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- Axelsson, Jan, 1966-
(författare)
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Imlook4d : introducing an extendable research 4d analysis software
- 2014
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Ingår i: XII Turku PET Symposium, 24-27 May 2014, Turku, Finland. ; , s. 63-63
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Imlook4d (http://www.dicom-port.com) is a free Matlab based graphical user interface (GUI) tool useful for static, dynamic and gated PET studies. It supports reading and writing DICOM, Nifti, Analyze, ECAT. The DICOM reader is orders of magnitude faster than the Matlab imaging toolbox. Imlook4d requires no additional Matlab toolboxes.The main benefit with imlook4d is that it is easily extendable with scripts, accessing exported variables such as the image matrix (4D) and a region-of-interest (ROI) matrix. Scripts are available via a menu in the imlook4d GUI, and can be used to manipulate the image-matrix and ROI data. There is also a menu option to export and import these variables to the Matlab workspace for interactive manipulation, useful for one-off fixes or for script development. There are presently about 30 scripts in categories such as ROI, Matrix, Header info etc. There is also direct export to ImageJ [1] and import back from ImageJ, thus giving access to all tools available within ImageJ.Imlook4d has a built in volume-of-interest editor, with a brush tool for quick interactive ROI delineation, and via scripts, different ways of thresholding ROIs from parts of the image. Time activity data is saved to a tab-delimited text file.The principal-component (PC) based Hotelling filter is an integrated part of the program, which allows for interactive noise reduction without loss of quantitation [2]. A typical work flow for a dynamic data set is to turn on the filter for ROI delineation, and then there is the choice of turning it off for export of time-activity data. Also the PC images can be used to draw ROIs on, which under some circumstances gives enhanced contrast.Calculation of parametric pharmacokinetic modelling images can be performed interactively, calculated slice by slice as the user scrolls through the volume. Reference models for Patlak, Logan and Averaged Simple Flow Model [3] applied on 15O-water are implemented, and it is relatively easy to implement other kinetic models. Similarly, scripts have been developed for regional Patlak and Logan models on ROI data.[1] Rasband, WS, ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, http://imagej.nih.gov/ij/, 1997-2014[2] Axelsson J, Sörensen J, The 2D Hotelling filter - a quantitative noise-reducing principal-component filter for dynamic PET data, with applications in patient dose reduction. BMC Med Phys. 2013 Apr 10;13:1. doi: 10.1186/1756-6649-13-1.[3] Yoshida, K, Mullani, N and Gould KL, Coronary Flow and Flow Reserve by PET Simplified for Clinical Applications Using Rubidium-82 or Nitrogen-13-Ammonia, J Nucl Med 1996; 37:1701-1712Figure 1. The imlook4d GUI with the user SCRIPTS menu selected. The group of ROI scripts was further selected. In the underlying image, a rough ROI is created.
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- Norrman, Eva, 1966-
(författare)
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Optimisation of radiographic imaging by means of factorial experiments
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the optimisation process of radiographic imaging, factorial designed experiments can be applied. The parameters (factors) are varied together instead of one at a time, making it possible to discover interactions between the factors as well as main influences of them on the result variable. A 2k design implies having k number of factors each one set to two different levels (low and high).A computer program, CoCIQ, designed to automatically analyse and evaluate test images of a contrast-detail phantom, was evaluated and adjusted to clinical situations using a flat panel detector. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF) for the X-ray image. It was shown that the program produces IQF with small variations. It was also found that there was a strong linear statistical relation between the computerised evaluation and the evaluation performed by human observers.2k factorial experiments were evaluated by investigating the influence of tube potential, tube loading, focus size and filtration on the result variables IQF, Kerma Area Product (KAP) and effective dose using a flat panel detector. It was found that the result variables were mainly influenced by tube loading, tube potential and filtration. Interactions between tube potential and filtration as well as between tube loading and filtration were observed, too. This work demonstrates that accepted knowledge was reproduced and that the effects of interactions between parameters were revealed.Extended 2k experiments were then applied at three different optimisation procedures. Two studies were performed using a flat panel detector for lumbar spine radiography. The aim was to find optimal settings for tube potential, system sensitivity and filtration for different sized patients and, in a separate study, to investigate the effect of the image post processing parameters and the possibility for dose reduction by adjusting these. The parameters are ROI (Region Of Interest) density, gamma, detail contrast enhancement, unsharp masking, kernel size and noise compensation.After determining the optimal settings from these experiments, X-ray images of the lumbar spine of an Alderson phantom were acquired and evaluated in a visual grading analysis (VGA).The results illustrated that the image quality was maintained at a lower effective dose by operating with a reduced tube potential and increased sensitivity of the X-ray system.The experiments on image post process parameters revealed their influence on image quality and indicated that image quality could be improved by changing the settings of the process parameters.Factorial experiments were also performed, using a multislice CT scanner to investigate the possibility for dose reduction at paediatric head examinations. An anthropomorphic phantom simulating a one-year-old child was scanned using different settings of tube potential, tube loading and reconstruction filter.The study showed that a 25 % reduction of dose was possible with maintained image quality by reducing the tube loading.Factorial designed experiments provide an effective method to simultaneously predict the influence of various parameters on image quality and radiation dose in the optimisation in diagnostic radiology.
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- Strandberg, Sara, 1976-
(författare)
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11C-Acetate-PET/CT in Primary Staging of High-Risk Prostate Cancer
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prostate cancer (PC) is the second most common cancer in men worldwide, affecting ~12%. Although most are clinically insignificant low-risk cancers, the more aggressive high-risk cancers require correct staging, prior to curative radiotherapy or surgery. Standard staging procedures and tools include clinical examination, estimated nomogram risk of pelvic lymph node (LN) metastases, and bone scintigraphy (BS). Additional staging information can be obtained with magnetic resonance imaging (MRI), computed tomography (CT) and positron-emission tomography/computed tomography (PET/CT). PET/CT can provide information on both functional and morphological changes.The aims of the present thesis were to investigate the diagnostic and prognostic value of 11C-acetate (ACE)-PET/CT in high-risk PC, and to optimize the ACE-PET protocol. In study I and II, higher detection rates of LN metastases and bone metastases were found with ACE-PET/CT, than with standard methods nomogram risk and BS. The higher ACE uptake in the prostate (prostate lipogenic tumor burden), the higher the risk of suspected LN metastases (N+ disease) on PET/CT. ACE-PET/CT findings correlated better than BS with follow-up data, and influenced therapy in 11-43%. In study III, PET reconstruction algorithm with resolution recovery showed more accurate functional tumor volumes compared to CT, and higher measurements of lipogenic activity, than reconstruction algorithm without resolution recovery. Study IV was part of an interventional radiotherapy study (PARAPLY) on high-risk PC, with addition of image-guided simultaneous integrated boost to delineated prostate tumors and pelvic LN metastases reported in ACE-PET/CT and MRI. Comparative analyses of clinical risk parameters and baseline ACE-PET/CT parameters showed significant associations between nomogram risk and prostate lipogenic tumor burden, between N+ disease on PET/CT and prostate lipogenic tumor burden, but surprisingly not between nomogram risk and N+ disease on PET/CT. PET with resolution recovery was superior in detection of N+ disease.In conclusion, ACE-PET/CT showed a higher detection rate of suspected metastases compared to standard methods clinical nomogram and BS, in high-risk PC. PET reconstruction with resolution recovery seems to improve the diagnostic added value of ACE-PET/CT. Prostate lipogenic tumor burden could serve as a predictor of N+ disease. The prognostic value of ACE-PET/CT remains to be investigated in future studies.
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