Multi-layered tissue head phantoms for noninvasive optical diagnostics

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with opt ical properties similar to those of living human tissues.Development and improvement of in vivo optical measurement systems requires the 1use of stable tissue phantoms with known characteristics,which are mainly used for calibration of such systems and testing their performance over time.Optical and mechanical properties of phantoms depend on their purpose.Nevertheless,they must accurately simulate specific tssues they are supposed to mimic.Many tsues and organs including head possess a multi-layered structure,with specifie optical properties of each layer.However,such a structure is not always addressed in the present-day phantoms.In this paper,we focus on the development of a plain-parallel multi-layered phantom with optical properties(reduced scattering oofficientμ'and absorption cofficientμa)corresponding to the human head layers,such as skin,skul,and gray and white matter of the brain tissue.The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy(NIRS)of humnan brain.Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method.The results show that polyinyl chloride plastisol(PVCP)and zinc oxide(ZnO)nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties.Good matching was found between optical properties of phantoms and the corresponding values found in the literature.

A Review on the 3D Printing of Functional Structures for Medical Phantoms and Regenerated Tissue and Organ Applications

Medical models, or ＂phantoms,＂ have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification and validation, and medical devices development. Such new applications demand high-fidelity, patient-specific, tissue-mimicking medical phantoms that can not only closely emulate the geometric structures of human organs, but also possess the properties and functions of the organ structure. With the rapid advancement of three-dimensional （3D） printing and 3D bioprinting technologies, many researchers have explored the use of these additive manufacturing techniques to fabricate functional medical phantoms for various applications. This paper reviews the applications of these 3D printing and 3D bioprinting technologies for the fabrication of functional medical phantoms and bio-structures. This review specifically discusses the state of the art along with new developments and trends in 3D printed functional medical phantoms （i.e., tissue-mimicking medical phantoms, radiologically relevant medical phantoms, and physiological medical phantoms） and 3D bio-printed structures （i.e., hybrid scaffolding materials, convertible scaffolds, and integrated sensors） for regenerated tissues and organs.

Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method

A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of X-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to express the patient’s anatomical structure. The human body can be well outlined by air, lung, adipose, muscle, soft bone and hard bone to calculate the dose distribution with Monte Carlo method. The effects of the calibration curves established by using various CT scanners are not clinically significant based on our investigation. The deviation from the values of cumulative dose volume histogram derived from CT-based voxel phantoms is less than 1% for the given target.

Dosimetric Verification at the Wuwei Heavy Ion Therapy Center Using Anthropomorphic Phantoms

The facility of Heavy lon Medical Machine(HIMM)at the Wuwei Heavy lon Therapy Center has passed the inspection of China's Food and Drug Administration.

Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance

Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.

Development of Chinese hybrid radiation adult phantoms and their application to external dosimetry

This paper presents the construction of Chinese hybrid radiation adult phantoms,which are compatible with anatomical parameters for the Chinese reference population.The phantoms were designed using polygonal mesh surface,which makes the phantom more flexible and realistic than previous generations.Voxelization of hybrid phantoms was performed to adopt Monte Carlo methods.External dose coefficients were calculated by Geant4 and compared to the ICRP reference phantom.The results show that the organ dose is different from ICRP116 with the low energy photons,which can be ascribed to the anatomy and topology difference of each organ.The effective dose of CHRAP is 19%higher than ICRP 116 in the energy range from10 to 100 keV and is almost the same in the energy range from 100 keV to 10 MeV.These phantoms can be used as the basic phantom to adjust the posture or organ volume to estimate dosimetry in medical and space explorations.

Microstrip Patch Antenna with an Inverted T-Type Notch in the Partial Ground for Breast Cancer Detections

This study designs a microstrip patch antenna with an inverted T-type notch in the partial ground to detect tumorcells inside the human breast.The size of the current antenna is small enough(18mm×21mm×1.6mm)todistribute around the breast phantom.The operating frequency has been observed from6–14GHzwith a minimumreturn loss of−61.18 dB and themaximumgain of current proposed antenna is 5.8 dBiwhich is flexiblewith respectto the size of antenna.After the distribution of eight antennas around the breast phantom,the return loss curveswere observed in the presence and absence of tumor cells inside the breast phantom,and these observations showa sharp difference between the presence and absence of tumor cells.The simulated results show that this proposedantenna is suitable for early detection of cancerous cells inside the breast.

循环纯phantom态射

通过引入循环纯phantom态射的概念,给出循环纯phantom态射的一些等价刻画,证明每个R-模都有核为循环纯内射模的满的循环纯phantom覆盖,并讨论循环纯phantom预覆盖在环变换下的传递性.

Effect of transcranial direct current stimulation on supernumerary phantom limb pain in spinal cord injured patient:A case report

BACKGROUND Supernumerary phantom limb(SPL)sensation is the experience of additional limbs,either single or a pair of limbs.Unique to traumatic spinal cord injuries,we report effect of transcranial direct current stimulation(tDCS)on SPL pain in a patient with cervical cord injury.CASE SUMMARY The subject was a 57-year-old man who was diagnosed with complete spinal cord injury(C6/C5,motor level;C5/C5,sensory level;AIS-A)approximately three months ago.After a period of 2 wk,we administered anodal tDCS over the motor cortex for 15 minutes at an intensity of 1.5 mA.Following that treatment,the patient experienced a decrease of SPL pain intensity and frequency,which lasted for 1 week after the end of treatment.CONCLUSION Targeting the motor cortex through neuromodulation appears to be a promising option for the management of SPL pain.

Reconstructive surgery for phantom and residual limb pain in post-conflict settings

Traumatic amputations remain one of the most frequent and disturbing wounds of armed conflict.In this scenario,most amputees develop residual and phantom limb pain,impacting their quality of life.There are several elective surgical procedures available for both conditions,such as neuroma excision followed by nerve reconstruction,nerve relocation,e.g.,surgically implanting a transected nerve into a muscle,nerve transfers in cases of associated paralysis,and most recently,regenerative peripheral nerve interface surgery.Whenever possible in the post-conflict phase,a coordinated effort between traveling humanitarian surgeons specializing in reconstructive microsurgery and local healthcare providers is essential for successfully treating phantom and chronic residual limb pain in post-conflict amputees.While providing a detailed logistical framework for global humanitarian missions is beyond the scope of this article,we provide a brief perspective on a topic of utmost importance for reconstructive surgeons worldwide:the high-quality care and treatment of refugees and those whose lives have been impacted by conflict,disaster,or displacement.

Preclinical Verification of Modulated Electro-Hyperthermia —Part I. In Vitro Research

Modulated electro-hyperthermia (mEHT) targets tissue’s natural electric and thermal heterogeneities to heat the cancer cells selectively. The applied 13.56 MHz radiofrequency (RF) is a carrier of the low-frequency modulation. The high-frequency part was chosen to select the malignant lesion using the specialties of the tumor: the higher conductivity and dielectric constant of the tumor than its host. The electric field selects the tumor, and the low-frequency amplitude modulation polarizes and excites the transmembrane proteins of the malignant cells. The dominant absorption of the energy by the microscopic clusters of the membrane rafts acts like nanoparticle heating. Exciting the membrane produces various apoptotic signals. The processes were modeled using silico and phantom experiments, which proved the concept. The preclinical verification was made in vitro and in vivo, and in the end, clinical proofs validated the method. Our objective is to follow all the development steps from the laboratory to the clinics in a trilogy of articles. This present is the first part, which deals with in silico, phantom, and in vitro research.

Convenient model of hard tissue simulation for dental radiographic research and instruction

BACKGROUND The authors describe a technique for building an alternative jawbone phantom using dental gypsum and rice for research and dental radiology instruction.AIM To investigate the potential of an alternative phantom to simulate the trabecular bone aspect of the human maxilla in periapical radiographs.METHODS Half-maxillary phantoms built from gypsum-ground rice were exposed to X-rays,and the resulting images(experimental group)were compared to standardized radiographic images produced from dry human maxillary bone(control group)(n=7).The images were blindly assessed according to strict criteria by three examiners for the usual trabecular aspects of the surrounding bone,and significant differences between groups and in assessment reliability were compared using Fisher’s exact and kappa tests(α=0.05).RESULTS The differences in the trabecular aspects between groups were not statistically significant.In addition,interobserver agreement among observers was 0.43 and 0.51 for the control and experimental groups,respectively,whereas intraobserver agreement was 0.71 and 0.73,respectively.CONCLUSION The tested phantom seemed to demonstrate potential for trabecular bone image Munhoz EA et al.Model of hard tissue simulation for dental radiography WJM https://www.wjgnet.com 2 March 20,2024 Volume 14 Issue 1 simulation on maxillary periapical radiographs.

免像控大疆Phantom4 RTK无人机在航电枢纽工程中的应用

免像控技术对提高航测技术的工作效率方面具有重要的意义,采用大疆Phantom4 RTK无人机和倾斜环绕航测技术得到龙溪口航电枢纽工程的原始影像数据,运用三维实景建模软件ContextCapture建立龙溪口航电枢纽工程的三维实景模型,使用蓝景PSG 3D裸眼三维全数字测量系统绘制龙溪口航电枢纽工程的地形图,同时使用徕卡全站仪用传统测量方法得到检核点的三维数据进行精度比对分析,结果是0.043 m的平面点中误差和0.022 m的高程点位中误差,精度均符合规范要求。

基于分级的PHANTOM交易一致排序协议研究

DAG(Directed Acyclic Graph)分布式账本是对比特币中存在的一些交易确认时间过长等问题的改进。DAG分布式账本具有交易速度快,吞吐量大等优点。DAG分布式账本的主要优点是交易效率高,交易不用打包,做轻量级的工作量证明(POW)就可以直接发布交易,但是DAG分布式账本中异步的发布交易带来了全局交易一致性排序的困难问题。PHANTOM协议是DAG分布式账本中的一种具体的协议。PHANTOM协议中交易的排序需要求解一个NP困难问题,因此不适合于实际应用。为了避免这种复杂的计算,高效的贪心算法GHOSTDAG协议是对PHANTOM协议的改进,不仅提高了吞吐量,而且增加了抵抗双花攻击的能力。GHOSTDAG协议使用连通度得分较高的链作为主链,再利用连通度得分对区块做线性排序,当连通度得分相同时,使用哈希函数打破僵局(tie-breaking),选择哈希值较小的排在前面。但是哈希函数是伪随机函数,因此这一排序不尽合理。本文提出了基于分级的PHANTOM区块一致排序协议,采用了区块分级的概念,解决了PHANTOM协议中区块排序不唯一性的问题,并且该协议排序速度更快,且排序更合理,吞吐量更大。模拟实验评估和分析表明:基于分级的PHANTOM交易一致排序协议方案的吞吐量为1300TPS,较之前的PHANTOM协议有显著的增加,并且新方案具有安全性和可扩展性。

3D Printed Multi-material Medical Phantoms for Needle-tissue Interaction Modelling of Heterogeneous Structures

The fabrication of multi-material medical phantoms with both patient-specificity and realistic mechanical properties is of great importance for the development of surgical planning and medical training.In this work,a 3D multi-material printing system for medical phantom manufacturing was developed.Rigid and elastomeric materials are firstly combined in such application for an accurate tactile feedback.The phantom is designed with multiple layers,where silicone ink,Thermoplastic Polyurethane(TPU),and Acrylonitrile Butadiene Styrene(ABS)were chosen as printing materials for skin,soft tissue,and bone,respectively.Then,the printed phantoms were utilized for the investigation of needle-phantom interaction by needle insertion experiments.The mechanical needle-phantom interaction was characterized by skin-soft tissue interfacial puncture force,puncture depth,and number of insertion force peaks.The experiments demonstrated that the manufacturing conditions,i.e.the silicone grease ratio,interfacial thickness and the infill rate,played effective roles in regulating mechanical needle-phantom interaction.Moreover,the influences of material properties,including interfacial thickness and ultimate stress,on needle-phantom interaction were studied by finite element simulation.Also,a patient-specific forearm phantom was printed,where the anatomical features were acquired from Computed Tomography(CT)data.This study provided a potential manufacturing method for multi-material medical phantoms with tunable mechanical properties and offered guidelines for better phantom design.

Hi'CT:a pixel sensor-based device for ion tomography

Carbon ions,commonly referred to as particle therapy,have become increasingly popular in the last decade.Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion radiotherapy.Range uncertainty is currently the largest contributor to dose uncertainty in normal tissues,leading to the use of safety margins in treatment planning.One potential method is the direct relative stopping measurement(RSP)with ions.Heavy-ion CT(Hi′CT),a compact segmented full digital tomography detector using monolithic active pixel sensors,was designed and evaluated using a 430 MeV/u high-energy carbon ion pencil beam in Geant4.The precise position of the individual carbon ion track can be recorded and reconstructed using a 30μm×30μm small pixel pitch size.Two types of customized image reconstruction algorithms were developed,and their performances were evaluated using three different modules of CAT-PHAN 600-series phantoms.The RSP measurement accuracy of the tracking algorithm for different types of materials in the CTP404 module was less than 1%.In terms of spatial resolution,the tracking algorithm could achieve a 20%modulation transfer function normalization value of CTP528 imaging results at 5 lp/cm,which is significantly better than that of the fast imaging algorithm(3 lp/cm).The density resolution obtained using the tracking algorithm of the customized CTP515 was approximately 10.5%.In conclusion,a compact digital Hi'CT system was designed,and its nominal performance was evaluated in a simulation.The RSP resolution and image quality provide potential feasibility for scanning most parts of an adult body or pediatric patient,particularly for head and neck tumor treatment.

A cadaveric breast cancer tissue phantom for phase-contrast X-ray imaging applications

Background:As mammography X-ray imaging technologies advance and provide elevated contrast in soft tissues,a need has developed for reliable imaging phantoms for use in system design and component calibration.In advanced imaging modalities such as refraction-based methods,it is critical that developed phantoms capture the biological details seen in clinical precancerous and cancerous cases while minimizing artifacts that may be caused due to phantom production.This work presents the fabrication of a breast tissue imaging phantom from cadaveric breast tissue suitable for use in both transmission and refraction-enhanced imaging systems.Methods:Human cancer cell tumors were grown orthotopically in nude athymic mice and implanted into the fixed tissue while maintaining the native tumor/adipose tissue interface.Results:The resulting human–murine tissue hybrid phantom was mounted on a clear acrylic housing for absorption and refraction X-ray imaging.Digital breast tomosynthesis was also performed.Conclusion:Both attenuation-based imaging and refraction-based imaging of the phantom are presented to confirm the suitability of this phantom's use in both imaging modalities.

THUDosePD:a three-dimensional Monte Carlo platform for phantom dose assessment

Monte Carlo simulations are frequently utilized in radiation dose assessments.However,many researchers find the prevailing computing platforms to be intricate.This highlights a pressing need for a specialized framework for phantom dose evalua-tion.To address this gap,we developed a user-friendly radiation dose assessment platform using the Monte Carlo toolkit,Geant4.The Tsinghua University Phantom Dose(THUDosePD)augments the flexibility of Monte Carlo simulations in dosi-metric research.Originating from THUDose,a code with generic,functional,and application layers,THUDosePD focuses predominantly on anatomical phantom dose assessment.Additionally,it enables medical exposure simulation,intricate geometry creation,and supports both three-dimensional radiation dose analysis and phantom format transformations.The system operates on a multi-threaded parallel CPU architecture,with some modules enhanced for GPU parallel computing.Benchmark tests on the ICRP reference male illustrated the capabilities of THUDosePD in phantom dose assessment,covering the effective dose,three-dimensional dose distribution,and three-dimensional organ dose.We also conducted a voxelization conversion on the polygon mesh phantom,demonstrating the method’s efficiency and consistency.Extended applications based on THUDosePD further underline its broad adaptability.This intuitive,three-dimensional platform stands out as a valuable tool for phantom radiation dosimetry research.

无人机在校园地形图测绘中的应用

无人机倾斜摄影测量技术对减少传统测量外业工作量和节省开支有重要意义。文章采用大疆Phantom 4RTK无人机进行外业测量获取校园数据影像,利用大疆智图三维建模软件建立三维模型,eps2016地理信息工作站三维测图专版软件绘制了校园二维地形图纸(CAD),实现了吉林铁道职业技术学院既有校区建筑物及二期规划校园地形图测绘,探索实践数字化测量生产体系替代传统测量生产体系的转化路径和实现方式。

Monte Carlo calculation of the exposure of Chinese female astronauts to earth’s trapped radiation on board the Chinese Space Station

With the development of China’s crewed space mission,the space radiation risk for astronauts is increasingly prominent.This paper describes a simulation of the radiation doses experienced by a Chinese female voxel phantom on board the Chinese Space Station(CSS)performed using the Monte Carlo N-Particle(MCNP)software.The absorbed dose,equivalent dose,and effective dose experienced by the voxel phantom and its critical organs are discussed for different levels of shielding of the Tianhe core module.The risk of space-radiation exposure is then assessed by comparing these doses with the current risk limits in China(the skin dose limit for short-term low-earth-orbit missions)and the NASA figures(National Council on Radiation Protection and Measurements Report No.98)for female astronauts.The results obtained can be used to guide and optimize the radiation protection provided for manned space missions.