Current landscape and potential future applications of artificial intelligence in medical physics and radiotherapy

Artificial intelligence(AI)has seen tremendous growth over the past decade and stands to disrupts the medical industry.In medicine,this has been applied in medical imaging and other digitised medical disciplines,but in more traditional fields like medical physics,the adoption of AI is still at an early stage.Though AI is anticipated to be better than human in certain tasks,with the rapid growth of AI,there is increasing concerns for its usage.The focus of this paper is on the current landscape and potential future applications of artificial intelligence in medical physics and radiotherapy.Topics on AI for image acquisition,image segmentation,treatment delivery,quality assurance and outcome prediction will be explored as well as the interaction between human and AI.This will give insights into how we should approach and use the technology for enhancing the quality of clinical practice.

Directivity of Spherical Polyhedron Sound Source Used in Near-Field HRTF Measurements

The omnidirectional character is one of important requirements for the sound source used in near-field head- related transfer function （HRTF） measurements. Based on the analysis on the radiation sound pressure and directivity character of various spherical polyhedron sound sources, a spherical dodecahedral sound source with radius of O. 035 m is proposed and manufactured. Theoretical and measured results indicate that the sound source is approximately omnidirectional below the frequency of 8 kHz. In addition, the sound source has reasonable magnitude response from 350Hz to 20 kHz and linear phase characteristics. Therefore, it is suitable for the near-field HRTF measurements.

Fabrication of Dry Electrode for Recording Bio-potentials

Development of minimally invasive dry electrodes for recording biopotentials is presented. The detailed fabrication process is outlined. A dry electrode is formed by a number of microneedles. The lengths of the microneedles are about 150μm and the diameters are about 50μm. The tips of the microneedles are sharp enough to penetrate into the skin. The silver/silver chloride is grown on microneedle arrays and demonstrates good character. The electrocardiogram shows that the dry electrode is suitable for recording biopotentials.

Analysis on the DNA Fingerprinting of Aspergillus Oryzae Mutant Induced by High Hydrostatic Pressure

The mutant strains of aspergillus oryzae （HP300a） are screened under 300 MPa for 20min. Compared with the control strains, the screened mutant strains have unique properties such as genetic stability, rapid growth, lots of spores, and high protease activity. Random amplified polymorphic DNA （RAPD） and inter simple sequence repeats （ISSR） are used to analyze the DNA fingerprinting of HP300a and the control strains. There are 67.9% and 51.3% polymorphic bands obtained by these two markers, respectively, indicating significant genetic variations between HP300a and the control strains. In addition, comparison of HP300a arid the control strains, the genetic distances of random sequence and simple sequence repeat of DNA are 0.51 and 0.34, respectively.

Using Gamma-Radiation for Drug Releasing from MWNT Vehicle

A drug delivery system via multi-walled carbon nanotube （MWNT） vehicle was synthesized in aqueous solution. MWNTs were first noncovalently functionalized with chitosan oligomers （CS） with a molecule weight of 4000-6000, making MWNTs water-soluble, and then a cancer ancillary drug tea polyphenols （TP） was conjugated mainly via the hydrogen bond between CS and TP molecules, making MWNTs efficient vehicle for drug delivering. The release of drug molecules can be realized by pH variation and γ-radiation, leading to new methods for controlling drug release from carbon nanotubes carrier. Due to the high penetrability of γ-rays, γ-radiation shows up new opportunities in controlled drug release, possibly facilitating the future cancer treatment in vivo.

Noise Effects on Temperature Encoding of Neuronal Spike Trains in a Cold Receptor

We examine how noise interacts with encoding mechanisms of neuronal stimulus in a cold receptor. From ISI series and bifurcation diagrams it is shown that there are considerable differences in interval distributions and impulse patterns caused by purely deterministic simulations and noisy simulations. The ISI-distance can be used as an effective and powerful way to measure the noise effects on spike trains of the cold receptor quantitatively. It is also found that spike trains observed in cold receptors can be more strongly affected by noise for low temperatures than for high temperatures in some aspects; meanwhile, the spike train has greater variability with increasing noise intensity.

Coarse-Grained Molecular Dynamics Simulation of a Red Blood Cell

A worm-like chain model based on a spectrin network is employed to study the biomechanics of red blood cells. Coarse-grained molecular dynamics simulations are performed to obtain a stable configuration free of external loadings. We also discuss the influence of two parameters： the average bending modulus and the persistence length. The change in shape of a malaria-infected red blood cell can contribute to the change in its molecular-based structure. As the persistence length of the membrane network in the infected red blood cell decreases, the deformability decreases and the biconcave shape is destroyed. The numerical results are comparable with previously reported experimental results. The coarse-grained model can be used to study the relationship between macro-mechanical properties and molecular-scale structures of cells.

Stochastic Alternating Dynamics for Synchronous EAD-Like Beating Rhythms in Cultured Cardiac Myocytes

Dissolved cardiac myocytes can couple together and generate synchronous beatings in culture. We observed a synchronized early after-depolarization（EAD）-like rhythm in cultured cardiac myocytes and reproduced the experimental observation in a network mathematical model whose dynamics are close to a Hopf bifurcation. The mechanism for this EAD-like rhythm is attributed to noised-induced stochastic alternatings between the focus and the limit cycle. These results provide novel understandings for pathological heart rhythms like the early immature beatings.

Correlation of Photosensitization and Binding Mode of Methylene Blue and DNA

Binding of methylene blue （MB） and DNA, photosensitization of MB in DNA, and correlation of photosensiti- zation and binding mode are studied at different concentration ratios of DNA and MB. The absorption spectra indicate that the electrostatic binding is the main mode at low γ ratios （γ≤ 2）, while at high γ ratios （γ 〉 2） the intercalative binding is dominated. Mudies on dynamics of photosensitization formation of singlet oxygen （102） for MB in DNA are carried out by using＂ time-resolved technology. There are no obvious changes of the singlet oxygen lifetime and the triplet state MB molecule （MB3＋＊） lifetime at low ratios, they are about 4 μs and 1 μs, respectively. However, we could not obtain the 1 O2 lifetime and MB3＋＊ lifetime due to the great decrease of 1 O2 phosphorescence signals at high ratios. These results show that the photosensitization and binding mode of MB in DNA possess high correlation. When MB binds with DNA by electrostatic interaction, type-lI photosen- sitization of MB plays a major role in photodynamic effect, the damage of DNA probably could be ascribed to 1 O2. However, at high ratios, binding mode between MB and DNA turns to intercalative binding, which greatly weakens the type-Ⅱ photosensitization process. Charge transfer between MB and DNA possibly becomes the main damage mechanism.

Magnetic Field Structure and Induced Electric Current Distribution on a Cylindrical Model： Application to Magnetic Nerve Stimulation

We study the relation between the magnetic field structure and the induced electric-current distribution based on a cylindrical model composed of a uniform electrically conductive medium. When the time-varying magnetic fields are axisymmetrically applied in the axial direction of the model, the electric fields are induced around the central axis in accordance with Faradays law. We examine the eddy-current distributions generated by loop-coils with various geometries carrying an alternating electric current. It is shown that the radial structure of the induced fields can significantly be controlled by the loop coil geometry, which will be suitable for practical use especially in magnetic nerve stimulation on bioelectromagneties, if we appropriately p/ace the exciting coil with optimum geometry.

Photon-Measurement Density Function of Fluorescence Molecular Tomography Based on Direct Method

Photon-measurement density function （PMDF）, which is the kernel of fluorescence molecular tomography （FMT）, largely determines the accuracy of reconstruction result of FMT. Based on the direct method, we propose an expression of PMDF in FMT, which is derived from the finite element method （FEM） solution of the diffusion equation. Compared with the traditional expression based on the perturbation method, the accuracy of expression based on the direct method is shown in theory. Lastly the reconstruction results of phantoms prove this accuracy in experiment.

Comparative Study on Polarization of DNA and CdSe Quantum Dots

The polarizabilities of DNA in transverse direction and CdSe semiconductor quantum dots （QDs） deposited on mica surface are compared by means of electrostatic force microscopy （EFM）. We observe clear EFM-phase shift over CdSe QDs, while no obvious signal on DNA is detected, suggesting that DNA molecules is an electrical insulator.

Numerical Simulations of Calcium Ions Spiral Wave in Single Cardiac Myocyte

The calcium ions （Ca^2＋） spark is an elementary Ca^2＋ release event in cardiac myocytes. It is believed to buildup cell-wide Ca^2＋ signals, such as Ca^2＋ transient and Ca^2＋ wave, through a Ca^2＋-induced Ca^2＋ release （CICR） mechanism. Here the excitability of the Ca^2＋ wave in a single cardiac myoeyte is simulated by employing the fire-diffuse-fire model. By modulating the dynamic parameters of Ca^2＋ release and re-uptake channels, we find three Ca^2＋ signaling states in a single cardiac myoeyte： no wave, plane wave, and spiral wave. The period of a spiral wave is variable in the different regimes. This study indicates that the spiral wave or the excitability of the system can be controlled through micro-modulation in a living excitable medium.

Effect of Time Delay on Stochastic Tumor Growth

We study the dynamics of tumor cell growth with time-delayed feedback driven by multiplicative noise in an asymmetrical bistable potential well. For a small delay time, the analytical solutions of the probability distribution and the first passage time show that, with the increasing delay time, the peak of the probability distribution in a lower population state would increase, but in a higher population state it decreases. It is shown that the multiplicative noise and the time delay play opposite roles in the tumor cell growth.

Can Be Done Better for the Diagnosis of Non-Differentiated Diseases in Community Hospital?

General Practice is a comprehensive subject with a wide spectrum of diseases. It is challenging to make a more correct diagnosis timely and reasonable treatment with the least instrument examination for the diagnosis of medically unexplained physical symptoms (MUPS). This article reviews the case report of a patient who presented to a community hospital with a one-month history of constant diffuse abdominal pain and underwent eight weeks of examinations, finally experienced deterioration of their condition. Based on this case, this article discusses the problems in the diagnosis of abdominal pain in a community hospital, and according to the clinical thinking mode and checklist of abdominal pain, the diagnostic process of abdominal pain can be improved, and the diagnosis of non-differentiated diseases can be done better, the harm caused by delayed diagnosis may be reduced.

Role of cyclic AMP signaling in the production and function of the incretin hormone glucagon-like peptide-1

Pancreatic cells express the proglucagon gene （ gcg ） and thereby produce the peptide hormone glucagon , which stimulates hepa tic glucose production and thereby increases blood glucose levels. The same gcg gene is also expressed in the intesti nal endocrine L cells and certain neural cells in the brain. In the gut, gcg expression leads to the production of glucagon-like peptide-1 （GLP-1）. This incretin hormone stimulates insulin secretion when blood glucose, level is high. In addition, GLP-1 stimulates pancreatic cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells.

Zebrafish:A Renewed Model System For Functional Genomics

In the post genome era, a major goal in molecular biology is to determine the function of the many thousands of genes present in the vertebrate genome. The zebrafish （ Danio redo） provides an almost ideal genetic model to identify the biological roles of these novel genes, in part because their embryos are transparent and develop rapidly, The zebrafish has many advantages over mouse for genome-wide mutagenesis studies, allowing for easier, cheaper and faster functional characterization of novel genes in the vertebrate genome. Many molecular research tools such as chemical mutagenesis, transgenesis , gene trapping, gene knockdown,