Browsing by Author "Sanderud, Audun"
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- An evaluation of SAFIRE’s potential to reduce the dose received by paediatric patients undergoing CT: a narrative reviewPublication . Borge, Synnøve; Campbell, Nina; Gomes, Ana; Raszkowski, Aysha M.; Rook, Jan Willem; Sanderud, Audun; Vallinga, Anique; Vouillamoz, Audrey; Buissink, CarstIntroduction: 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 maintaining image 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 three is 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 for paediatric 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.
- Analysis of image quality and effective dose in adult chest phantom radiography with high BMIPublication . Sanderud, Audun; Aymon, Emmanuel; Burke, Andrea A.; Dijkstra, Susanne; Fosskaug, Julie; Sanders, Sabine N.; Silva, Andreia F. N.; Soares, Flavio A.P.Aim: To investigate the impact of different kVp and mAs values on effective dose and image quality using a chest phantom that simulates a normal sized and an obese patient. Methods and materials: A chest phantom with simulated pathological nodules was imaged at various kVp and mAs values. To determine the image quality, CNR and SNR were calculated. An observer study was carried out using relative visual grading with a 3-point Likert scale to assess image quality and nodule visibility. The VGA-study reference image was of the phantom at standard size without the chest plates using 125kVp, 2.4mAs by AEC and 24μSv. Visual grading scores were compared against SNR and CNR values in order to determine the optimal acquisition parameters. Effective dose was calculated using Monte Carlo simulation software, and a Figure of Merit was calculated. Results: The image obtained with 125 kVp and 4.0 mAs had the highest SNR, and the one with 125 kVp and 2.0 mAs had the highest CNR. The observers found that 125 kVp/4.0 mAs was the most optimal image and 125 kVp/6.88 mAs had the least image quality, when compared to the reference image. On calculating the Figure of Merit, 125 kVp/2.0 mAs has the highest score. The effective dose varied from 5.34 μSv to 73.5 μSv for the range of parameters used. Conclusion: It is possible to get higher SNR, CNR and VGA-scores in large sized patient chest radiography at lower mAs than that given by using standard AEC, due to post-processing. Manual mAs better control the image quality than using AEC. Anatomical features are better detected using a higher mAs and a standard kVp. Better image contrast is achieved when a lower kVp and standard mAs is utilised. A protocol for larger patients needs to be tailored accordingly.
- Are antimony-bismuth aprons as efficient as lead rubber aprons in providing shielding against scattered radiation?Publication . Johansen, Safora; Hauge, Ingrid; Hogg, Peter; England, Andrew; Lança, Luís; Gunn, Catherine; Sanderud, AudunAim: The aim of this study is to compare the absorption ability of two lead-free aprons with a lead apron. Method: The absorption ability of three aprons was measured and compared; Opaque Fusion 0.35 mm (OpaqFu) bilayer apron containing bismuth and antimony, No Lead 0.35 mm (NoLead) one-layer apron containing antimony, and a lead apron. The measurements were repeated with and without each of the aprons present in both primary and scattered beams. The selected tube voltages were between 60 and 113 kVp with constant mAs, a fixed field size, and fixed source-to-object distance. Results: No significant difference in absorption ability of the two lead-free aprons compared with that of the lead apron was observed when the dose was measured in the primary beam. When measurements were performed in the scatter radiation field, the absorption ability of the OpaqFu apron was 1.3 times higher than that of NoLead apron and nearly equal to the absorption ability of the lead apron. An increase in the difference between the OpaqFu and NoLead aprons was observed for the tube energies higher than 100 kVp in favor of OpaqFu apron. Conclusion: It is safe to use the lead-free aprons that were tested in this study in a clinical environment for the tube energy range of 60 kVp–113 kVp.
- Guest editorial: OPTIMAX 2013Publication . Lança, Luís; Buissink, C.; Jorge, José; Sanderud, Audun; Hogg, PeterIn 2012 we were awarded an Erasmus Intensive Programme grant to facilitate OPTIMAX 2013, a three week duration residential summer school held within the UK during August 2013. The summer school helped to further develop student radiographer skills in optimising x-radiation dose and image quality. With a major emphasis on visual techniques to determine image quality, lesion visibility, lesion detection performance and physical measures of image quality (eg signal to noise ratio (SNR)) we conducted controlled laboratory experiments on phantoms using Computed Radiography, CT and Full Field Digital Mammography. Mathematical modelling was used for radiation dose estimation. Sixty seven people from 5 European countries participated. This included 49 PhD, MSc and BSc students. Discipline areas included radiography, physics, biomedical science and nuclear medicine.
- Lesion detection performance in an anthropomorphic chest phantom: comparative analysis of low-dose CT data on two hybrid imaging systemsPublication . Jessop, M.; Thompson, John D.; Coward, J.; Sanderud, Audun; Jorge, José; de Groot, M.; Lança, Luís; Hogg, PeterIntroduction: multimodality environment; requirement for greater understanding of the imaging technologies used, the limitations of these technologies, and how to best interpret the results; dose optimization; introduction of new techniques; current practice and best practice; incidental findings, in low-dose CT images obtained as part of the hybrid imaging process, are an increasing phenomenon with advancing CT technology; resultant ethical and medico-legal dilemmas; understanding limitations of these procedures important when reporting images and recommending follow-up; free-response observer performance study was used to evaluate lesion detection in low-dose CT images obtained during attenuation correction acquisitions for myocardial perfusion imaging, on two hybrid imaging systems.
- Lesion detection performance: comparative analysis of low-dose CT data of the chest on two hybrid imaging systemsPublication . Jessop, Maryam; Thompson, John D.; Coward, Joanne; Sanderud, Audun; Jorge, José; de Groot, Martijn; Lança, Luís; Hogg, PeterIncidental findings on low-dose CT images obtained during hybrid imaging are an increasing phenomenon as CT technology advances. Understanding the diagnostic value of incidental findings along with the technical limitations is important when reporting image results and recommending follow-up, which may result in an additional radiation dose from further diagnostic imaging and an increase in patient anxiety. This study assessed lesions incidentally detected on CT images acquired for attenuation correction on two SPECT/CT systems. Methods: An anthropomorphic chest phantom containing simulated lesions of varying size and density was imaged on an Infinia Hawkeye 4 and a Symbia T6 using the low-dose CT settings applied for attenuation correction acquisitions in myocardial perfusion imaging. Twenty-two interpreters assessed 46 images from each SPECT/CT system (15 normal images and 31 abnormal images; 41 lesions). Data were evaluated using a jackknife alternative free-response receiver-operating-characteristic analysis (JAFROC). Results: JAFROC analysis showed a significant difference (P < 0.0001) in lesion detection, with the figures of merit being 0.599 (95% confidence interval, 0.568, 0.631) and 0.810 (95% confidence interval, 0.781, 0.839) for the Infinia Hawkeye 4 and Symbia T6, respectively. Lesion detection on the Infinia Hawkeye 4 was generally limited to larger, higher-density lesions. The Symbia T6 allowed improved detection rates for midsized lesions and some lower-density lesions. However, interpreters struggled to detect small (5 mm) lesions on both image sets, irrespective of density. Conclusion: Lesion detection is more reliable on low-dose CT images from the Symbia T6 than from the Infinia Hawkeye 4. This phantom-based study gives an indication of potential lesion detection in the clinical context as shown by two commonly used SPECT/CT systems, which may assist the clinician in determining whether further diagnostic imaging is justified.
- Maintaining image quality for paediatric chest CTs while lowering dose: FBP versus SAFIREPublication . Borge, Synnøve; Campbell, Nina; Gomes, Ana; Raszkowski, Aysha M.; Rook, Jan Willem; Sanderud, Audun; Vallinga, Anique; Vouillamoz, Audrey; Buissink, CarstObjectives: Children have a greater risk from radiation, per unit dose, due to increased radiosensitivity and longer life expectancies. It is of paramount importance to reduce the radiation dose received by children. This research concerns chest CT examinations on paediatric patients. The purpose of this study was to compare the image quality and the dose received from imaging with images reconstructed with filtered back projection (FBP) and five strengths of Sinogram-Affirmed Iterative Reconstruction (SAFIRE). Methods: Using a multi-slice CT scanner, six series of images were taken of a paediatric phantom. Two kVp values (80 and 110), 3 mAs values (25, 50 and 100) and 2 slice thicknesses (1 mm and 3 mm) were used. All images were reconstructed with FBP and five strengths of SAFIRE. Ten observers evaluated visual image quality. Dose was measured using CT-Expo. Results: FBP required a higher dose than all SAFIRE strengths to obtain the same image quality for sharpness and noise. For sharpness and contrast image quality ratings of 4, FBP required doses of 6.4 and 6.8 mSv respectively. SAFIRE 5 required doses of 3.4 and 4.3 mSv respectively. Clinical acceptance rate was improved by the higher voltage (110 kV) for all images in comparison to 80 kV, which required a higher dose for acceptable image quality. 3 mm images were typically better quality than 1 mm images. Conclusion: SAFIRE 5 was optimal for dose reduction and image quality.
- OPTIMAX research summer school: um projeto pedagógico para a promoção da investigação em radiologiaPublication . Lança, Luís; Buissink, Carst; Sanderud, Audun; Jorge, José; Hogg, PeterPorquê este projeto? Conhecimentos, aptidões, competências; desenvolvimento de competências (instrumentais, interpessoais, sistémicas); contributo para uma concepção de carácter multidimensional do estudante, preparando-o para apreender a importância da investigação, preparando-o para uma profissão de saúde; as novas soluções tecnológicas, a par da inovação e a mudança nos cuidados de saúde e dos processos de trabalho, constituem hoje os desafios do presente e do futuro para os profissionais de saúde [o desenvolvimento da tecnologia e da informática, a educação e a prática baseada na evidência (investigação), as mudanças nos processos de trabalho, o trabalho em equipa, a dimensão internacional]; a investigação e o seu impacto na profissão (desenvolvimento de conhecimentos próprios das profissões, autonomia, impacto positivo nas práticas profissionais, benefício do doente); a investigação auxilia no processo de definição dos parâmetros de uma profissão (nenhuma profissão terá um desenvolvimento sustentado sem o contributo da investigação; é através da investigação que se constitui um domínio de conhecimentos baseados na evidência que permitam as boas práticas); apostar num projeto associado à investigação, com uma base científica que contribua para uma melhor educação e prática profissional visando assegurar a credibilidade da profissão; aprendizagem centrada no estudante; adopção de metodologias de ensino que promovam a autonomia, o raciocínio, a capacidade crítica e a resolução de problemas.
- The influence of experience and training in a group of novice observers: a jackknife alternative free-response receiver operating characteristic analysisPublication . Buissink, C.; Thompson, John D.; Voet, M.; Sanderud, Audun; Kamping, L. V.; Savary, L.; Mughal, M.; Rocha, C. S.; Hart, G. E.; Parreiral, R.; Martin, G.; Hogg, PeterPurpose - The study evaluates the pre- and post-training lesion localisation ability of a group of novice observers. Parallels are drawn with the performance of inexperienced radiographers taking part in preliminary clinical evaluation (PCE) and ‘red-dot’ systems, operating within radiography practice. Materials and methods - Thirty-four novice observers searched 92 images for simulated lesions. Pre-training and post-training evaluations were completed following the free-response the receiver operating characteristic (FROC) method. Training consisted of observer performance methodology, the characteristics of the simulated lesions and information on lesion frequency. Jackknife alternative FROC (JAFROC) and highest rating inferred ROC analyses were performed to evaluate performance difference on lesion-based and case-based decisions. The significance level of the test was set at 0.05 to control the probability of Type I error. Results - JAFROC analysis (F(3,33) = 26.34, p < 0.0001) and highest-rating inferred ROC analysis (F(3,33) = 10.65, p = 0.0026) revealed a statistically significant difference in lesion detection performance. The JAFROC figure-of-merit was 0.563 (95% CI 0.512,0.614) pre-training and 0.677 (95% CI 0.639,0.715) post-training. Highest rating inferred ROC figure-of-merit was 0.728 (95% CI 0.701,0.755) pre-training and 0.772 (95% CI 0.750,0.793) post-training. Conclusions - This study has demonstrated that novice observer performance can improve significantly. This study design may have relevance in the assessment of inexperienced radiographers taking part in PCE or commenting scheme for trauma.