Journal of X-Ray Science and Technology - Volume 22, issue 5

Authors: Price, Samantha G. | Silvius, Alexander A. | Izaguirre, Enrique W.

Article Type: Research Article

Abstract: Image guided conformal small animal orthovoltage microirradiators are currently under development to perform radiobiological experiments with preclinical cancer models. An important component of these instruments is the treatment delivery image guidance system, a microelectronic portal imaging device (μEPID). Here, we present the design and implementation of a μEPID, specifically designed and constructed for small animal orthovoltage microirradiators. The μEPID can acquire images in the range of 60 kVp to 320 kVp …x-ray photon energies and can endure high doses from orthovoltage beams without radiation damage. The μEPID can acquire 200 μm resolution images at a rate of 17 frames per second for online in vivo co-registration between irradiation beams and small animal anatomy. An exposure with less than 1% of a 2 Gy treatment field is required for imaging, which is an adequate ratio between imaging dose and treatment dose to avoid undesired irradiation of healthy tissue or alteration of the preclinical cancer model. The μEPID was calibrated for microdosimetry with a precision of 4.1% with respect to an ion chamber, used as a gold standard. To validate the in vivo device performance, irradiations of lung, brain, and xenograft breast cancer preclinical models were performed and analyzed. Show more

Keywords: Preclinical radiobiology, microirradiator, high resolution imaging, orthovoltage imaging

DOI: 10.3233/XST-140445

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 551-567, 2014

Authors: Tracey, Brian H. | Miller, Eric L. | Wu, Yue | Alvino, Christopher | Schiefele, Markus | Al-Kofahi, Omar

Article Type: Research Article

Abstract: While recent years have seen considerable progress in image denoising, the leading techniques have been developed for digital photographs or other images that can have very different characteristics than those encountered in X-ray applications. In particular here we examine X-ray backscatter (XBS) images collected by airport security systems, where images are piecewise smooth and edge information is typically more correlated with objects while texture is dominated by statistical noise in the detected signal. …In this paper, we show how multiple estimates for a denoised XBS image can be combined using a variational approach, giving a solution that enhances edge contrast by trading off gradient penalties against data fidelity terms. We demonstrate the approach by combining several estimates made using the non-local means (NLM) algorithm, a widely used patch-based denoising method. The resulting improvements hold the potential for improving automated analysis of low-SNR X-ray imagery and can be applied in other applications where edge information is of interest. Show more

Keywords: X-ray backscatter, image denoising, non-local means

DOI: 10.3233/XST-140446

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 569-586, 2014

Authors: Chikawa, Jun-ichi | Mouri, Yoshitaka | Shima, Hiroki | Yamada, Kousaku | Yamamoto, Hitoshi | Yamamoto, Shingo

Article Type: Research Article

Abstract: Time variations of elemental concentrations and their abnormalities due to breast cancer have been observed along single hair strands by X-ray fluorescence excited by synchrotron radiation. The renal-controlled elements Ca, Sr, S, K, Cl, Br and P have upper and lower levels associated with gating and closing of ion channels in the hair-making cells. The Ca lower level is normal. In cases of Ca deficiency, with a decrease from the normal, store-operated Ca channel gating occurs …so as to keep the hair Ca at the normal, and paradoxically high Ca levels near or at the upper level are produced by PTH-operated channel gating of the cells. Chronic Ca deficiency shows a temporal pattern along the hair consisting of a long-term duration of the upper [Ca] level, 10-month long decay to the lower level and abrupt increase to the upper level. The observation for hair from breast-cancer patients also shows the upper Ca level for the time period well before detection, and suggests that cancer is always generated at the long-lasting [Ca] upper level and the hair [Ca] decreases gradually toward the lower level with the cancer growth. This decay of [Ca] is accompanied by those of [Sr] and [K]. Their different decay forms can be explained by parathyroid hormone related peptide (PTHrP) in serum secreted from the cancer having 150 times longer dwell time on the PTH receptors than that of PTH. Patient hair has a memory for the entire cancer process from the state before cancer generation, and the pattern can be distinguished from concentration variation due to the chronic Ca deficiency without cancer, leading to a criterion for cancer detection by the ratio of [Sr]/[Ca]. The hair analysis is useful for early detection of cancer. Show more

Keywords: Hair and serum elements, Ca deficiency, ion channels, PTH, PTHrP, breast cancer, Sr/Ca ratio

DOI: 10.3233/XST-140447

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 587-603, 2014

Authors: Xu, Ji-Fei | Wu, Xing-Wang | Wang, Wan-Qin | Kong, Ling-Ling | Wu, Li-Ming | Wang, Fan

Article Type: Research Article

Abstract: PURPOSE: To explore the value of diffusion-weighted imaging (DWI) and magnetic resonance imaging (MRI) on the follow-up of nasopharyngeal carcinoma (NPC) after radiotherapy. MATERIAL AND METHODS: Eighty-three NPC patients after radiotherapy were divided into two groups: 4 cases of residual tumor and 33 cases of non-residual within 6 months, the cases of recurrent and non-recurrent were 5 and 41 over 6 months, respectively. MRI and DWI imaging of these cases were closely analyzed, and …the apparent diffusion coefficient (ADC) of the nasopharyngeal residual mass and nasopharyngeal wall thickening, skull base destruction and lateral pterygoid muscle were measured. RESULTS: The ADC of the lateral pterygoid muscle was (1.501 ± 0.069) × 10^{ - 3} mm^{2} /s in 83 cases. The ADCs of the non-residual group, residual group, non-recurrent group and recurrent group were (1.843 ± 0.133.4) × 10^{ - 3} mm^{2} /s, (1.097 ± 0.183) × 10^{ - 3} mm^{2} /s, (1.884 ± 0.134) × 10^{ - 3} mm^{2} /s and (0.787 ± 0.067) × 10^{ - 3} mm^{2} /s respectively.The ADCs of the residual group and recurrent group were lower than that of the lateral pterygoid muscle, while the ADCs of the non-residual group and non-recurrent group were higher than that of the lateral pterygoid muscle.The differences were statistically significant (P < 0.05). CONCLUSION: DWI can provide qualitative and quantitative information about the tumor cellular level; it can also identify residual, local fibrosis and recurrence after NPC radiotherapy sensitively and accurately by measuring the ADC of the region of interest. Show more

Keywords: Magnetic resonance imaging, diffusion, nasopharyngeal neoplasms, radiotherapy

DOI: 10.3233/XST-140448

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 605-612, 2014

Authors: Al Qaroot, Bashar | Hogg, Peter | Twiste, Martin | Howard, David

Article Type: Research Article

Abstract: BACKGROUND: Patients with vertebral column deformations are exposed to high risks associated with ionising radiation exposure. Risks are further increased due to the serial X-ray images that are needed to measure and asses their spinal deformation using Cobb or superimposition methods. Therefore, optimising such X-ray practice, via reducing dose whilst maintaining image quality, is a necessity. OBJECTIVES: With a specific focus on lateral thoraco-lumbar images for Cobb and superimposition measurements, …this paper outlines a systematic procedure to the optimisation of X-ray practice. METHODS: Optimisation was conducted based on suitable image quality from minimal dose. Image quality was appraised using a visual-analogue-rating-scale, and Monte-Carlo modelling was used for dose estimation. The optimised X-ray practice was identified by imaging healthy normal-weight male adult living human volunteers. RESULTS: The optimised practice consisted of: anode towards the head, broad focus, no OID or grid, 80 kVp, 32 mAs and 130 cm SID. CONCLUSION: Images of suitable quality for laterally assessing spinal conditions using Cobb or superimposition measurements were produced from an effective dose of 0.05 mSv, which is 83% less than the average effective dose used in the UK for lateral thoracic/lumbar exposures. This optimisation procedure can be adopted and use for optimisation of other radiographic techniques. Show more

Keywords: Optimisation of X-ray imaging, lateral thoraco-lumbar imaging, exposure dose reduction, image quality preservation, Cobb method, superimposition method

DOI: 10.3233/XST-140449

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 613-625, 2014

Authors: Tokala, Krishna T. | Piao, Daqing | Xu, Guan

Article Type: Research Article

Abstract: A geometric-sensitivity-difference (GSD) based reconstruction method is demonstrated in fluorescence diffuse optical tomography (FDOT) for improving the depth-localization of objects. The GSD method optimizes the data-model fit based on paired-measurements between source-detector pairs sharing either the source or the detector channel, as comparing to conventional methods that optimize the data-model fit based on un-paired measurements of individual source-detector pairs. This in silico study is limited to continuous-wave and 2-dimension, for a circular-array …outward-imaging geometry of which the native sensitivity of measurement varies strongly with respect to the depth of the object. The outcomes of GSD method are compared to that of two conventional methods: one is the baseline method which does not involve any scheme to compensate the variation of native sensitivity; the other applies a depth-adapted weight to counteract the depth-variance of the native sensitivity. These three methods were evaluated using synthetic data corresponding to the following conditions of the object: (1) Single object with a 3-folds of positive contrast of fluorescence over the background was set at edge-depths of 0.5 mm, 5 mm and 10 mm; (2) Two objects with identical 3-folds of positive or 1/3-folds of negative contrast of fluorescence over the background were set at a fixed edge-depth of 10 mm and different azimuthal separations of 45 degree, 135 degree, and 180 degree; (3) Two objects with identical 3-folds of positive or 1/3-folds of negative contrast of fluorescence over the background were set at a fixed azimuthal separation of 90° and at edge-depths of 0.5 mm, 5 mm and 10 mm. The GSD method outperforms the other two methods in localizing a single anomaly and resolving two anomalies, for the anomaly possessing either the 3 folds positive or 1/3-folds negative contrast of fluorescence over the background. The case of objects with negative contrast over the background has specific implications to imaging zinc-specific fluorophore uptake in prostate. Show more

Keywords: Fluorescence diffuse optical tomography, image reconstruction, continuous-wave, sensitive matrix, geometric-sensitivity-difference

DOI: 10.3233/XST-140450

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 627-643, 2014

Authors: Kuo, Jen-Chen | Lu, Nan-Han | Huang, Yung-Hui | Hshiao, Ming-Hong | Lin, Yao-Nan | Lee, Chen-Chang | Chao, Shih-Yu | Chen, Tai-Been

Article Type: Research Article

Abstract: PURPOSE: This study evaluated and monitored the outcome of angiographic embolization of hepatic carcinoma by real-time C-arm angiographic computed tomography under number of tumors, size of tumors, and patient's age. METHODS AND MARTIALS: In total, 142 patients underwent angiographic embolization of hepatic carcinoma. The control group, 71 patients, underwent conventional angiographic (CA) embolization of hepatic carcinoma. The experimental group, 71 patients, underwent C-arm angiographic computed tomography (CCT) embolization of hepatic carcinoma. The numbers of angiographic …embolization, number of tumors, size of tumors, and patients ages were recorded for comparisons between groups by analysis of variance (ANOVA) with cross-interaction and the chi-square test (cross table). RESULTS: The age ranges were 20–84 and 35–84 years old for the experimental and control groups respectively. Average number of angiographic embolizations of hepatic carcinomas were 2.63 ± 1.84 and 5.32 ± 2.01 for the experimental and control groups. The number of angiographic embolizations under number of tumors, size of tumors, and patients ages between groups were significantly different (P< 0.05). The effective analyses of transcatheter arterial chemoembolization (TACE) by CCT were significant by chi-square test (P< 0.05) under ⩽ 3 cm and patients aged ⩽ 60. CONCLUSION: The main advantage by CCT for undergoing TACE under tumor size smaller than 3 cm and numbers of tumor smaller 3 times were more significantly effective than those by CA. The CCT combined with TACE had high potentially reduced numbers of undergoing TACE. Show more

Keywords: Traditional angiographic embolization, c-arm angiographic computed tomography, ANOVA with Cross-Interaction, Chi-Square Test

DOI: 10.3233/XST-140451

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 645-651, 2014

Authors: Ai, Kai | Gao, Yanhua | Yu, Gang

Article Type: Research Article

Abstract: PURPOSE: To develop a novel scatter correction method without additional patient dose for dual-energy digital mammography (DEDM) to reduce scatter's impacts and enhance microcalcification detectability in dual-energy X-ray subtraction image. METHODS: Combining scatter radiation is lower spatial frequency component and calcifications are sparsely distributed in digital mammogram, we develop a new scatter correction strategy. First, an adaptive sampling scheme is presented to find possible noncalcification (zero calcification) pixels. Then the …maximum likelihood expectation maximization (MLEM) algorithm is applied to evaluate initial scatter surface. The accurate scatter radiation of sampling pixels is obtained by solving dual-energy computational formula with zero calcification constraint and scatter surface constraint. RESULTS: After scatter correction, the scatter-to-primary ratio (SPR) of wedge phantom is reduced from ∼36.0% to ∼3.1% for low-energy (LE) image and ∼29.6% to ∼0.6% for high-energy (HE) image. For step phantom, the SPR is reduced from ∼42.1% and ∼30.3% to ∼3.9% and ∼0.9% for LE and HE image, respectively. The calcification contrast-to-noise ratio is improved by two orders of magnitudes in calcification images. CONCLUSIONS: The proposed method shows an excellent performance on scatter reduction and calcification detection. Compared with hardware based scatter correction strategy, our method need no extra exposure and is easy to implementation. Show more

Keywords: Scatter correction, dual-energy mammography, calcification, monte carlo

DOI: 10.3233/XST-140452

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 653-671, 2014

Authors: Liu, Fenglin | Yu, Hengyong | Cong, Wenxiang | Wang, Ge

Article Type: Research Article

Abstract: The goal is to develop new architectures for computed tomography (CT) which are at an ultra-low-cost for developing countries, especially in rural areas. The proposed general scheme is inspired by the recently developed compressive sensing and interior tomography techniques, where the data acquisition system targets a region of interest (ROI) to acquire limited and truncated data. Similar to linear tomosynthesis, the source and detector are translated in opposite directions but in contrast to conventional …tomosynthesis, our proposal is for either ROI reconstruction with one or more localized linear scans or global reconstruction by combining multiple ROI reconstructions. In other words, the popular slip ring is replaced by a translation based setup, and the instrumentation cost is reduced by a relaxation of the imaging speed requirement. The various translational scanning modes are theoretically analyzed, and the scanning parameters are optimized. The numerical simulation results from different numbers of linear scans confirm the feasibility of the proposed scheme, and suggest two preferred low-end systems for horizontal and vertical patient positions respectively. Ultra-low-cost x-ray CT is feasible with our proposed combination of linear scanning, compressive sensing, and interior tomography. The proposed architecture can be tailored into permanent, movable, or reconfigurable systems as desirable. Advanced image registration and spectral imaging features can be included as well. Show more

Keywords: Computed tomography (CT), linear scanning, compressive sensing, interior tomography, low-cost

DOI: 10.3233/XST-140453

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 673-686, 2014

Authors: Liu, Jie | Lv, Pei-Jie | Wu, Runze | Zhang, Yong-Gao | Hu, Li-Li | Hou, Ping | Gao, Jian-Bo

Article Type: Research Article

Abstract: The contrast medium (CM) induced nephropathy required new CT imaging protocol. This study evaluated the feasibility of low contrast medium (CM) volume and injection flow using aortic dual-energy CT (DECT) angiography with non-linear blending technique. Sixty patients were randomly assigned to two groups: control group (n=30), single-energy CT 70 ml CM at injection rate of 5 ml/s; study group (n=30), DECT mode, 0.5 ml per kg of patient weight CM at injection rate=(weight × 0.5 ml/kg)/(4+scan …time). Non-linear blending technique was used for dual-energy images. Mean attention, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of aorta were compared. The level of visible renal artery branches was scored. There was no significant difference between the two groups in the mean aortic attention, SNR and CNR (all P > 0.05). Significant difference was showed in CM injection rate (p < 0.001) and volume (P < 0.001). The renal artery score had no statistically significant difference (P=0.771). Compared conventional scan and CM injection protocol, DECT with non-linear blending technique maintained the image quality of aortic CT angiography with reduced CM volume and flow rate, which could reduce the risks associated with CM injection. Show more

Keywords: Dual-energy CT, contrast medium, aortic angiography

DOI: 10.3233/XST-140454

Citation: Journal of X-Ray Science and Technology, vol. 22, no. 5, pp. 689-696, 2014