bluuebunny/crossref_metadata_2025 huggingface dataset:
How different molarities of oleic acid as enhancer exert its	effect on optical clearing of skin tissue in vitro
Authors: Jiang Jingying , Wang Ruikang K.
Published: November 2024

Currently, there is an increasing interest in tissue optical clearing by the use of hyperosmotic agents due to its consequence in increasing light penetration into tissue. This has shown a great potential in enhancing the capabilities of non-invasive light-based diagnostic and imaging techniques. In this study, we introduce the oleic acid, a mono-unsaturated fatty acid, as an enhancer and investigate how its different molarities exert its effect on optical clearing of skin tissue in vitro. Experimental results from near infrared spectroscopy and mass loss measurement showed that OA01PG40, i.e. 0.1 M oleic acid in 40% propylene glycol, obtained the best clearing effect. Meanwhile, it is noticed that the molarity of oleic acid in propylene glycol is important when used in optical clearing of skin tissue in vitro.
Interpretation of microfibril angle distributions in wood using	microdiffraction experiments on single cells
Authors: Sarén Matti-P. , Peura Marko , Serimaa Ritva
Published: November 2024

Partially crystalline cellulose microfibrils are wound helically around the longitudinal axis of the wood cell. Microfibril angle distributions were determined using x-rays from single cells and slices of wood. Differences in results are discussed using model calculations, which are based on diffraction conditions. Microfibril angle distributions (MFA) in single wood cells were measured through a bordered pit using microbeam produced by capillary optics and synchrotron radiation. For all cells measured, the MFA distribution was asymmetric and narrow with full-width at half-maximum around 18 degrees. The mean MFA distributions of slices of wood were determined using a conventional sealed x-ray tube. MFA distributions of single cells differed from those determined from slices of wood. On the basis of model calculations the differences were attributed to the variation in MFA distributions of different cells of the wood sample, in the orientation of the cells, and in the cross-sectional shape of the cells. These factors are hard to take into account in data analysis, thus microdiffraction experiments offer a unique means for studies of the detailed structure of single wood cells.
Study of an adaptive bolus chasing CT angiography
Authors: Bai Er-Wei , Bennett James R. , McCabe Robert , Sharafuddin Melhem J. , Bai Henri , Halloran John , Vannier Michael , Liu Ying , Wang Chenglin , Wang Ge
Published: November 2024

To improve imaging quality and to reduce contrast dose and radiation exposure, an adaptive bolus chasing CT angiography was proposed so that the bolus peak position and the imaging aperture can be synchronized. The performance of the proposed adaptive bolus chasing CT angiography was experimentally evaluated based on the actual bolus dynamics. The experimental results show that the controlled table position and the bolus peak position were highly consistent. The results clearly demonstrate that the proposed adaptive bolus chasing CT angiography that synchronizes the bolus peak position with the imaging aperture by a simple adaptive system is computationally and clinically feasible. Similar techniques may also be applied to conventional angiography to improve imaging quality and to reduce contrast dose and/or radiation exposure.
X-ray CT metal artifacts reduction through curvature based	sinogram inpainting
Authors: Gu Jianwei , Zhang Li , Yu Guoqiang , Xing Yuxiang , Chen Zhiqiang
Published: November 2024

We present a sinogram inpainting approach for X-ray computed tomography (CT) with the intent of reducing metal artifacts, where "inpainting" is a synonym for "image interpolation". Metal artifacts arise in CT when rays traverse the high attenuating objects such as metal bodies and portions of projection become unavailable. In this paper, we propose a sinogram inpainting method based on Euler's elastica and curvature for metal artifacts reduction, in which the unavailable data are regarded as an occlusion and can be inpainted inside the inpainting domain based on elastica interpolants. Numerical simulations demonstrate that, compared to conventional interpolation methods, the algorithm proposed connects the unavailable projection region more smoothly and accurately, and thus better reduces metal artifacts and more accurately reveals cross section structures, especially in the immediate neighborhood of the metallic objects.
X-ray image enhancement based on the dyadic wavelet	transform
Authors: Qi Zhihua , Zhang Li , Xing Yuxiang , Li Shuanglei
Published: November 2024

X-ray images are often of low contrast due to the subtle distinction of attenuation coefficients and scatter effect, which makes it difficult to distinguish signals from background. This paper proposes an image enhancement algorithm using the multi-scale dyadic wavelet transform. The algorithm includes two steps: 1) In order to enhance contrast, a non-linear mapping is performed on wavelet coefficients at different scales. Inhibition factors are then applied to reduce the impact of scatter; 2) In order to reduce the negative impact of noise amplification from the first step, wavelet coefficients are classified into two categories: irregular coefficients and edge-related and regular coefficients, and then filtered with different schemes for each category. Experimental results demonstrate that this algorithm effectively enhance the contrast of x-ray images. Examination is also done on CT reconstructions from multi-view projection data processed by the proposed method and significant improvement of image quality is observed. Our results are expected to offer great help to follow-up detection and recognition tasks.
Minimum detection window and inter-helix PI-line with	triple-source helical cone-beam scanning
Authors: Zhao Jun , Jiang Ming , Zhuang Tiange , Wang Ge
Published: November 2024

In this paper, we propose a helical cone-beam scanning configuration of triple symmetrically located X-ray sources, and study minimum detection windows to extend the traditional Tam-Danielsson window for exact image reconstruction. For three longitudinally displaced scanning helices of the same radius and a source location on any helix, the corresponding minimum detection window is bounded by the most adjacent turns respectively selected from the other two helices. The height of our proposed minimum detector window is only 1/3 of that in the single helix case. Associated with proposed minimum detection windows, we define the inter-helix PI-line and establish its existence and uniqueness property: through any point inside the triple helices, there exists one and only one inter-helix PI-line for any pair of the helices. Furthermore, we prove that cone-beam projection data from such a triple-source helical scan are sufficient for exact image reconstruction. Although there are certain redundancies among those projection data, the redundant part cannot be removed by shrinking the detector window without violating the data sufficiency condition. Those results are important components for development of exact or quasi-exact image reconstruction algorithms in the case of triple-source helical cone-beam scanning in the future.
DQE measurements in magnification X-ray imaging
Authors: Zhang Da , Rong John , Chu Robert , Chen Wei R. , Liu Hong
Published: November 2024

In radiographic imaging, the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE) are usually determined and expressed as functions of spatial frequency in the detector plane. Values thus specified would be insufficient for describing the performance of the imaging system when magnification is used to offer better spatial resolution. We are presenting a computation of DQE at the object plane as descriptor. The derivation of this quantity from measurements at the detector and object planes is presented. With source-to-image receptor distance (SID) remains constant, changes in the DQE with magnification are shown to be determined primarily by the corresponding changing MTF. Measurements with a small animal X-ray imaging system of constant SID agreed with theoretical analysis.
The FDK algorithm with an expanded definition domain for cone-beam	reconstruction preserving oblique line integrals
Authors: Li Liang , Kang Kejun , Chen Zhiqiang , Zhang Li , Xing Yuxiang , Wang Ge
Published: November 2024

The FDK algorithm is a widely used filtered-backprojection (FBP) algorithm for 3D image reconstruction from circular cone-beam projections. In this paper, we redefine the x-ray transform and expand the definition domain of FDK reconstruction to all points in 3D space. We prove that the FDK reconstruction, in this expanded definition domain, preserves the value of integrals along oblique lines in an angular range larger than the original FDK reconstruction proven by Rodet et al. Based on this result, an efficient FBP-type method is proposed to synthesize radiographs from cone-beam projections. Finally, numerical experiments are done to validate this stereogram synthesis algorithm.
Dual energy computed tomography for explosive detection
Authors: Ying Zhengrong , Naidu Ram , Crawford Carl R.
Published: November 2024

Single energy computed tomography (CT) scanners use measurements of densities to detect explosives in luggage. It is desirable to apply dual energy techniques to these CT scanners to obtain atomic number measurements to reduce false alarm rates. However, the direct application of existing dual energy techniques has practical problems, such as, approximation errors and lack of boundary constraints in dual energy decomposition, image artifacts, and x-ray spectral drifts. In this paper, we present methods to reduce these problems. The methods include constrained dual energy decomposition, adaptive scatter correction, nonlinear filtering of decomposed projections, and real-time image-based correction for x-ray spectral drifts. We demonstrate the effectiveness of the methods using simulated data and real data obtained from a commercial dual energy CT scanner.
Technical advancement and clinical prospective of proton	radiotherapy
Authors: Zhong Yubin , Li Jiamin
Published: November 2024

Proton therapy is a new and advanced external beam radiotherapy technique where the energetic ionizing particles, protons, are directed to the target turmors. This report reviews the basic principle and the advantages of proton therapy in terms superior dose distribution as compared to photon therapy. The suitable clinical application of this new technique is also described based on the experiences at Wanjie Hospital in China. It is reasonable to expect that, with the rapid advancements in equipment and planning methods, proton therapy will become an important clinical choice in cancer treatments in near future.
Study on the performance of recommended standards in the	diagnostic radiology units of the hospitals affiliated to the Mazandaran	University of Medical Sciences
Authors: Rahimi Seyed Ali
Published: November 2024

Background and purpose: Access to health care is the basic right of people. Diagnostic radiology is one of the main procedures which appropriate planning and management are essential. Maintenance and supervision of the operating conditions following the recommended standards play a key role in ensuring the benefit of the instruments. Data show that more than 80% of patients referred to hospitals need radiology image. Improper service causes unnecessary duplications of radiation and even wrong diagnosis, as a results threatening health of the patients. Lack of protective barrier leads to the hazardous radiation exposure to the staff and patients. Improper use of radiation instrumentation, such as asymmetry of X-ray field, defects in collimators, lack of adjusting ray field, low quality or defective developing machine, lack of proper protective barrier, low quality film and drugs, can cause severe damage. The purpose of this study was to assess the conditions of radiology units at Mazandaran University hospitals and compare them with the standards of ICRU NCRP and ICRP.

Materials and methods: The following six categories of conditions of radiography centers affiliated to the Mazandaran University of Medical Sciences were studied for the types and the rates of deficiency. (1) Conditions of radiography room; (2) Conditions of radiography instruments; (3) Conditions of control room; (4) Conditions of dark room; (5) Conditions of installation; and (6) Conditions of the other facilities.

Results: The results showed that, none of the dark rooms are standard, and do not have proper alarm signal. In 63% of these units there was no tiling system for staff protection from radiation. Defects in radiography room, protective barrier and lack looking rays were 60%, 51% and 47% respectively. Referring to the obtained data, periodic supervision, and obeying of the standards are necessary. Data were collected through, observation, interviewing and questionnaire. The data show that the radiology units are far from the international standards; only about 50% of the conditions on average are satisfactory.

Conclusion: Overall, about 50% of the units are deficient in the six categories, comparing with international standards. The improvement of the conditions is needed.
Robustness of a phase-retrieval approach based on	phase-attenuation duality
Authors: Wu Xizeng , Liu Hong , Yan Aimin
Published: November 2024

In this work we study the robustness of a phase-retrieval approach, which is based on the phase-attenuation duality. We discuss the critical importance of retrieval robustness for diagnostic imaging in perspective of the radiation dose limit and lesion-detection sensitivity. We compare the robustness of duality-based phase retrieval with that of the transport of intensity equation (TIE)-based phase-retrieval approach, and we show by means of simulation that the duality-based retrieval approach is superior to the TIE-based approach. A generalization of TIE per se is presented for incorporating the coherence degree of incident x-ray wavefield.
Optimization and evaluation of a three-dimensional diffuse optical	tomography system for brain imaging
Authors: Wang Qiang , Liu Zhao , Jiang Huabei
Published: November 2024

Diffuse optical tomography (DOT) is an emerging imaging modality for non-invasive brain functional mapping. The hemodynamic and metabolic images derived from optical properties are unique and complementary to those of magnetic resonance imaging (MRI) and positron emission tomography (PET). In this paper we present a procedure to optimize the number of sources and detectors as well as mesh size that can be used for image reconstruction in reflectance mode through a series of numerical simulations and tissue-like phantom experiments where both the absorption and scattering images are obtained. In these studies, we also tested the system ability to image a target with small size as well as with low contrast relative to the background medium. Image results were quantitatively analyzed and discussed.
Correction algorithm based on fuzzy modeling for the distorted	image in the digital X-ray scanner system
Authors: Baek Jaeho , Park Mignon
Published: November 2024

The Digital X-ray Scanner System (DX-Scanner) using the Multichannel Ionization Chamber (MIC) has many advantages. On the other hand, the scanned medical image has distorted pixels because of unsuitable integration time at the nonlinear acceleration period and vibration of the AC servo motor during scanning a patient in the system.

This paper proposes a correction algorithm based on fuzzy modeling. The proposed correction algorithm can correct the distorted medical image during scanning. Fuzzy modeling uses a clustering method for the nonlinear motor velocity in the algorithm. The algorithm reconstructs the normal medical image lines by calculating the moving distance every integration time during acceleration period of AC servo motor. The algorithm analyzes by comparing the distance of the acceleration period with the distance of the uniform velocity period in every integration time. The velocity for the acceleration period is able to be compensated via this algorithm. In addition, several image processing procedures are also included in the algorithm.

When the proposed correction algorithm is applied to the test pattern for checking the image resolution, its effectiveness is verified at scanning of 3.5 cm/sec, 7 cm/sec, and 14 cm/sec. The corrected image is a better image.
Laser photothermal effects on tumor vasculature using laser	Doppler flowmetry
Authors: Deans Abby , Hess Linda , Koss Michael , Liu Hong , Chen Wei R.
Published: November 2024

Laser Doppler perfusion monitors have been used to study blood flow in tissue. They are useful tools to understand and monitor vascular changes during the treatment of lesions. In addition, lasers have been used in the treatment of cancers through photothermal and photochemical interactions, and the effects of laser treatment in many cases depend on the vasculature of the tumors and their surrounding tissue. In this study, an 805-nm laser was used to non-invasively irradiate subcutaneous mammary and prostatic tumors in rats. The perfusions on the tumor surface, the overlying skin, and underlying muscle tissues were measured using laser Doppler flowmetry during the near-infrared laser treatment. The perfusion probe was fitted into a 16-gauge needle so that the probe could be inserted into the target tissue for the perfusion measurement. The perfusion on the surface of the tumor decreased at the beginning of the laser irradiation, followed by a significant increase. Then, the perfusion was decreased again to a pre-treatment level. The perfusion of the skin tissue and muscle tissue, however, remained relatively unchanged during laser irradiation. Our experimental results indicate that laser photothermal effects could be monitored by the laser Doppler flowmetry and that tumor vascular information could be used to improve the effectiveness of the laser treatment of cancer.
A practical reconstruction method for dual energy computed	tomography
Authors: Zhang Guowei , Cheng Jianping , Zhang Li , Chen Zhiqiang , Xing Yuxiang
Published: November 2024

Quantitative imaging based on dual energy computed tomography (DECT) is useful in both medical and industrial areas. However, the dependence of the attenuation coefficient on X-ray energy and the polychromatic property of X-ray beams bring obstacles for dual energy image reconstruction. In this paper, attenuation coefficient function μ(E) is approximated with the basis material model. And X-ray spectra which govern the projection functions are estimated from transmission measurements. With these two foundations, we obtain a practical reconstruction method for DECT. The distribution of effective atomic number, electron density, and linear attenuation coefficient at any desirable energy can be reconstructed using the proposed method. Numerical simulations and practical experiments were conducted to evaluate the accuracy and practicability of the method.
Optimal densitometry wavelengths that maximize radiochromic film	sensitivity while minimizing OD growth and temperature sensitivity	artifacts
Authors: Ali Imad , Ahmad Salahuddin , Joel Suresh , Williamson Jeffrey F.
Published: November 2024

It is well known that optical density (OD) of the radiochromic film (RCF) continues to grow after exposure at rates that have a complex dependence on dose, temperature, and densitometry wavelength. Dose rate and fractionation artifacts associated with variations in OD growth may limit the accuracy achievable by RCF dosimetry in brachytherapy and external beam applications, particularly at low doses (<5 Gy) and low dose rates (<10 cGy/h) where OD growth and sensitivity effects are large. To identify densitometry wavelengths that minimize OD growth artifacts and enhance RCF sensitivity at low doses, we have investigated Model MD-55-2 RCF response as a function of densitometry wavelength, irradiation-to-densitometry time interval, dose and temperature. Using a Perkin Elmer spectrophotometer, the absorption spectrum in the 500–700 nm range was measured for doses ranging from 1–100 Gy, over post-irradiation times from 1 h to 60 days. An empirical model with time-independent, fast and slow growth components was used to fit single exposure data and the dependence of the resulting best-fit parameters on dose and densitometry wavelength was investigated. RCF OD variation with temperature in the range 22–40� was measured. Wavelengths in the 660–690 nm range were found to minimize the dose-dependence of OD post-exposure growth. Densitometry wavelengths in the range of 670–680 nm enhance RCF sensitivity and show small variations in OD with temperature in the range from 22–40�. Compared to 633 nm light, 675 nm densitometry reduces OD growth at 1 Gy from 70% to 10% over a period of nearly 1174.0 h relative to the initial OD measured at 1.7 h post-irradiation. In addition, RCF sensitivity is nearly doubled at this wavelength for all dose levels.
NPS characterization and evaluation of a cone beam CT breast	imaging system
Authors: Benítez Ricardo Betancourt , Ning Ruola , Conover David , Liu Shaohua
Published: November 2024

The Noise Power Spectrum (NPS) is a function that yields information about the spatial frequency composition of noise in images obtained by a system. It is evaluated by calculating the absolute value squared of the noise image and normalizing it with respect to the voxel and matrix sizes. Consequently, the NPS has been one of the physical characteristics that is commonly used to quantitatively measure the physical performance of a system. In this article, we evaluated the NPS of a Cone Beam CT Breast Imaging system by considering the following factors. First, we evaluated its symmetry around the x- and y-axis along with the influence of the cone angle and the matrix size on the NPS. Then, an analytical curve was suggested to best represent the NPS. Second, we analyzed the influence on the NPS of a set of seven parameters, namely the pixel size, exposure level, kVp value, number of projections acquired, voxel size, back projection filter, and the reconstruction algorithm employed. In addition, since the breast induced scattering in the image, we investigated the effect of the scattering-correction algorithm used in this system. Finally, we evaluated the uniformity of the NPS as a function of z with the matrix center located at {r = 0 mm}. The results demonstrate that the proposed curve is an ideal candidate that best represents the NPS. Hence, two parameters, the amplitude (A) and the width (σ), can be used to characterize the curve. The results also demonstrate that the voxel size and the cone angle are the only two parameters investigated in this study that do not affect the NPS. On the other hand, the matrix and pixel sizes, the back-projection filter and the reconstruction algorithm, the exposure level and the scattering correction, all influence the NPS. Finally, the results of the last part of this investigation suggest that this imaging system does not have a 3D isotropic noise distribution along the z-axis; yielding less noisy images at around z = 0.00 m and z = 80 mm.
Parametric boundary reconstruction algorithm for industrial CT	metrology application
Authors: Yin Zhye , Khare Kedar , De Man Bruno
Published: November 2024

High-energy X-ray computed tomography (CT) systems have been recently used to produce high-resolution images in various nondestructive testing and evaluation (NDT/NDE) applications. The accuracy of the dimensional information extracted from CT images is rapidly approaching the accuracy achieved with a coordinate measuring machine (CMM), the conventional approach to acquire the metrology information directly. On the other hand, CT systems generate the sinogram which is transformed mathematically to the pixel-based images. The dimensional information of the scanned object is extracted later by performing edge detection on reconstructed CT images. The dimensional accuracy of this approach is limited by the grid size of the pixel-based representation of CT images since the edge detection is performed on the pixel grid. Moreover, reconstructed CT images usually display various artifacts due to the underlying physical process and resulting object boundaries from the edge detection fail to represent the true boundaries of the scanned object.

In this paper, a novel algorithm to reconstruct the boundaries of an object with uniform material composition and uniform density is presented. There are three major benefits in the proposed approach. First, since the boundary parameters are reconstructed instead of image pixels, the complexity of the reconstruction algorithm is significantly reduced. The iterative approach, which can be computationally intensive, will be practical with the parametric boundary reconstruction. Second, the object of interest in metrology can be represented more directly and accurately by the boundary parameters instead of the image pixels. By eliminating the extra edge detection step, the overall dimensional accuracy and process time can be improved. Third, since the parametric reconstruction approach shares the boundary representation with other conventional metrology modalities such as CMM, boundary information from other modalities can be directly incorporated as prior knowledge to improve the convergence of an iterative approach. In this paper, the feasibility of parametric boundary reconstruction algorithm is demonstrated with both simple and complex simulated objects. Finally, the proposed algorithm is applied to the experimental industrial CT system data.
Cone Beam Breast CT noise reduction using 3D adaptive Gaussian	filtering
Authors: Zhang Xiaohua , Ning Ruola , Yang Dong
Published: November 2024

In Cone Beam Breast CT (CBBCT) imaging, noise causes degradation of three dimensional breast images, impeding correct diagnosis of breast cancer. Within Feldkamp's cone beam reconstruction framework, applying weighted reconstruction filters to the projection images after pre-processing procedures has long been used to reduce noise and improve image quality. However, CBBCT noise is distributed across frequencies along with the useful signal. Various reconstruction filters working in the frequency domain suppress noise as well as the edge detail signal. Based on fuzzy c-means clustering and the two-dimensional histogram analysis of a large number of clinical CBBCT data, we managed to discriminate fatty stroma, glandular tissues and the transition areas between these tissues by the local mean and standard deviation values. We also proposed a three-dimensional Gaussian filtering scheme to reduce the noise in 3D reconstructed images adaptively without much blurring of detail signal.
Light distribution in intravascular low level laser therapy	applying mathematical simulation: A comparative study
Authors: Li Xiaosong , Cheng Gang , Huang Naiyan , Wang Lei , Liu Fanguang , Gu Ying
Published: November 2024

Intravascular low level laser therapy (ILLLT) has been applied in the treatment of many diseases for about twenty years. However, much fundamental work has not been done on its dosimetry. The study was designed to compare the difference of light distribution during ILLLT between using flat end fiber and optical fiber coupled with cylindrical light diffuser. Light distribution of He-Ne laser was processed by Monte Carlo model. The laser output was 5 mW. The diameter of both optical fibers was 400 μ. Four tissue optical parameters were chosen for simulation. The results showed that optical parameters of blood are important to determine the distribution of laser energy. The highest power density could increase to over 5000 mW/cm $^{2}$ using flat end fiber. And the laser energy was absorbed by the blood cells in very small area before the tip of flat end fiber. But when using optical fiber coupled with cylindrical light diffuser, the highest power density was about 100 mW/cm $^{2}$ . More volume of blood cells could be irradiated by laser light. In summary, optical fiber coupled with cylindrical light diffuser is superior to flat end fiber at the aspect of increasing the volume of irradiated blood and decreasing unwanted damage to blood cells during intravascular low level laser therapy.
Improving visibility of X-ray phase-contrast imaging with Wiener filtering
Authors: Gong Shaorun , Gao Feng , Zhou Zhongxing
Published: November 2024

To investigate the degrading effects of the physical parameters on the in-line X-ray phase-contrast imaging (XPCi), a simulation tool based on the Fresnel/Kirchhoff diffraction integral was firstly developed with comprehensively considering effects of the source-to-sample (S-S) and sample-to-detector (S-D) distances, the practical characteristics of a polychromatic and finite size source, the point spread function (PSF) of the fluorescent screen and the spatial resolution of the detector on the theoretical phase-contrast pattern. By a comparison between the simulative profile and the experimental one under the commonly-used parameters, an acceptable consistency has been demonstrated in despite of the deviation between the theoretically-predicted contrast (0.188) and the original experimental one (0.12). From the simulations, it is apparently observed that the fine interference pattern has been severely degraded by the finite spatial resolution, and will inevitably be further deteriorated by the system noise in practice. Since the image quality of the X-ray phase-contrast imaging is strongly dependent on the physical parameters of the system, a model-based deblurring procedure to upgrade the image visibility is preferably desired. As a simple restoration way, a Wiener filter was then introduced to offer an optimal tradeoff between the contrast preservation and the noise suppression. Finally, to minimize the deviation resulting from the finite spatial resolution, one-dimensional interpolation was performed by positioning the set square at a tiny angle to the vertical direction. The result after the Wiener-filtering-based deblurring has shown a considerably improved profile visibility: the processed experimental contrast (0.156) increased by 30% as compared to the original one (0.12) in company with the increase in the signal-to-noise ratio (SNR) by 0.9dB. With the trend of the post-filtered experimental contrast to the theoretical one, it could be motivated that higher visibility would be achieved with the introduction of more precise blurring mask and noise spectrum estimation.
Quantitative evaluation of increase in surface dose by	immobilization thermoplastic masks and superficial dosimetry using Gafchromic	EBT film and Monte Carlo calculations
Authors: Ali Imad , Matthiesen Chance , Algan Ozer , Thompson Spencer , Bogardus Carl , Herman Terence , Ahmad Salahuddin
Published: November 2024

Purpose: To investigate the increase in surface dose under immobilization thermoplastic masks by measurements and calculation in the build-up region using Gafchromic films and Monte Carlo simulation.

Materials and methods: Surface doses were measured underneath three thermoplastic masks in open fields using 6 and 18 MV photon beams. These masks are used to immobilize patients for head and neck (H&N), pelvis and thoracic treatment. Gafchromic EBT films were placed on the top of the flat surface of a phantom partially underneath the mask and exposed in open 10 × 10 cm $^2$ photon fields. The depth doses were calculated using BEAMnrc Monte Carlo code for water-equivalent film detectors with different layers of thickness ranging from 50 μm to 2.5 mm and compared with film measurements.

Results: Surface dose increased by a factor of 3 to 4 underneath the mask relative to the open areas and 6 MV beam delivers more skin dose than 18 MV. H&N mask increased surface dose by a factor of 3 using 18 MV and a factor of 4 using 6 MV. In addition, increase in surface dose depended on the type of the mask, the size of openings, and the amount of stretching performed during the mask preparation. The measured depth doses were compared with BEAMnrc Monte Carlo calculation for water-equivalent detectors using different sizes. The calculated depth dose depended significantly on the thickness of film detector and varies by more than 15% using layer thickness of 2.5 mm compared to 50 μm. Surface doses measured by Gafchromic EBT films agreed within 3% with the Monte Carlo calculations using a small detector layer of 50 μm.

Conclusion: Thermoplastic masks used for patient immobilization can significantly increase skin doses by up to a factor of 4 more than that without the mask using 6 MV beams. The skin reactions resulting from thermoplastic masks should be monitored and corrective measures should be taken during treatment such as partially removing the mask over skin areas with complications and optimizing the skin dose in IMRT planning. Gafchromic EBT films provide accurate skin dosimetry which agrees within 3% with Monte Carlo calculations. Gafchromic EBT film makes an excellent tool for measuring depth doses in the buildup region and these data can be applied for treatment planning calculations and IMRT optimization.
High resolution in vivo micro-CT with flat	panel detector based on amorphous silicon
Authors: Yang Xiaoquan , Meng Yuanzheng , Luo Qingming , Gong Hui
Published: November 2024

A high-resolution in vivo micro-CT system for combining with fluorescence molecular tomography (FMT), was constructed and applied in small animal imaging. The fast scanning micro-CT system designed to provide high-resolution anatomic information and reconstruction priors, consisted of a flat panel detector (FPD) based on amorphous silicon (a-Si) and a micro-focus x-ray tube. The Feldkamp algorithm was adopted in image reconstruction with graphic processing unit (GPU). The system spatial resolution of 13 lp/mm was achieved when the diameter of image field was 6 cm with the system magnification factor of 4. No obvious beam hardening artifact was observed in transaxial image of a water phantom after correction. The contrast-to-noise ratio (CNR) study of various tissue phantoms was also presented. The in-vivo imaging of an anesthetic mouse was performed to demonstrate the feasibility of our system.
Intensity modulated radiation therapy versus three dimensional	conformal radiation therapy for treatment of high grade glioma: A	radiobiological modeling study
Authors: De La Fuente Herman Tania , Ahmad Salahuddin , Vlachaki Maria T.
Published: November 2024

Treatment of glioblastoma results in a median survival of 12 months. Radiation dose escalation trials for high grade gliomas have resulted in modest improvements in survival in selected patients with small peripheral tumors at the expense of normal brain toxicity. Neurotoxicity includes radiation necrosis but it is increasingly recognized that long-term survivors may develop neuro-cognitive deficits. Tumor control probability (TCP) and normal tissue complication probability (NTCP) are radiobiological models used to predict treatment outcomes. This study assesses the impact of radiation dose escalation from 59.6 Gy to 90 Gy on TCP and NTCP in ten patients planned with Three Dimensional Conformal Therapy (3DCRT) and Intensity Modulated Radiation Therapy (IMRT). No difference in TCP was observed between 3DCRT and IMRT at doses of 59.4 Gy and 90 Gy. However, dose escalation to 90 Gy resulted in about 25% relative TCP increase. Compared to 3DCRT, dose escalation with IMRT significantly reduced NTCP by 70% (10.75% v. 3.75%, respectively). As a result, highly conformal techniques are recommended to obviate radiation exposure of normal brain especially when radiation dose escalation is used. Further understanding of the molecular mechanisms underlying neurotoxicity will allow the development of more precise radiobiological predictive models and of approaches to prevent or treat radiation-induced brain damage.
A binary image reconstruction technique for accurate determination	of the shape and location of metal objects in x-ray computed tomography
Authors: Wang Jing , Xing Lei
Published: November 2024

The presence of metals in patients causes streaking artifacts in X-ray CT and has been recognized as a problem that limits various applications of CT imaging. Accurate localization of metals in CT images is a critical step for metal artifacts reduction in CT imaging and many practical applications of CT images. The purpose of this work is to develop a method of auto-determination of the shape and location of metallic object(s) in the image space. The proposed method is based on the fact that when a metal object is present in a patient, a CT image can be divided into two prominent components: high density metal and low density normal tissues. This prior knowledge is incorporated into an objective function as the regularization term whose role is to encourage the solution to take a form of two intensity levels. A computer simulation study and four experimental studies are performed to evaluate the proposed approach. Both simulation and experimental studies show that the presented algorithm works well even in the presence of complicated shaped metal objects. For a hexagonally shaped metal embedded in a water phantom, for example, it is found that the accuracy of metal reconstruction is within sub-millimeter.
Near-infrared frequency domain system and fast inverse Monte Carlo	algorithm for endoscopic measurement of tubular tissue
Authors: Zhao Huijuan , Zhou Xiaoqing , Fan Ying , Gao Feng
Published: November 2024

A near infrared diffuse reflectance system for endoscopic measurement and an inverse algorithm for extracting optical properties of tubular tissues were developed in this paper. The measurement system worked in the frequency domain mode and a custom probe was employed for endoscopic detection of cervical cancer. Experiments for evaluating the measurement accuracy indicate that the model-to-data mismatch for the AC amplitude and phase lag is less than 3.7% and 6.7%, respectively. To facilitate the extraction of the optical properties in tubular tissues and to minimize the influence of the initial guess on the reconstruction accuracy, a fast inverse Monte Carlo simulation algorithm with cluster analysis method was proposed. Simulation results showed that the relative errors of the absorption coefficient recovered using the proposed inverse algorithm are less than 5.8% and those of the sacttering coefficient are less than 10.2%. Endoscopic measurement on two tubular solid phantoms were also carried out to evaluate the system and the inversion scheme. The results demonstrated that less than 20% relative error can be achieved.
Interior reconstruction using local inverse
Authors: Zhao Shuangren , Yang Kang , Jiang Dazong , Yang Xintie
Published: November 2024

Truncated projections can arise from a detector with a limited field of view (LFOV). Truncation artifacts can be reduced through extrapolation methods; however the reconstructed images with extrapolation are often over-corrected or under-corrected. Recently, an iterative reconstruction-reprojection algorithm was developed, which incorporated extrapolation with iterative algorithm. It gave the possibility to better reduce truncation artifacts compared to using the extrapolation method alone. This article builds a theoretic foundation for the above iterative reconstruction-reprojection algorithm. The theoretic foundation is suitable to parallel-beam, fan-beam and cone-beam computed tomography(CT). Two assumptions are summarized from the CT system. Then, a truncation-artifact-free solution for the problem of LFOV is derived from these assumptions. The solution contains a "local inverse" of matrix. The local inverse of a matrix is defined using the sub-matrix and its general inverse. The solution can be approximately implemented as the iterative reconstruction-reprojection algorithm which is just the algorithm mentioned above.
An improved half-covered helical cone-beam CT reconstruction	algorithm based on localized reconstruction filter
Authors: Guo Jiqiang , Zeng Li , Zou Xiaobing
Published: November 2024

Traditional helical cone-beam Computed Tomography (CT) is based on the assumption that the entire cross-section of the scanned object is covered by x-rays at each view angle. Because of the size limitation of planar detector, the traditional helical cone-beam CT scanning is restricted when the cross-section of the object is larger than the field of view (FOV) of the CT system. The helical cone-beam CT scanning based on FOV half-covered can almost double the FOV, whose mechanism is simple and the scanning efficiency is the same as that of traditional helical cone-beam CT. During reconstruction, the extended helical cone-beam FDK algorithm (called half-covered helical FDK for short) is developed, and the computational efficiency of this algorithm is high. But the reconstruction image has truncation error. Regarding this problem, this paper extends the idea of 2D local reconstruction to 3D half-covered helical cone-beam CT, and develops an improved half-covered helical cone-beam CT reconstruction algorithm based on localized reconstruction filter. Experimental results indicate that the presented algorithm well solves the truncation error of the half-covered helical FDK algorithm, improves the quality of the reconstruction image. And for the noise projection data, the presented algorithm can suppress noise and get better results. Moreover, the reconstruction time is much less.
New relationship between the divergent beam projection and the	Radon transform
Authors: Wei Yuchuan , Wang Ge
Published: November 2024

In this paper, we present some new relationship between the divergent beam projection and the Radon transform. An application of our results is to implement the Radon inversion from divergent beam projection.
A 1st generation scatter CT algorithm for electron density breast	imaging which accounts for bound incoherent, coherent and multiple scatter: A Monte Carlo study
Authors: Aviles Jorge E. Alpuche , Pistorius Stephen , Elbakri Idris A. , Gordon Richard , Ahmad Bashir
Published: November 2024

Breast CT is an emerging modality that reconstructs 3D linear attenuation coefficient (μ) images of the breast. Its tomographic nature reduces the overlap of structures and may improve tissue visualization. Current prototype systems produce large levels of scatter that could be used to reconstruct electron density (ρ $ _{e}$ ) images. This could potentially enhance diagnosis. We are developing a first generation bench top CT system to investigate the benefits of simultaneous imaging μ and ρ $ _{e}$ of the intact breast. The system uses an algorithm capable of reconstructing ρ $_{e}$ images from single Klein-Nishina scatter. It has been suggested that this algorithm may be impractical since measurements include coherent, bound incoherent and multiple scatter. To investigate this, the EGSnrc Monte Carlo (MC) code was used to simulate scans using a first generation system. These simulations were used to quantify the dose per scan, to provide raw data for the ρ $ _{e}$ reconstructions and to investigate corrections for multiple and coherent scatter since these can not be directly related to ρ $ _{e}$ . MC simulations show that the dose coefficients are similar to those of cone beam breast CT. Coherent scatter is only ∼9% concentrated in scattering angles < 8°. Electron binding reduces the number of incoherently scattered photons but this reduction can be included in the quantification of scatter measured by the system. Multiple scatter was found to be the major source of errors and, if not corrected for, can result in an overestimation of ρ $ _{e}$ by more than a factor of two. Empirical corrections, based on breast thickness or radiological path, can be used to reconstruct images where the variance in ρ $ _{e}$ error is half of that found in images derived from primary photons only. Although some practical challenges remain in creating a laboratory system, this work has shown that it is possible to reconstruct scatter images of the breast with a 4 mGy dose and further experimental evaluation of this technique is warranted.
Kepastian Hukum Penerapan Asas Kebebasan Berkontrak Dalam Sebuah Perjanjian Baku Ditinjau Berdasarkan Pasal 1338 Kitab Undang-Undang Hukum Perdata
Authors: Susanti Nia
Published: November 2024

This research aims to analyse the application of the principle of freedom of contract in standard agreements in Indonesia, particularly in the context of Article 1338 of the Civil Code, which guarantees legal certainty and justice for the parties. The focus of this research is to identify the gap between freedom of contract and the potential injustice arising in standard agreements, especially against parties who have a weaker bargaining position. The method used is normative juridical research with a literature study approach. The results show that the principle of freedom of contract is often limited in standard agreements due to the dominance of the stronger party, which results in inequality in rights and obligations between parties. The conclusion of this research confirms the need for clearer regulations to maintain the balance of rights in standard agreements in order to protect weak parties and prevent exploitation.
Efforts To Overcome Training Burnout Among Badminton Athletes: A Quantitative Analysis
Authors: Muhammad Rizky Putra Hadi  , Rahmadi  , Abd. Hamid
Published: November 2024

This study aims to examine the efforts to address training burnout among badminton athletes at PB Berkat Abadi in Banjar Regency. Utilizing a descriptive quantitative approach with a survey method, this research analyzes the intrinsic and extrinsic factors contributing to the efforts to overcome training burnout among badminton athletes. The study involved 38 athletes, selected through total sampling. Data collection was conducted using a questionnaire adapted from previous research on levels of effort to overcome training burnout, assessing various indicators including determination, awareness, discipline, psychological aspects, variation, communication, facilities, rewards, and individual training planning. The results reveal that intrinsic factors contribute 45% to the overcoming burnout efforts, with psychological/mental aspects showing the highest individual contribution (11.48%), followed by determination and inner strength (15.39%), discipline (9.09%), and awareness of the importance of training (9.04%). Extrinsic factors account for 39.02% of the total effort, with the highest contribution from facilities and infrastructure (9.21%), followed by training variation (8.48%), individual-based training planning (8.27%), rewards (7.24%), and communication (5.82%). All indicators were categorized as "Very Low" in their contribution to overcoming burnout. The study emphasizes the need for interventions targeting intrinsic and extrinsic factors to improve burnout overcome efforts among badminton athletes.