Het doel van het onderzoek is om te bepalen welke voordelen de fusie van PET-CT en MRI-CT hebben in het voorbereidingstraject van de behandeling van de gynaecologische patiënt met radiotherapie ten opzichte van CT alleen. Hierbij is gekeken naar voordelen met betrekking tot intekenen van doelvolumina en risico organen, effecten op intekenvariaties en ook de effecten op het bestralingsplan. Vooral MRI blijkt nuttig te zijn voor de intekening van lymfeklieren, het gebruik van PET in combinatie met CT laat een afname van het doelvolume zien van de primaire tumor. Bij het maken van het bestralingsplan wordt het gebruik van één van beide modaliteiten daarom aanbevolen.
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Introduction: The purpose of this review is to gather and analyse current research publications to evaluate Sinogram-Affirmed Iterative Reconstruction (SAFIRE). The aim of this review is to investigate whether this algorithm is capable of reducing the dose delivered during CT imaging while maintainingimage quality. Recent research shows that children have a greater risk per unit dose due to increased radiosensitivity and longer life expectancies, which means it is particularly important to reduce the radiation dose received by children.Discussion: Recent publications suggest that SAFIRE is capable of reducing image noise in CT images, thereby enabling the potential to reduce dose. Some publications suggest a decrease in dose, by up to 64% compared to filtered back projection, can be accomplished without a change in image quality.However, literature suggests that using a higher SAFIRE strength may alter the image texture, creating an overly ‘smoothed’ image that lacks contrast. Some literature reports SAFIRE gives decreased low contrast detectability as well as spatial resolution. Publications tend to agree that SAFIRE strength threeis optimal for an acceptable level of visual image quality, but more research is required. The importance of creating a balance between dose reduction and image quality is stressed. In this literature review most of the publications were completed using adults or phantoms, and a distinct lack of literature forpaediatric patients is noted.Conclusion: It is necessary to find an optimal way to balance dose reduction and image quality. More research relating to SAFIRE and paediatric patients is required to fully investigate dose reduction potential in this population, for a range of different SAFIRE strengths.
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How to find the right balance
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Introduction: Zygomatic fractures can be diagnosed with either computed tomography (CT) or direct digital radiography (DR). The aim of the present study was to assess the effect of CT dose reduction on the preference for facial CT versus DR for accurate diagnosis of isolated zygomatic fractures. Materials and methods: Eight zygomatic fractures were inflicted on four human cadavers with a free fall impactor technique. The cadavers were scanned using eight CT protocols, which were identical except for a systematic decrease in radiation dose per protocol, and one DR protocol. Single axial CT images were displayed alongside a DR image of the same fracture creating a total of 64 dual images for comparison. A total of 54 observers, including radiologists, radiographers and oral and maxillofacial surgeons, made a forced choice for either CT or DR. Results: Forty out of 54 observers (74%) preferred CT over DR (all with P < 0.05). Preference for CT was maintained even when radiation dose reduced from 147.4 mSv to 46.4 mSv (DR dose was 6.9 mSv). Only a single out of all raters preferred DR (P ¼ 0.0003). The remaining 13 observers had no significant preference. Conclusion: This study demonstrates that preference for axial CT over DR is not affected by substantial (~70%) CT dose reduction for the assessment of zygomatico-orbital fractures.
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The main objective of this study was to make the transition from afilm (2D) based pre-treatment IMRT / IMAT QA into a moreefficient and clinical relevant method of verification byreconstructing the dose directly in the patient CT using theCOMPASS system. The evaluation of the reconstructeddose includes DVHs and a gamma index evaluation.
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Cone beam CT scanners use much less radiation than to normal CT scans. However, compared to normal CT scans the images are noisy, showing several artifacts. The UNet Convolutional Neural Network may provide a way to reconstruct the a CT image from cone beam scans.
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Background: Computed tomography (CT) is one of the most used modalities for diagnostics in paediatric populations, which is a concern as it also delivers a high patient dose. Research has focused on developing computer algorithms that provide better image quality at lower dose. The iterative reconstruction algorithm Sinogram-Affirmed Iterative Reconstruction (SAFIRE) was introduced as a new technique that reduces noise to increase image quality.Purpose: The aim of this study is to compare SAFIRE with the current gold standard, Filtered Back Projection (FBP), and assess whether SAFIRE alone permits a reduction in dose while maintaining image quality in paediatric head CT.Methods: Images were collected using a paediatric head phantom using a SIEMENS SOMATOMPERSPECTIVE 128 modulated acquisition. 54 images were reconstructed using FBP and 5 different strengths of SAFIRE. Objective measures of image quality were determined by measuring SNR and CNR. Visual measures of image quality were determined by 17 observers with different radiographic experiences. Images were randomized and displayed using 2AFC; observers scored the images answering 5 questions using a Likert scale.Results: At different dose levels, SAFIRE significantly increased SNR (up to 54%) in the acquired images compared to FBP at 80kVp (5.2-8.4), 110kVp (8.2-12.3), 130kVp (8.8-13.1). Visual image quality was higher with increasing SAFIRE strength. The highest image quality was scored with SAFIRE level 3and higher.Conclusion: The SAFIRE algorithm is suitable for image noise reduction in paediatric head CT. Our data demonstrates that SAFIRE enhances SNR while reducing noise with a possible reduction of dose of 68%.
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A growing body of evidence indicates that natural environments can positively influence people. This study investigated whether the use of motion nature projection in computed tomography (CT) imaging rooms is effective in mitigating psycho-physiological anxiety (vs. no intervention) using a quasirandomized experiment (N ¼ 97). Perceived anxiety and pleasantness of the room were measured using a questionnaire, and physiological arousal was measured using a patient monitor system. A mediation analysis showed that motion nature projection had a negative indirect effect on perceived anxietythrough a higher level of perceived pleasantness of the room. A linear-mixed-model showed that heart rate and diastolic blood pressure were lower when motion nature was projected. In conclusion, by creating a more pleasant imaging room through motion nature projection, hospitals can indirectly reduce patient's psycho-physiological anxiety (vs. no image projection) during a CT scan.
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Soms is het nodig om röntgenonderzoek te laten doen. Met een röntgenonderzoek kunnen eventuele afwijkingen in het lichaam worden gevonden. Bijvoorbeeld met een röntgenfoto van je gebit bij de tandarts. Of een CT-scan van je buik om te kijken of hier een afwijking zit. Maar, is dit ook veilig wanneer je zwanger bent? Ongeboren kinderen zijn gevoeliger voor röntgenstraling dan volwassenen vanwege snel delende weefsels, vertelt onderzoeker en verloskundige Maria Dalmaijer. De risico’s lijken echter erg klein te zijn. Bovendien is de hoeveelheid straling die bij de baby komt verwaarloosbaar. Harmen Bijwaard, lector Medische Technologie aan Hogeschool Inholland legt uit dat röntgenonderzoeken tijdens de zwangerschap daarom veilig zijn. Bij een uitgebreidere CT-scan van de buik zal de arts bekijken of er andere onderzoeken mogelijk zijn.
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Exposures to ionizing radiation frommedical examinations are on the rise. An important cause for this has been the advent and ever-increasing use of computed tomography (CT) scans for diagnostic purposes. It is often implied that population aging contributes significantly to this rise. Here, the trends in population statistics are compared to the trend in the number of CT scans in the Netherlands for the period 2002–2010. It is concluded that population growth and population aging cannot explain the observed rise in CTexaminations. In fact, these factors contribute only 17% to this rise, indicating that there must be other factors that are far more important.
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