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Journal articles on the topic '4D dynamická CT data'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Ehrhardt, J., T. Frenzel, D. Säring, W. Lu, D. Low, H. Handels, and R. Werner. "Motion Artifact Reducing Reconstruction of 4D CT Image Data for the Analysis of Respiratory Dynamics." Methods of Information in Medicine 46, no. 03 (2007): 254–60. http://dx.doi.org/10.1160/me9040.

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Summary Objectives: Respiratory motion represents a major problem in radiotherapy of thoracic and abdominal tumors. Methods for compensation require comprehensive knowledge of underlying dynamics. Therefore, 4D (= 3D + t) CT data can be helpful. But modern CT scanners cannot scan a large region of interest simultaneously. So patients have to be scanned in segments. Commonly used approaches for reconstructing the data segments into 4D CT images cause motion artifacts. In orderto reduce the artifacts, a new method for 4D CT reconstruction is presented. The resulting data sets are used to analyze respiratory motion. Methods: Spatiotemporal CT image sequences of lung cancer patients were acquired using a multi-slice CT in cine mode during free breathing. 4D CT reconstruction was done by optical flow based temporal interpolation. The resulting 4D image data were compared with data generated bythe commonly used nearest neighbor reconstruction. Subsequent motion analysis is mainly concerned with tumor mobility. Results: The presented optical flow-based method enables the reconstruction of 3D CT images at arbitrarily chosen points of the patient’s breathing cycle. A considerable reduction of motion artifacts has been proven in eight patient data sets. Motion analysis showed that tumor mobility differs strongly between the patients. Conclusions: Due to the proved reduction of motion artifacts, the optical flow-based 4D CT reconstruction offers the possibility of high-quality motion analysis. Because the method is based on an interpolation scheme, it additionally has the potential to enable the reconstruction of 4D CT data from a lesser number of scans.

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Gill, Gurman, and Reinhard R. Beichel. "Lung Segmentation in 4D CT Volumes Based on Robust Active Shape Model Matching." International Journal of Biomedical Imaging 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/125648.

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Dynamic and longitudinal lung CT imaging produce 4D lung image data sets, enabling applications like radiation treatment planning or assessment of response to treatment of lung diseases. In this paper, we present a 4D lung segmentation method that mutually utilizes all individual CT volumes to derive segmentations for each CT data set. Our approach is based on a 3D robust active shape model and extends it to fully utilize 4D lung image data sets. This yields an initial segmentation for the 4D volume, which is then refined by using a 4D optimal surface finding algorithm. The approach was evaluated on a diverse set of 152 CT scans of normal and diseased lungs, consisting of total lung capacity and functional residual capacity scan pairs. In addition, a comparison to a 3D segmentation method and a registration based 4D lung segmentation approach was performed. The proposed 4D method obtained an average Dice coefficient of0.9773±0.0254, which was statistically significantly better (pvalue≪0.001) than the 3D method (0.9659±0.0517). Compared to the registration based 4D method, our method obtained better or similar performance, but was 58.6% faster. Also, the method can be easily expanded to process 4D CT data sets consisting of several volumes.

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Ghariq, Elyas, Adriënne M. Mendrik, Peter W. A. Willems, Raoul M. S. Joemai, Eidrees Ghariq, Evert-jan Vonken, Matthias J. P. van Osch, and Marianne A. A. van Walderveen. "Total Bolus Extraction Method Improves Arterial Image Quality in Dynamic CTAs Derived from Whole-Brain CTP Data." BioMed Research International 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/603173.

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Background and Purposes. The 320-detector row CT scanner enables visualization of whole-brain hemodynamic information (dynamic CT angiography (CTA) derived from CT perfusion scans). However, arterial image quality in dynamic CTA (dCTA) is inferior to arterial image quality in standard CTA. This study evaluates whether the arterial image quality can be improved by using a total bolus extraction (ToBE) method.Materials and Methods. DCTAs of 15 patients, who presented with signs of acute cerebral ischemia, were derived from 320-slice CT perfusion scans using both the standard subtraction method and the proposed ToBE method. Two neurointerventionalists blinded to the scan type scored the arterial image quality on a 5-point scale in the 4D dCTAs in consensus. Arteries were divided into four categories: (I) large extradural, (II) intradural (large, medium, and small), (III) communicating arteries, and (IV) cerebellar and ophthalmic arteries.Results. Quality of extradural and intradural arteries was significantly higher in the ToBE dCTAs than in the standard dCTAs (extraduralP=0.001, large intraduralP<0.001, medium intraduralP<0.001, and small intraduralP<0.001).Conclusion. The 4D dCTAs derived with the total bolus extraction (ToBE) method provide hemodynamic information combined with improved arterial image quality as compared to standard 4D dCTAs.

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Carr, Renee, Simon MacLean, John Slavotinek, and Gregory Bain. "Four-Dimensional Computed Tomography Scanning for Dynamic Wrist Disorders: Prospective Analysis and Recommendations for Clinical Utility." Journal of Wrist Surgery 08, no. 02 (November 14, 2018): 161–67. http://dx.doi.org/10.1055/s-0038-1675564.

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Background Four-dimensional computed tomography (4D CT) is a rapidly developing diagnostic tool in the assessment of dynamic upper limb disorders. Functional wrist anatomy is incompletely understood, and traditional imaging methods are often insufficient in the diagnosis of dynamic disorders. Technique This study has developed a protocol for 4D CT of the wrist, with the aim of reviewing the clinical utility of this technology in surgical assessment. A Toshiba Aquilion One Vision scanner was used in the protocol, in which two- and three-dimensional “static” images, as well as 4D “dynamic” images were produced and assessed in the clinical context of each patient. These consisted of a series of multiple 7-second movement clips exploring the nature and range of joint motion. Patients and Methods Nineteen patients with symptoms of dynamic instability were included in the study. Patients were assessed clinically by two orthopaedic surgeons, and qualitative data were obtained from radiological interpretation. Results The study demonstrated varied abnormalities of joint movement attributed to a range of wrist pathology, including degenerative arthritis, ligamentous injuries, Kienbock's disease, and pain following previous surgical reconstructive procedures. Interpretation of the 4D CT scan changed the clinical diagnosis in 13 cases (68.4%), including the primary (15.8%) or secondary diagnosis (52.6%). In all cases, the assessment of the dynamic wrist motion assisted in understanding the clinical problem and led to a change in management in 11 cases (57.9%). The mean effective radiation dose for the scan was calculated at 0.26 mSv. Conclusion We have found that the clinical utility of 4D CT lies in its ability to provide detailed information about dynamic joint pathology not seen in traditional imaging, targeting surgical treatment. Limitations to the use of 4D CT scan include lack of availability of the technology, potential radiation dose, and radiographer training requirements, as well as limited understanding of the nature of normal motion.

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Choi, Sanghun, Sujin Yoon, Jichan Jeon, Chunrui Zou, Jiwoong Choi, Merryn H. Tawhai, Eric A. Hoffman, et al. "1D network simulations for evaluating regional flow and pressure distributions in healthy and asthmatic human lungs." Journal of Applied Physiology 127, no. 1 (July 1, 2019): 122–33. http://dx.doi.org/10.1152/japplphysiol.00016.2019.

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This study aimed to introduce a one-dimensional (1D) computational fluid dynamics (CFD) model for airway resistance and lung compliance to examine the relationship between airway resistance, pressure, and regional flow distribution. We employed five healthy and five asthmatic subjects who had dynamic computed tomography (CT) scans (4D CT) along with two static scans at total lung capacity and functional residual capacity. Fractional air-volume change ([Formula: see text]) from 4D CT was used for a validation of the 1D CFD model. We extracted the diameter ratio from existing data sets of 61 healthy subjects for computing mean and standard deviation (SD) of airway constriction/dilation in CT-resolved airways. The lobar mean (SD) of airway constriction/dilation was used to determine diameters of CT-unresolved airways. A 1D isothermal energy balance equation was solved, and pressure boundary conditions were imposed at the acinar region ( model A) or at the pleural region ( model B). A static compliance model was only applied for model B to link acinar and pleural regions. The values of 1D CFD-derived [Formula: see text] for model B demonstrated better correlation with 4D CT-derived [Formula: see text] than model A. In both inspiration and expiration, asthmatic subjects with airway constriction show much greater pressure drop than healthy subjects without airway constriction. This increased transpulmonary pressures in the asthmatic subjects, leading to an increased workload (hysteresis). The 1D CFD model was found to be useful in investigating flow structure, lung hysteresis, and pressure distribution for healthy and asthmatic subjects. The derived flow distribution could be used for imposing boundary conditions of 3D CFD. NEW & NOTEWORTHY A one-dimensional (1D) computational fluid dynamics (CFD) model for airway resistance and lung compliance was introduced to examine the relationship between airway resistance, pressure, and regional flow distribution. The 1D CFD model investigated differences of flow structure, lung hysteresis, and pressure distribution for healthy and asthmatic subjects. The derived flow distribution could be used for imposing boundary conditions of three-dimensional CFD.

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Denby, C. E., K. Chatterjee, R. Pullicino, S. Lane, M. R. Radon, and K. V. Das. "Is four-dimensional CT angiography as effective as digital subtraction angiography in the detection of the underlying causes of intracerebral haemorrhage: a systematic review." Neuroradiology 62, no. 3 (January 4, 2020): 273–81. http://dx.doi.org/10.1007/s00234-019-02349-z.

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Abstract Purpose To determine whether the sensitivity and specificity of four-dimensional CTA (4D-CTA) are equivalent to digital subtraction angiography (DSA) in the detection of underlying vascular abnormalities in patients with intracerebral haemorrhage (ICH). Methods A systematic review of studies comparing 4D-CTA with DSA in the detection of the underlying structural causes of ICH was performed on the literature published between 1998 and 2019. Results We identified a total of 237 articles from PubMed, SCOPUS and Web of Science using the following Medical Subject Headings (MeSH) terms: primary intracerebral haemorrhage, 4D-CTA, DSA, cerebral haemorrhage, angiography, digital subtraction, arteriovenous malformations, 4D, CTA, dynamic-CTA and time-resolved CTA. Following the removal of duplicate publications and articles failing to meet our inclusion criteria, there were four articles potentially viable for analysis. Therefore, there were not sufficient studies to provide a statistically meaningful meta-analysis. Conclusion The review of current literature has demonstrated that there are few published studies comparing 4D-CTA with DSA in spontaneous ICH, with only four suitable studies identified for potential analysis. However, due to the restricted number of patients and high sensitivity and specificity of 3 studies (100%), performing a meta-analysis was not meaningful. Qualitative analysis of the data concluded that 4D-CTA has the diagnostic potential to replace invasive DSA in certain cases with vascular abnormalities. However, further research studies directly comparing 4D-CTA with DSA using larger prospective patient cohorts are required to strengthen the evidence base.

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Albrecht, Moritz, Thomas Vogl, Julian Wichmann, Simon Martin, Jan-Erik Scholtz, Sebastian Fischer, Renate Hammerstingl, et al. "Dynamic 4D-CT Angiography for Guiding Transarterial Chemoembolization: Impact on the Reduction of Contrast Material, Operator Radiation Exposure, Catheter Consumption, and Diagnostic Confidence." RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren 190, no. 06 (May 15, 2018): 513–20. http://dx.doi.org/10.1055/a-0595-7964.

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Purpose This study was carried out to investigate the impact of abdominal dynamic four-dimensional CT angiography (4D-CTA) for guiding transarterial chemoembolization (TACE) on the amount of contrast material used, operator radiation exposure, catheter consumption, and diagnostic confidence. Materials and Methods Written consent was waived for this IRB-approved retrospective study. 29 patients (20 men; mean age: 65.7 ± 11.5 years) with malignant liver lesions underwent 4D-CTA, prior to initial TACE. Time-resolved volume-rendering technique (VRT), maximum-intensity projection (MIP), and multiplanar reconstruction (MPR) series were reconstructed, enabling a direct selective catheterization of the tumor-supplying artery without prior conventional digital subtraction angiography (DSA). 29 patients (16 men; mean age: 69.4 ± 13.9) who underwent traditional TACE served as the control group. The amount of administered contrast media, operator radiation exposure, and catheter consumption during TACE were compared. Two radiologists assessed diagnostic confidence in the exclusion of portal vein thrombosis. Results 4D-CTA TACE resulted in a significant reduction in the amount of contrast media used, compared to traditional TACE (–61.0 ml/ –66.3 % intra-arterial, –12.8 ml/ –13.8 % overall; P < 0.001). The dose-area product indicating operator radiation exposure during intervention was reduced by 50.5 % (P < 0.001), and 0.7 fewer catheters on average were used (P = 0.063), while 4D-CTA data was available to guide TACE. Diagnostic confidence in the exclusion of portal vein thrombosis was significantly enhanced by 4D-CTA, compared to traditional DSA images (scores, 3.9 and 2.4, respectively; P < 0.001). Conclusion Dynamic 4D-CTA enables TACE with a substantially reduced amount of contrast material, decreases operator radiation exposure, and increases diagnostic confidence in the exclusion of portal vein thrombosis. Key points Citation Format

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Kim, F. H., D. Penumadu, P. Patel, X. Xiao, E. J. Garboczi, S. P. Moylan, and M. A. Donmez. "Synchrotron 4-dimensional imaging of two-phase flow through porous media." MRS Advances 1, no. 40 (2016): 2757–61. http://dx.doi.org/10.1557/adv.2016.505.

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ABSTRACTNear real-time visualization of complex two-phase flow in a porous medium was demonstrated with dynamic 4-dimensional (4D) (3D + time) imaging at the 2-BM beam line of the Advanced Photon Source (APS) at Argonne National Laboratory. Advancing fluid fronts through tortuous flow paths and their interactions with sand grains were clearly captured, and formations of air bubbles and capillary bridges were visualized. The intense X-ray photon flux of the synchrotron facility made 4D imaging possible, capturing the dynamic evolution of both solid and fluid phases. Computed Tomography (CT) scans were collected every 12 s with a pixel size of 3.25 μm. The experiment was carried out to improve understanding of the physics associated with two-phase flow. The results provide a source of validation data for numerical simulation codes such as Lattice-Boltzmann, which are used to model multi-phase flow through porous media.

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Garreau, Mireille, Antoine Simon, Dominique Boulmier, Jean-Louis Coatrieux, and Hervé Le Breton. "Assessment of Left Ventricular Function in Cardiac MSCT Imaging by a 4D Hierarchical Surface-Volume Matching Process." International Journal of Biomedical Imaging 2006 (2006): 1–10. http://dx.doi.org/10.1155/ijbi/2006/37607.

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Multislice computed tomography (MSCT) scanners offer new perspectives for cardiac kinetics evaluation with 4D dynamic sequences of high contrast and spatiotemporal resolutions. A new method is proposed for cardiac motion extraction in multislice CT. Based on a 4D hierarchical surface-volume matching process, it provides the detection of the heart left cavities along the acquired sequence and the estimation of their 3D surface velocity fields. A Markov random field model is defined to find, according to topological descriptors, the best correspondences between a 3D mesh describing the left endocardium at one time and the 3D acquired volume at the following time. The global optimization of the correspondences is realized with a multiresolution process. Results obtained on simulated and real data show the capabilities to extract clinically relevant global and local motion parameters and highlight new perspectives in cardiac computed tomography imaging.

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Mitha, Alim P., Benjamin Reichardt, Michael Grasruck, Eric Macklin, Soenke Bartling, Christianne Leidecker, Bernhard Schmidt, et al. "Dynamic imaging of a model of intracranial saccular aneurysms using ultra-high-resolution flat-panel volumetric computed tomography." Journal of Neurosurgery 111, no. 5 (November 2009): 947–57. http://dx.doi.org/10.3171/2009.2.jns08828.

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Object Imaging of intracranial aneurysms using conventional multidetector CT (MDCT) is limited because of nonvisualization of features such as perforating vessels, pulsatile blebs, and neck remnants after clip placement or coil embolization. In this study, a model of intracranial saccular aneurysms in rabbits was used to assess the ultra-high resolution and dynamic scanning capabilities of a prototype flat-panel volumetric CT (fpVCT) scanner in demonstrating these features. Methods Ten New Zealand white rabbits underwent imaging before and after clipping or coil embolization of surgically created aneurysms in the proximal right carotid artery. Imaging was performed using a prototype fpVCT scanner, a 64-slice MDCT scanner, and traditional catheter angiography. In addition to the slice data and 3D views, 4D dynamic views, a capability unique to fpVCT, were also created and reviewed. The images were subjectively compared on 1) 4 image quality metrics (spatial resolution, noise, motion artifacts, and aneurysm surface features); 2) 4 posttreatment features reflecting the metal artifact profile of the various imaging modalities (visualization of clip or coil placement, perianeurysmal clip/coil anatomy, neck remnant, and white-collar sign); and 3) 2 dynamic features (blood flow pattern and aneurysm pulsation). Results Flat-panel volumetric CT provided better image resolution than MDCT and was comparable to traditional catheter angiography. The surface features of aneurysms were demonstrated with much higher resolution, detail, and clarity by fpVCT compared with MDCT and angiography. Flat-panel volumetric CT was inferior to both MDCT and angiography in terms of image noise and motion artifacts. In fpVCT images, the metallic artifacts from clips and coils were significantly fewer than those in MDCT images. As a result, clinically important information about posttreatment aneurysm neck remnants could be derived from fpVCT images but not from MDCT images. Time-resolved dynamic sequences were judged slightly inferior to conventional angiography but superior to static MDCT images. Conclusions The spatial resolution, surface anatomy visualization, metal artifact profile, and 4D dynamic images from fpVCT are superior to those from MDCT. Flat-panel volumetric CT demonstrates aneurysm surface features to better advantage than angiography and is comparable to angiography in metal artifact profile. Even though the temporal resolution of fpVCT is not quite as good as that of angiography, fpVCT images yield clinically important anatomical information about aneurysm surface features and posttreatment neck remnants not attainable with either angiography or MDCT images.

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Choi, Jang-Hwan, and Sooyeul Lee. "Real-Time Tumor Motion Tracking in 3D Using Planning 4D CT Images during Image-Guided Radiation Therapy." Algorithms 11, no. 10 (October 11, 2018): 155. http://dx.doi.org/10.3390/a11100155.

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In this paper we propose a novel method for tracking the respiratory phase and 3D tumor position in real time during treatment. The method uses planning four-dimensional (4D) computed tomography (CT) obtained through the respiratory phase, and a kV projection taken during treatment. First, digitally rendered radiographs (DRRs) are generated from the 4DCT, and the structural similarity (SSIM) between the DRRs and the kV projection is computed to determine the current respiratory phase and magnitude. The 3D position of the tumor corresponding to the phase and magnitude is estimated using non-rigid registration by utilizing the tumor path segmented in the 4DCT. This method is evaluated using data from six patients with lung cancer and dynamic diaphragm phantom data. The method performs well irrespective of the gantry angle used, i.e., a respiration phase tracking accuracy of 97.2 ± 2.5%, and tumor tracking error in 3D of 0.9 ± 0.4 mm. The phantom study reveals that the DRRs match the actual projections well. The time taken to track the tumor is 400 ± 53 ms. This study demonstrated the feasibility of a technique used to track the respiratory phase and 3D tumor position in real time using kV fluoroscopy acquired from arbitrary angles around the freely breathing patient.

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Giovenco, Elena, Jean-Philippe Perrillat, Eglantine Boulard, Andrew King, Nicolas Guignot, and Yann Le Godec. "Quantitative 4D X-ray microtomography under extreme conditions: a case study on magma migration." Journal of Synchrotron Radiation 28, no. 5 (August 16, 2021): 1598–609. http://dx.doi.org/10.1107/s1600577521007049.

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X-ray computed tomography (XCT) is a well known method for three-dimensional characterization of materials that is established as a powerful tool in high-pressure/high-temperature research. The optimization of synchrotron beamlines and the development of fast high-efficiency detectors now allow the addition of a temporal dimension to tomography studies under extreme conditions. Presented here is the experimental setup developed on the PSICHE beamline at SOLEIL to perform high-speed XCT in the Ultra-fast Tomography Paris–Edinburgh cell (UToPEc). The UToPEc is a compact panoramic (165° angular aperture) press optimized for fast tomography that can access 10 GPa and 1700°C. It is installed on a high-speed rotation stage (up to 360° s−1) and allows the acquisition of a full computed tomography (CT) image with micrometre spatial resolution within a second. This marks a major technical breakthrough for time-lapse XCT and the real-time visualization of evolving dynamic systems. In this paper, a practical step-by-step guide to the use of the technique is provided, from the collection of CT images and their reconstruction to performing quantitative analysis, while accounting for the constraints imposed by high-pressure and high-temperature experimentation. The tomographic series allows the tracking of key topological parameters such as phase fractions from 3D volumetric data, and also the evolution of morphological properties (e.g. volume, flatness, dip) of each selected entity. The potential of this 4D tomography is illustrated by percolation experiments of carbonate melts within solid silicates, relevant for magma transfers in the Earth's mantle.

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Wink, Nicole, Christoph Panknin, and Timothy D. Solberg. "Phase versus amplitude sorting of 4D-CT data." Journal of Applied Clinical Medical Physics 7, no. 1 (February 15, 2006): 77–85. http://dx.doi.org/10.1120/jacmp.2027.25373.

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Wink, Nicole M., Christoph Panknin, and Timothy D. Solberg. "Phase versus amplitude sorting of 4D-CT data." Journal of Applied Clinical Medical Physics 7, no. 1 (February 21, 2006): 77–85. http://dx.doi.org/10.1120/jacmp.v7i1.2198.

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Han, D., J. Bayouth, and X. Wu. "Detection and Measuring Geometric Errors within 4D-CT Image Data." International Journal of Radiation Oncology*Biology*Physics 75, no. 3 (November 2009): S435—S436. http://dx.doi.org/10.1016/j.ijrobp.2009.07.997.

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Smaxwil, Constantin, Philip Aschoff, Gerald Reischl, Mirjam Busch, Joachim Wagner, Julia Altmeier, Oswald Ploner, and Andreas Zielke. "[18F]fluoro-ethylcholine-PET Plus 4D-CT (FEC-PET-CT): A Break-Through Tool to Localize the “Negative” Parathyroid Adenoma. One Year Follow Up Results Involving 170 Patients." Journal of Clinical Medicine 10, no. 8 (April 13, 2021): 1648. http://dx.doi.org/10.3390/jcm10081648.

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Background: The diagnostic performance of [18F]fluoro-ethylcholine-PET-CT&4D-CT (FEC-PET&4D-CT) to identify parathyroid adenomas (PA) was analyzed when ultrasound (US) or MIBI-Scan (MS) failed to localize. Postsurgical one year follow-up data are presented. Methods: Patients in whom US and MS delivered either incongruent or entirely negative findings were subjected to FEC-PET&4D-CT and cases from July 2017 to June 2020 were analyzed, retrospectively. Cervical exploration with intraoperative PTH-monitoring (IO-PTH) was performed. Imaging results were correlated to intraoperative findings, and short term and one year postoperative follow-up data. Results: From July 2017 to June 2020 in 171 FEC-PET&4D-CTs 159 (92.9%) PAs were suggested. 147 patients already had surgery, FEC-PET&4D-CT accurately localized in 141; false neg. 4, false pos. 2, global sensitivity 0.97; accuracy 0.96, PPV 0.99. All of the 117 patients that already have completed their 12-month postoperative follow up had normal biochemical parameter, i.e., no signs of persisting disease. However, two cases may have a potential for recurrent disease, for a cure rate of at least 98.3%. Conclusion: FEC-PET&4D-CT shows unprecedented results regarding the accuracy localizing PAs. The one-year-follow-up data demonstrate a high cure rate. We, therefore, suggest FEC-PET-CT as the relevant diagnostic tool for the localization of PAs when US fails to localize PA, especially after previous surgery to the neck.

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Michalski, D., G. Bednarz, M. Huq, G. Kubicek, and D. Heron. "Synchronized-averaging of 4D CT Data Set For Improved Quality Treatment Planning CT Scan." International Journal of Radiation Oncology*Biology*Physics 81, no. 2 (October 2011): S818. http://dx.doi.org/10.1016/j.ijrobp.2011.06.1440.

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Ahmed, Naseer, Sankar Venkataraman, Kate Johnson, Keith Sutherland, and Shaun K. Loewen. "Does Motion Assessment With 4-Dimensional Computed Tomographic Imaging for Non–Small Cell Lung Cancer Radiotherapy Improve Target Volume Coverage?" Clinical Medicine Insights: Oncology 11 (January 1, 2017): 117955491769846. http://dx.doi.org/10.1177/1179554917698461.

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Introduction: Modern radiotherapy with 4-dimensional computed tomographic (4D-CT) image acquisition for non–small cell lung cancer (NSCLC) captures respiratory-mediated tumor motion to provide more accurate target delineation. This study compares conventional 3-dimensional (3D) conformal radiotherapy (3DCRT) plans generated with standard helical free-breathing CT (FBCT) with plans generated on 4D-CT contoured volumes to determine whether target volume coverage is affected. Materials and methods: Fifteen patients with stage I to IV NSCLC were enrolled in the study. Free-breathing CT and 4D-CT data sets were acquired at the same simulation session and with the same immobilization. Gross tumor volume (GTV) for primary and/or nodal disease was contoured on FBCT (GTV_3D). The 3DCRT plans were obtained, and the patients were treated according to our institution’s standard protocol using FBCT imaging. Gross tumor volume was contoured on 4D-CT for primary and/or nodal disease on all 10 respiratory phases and merged to create internal gross tumor volume (IGTV)_4D. Clinical target volume margin was 5 mm in both plans, whereas planning tumor volume (PTV) expansion was 1 cm axially and 1.5 cm superior/inferior for FBCT-based plans to incorporate setup errors and an estimate of respiratory-mediated tumor motion vs 8 mm isotropic margin for setup error only in all 4D-CT plans. The 3DCRT plans generated from the FBCT scan were copied on the 4D-CT data set with the same beam parameters. GTV_3D, IGTV_4D, PTV, and dose volume histogram from both data sets were analyzed and compared. Dice coefficient evaluated PTV similarity between FBCT and 4D-CT data sets. Results: In total, 14 of the 15 patients were analyzed. One patient was excluded as there was no measurable GTV. Mean GTV_3D was 115.3 cm3 and mean IGTV_4D was 152.5 cm3 ( P = .001). Mean PTV_3D was 530.0 cm3 and PTV_4D was 499.8 cm3 ( P = .40). Both gross primary and nodal disease analyzed separately were larger on 4D compared with FBCT. D95 (95% isodose line) covered 98% of PTV_3D and 88% of PTV_4D ( P = .003). Mean dice coefficient of PTV_3D and PTV_4D was 84%. Mean lung V20 was 24.0% for the 3D-based plans and 22.7% for the 4D-based plans ( P = .057). Mean heart V40 was 12.1% for the 3D-based plans and 12.7% for the 4D-based plans ( P = .53). Mean spinal cord Dmax was 2517 and 2435 cGy for 3D-based and 4D-based plans, respectively ( P = .019). Mean esophageal dose was 1580 and 1435 cGy for 3D and 4D plans, respectively ( P = .13). Conclusions: IGTV_4D was significantly larger than GTV_3D for both primary and nodal disease combined or separately. Mean PTV_3D was larger than PTV_4D, but the difference was not statistically significant. The PTV_4D coverage with 95% isodose line was inferior, indicating the importance of incorporating the true size and shape of the target volume. Relatively less dose was delivered to spinal cord and esophagus with plans based on 4D data set. Dice coefficient analysis for degree of similarity revealed that 16% of PTVs from both data sets did not overlap, indicating different anatomical positions of the PTV due to tumor/nodal motion during a respiratory cycle. All patients with lung cancer planned for radical radiotherapy should have 4D-CT simulation to ensure accurate coverage of the target volumes.

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Colgan, R., J. McClelland, D. McQuaid, P. M. Evans, D. Hawkes, J. Brock, D. Landau, and S. Webb. "Planning lung radiotherapy using 4D CT data and a motion model." Physics in Medicine and Biology 53, no. 20 (September 30, 2008): 5815–30. http://dx.doi.org/10.1088/0031-9155/53/20/017.

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Zhang, G. G., K. Latifi, T. Huang, V. Feygelman, E. G. Moros, C. W. Stevens, and T. J. Dilling. "Normalization of 4D-CT-Derived Ventilation Data to Facilitate Intrapatient Comparisons." International Journal of Radiation Oncology*Biology*Physics 87, no. 2 (October 2013): S692. http://dx.doi.org/10.1016/j.ijrobp.2013.06.1835.

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Huang, Tzung-Chi, Kuei-Ting Chou, Yao-Ching Wang, and Geoffrey Zhang. "Motion Freeze for Respiration Motion Correction in PET/CT: A Preliminary Investigation with Lung Cancer Patient Data." BioMed Research International 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/167491.

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Purpose. Respiratory motion presents significant challenges for accurate PET/CT. It often introduces apparent increase of lesion size, reduction of measured standardized uptake value (SUV), and the mismatch in PET/CT fusion images. In this study, we developed the motion freeze method to use 100% of the counts collected by recombining the counts acquired from all phases of gated PET data into a single 3D PET data, with correction of respiration by deformable image registration.Methods. Six patients with diagnosis of lung cancer confirmed by oncologists were recruited. PET/CT scans were performed with Discovery STE system. The 4D PET/CT with the Varian real-time position management for respiratory motion tracking was followed by a clinical 3D PET/CT scan procedure in the static mode. Motion freeze applies the deformation matrices calculated by optical flow method to generate a single 3D effective PET image using the data from all the 4D PET phases.Results. The increase in SUV and decrease in tumor size with motion freeze for all lesions compared to the results from 3D and 4D was observed in the preliminary data of lung cancer patients. In addition, motion freeze substantially reduced tumor mismatch between the CT image and the corresponding PET images.Conclusion. Motion freeze integrating 100% of the PET counts has the potential to eliminate the influences induced by respiratory motion in PET data.

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Laurent, R., M. Salomon, J. Henriet, M. Sauget, R. Gschwind, and L. Makovicka. "DATA PROCESSING USING ARTIFICIAL NEURAL NETWORKS TO IMPROVE THE SIMULATION OF LUNG MOTION." Biomedical Engineering: Applications, Basis and Communications 24, no. 06 (December 2012): 563–71. http://dx.doi.org/10.4015/s1016237212500524.

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To optimize the delivery in lung radiation therapy, a better understanding of the tumor motion is required, on one hand, to have a better tumor-targeting efficiency, and on the other hand to avoid as much as possible normal tissues. The four-dimensional computed tomography (4D-CT) allows to quantify tumor motion, but due to artifacts, it introduces biases and errors in tumor localization. Despite this disadvantage, we propose a method to simulate lung motion based on data provided by the 4D-CT for several patients. To reduce uncertainties introduced by the 4D-CT scan, we conveniently treated data using artificial neural networks. More precisely, our approach consists of a data augmentation technique. The data resulting from this processing step are then used to build a training set for another artificial neural network that learns the lung motion. To improve the learning accuracy, we have studied the number of phases required to precisely describe the displacement of each point. Thus, from 1118 points scattered across five patients and defined over 8 or 10 phases, we obtained 5800 points from 50 phases. After training, the network is used to compute the positions of 40 points from five other patients on 10 phases. These points allow to quantify the prediction performance. In comparison with the original data, the ones issued from our treatment process provide a significant increase of the prediction accuracy: an average improvement of 16% can be observed. The motion computed for several points by the neural network that has learnt the lung one exhibits an hysteresis near the one given by the 4D-CT, with an error smaller than 1 mm in the cranio-caudal axis.

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Guo, B., W. He, J. Eom, S. De, X. Xu, and C. Shi. "SU-FF-J-107: 4D Predictive Patient-Specific Anatomical Model Based On 4D CT Data: A Feasibility Study." Medical Physics 36, no. 6Part7 (June 2009): 2501. http://dx.doi.org/10.1118/1.3181399.

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Martin, Rachael, and Tinsu Pan. "Target volume and artifact evaluation of a new data-driven 4D CT." Practical Radiation Oncology 7, no. 5 (September 2017): e345-e354. http://dx.doi.org/10.1016/j.prro.2017.01.014.

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Wang, Hui, Yong Yin, Hong Jun Wang, and Deng Wang Li. "A New Deformable Image Registration Method Based on B-Spline for Clinical 4D CT." Applied Mechanics and Materials 195-196 (August 2012): 566–71. http://dx.doi.org/10.4028/www.scientific.net/amm.195-196.566.

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Four-dimensional computed tomography (4D CT) which clearly includes the temporal changes in anatomy during the diagnosis, planning, and delivery of radiotherapy has great promise. Deformable image registration has the potential to reduce the geometrical uncertainty of the target, and makes it possible to signally improve the treatment accuracy by optimizing treatment in response to anatomical uncertainty. In this paper, we used Scale Invariant Feature Transform (SIFT) algorithm to extract landmark points, and we proposed a registration method based on B-Spline model, then used a limited memory quasi-Newton method to optimize the system, also calls the limited memory BFGS (L-BFGS) method. The deformable registration model B-Spline model can derive the images at all intermediate phases from sets of 3D images acquired at a few known phase points. Because 4D CT can track the location of region of interest (ROI) and tumors over several respiratory cycles, so 4D CT can make the apparent size of the tumor which is caused by breathing motion more accurate. The method is evaluated on 10 4D-CT data sets of patients in a breathing cycle.

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Clark, Darin, Alexandra Badea, Yilin Liu, G. Allan Johnson, and Cristian T. Badea. "Registration-based segmentation of murine 4D cardiac micro-CT data using symmetric normalization." Physics in Medicine and Biology 57, no. 19 (September 13, 2012): 6125–45. http://dx.doi.org/10.1088/0031-9155/57/19/6125.

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Barfett, Joe J., Jorn Fierstra, Peter W. A. Willems, David J. Mikulis, and Timo Krings. "Intravascular Functional Maps of Common Neurovascular Lesions Derived From Volumetric 4D CT Data." Investigative Radiology 45, no. 7 (July 2010): 370–77. http://dx.doi.org/10.1097/rli.0b013e3181e1939d.

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Zhang, Yu, Pew-Thian Yap, Guorong Wu, Qianjin Feng, Jun Lian, Wufan Chen, and Dinggang Shen. "Resolution enhancement of lung 4D-CT data using multiscale interphase iterative nonlocal means." Medical Physics 40, no. 5 (May 1, 2013): 051916. http://dx.doi.org/10.1118/1.4802747.

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Helf, Eike, Oliver Waletzko, Christian Mehrens, Ralf Rohn, and Andreas Block. "Impact of 4D CT for treatment planning of moving targets: a computer-based biological evaluation." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 665–68. http://dx.doi.org/10.1515/cdbme-2017-0140.

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AbstractThis study deals with comparison of conventional and 4D CT (GE Lightspeed) planning on the tumour control probability (TCP), using the TCP model of the AAPM-Report Task Group 166. In the first step a VMAT treatment plan was calculated (Varian Eclipse 13.7) on basis of conventional CT data. This treatment plan was transferred to the complete 4D CT, which represents the tumour volume in motion. Due to the increased volume and the resulting decrease of tumour coverage the TCP went down from 97,6% to 91,2%. After adding an internal target volume (ITV, ICRU 62) to the conventional CT according to our clinical protocols (1,0 cm cc and 0,3 cm axial plane) the TCP increased to 98,0% when applying the conventional plan to the 4D CT. This finding demonstrates the need of 4D CT for moving tumours in chest and abdomen region.Average IPs with increasing width have been created to evaluate the impact on the TCP and the non-malignant tissue. Our observations had shown that heart, lung and spinal cord radiation exposure did not correlate to chosen respiration segment. This could be explained by the extremely slight ratio of the planning target volume and the irradiated normal tissue.This procedure enables us to evaluate the efficacy of treatment plans. Furthermore, optimizing trials like the influence of respiration-gated RT, setting individual margins and fitting planning objectives and parameters are still under investigation.

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Zhang, G. G., K. Latifi, T. Huang, V. Feygelman, C. W. Stevens, T. J. Dilling, E. G. Moros, W. van Elmpt, and A. Dekker. "Effects of Noise in 4D CT on Deformable Image Registration and Derived Ventilation Data." Practical Radiation Oncology 3, no. 2 (April 2013): S7—S8. http://dx.doi.org/10.1016/j.prro.2013.01.025.

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Boccalatte, L. A., N. L. Gómez, M. Musumeci, A. M. Galich, C. Collaud, and M. F. Figari. "18F-choline PET/4D CT in hyperparathyroidism: correlation between biochemical data and study parameters." Revista Española de Medicina Nuclear e Imagen Molecular (English Edition) 39, no. 5 (September 2020): 273–78. http://dx.doi.org/10.1016/j.remnie.2020.07.003.

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Wang, Tingting, Lei Cao, Wei Yang, Qianjin Feng, Wufan Chen, and Yu Zhang. "Adaptive patch-based POCS approach for super resolution reconstruction of 4D-CT lung data." Physics in Medicine and Biology 60, no. 15 (July 17, 2015): 5939–54. http://dx.doi.org/10.1088/0031-9155/60/15/5939.

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Werner, René, Jan Ehrhardt, Rainer Schmidt, and Heinz Handels. "Patient-specific finite element modeling of respiratory lung motion using 4D CT image data." Medical Physics 36, no. 5 (April 7, 2009): 1500–1511. http://dx.doi.org/10.1118/1.3101820.

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Shen, Zhengwen, Huafeng Wang, Weiwen Xi, Xiaogang Deng, Jin Chen, and Yu Zhang. "Multi-phase simultaneous segmentation of tumor in lung 4D-CT data with context information." PLOS ONE 12, no. 6 (June 16, 2017): e0178411. http://dx.doi.org/10.1371/journal.pone.0178411.

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Marx, Mirko, Jan Ehrhardt, René Werner, Heinz-Peter Schlemmer, and Heinz Handels. "Simulation of spatiotemporal CT data sets using a 4D MRI-based lung motion model." International Journal of Computer Assisted Radiology and Surgery 9, no. 3 (December 10, 2013): 401–9. http://dx.doi.org/10.1007/s11548-013-0963-y.

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Resmana, Tito Aditya, Darmini Darmini, and Sigit Wijokongko. "Analisis Image Noise dan Nilai Dosis Radiasi Penggunaan Aplikasi Care Dose 4D dan Non Care Dose 4D pada Pesawat MSCT Siemens." Jurnal Imejing Diagnostik (JImeD) 3, no. 2 (July 10, 2017): 258–65. http://dx.doi.org/10.31983/jimed.v3i2.3196.

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Background : One effective technique is contained in a CT Scan to decrease the amount of radiation dose that is received in the use of automatic exposure control (AEC). AEC system of Siemens equipment is called Care Dose 4D. The research is based on unused of the application Care Dose 4D on CT Scan Imaging. The purpose of the research is to determine the differences of image noise and the differences of radiation doses (CTDI) using care dose 4D and Non Care Dose 4D in Siemens MSCT.Methods :The research was quantitative study with experimental approaches that is tested on four water phantom size type. Analysts data is done by statistical tests of Paired T-Test Samples to test the hypothesis and the level difference image information. In this statistical analysis is determined the level of confidence (level of Significance) with a value of α = 0.05.Results : On the using of Nasopharing protocol for children with 130 kV and 130 mAs parameters, using of Care Dose 4D has ability to decrease the image noise value is compared with non Care Dose 4D application. While the adult Nasopharing protocol with 130 kV and 220 mAs parameters, Care Dose 4D doesn’t provide enough impact in the reduction of image noise value if compared with conventional techniques or without using Care Dose 4D applications. Using of children nasopharing protocol application Care Dose 4D even increase radiation closes high enough value in CTDI vol that is 5,03 mGy, but using Nasopharing Care Dose 4D applications for adult can decrease radiation doses high enough value in CTDIvol, that is 2,64 mGy.Conclusion : On the use of children nasopharing protocol application Care Dose 4D even increase radiation closes high enough value in CTDI vol that is 5,03 mGy, while the adult Nasopharing using Care Dose 4D applications can decrease radiation doses high enough value in CTDIvol, that is 2,64 mGy.

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Eklund, Anders, Mats Andersson, and Hans Knutsson. "True 4D Image Denoising on the GPU." International Journal of Biomedical Imaging 2011 (2011): 1–16. http://dx.doi.org/10.1155/2011/952819.

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The use of image denoising techniques is an important part of many medical imaging applications. One common application is to improve the image quality of low-dose (noisy) computed tomography (CT) data. While 3D image denoising previously has been applied to several volumes independently, there has not been much work done on true 4D image denoising, where the algorithm considers several volumes at the same time. The problem with 4D image denoising, compared to 2D and 3D denoising, is that the computational complexity increases exponentially. In this paper we describe a novel algorithm for true 4D image denoising, based on local adaptive filtering, and how to implement it on the graphics processing unit (GPU). The algorithm was applied to a 4D CT heart dataset of the resolution 512 × 512 × 445 × 20. The result is that the GPU can complete the denoising in about 25 minutes if spatial filtering is used and in about 8 minutes if FFT-based filtering is used. The CPU implementation requires several days of processing time for spatial filtering and about 50 minutes for FFT-based filtering. The short processing time increases the clinical value of true 4D image denoising significantly.

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Muehlen, Iris, Stephan P. Kloska, Philipp Gölitz, Philip Hölter, Lorenz Breuer, Hendrik Ditt, and Arnd Doerfler. "Noninvasive Collateral Flow Velocity Imaging in Acute Ischemic Stroke: Intraindividual Comparison of 4D-CT Angiography with Digital Subtraction Angiography." RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren 191, no. 09 (January 21, 2019): 827–35. http://dx.doi.org/10.1055/a-0825-6660.

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Purpose The collateral status can be defined not only by its morphological extent but also by the velocity of collateral filling characterized by the relative filling time delay (rFTD). The aim of our study was to compare different methods of noninvasive visualization of rFTD derived from 4D-CT angiography (4D-CTA) with digital substraction angiography (DSA) and to investigate the correlation between functional and morphological collateral status on timing-invariant CTA. Materials and Methods 50 consecutive patients with acute occlusion in the M1 segment who underwent DSA for subsequent mechanical recanalization after multimodal CT were retrospectively analyzed. 4D-CTA data were used to assess the relative filling time delay between the A1 segment of the affected hemisphere and the sylvian branches distal to the occluded M1 segment using source images (4D-CTA-SI) and color-coded flow velocity visualization with prototype software (fv-CTA) in comparison to DSA. The morphological extent of collaterals was assessed on the basis of the Collateral Score (CS) on temporal maximum intensity projections (tMIP) derived from CT perfusion data. Results There was very good correlation of rFTD between fv-CTA and DSA (n = 50, r = 0.9, p < 0.05). Differences of absolute rFTD values were not significant. 4D-CTA-SI and DSA also showed good correlation (n = 50, r = 0.6, p < 0.05), but mean values of rFTD were significantly different (p < 0.05). rFTD derived from fvCTA and CS derived from timing-invariant CTA showed a negative association (R = – 0.5; P = 0.000). In patients with a favorable radiological outcome defined by a TICI score of 2b or 3, there was a significant negative correlation of CS and mRS at 3 months (R = – 0.4, P = 0.006). Conclusion Collateral status plays an important role in the outcome in stroke patients. rFTD derived from 4D-CTA is a suitable parameter for noninvasive imaging of collateral velocity, which correlates with the morphological extent of collaterals. Further studies are needed to define valid thresholds for rFTD and to evaluate the diagnostic and prognostic value. Key points: Citation Format

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Ionascu, D., S. Park, M. Mamede-Lewer, V. Gerbaudo, J. Killoran, and R. Berbeco. "SU-FF-I-142: Quantifying the 4D PET/CT Volumetric Distortions: A 4D Dynamic Phantom Study Based On Pre-Recorded Patient Data." Medical Physics 36, no. 6Part5 (June 2009): 2467. http://dx.doi.org/10.1118/1.3181263.

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Gao, Yuanyuan, Zhengwen Shen, Yu Zhang, and Wufan Chen. "Tumor Segmentation for Lung 4D-CT Data Using Graph Cuts with Inter-Phase Shape Prior." Journal of Medical Imaging and Health Informatics 6, no. 3 (June 1, 2016): 634–39. http://dx.doi.org/10.1166/jmihi.2016.1727.

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Latifi, Kujtim, Tzung-Chi Huang, Vladimir Feygelman, Mikalai M. Budzevich, Eduardo G. Moros, Thomas J. Dilling, Craig W. Stevens, Wouter van Elmpt, Andre Dekker, and Geoffrey G. Zhang. "Effects of quantum noise in 4D-CT on deformable image registration and derived ventilation data." Physics in Medicine and Biology 58, no. 21 (October 11, 2013): 7661–72. http://dx.doi.org/10.1088/0031-9155/58/21/7661.

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Fang, Shiting, Huafeng Wang, Yueliang Liu, Minghui Zhang, Wei Yang, Qianjin Feng, Wufan Chen, and Yu Zhang. "Super-resolution reconstruction of 4D-CT lung data via patch-based low-rank matrix reconstruction." Physics in Medicine & Biology 62, no. 20 (October 3, 2017): 7925–37. http://dx.doi.org/10.1088/1361-6560/aa8a48.

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Ruppertshofen, Heike, Sven Kabus, and Bernd Fischer. "Tensor grid based image registration with application to ventilation estimation on 4D CT lung data." International Journal of Computer Assisted Radiology and Surgery 5, no. 6 (April 23, 2010): 583–93. http://dx.doi.org/10.1007/s11548-010-0419-6.

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Forsberg, Daniel, Maria Lindblom, Petter Quick, and Håkan Gauffin. "Quantitative analysis of the patellofemoral motion pattern using semi-automatic processing of 4D CT data." International Journal of Computer Assisted Radiology and Surgery 11, no. 9 (March 1, 2016): 1731–41. http://dx.doi.org/10.1007/s11548-016-1357-8.

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Fishman, E. K. "CT scanning and data post-processing with 3D and 4D reconstruction: Are we there yet?" Diagnostic and Interventional Imaging 101, no. 11 (November 2020): 691–92. http://dx.doi.org/10.1016/j.diii.2020.10.005.

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Chon, Deokiee, Kenneth C. Beck, Ranae L. Larsen, Hidenori Shikata, and Eric A. Hoffman. "Regional pulmonary blood flow in dogs by 4D-X-ray CT." Journal of Applied Physiology 101, no. 5 (November 2006): 1451–65. http://dx.doi.org/10.1152/japplphysiol.01131.2005.

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ECG-triggered computed tomography (CT) was used during passage of iodinated contrast to determine regional pulmonary blood flow (PBF) in anesthetized prone/supine dogs. PBF was evaluated as a function of height within the lung (supine and prone) as a function of various normalization methods: raw unit volume data (PBFraw) or PBF normalized to regional fraction air (PBFair), fractional non-air (PBFgm), or relative number of alveoli (PBFalv). The coefficient of variation of PBFraw, PBFair, PBFalv, and PBFgm ranged between 30 and 50% in both lungs and both body postures. The position of maximal flow along the height of the lung (MFP) was calculated for PBFraw, PBFair, PBFalv, and PBFgm. Only PBFgm showed a significantly different MFP height supine vs. prone (whole lung: 2.60 ± 1.08 cm supine vs. 5.08 ± 1.61 cm prone, P < 0.01). Mean slopes (ml/min/gm water content/cm) of PBFgm were steeper supine vs. prone in the right (RL) but not left lung (LL) (RL: −0.65 ± 0.29 supine vs. −0.26 ± 0.25 prone, P < 0.02; LL: −0.47 ± 0.21 supine vs. −0.32 ± 0.26 prone, P > 0.10). Mean slopes of PBFgm vs. vertical lung height were not different prone vs. supine above this vertical height of MFP (VMFP), but PBFgm slopes were steeper in the supine position below the VMFP in the RL. We conclude that PBFgm distribution was posture dependent in RL but not LL. Support of the heart may play a role. We demonstrate that normalization factors can lead to differing attributions of gravitational effects on PBF heterogeneity.

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Lingaiah, Ramaa, Md Abbas Ali, Ummay Kulsum, Muhtasim Aziz Muneem, Karthick Raj Mani, Sharif Ahmed, Md Shakilur Rahman, and M. Salahuddin. "GTV volume estimation using different mode of computer tomography for lung tumors in stereotactic body radiation therapy." Polish Journal of Medical Physics and Engineering 25, no. 1 (March 1, 2019): 29–34. http://dx.doi.org/10.2478/pjmpe-2019-0005.

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Abstract Aim: To estimate the Gross Tumor Volume (GTV) using different modes (axial, helical, slow, KV-CBCT & 4D-CT) of computed tomography (CT) in pulmonary tumors. Materials & Methods: We have retrospectively included ten previously treated case of carcinoma of primary lung or metastatic lung using Stereotactic Body Radiation Therapy (SBRT) in this study. All the patients underwent 4 modes of CT scan Axial, Helical, Slow & 4D-CT using GE discovery 16 Slice PET-CT scanner and daily KV-CBCT for the daily treatment verification. For standardization, all the patients underwent different modes of scan using 2.5 mm slice thickness, 16 detectors rows and field of view of 400mm. Slow CT was performed using axial mode scan by increasing the CT tube rotation time (typically 3 – 4 sec.) as per the breathing period of the patients. 4D-CT scans were performed and the entire respiratory cycle was divided into ten phases. Maximum Intensity Projections (MIP), Minimum Intensity Projections (MinIP) and Average Intensity Projections (AvIP) were derived from the 10 phases. GTV volumes were delineated for all the patients in all the scanning modes (GTVAX - Axial, GTVHL - Helical, GTVSL – Slow, GTVMIP -4DCT and GTVCB – KV-CBCT) in the Eclipse treatment planning system version 11.0 (M/S Varian Medical System, USA). GTV volumes were measured, documented and compared with the different modes of CT scans. Results: The mean ± standard deviation (range) for MIP, slow, axial, helical & CBCT were 36.5 ± 40.5 (2.29 – 87.0), 35.38 ± 39.52 (2.1 – 82), 31.95 ± 37.29 (1.32 – 66.9), 28.98 ± 33.36 (1.01 – 65.9) & 37.16 ± 42.23 (2.29 – 92). Overall underestimation of helical scan and axial scan compared to MIP is 21% and 12.5%. CBCT and slow CT volume has a good correlation with the MIP volume. Conclusion: For SBRT in lung tumors better to avoid axial and helical scan for target delineation. MIP is a still a golden standard for the ITV delineation, but in the absence of 4DCT scanner, Slow CT and KV-CBCT data may be considered for ITV delineation with caution.

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Zhang, Geoffrey G., Kujtim Latifi, Kaifang Du, Joseph M. Reinhardt, Gary E. Christensen, Kai Ding, Vladimir Feygelman, and Eduardo G. Moros. "Evaluation of the ΔV 4D CT ventilation calculation method using in vivo xenon CT ventilation data and comparison to other methods." Journal of Applied Clinical Medical Physics 17, no. 2 (March 2016): 550–60. http://dx.doi.org/10.1120/jacmp.v17i2.5985.

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van der Geld, Y., S. Senan, J. van Sörnsen de Koste, H. van Tinteren, R. Underberg, B. Slotman, and E. Lagerwaard. "PD-120 Determining lung tumor mobility for radiotherapy planning: Acomparison of fluoroscopy and 4D CT data." Lung Cancer 49 (July 2005): S102. http://dx.doi.org/10.1016/s0169-5002(05)80453-2.

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Latifi, Kujtim, Vladimir Feygelman, Eduardo G. Moros, Thomas J. Dilling, Craig W. Stevens, and Geoffrey G. Zhang. "Normalization of Ventilation Data from 4D-CT to Facilitate Comparison between Datasets Acquired at Different Times." PLoS ONE 8, no. 12 (December 17, 2013): e84083. http://dx.doi.org/10.1371/journal.pone.0084083.

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