ml/dag oorskry het, is ‘n tegnesium 99m (Tc 99m) studie gedoen. Hierdie studies is met die kliniese bevindinge gekorreleer. Resultate
‘n Totaal van 59 Cr-51 RBS studies is in 36 vroue en 21 mans (n = 57) gedoen. Die gemerkte chroomstudies was positief in 32 (54%), met 75% van die bloedings wat meer as 5 dae na versameling van die stoelgang plaasgevind het. In veertien (82%) van die 17 gevalle waar Tc-99m RBS studies gedoen is, was die studies positief. Spesifieke anatomiese gebiede van bloeding kon in 12 hiervan suksesvol bevestig word. Tc-99m RBS studies was positief in al die pasiënte met ‘n bloedverlies van >100 ml/24h, en kon gelokaliseer word. Tien van die 17 Tc-99m RBS studies is verder ondersoek en die helfte daarvan gediagnoseer met dunderm angiodisplasie. Gevolgtrekking
Die opeenvolgende twee isotoopmetode om andersins asimptomatiese dermbloeding op te spoor, is prakties uitvoerbaar. Alhoewel die studies goed deur pasiënte aanvaar is, en ook van kliniese en diagnostiese waarde in die hantering van die pasiënte is, is verdere studies nodig om die afsnypunt vir die hoeveelheid bloedverlies om beeldingstudies uit te voer, sonder twyfel vas te stel, asook om die impak van die bevindings op ‘n groter pasiëntpopulasie vas te stel.
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Reconstrução espectral de feixes de raios X diagnósticos / Spectral Reconstruction of Diagnostic X-Ray BeamsSouza, Daiane Miron de 13 December 2017 (has links)
A caracterização completa de um feixe de raios X diagnósticos baseia-se na medição de seu espectro de fluência. O espectro de fluência pode ser medido diretamente utilizando métodos espectroscópicos, no entanto, exige equipamento especializado e não é facilmente realizável em ambiente clínico. Neste trabalho foi implementada uma metodologia que permite obter o espectro de raios X de forma indireta. Esta metodologia baseia-se na aplicação de um modelo matemático que utiliza a transformada inversa de Laplace da curva de atenuação do feixe, gerando dados sobre a distribuição espectral deste. As curvas de atenuação foram medidas por meio de uma câmara de ionização e filtros de alumínio de alta pureza. Os espectros reconstruídos foram validados por meio da comparação da fluência em energia calculada a partir destes e a fluência em energia calculada a partir das curvas de atenuação obtidas experimentalmente. Como aplicação também foram calculados alguns dados característicos do feixe, como primeira e segunda camada semirredutora, energia média, 10º percentil e fator de kerma. Os resultados da fluência em energia calculada a partir dos espectros reconstruídos e da fluência em energia calculada a partir das curvas de atenuação obtidas experimentalmente apresentaram boa concordância, validando os espectros reconstruídos e mostrando o valor da análise da curva de atenuação em comparação com métodos espectroscópicos uma vez que os dados de atenuação podem ser obtidos com comparativa facilidade. Os dados característicos do feixe calculados a partir dos espectros obtidos neste trabalho apresentaram resultados satisfatórios, como era de se esperar, uma vez que a integração é um processo de regularização para a distribuição espectral / A complete characterization of a diagnostic X-ray beam is based on the measurement of its fluency spectrum. The fluency spectrum can be measured directly using spectroscopic methods, however, require specialized equipment and is not easily performed in a clinical environment. In this work a methodology was implemented that allows to obtain the X-ray spectrum in an indirect way. This methodology is based on the application of a mathematical model that uses an inverse Laplace transform of the beam attenuation curve, generating data on a spectral distribution of this beam. The attenuation curves are measured by means of an ionization chamber and high purity aluminum filters. The reconstructed spectra were validated by means of the comparison of energy fluency calculated from them and an energy fluence calculated from the experimentally obtained attenuation curves. As an application, some characteristic beam data were also calculated, such as first and second half-value layers, mean energy, 10th percentile and kerma factor. The energy fluency calculated from the reconstructed spectra and the energy fluence calculated from the experimentally obtained attenuation curves showed good agreement, validating the reconstructed spectra and showing the value of the attenuation curve analysis in comparison with one spectroscopic methods attenuation data can be obtained with comparative ease. The characteristic beam data calculated from the spectra obtained in this work presented satisfactory results, as expected, since it is a regularization process for a spectral distribution
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Reconstrução espectral de feixes de raios X diagnósticos / Spectral Reconstruction of Diagnostic X-Ray BeamsDaiane Miron de Souza 13 December 2017 (has links)
A caracterização completa de um feixe de raios X diagnósticos baseia-se na medição de seu espectro de fluência. O espectro de fluência pode ser medido diretamente utilizando métodos espectroscópicos, no entanto, exige equipamento especializado e não é facilmente realizável em ambiente clínico. Neste trabalho foi implementada uma metodologia que permite obter o espectro de raios X de forma indireta. Esta metodologia baseia-se na aplicação de um modelo matemático que utiliza a transformada inversa de Laplace da curva de atenuação do feixe, gerando dados sobre a distribuição espectral deste. As curvas de atenuação foram medidas por meio de uma câmara de ionização e filtros de alumínio de alta pureza. Os espectros reconstruídos foram validados por meio da comparação da fluência em energia calculada a partir destes e a fluência em energia calculada a partir das curvas de atenuação obtidas experimentalmente. Como aplicação também foram calculados alguns dados característicos do feixe, como primeira e segunda camada semirredutora, energia média, 10º percentil e fator de kerma. Os resultados da fluência em energia calculada a partir dos espectros reconstruídos e da fluência em energia calculada a partir das curvas de atenuação obtidas experimentalmente apresentaram boa concordância, validando os espectros reconstruídos e mostrando o valor da análise da curva de atenuação em comparação com métodos espectroscópicos uma vez que os dados de atenuação podem ser obtidos com comparativa facilidade. Os dados característicos do feixe calculados a partir dos espectros obtidos neste trabalho apresentaram resultados satisfatórios, como era de se esperar, uma vez que a integração é um processo de regularização para a distribuição espectral / A complete characterization of a diagnostic X-ray beam is based on the measurement of its fluency spectrum. The fluency spectrum can be measured directly using spectroscopic methods, however, require specialized equipment and is not easily performed in a clinical environment. In this work a methodology was implemented that allows to obtain the X-ray spectrum in an indirect way. This methodology is based on the application of a mathematical model that uses an inverse Laplace transform of the beam attenuation curve, generating data on a spectral distribution of this beam. The attenuation curves are measured by means of an ionization chamber and high purity aluminum filters. The reconstructed spectra were validated by means of the comparison of energy fluency calculated from them and an energy fluence calculated from the experimentally obtained attenuation curves. As an application, some characteristic beam data were also calculated, such as first and second half-value layers, mean energy, 10th percentile and kerma factor. The energy fluency calculated from the reconstructed spectra and the energy fluence calculated from the experimentally obtained attenuation curves showed good agreement, validating the reconstructed spectra and showing the value of the attenuation curve analysis in comparison with one spectroscopic methods attenuation data can be obtained with comparative ease. The characteristic beam data calculated from the spectra obtained in this work presented satisfactory results, as expected, since it is a regularization process for a spectral distribution
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Radioaktivně značené protilátky - perspektiva pro diagnostiku a terapii / Radiolabelled antibodies - the perspective for diagnosis and therapyMejtská, Jana January 2017 (has links)
1 CHARLES UNIVERSITY FAKULTY OF PHARMACY IN HRADEC KRÁLOVÉ DEPARTMENT OF BIOPHYSICS AND PHYSICAL CHEMISTRY DISSERTATION THESIS RADIOLABELED ANTIBODIES - THE PERSPECTIVE FOR DIAGNOSIS AND THERAPY Supervizor: Mgr. PAVEL BÁRTA, Ph.D. HRADEC KRÁLOVÉ, 2017 Bc. JANA MEJTSKÁ 2 ABSTRACT EN Different types of tissues have a characteristic cell morphology. Each cell has typical molecules on its surface, which may be either of physiological or pathological type. The presence of these surface structures can be interesting for possible modulation of specific cell populations from neighboring cells. Utilization of this property is then essential particularly in a case of tumor cells. Targeting on tumor specific cell structures involves the use of receptor specific peptides or monoclonal antibodies. The discovery of the preparation of monoclonal antibodies has opened a new chapter in the treatment and diagnosis not only tumor diseases. The advantage of monoclonal antibodies is their specificity and also high affinity to the type of the target cell structures. This study is focused on the summary of monoclonal antibodies which are currently being applied on the treatment or diagnosis of a particular cancer. Furthermore, this work also includes antibodies which are under development for intended medical applications with...
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