Towards automated < i > in vivo < /i > tracheal mucociliary transport measurement: detecting and tracking particle movement in synchrotron phase-contrast X-ray images.
Towards automated in vivo tracheal mucociliary transport measurement: detecting and tracking particle movement in synchrotron phase-contrast X-ray images. Phys Med Biol. 2020 Feb 11;: Authors: Gardner M, Parsons D, Morgan KS, McCarron A, Cmielewski P, Gradl R, Donnelley M Abstract Accurate in vivo quantification of airway mucociliary transport (MCT) in animal models is important for understanding diseases such as cystic fibrosis, as well as for developing therapies. A non-invasive method of measuring MCT behaviour, based on tracking the position of micron sized particles using Synchrotron X-ray imagin...
Source: Physics in Medicine and Biology - February 11, 2020 Category: Physics Authors: Gardner M, Parsons D, Morgan KS, McCarron A, Cmielewski P, Gradl R, Donnelley M Tags: Phys Med Biol Source Type: research

Novel test field diversity method for demonstrating magnetic resonance imaging safety of active implantable medical devices.
Abstract Electromagnetic (EM) radiofrequency (RF) safety testing of elongated active implantable medical devices (AIMD) during magnetic resonance imaging (MRI) requires an RF response model of the implant to assess a wide range of exposure conditions. The model must be validated using a sufficiently large set of incident tangential electric field (Etan) conditions that provide diversified exposure. Until now, this procedure was very time consuming and often resulted in poorly definedEtanconditions. In this paper, we propose a test field diversity (TFD) validation method that provides more diverse exposure conditio...
Source: Physics in Medicine and Biology - February 11, 2020 Category: Physics Authors: Yao A, Zastrow E, Neufeld E, Cabanes-Sempere M, Samaras T, Kuster N Tags: Phys Med Biol Source Type: research

Anthropomorphic phantom for deformable lung and liver CT and MR imaging for radiotherapy.
In this study, a functioning and ventilated anthropomorphic phantom was further enhanced for the purpose of CT and MR imaging of the lung and liver. A deformable lung, including respiratory tract was 3D printed. Within the lung's inner structures is a solid region shaped from a patient's lung tumour and six nitro-glycerine capsules as reference landmarks. The full internal mesh was coated, and the tumour filled, with polyorganosiloxane based gel. A moulded liver was created with an external casing of silicon filled with polyorganosiloxane gel and flexible plastic internal structures. The liver, fitted to the inferior porti...
Source: Physics in Medicine and Biology - February 11, 2020 Category: Physics Authors: Colvill E, Krieger M, Bosshard P, Steinacher P, Rohrer Schnidrig BA, Parkel TC, Stergiou I, Zhang Y, Peroni M, Safai S, Weber DC, Lomax AJ, Fattori G Tags: Phys Med Biol Source Type: research

Cerenkov luminescence and PET imaging of < sup > 90 < /sup > Y: capabilities and limitations in small animal applications.
Cerenkov luminescence and PET imaging of 90Y: capabilities and limitations in small animal applications. Phys Med Biol. 2020 Feb 11;: Authors: Mitchell GS, Lloyd PNT, Cherry SR Abstract The in vivo sensitivity limits and quantification performance of Cerenkov luminescence imaging have been studied using a tissue-like mouse phantom and 90Y. For a small, 9 mm deep target in the phantom, with no background activity present, the Cerenkov luminescence 90Y detection limit determined from contrast-to-noise ratios is 10 nCi for a 2 min exposure with a sensitive CCD camera and no filters. For quantitative perf...
Source: Physics in Medicine and Biology - February 11, 2020 Category: Physics Authors: Mitchell GS, Lloyd PNT, Cherry SR Tags: Phys Med Biol Source Type: research

Proton range verification with ultrasound imaging using injectable radiation sensitive nanodroplets: a feasibility study.
Abstract Technologies enabling in vivo range verification during proton therapy are actively sought as a means to reduce the clinical safety margins currently adopted to avoid tumor underdosage. In this contribution, we applied the semi-empirical theory of radiation-induced vaporization of superheated liquids to coated nanodroplets. Nanodroplets are injectable phase-change contrast agents that can vaporize into highly echogenic microbubbles to provide contrast in ultrasound images. We exposed nanodroplet dispersions in aqueous phantoms to monoenergetic proton beams of varying energies and doses. Ultrasound imaging...
Source: Physics in Medicine and Biology - February 11, 2020 Category: Physics Authors: Carlier B, Heymans S, Nooijens S, Toumia Y, Ingram M, Paradossi G, d'Agostino E, Himmelreich U, D'hooge J, Van Den Abeele K, Sterpin E Tags: Phys Med Biol Source Type: research

Automatic bi-objective parameter tuning for inverse planning of high-dose-rate prostate brachytherapy.
We present an automatic bi-objective parameter-tuning approach for inverse planning methods for high-dose-rate prostate brachytherapy, which aims to overcome the difficult and time-consuming manual parameter tuning that is currently required to obtain patient-specific high-quality treatment plans. We modelled treatment planning as a bi-objective optimization problem, in which dose-volume-based planning criteria related to target coverage are explicitly separated from organ-sparing criteria. When this model is optimized, a large set of high-quality plans with different trade-offs can be obtained. This set can be visualized ...
Source: Physics in Medicine and Biology - February 6, 2020 Category: Physics Authors: Maree SC, Bosman PAN, van Wieringen N, Niatsetski Y, Pieters BR, Bel A, Alderliesten T Tags: Phys Med Biol Source Type: research

Locally optimized correlation-guided Bayesian adaptive regularization for ultrasound strain imaging.
Abstract Ultrasound strain imaging utilizes radio-frequency (RF) ultrasound echo signals to estimate the relative elasticity of tissue under deformation. Due to the diagnostic value inherent in tissue elasticity, ultrasound strain imaging has found widespread clinical and preclinical applications. Accurate displacement estimation using pre and post-deformation RF signals is a crucial first step to derive high quality strain tensor images. Incorporating regularization into the displacement estimation framework is a commonly employed strategy to improve estimation accuracy and precision. In this work, we propose an ...
Source: Physics in Medicine and Biology - February 6, 2020 Category: Physics Authors: Mukaddim RA, Meshram NH, Varghese T Tags: Phys Med Biol Source Type: research

Pre-clinical evaluation of dual-layer spectral computed tomography-based stopping power prediction for particle therapy planning at the Heidelberg Ion Beam Therapy Center.
This study demonstrated in homogeneous and heterogeneous phantoms that spectral CT is feasible for particle therapy planning to improve range estimates for high-precision particle therapy. PMID: 32028273 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - February 6, 2020 Category: Physics Authors: Faller FK, Mein S, Ackermann B, Debus J, Stiller W, Mairani A Tags: Phys Med Biol Source Type: research

A practical method for quantifying dose in bone and lung using TLDs when using 6 and 15 MV photon beams.
n B Abstract This paper presents a practical method for converting dose measured with thermoluminescent dosimeters (TLD) to dose in lung and bone for 6 MV and 15 MV photon beams. Monte Carlo (MC) simulations and Burlin cavity theory calculations were performed to calculate fmediumTLD, the dose-to-TLD to dose-to-medium conversion factor. A practical method was proposed for converting TLD-measured-dose to dose-in-medium using the TLD dose calibration in water and fwatermedium, dose-to-medium to dose-to-water conversion factor. Theoretical calculations for fwatermediumwere performed using photon spectrum weighted par...
Source: Physics in Medicine and Biology - February 6, 2020 Category: Physics Authors: Sarıgül N, Surucu M, Reft CS, Malin M, Yeğingil Z, Ayadogan B Tags: Phys Med Biol Source Type: research

Chemical radiation dosimetry in magnetic fields: characterization of a Fricke-type chemical detector in 6 MV photon beams and magnetic fields up to 1.42 T.
In this study, the influence of magnetic fields on the readings of a Fricke detector, a chemical dosimeter, have been investigated in 6 MV photon beams. This type of detector has been chosen, as the Federal Office of Metrology (METAS, Switzerland) has great experience with Fricke dosimetry and since it is not expected that this detector is greatly affected by the presence of a magnetic field. Magnetic fields with field strengths between 0 T and 1.42 T were applied during the detector irradiation. In a 5 x 10 cm2irradiation field, the Fricke readings are affected less than 0.9% by the applied magnetic fields. Taking the alt...
Source: Physics in Medicine and Biology - February 6, 2020 Category: Physics Authors: Trachsel MA, Pojtinger S, Meier M, Schrader M, Kapsch RP, Kottler C Tags: Phys Med Biol Source Type: research

Development of realistic multi-contrast textured XCAT (MT-XCAT) phantoms using a dual-discriminator conditional-generative adversarial network (D-CGAN).
CONCLUSIONS: The study demonstrated the feasibility of generating realistic MT-XCAT phantoms using D-CGAN. The MT-XCAT phantoms can be further expanded to include other modalities (MRI, PET, ultrasound, etc.) under the same scheme. This crucial development greatly enhances the value of the phantom for various clinical applications, including testing and optimizing novel imaging techniques, validation of radiomics analysis methods, and virtual clinical trials. PMID: 32023555 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - February 5, 2020 Category: Physics Authors: Chang Y, Lafata K, Segars PW, Yin FF, Ren L Tags: Phys Med Biol Source Type: research

Learning-based estimation of dielectric properties and tissue density in head models for personalized radio-frequency dosimetry.
In this study, we develop a learning-based approach for fast and accurate estimation of tissue dielectric properties from magnetic resonance images. Smooth distribution of dielectric properties in head models, which was realized by the procedure without tissue segmentation, improves the smoothness of specific absorption rate (SAR) distribution as compared to commonly-used procedure. The estimated SAR distributions as well as that averaged over 10-g of tissue in cubic shape are found to be of high consistency with those computed using a conventional methods employing a segmentation. PMID: 32023556 [PubMed - as supplied...
Source: Physics in Medicine and Biology - February 5, 2020 Category: Physics Authors: Rashed E, Diao Y, Hirata A Tags: Phys Med Biol Source Type: research

On the concepts of dose-mean lineal energy, unrestricted and restricted dose-averaged LET in proton therapy.
CONCLUSIONS: Unrestricted LETd, restricted LETd and y_D can be analytically computed and compared for clinical plans. Two important consequences of the calculation of y_D are: 1) its distribution can be verified by directly measuring it in clinical beams; and 2), optimization of proton treatments based on these quantities is enabled as well as future developments of RBE models based on them. PMID: 32023557 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - February 5, 2020 Category: Physics Authors: Bertolet A, Cortes-Giraldo MA, Carabe A Tags: Phys Med Biol Source Type: research

Association Between Polymorphisms in DNA Damage Repair Genes and Radiation Therapy-Induced Early Adverse Skin Reactions in a Breast Cancer Population: A Polygenic Risk Score Approach.
Abstract PURPOSE: Genetic variations in DNA damage repair (DDR) genes may influence radiation therapy (RT)-induced acute normal tissue toxicity in patients with breast cancer. Identifying an individual or multiple single-nucleotide polymorphisms (SNPs) associated with RT-induced early adverse skin reactions (EASR) is critical for precision medicine in radiation oncology. METHODS AND MATERIALS: At the completion of RT, EASR was assessed using the Oncology Nursing Society scale (0-6) in 416 patients with breast cancer, and Oncology Nursing Society score ≥4 was considered RT-induced EASR. PLINK set-based test...
Source: Physics in Medicine and Biology - January 29, 2020 Category: Physics Authors: Lee E, Eum SY, Slifer SH, Martin ER, Takita C, Wright JL, Hines RB, Hu JJ Tags: Int J Radiat Oncol Biol Phys Source Type: research

Erectile dysfunction and absorbed dose to penile base structures in a randomized trial comparing ultra-hypofractionated and conventionally fractionated radiotherapy for prostate cancer.
CONCLUSIONS: The frequency of EDS was similar in the CF and UHF treatment groups. Age at radiotherapy was the strongest predictor for EDs followed by dose to PB, most evident for younger patients. We propose D2 %
Source: Physics in Medicine and Biology - January 28, 2020 Category: Physics Authors: Rasmusson E, Gunnlaugsson A, Wieslander E, Höglund P, Widmark A, Fransson P, Kjellén E, Nilsson P Tags: Int J Radiat Oncol Biol Phys Source Type: research

A theoretical framework for comparing noise characteristics of spectral, differential phase-contrast and spectral differential phase-contrast X-ray imaging.
Abstract Spectral and grating-based differential phase-contrast X-ray imaging are two emerging technologies that offer additional information compared with conventional attenuation-based X-ray imaging. In the case of spectral imaging, energy-resolved measurements allow the generation of material-specific images by exploiting differences in the energy-dependent attenuation. Differential phase-contrast imaging uses the phase shift that an X-ray wave exhibits when traversing an object as contrast generation mechanism. Recently, we have investigated the combination of these two imaging techniques (spectral differentia...
Source: Physics in Medicine and Biology - January 28, 2020 Category: Physics Authors: Mechlem K, Sellerer T, Viermetz M, Herzen J, Pfeiffer F Tags: Phys Med Biol Source Type: research

Single-shot K-Edge subtraction X-ray discrete computed tomography with a polychromatic source and the Pixie-III detector.
Abstract K-Edge Subtraction (KES) imaging is a technique able to map a specific element such as e.g. a contrast agent within the tissues, by exploiting the sharp rise of its absorption coefficient at the K-Edge energy. Whereas mainly explored at synchrotron radiation sources, the energy discrimination properties of modern X-ray Photon Counting Detectors (XPCDs) pave the way for an implementation of single-shot KES imaging with conventional polychromatic sources. In this work we present an X-ray CT imaging system based on the innovative Pixie-III detector and discrete reconstruction. The results reported here show ...
Source: Physics in Medicine and Biology - January 28, 2020 Category: Physics Authors: Brun F, Di Trapani V, Albers J, Sacco P, Dreossi D, Brombal L, Rigon L, Longo R, Mittone A, Dullin C, Bravin A, Delogu P Tags: Phys Med Biol Source Type: research

Calculated beam quality correction factors for ionization chambers in MV photon beams.
ve; C Abstract The beam quality correction factor,kQ, which corrects for the difference in the ionization chamber response between the reference and clinical beam quality, is an integral part of radiation therapy dosimetry. The uncertainty ofkQis one of the most significant sources of uncertainty in the dose determination. To improve the accuracy of availablekQdata, four partners calculatedkQfactors for 10 ionization chamber models in linear accelerator beams with accelerator voltages ranging from 6 MV to 25 MV, including flattening-filter-free (FFF) beams. The software used in the calculations were EGSnrc and PEN...
Source: Physics in Medicine and Biology - January 28, 2020 Category: Physics Authors: Tikkanen JS, Zink K, Pimpinella M, Teles P, Borbinha J, Ojala J, Siiskonen T, Pinto M, Gomà C Tags: Phys Med Biol Source Type: research

A novel radiomic nomogram for predicting epidermal growth factor receptor mutation in peripheral lung adenocarcinoma.
CONCLUSION: The prediction model built by radiomic biomarkers and clinicopathological features, including the radiomic signature, sex, smoking, vascular infiltration, and pathological type, outperformed the other two models and could effectively predict the EGFR mutation status in patients with peripheral lung adenocarcinoma. The radiomic nomogram of this model is expected to become an effective biomarker for patients with lung adenocarcinoma requiring adjuvant targeted treatment. PMID: 31978901 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 24, 2020 Category: Physics Authors: Lu X, Li M, Zhang HM, Hua S, Meng F, Yang H, Li X, Cao D Tags: Phys Med Biol Source Type: research

Simulation study to improve the performance of a whole-body PbF < sub > 2 < /sub > Cherenkov TOF-PET scanner.
Simulation study to improve the performance of a whole-body PbF2 Cherenkov TOF-PET scanner. Phys Med Biol. 2020 Jan 24;: Authors: Consuegra D, Korpar S, Krizan P, Pestotnik R, Razdevšek G, Dolenec R Abstract Using Cherenkov radiation in positron emission tomography (PET) has the potential to improve the time of flight (TOF) resolution and reduce the cost of detectors. In previous studies promising TOF results were achieved when lead fluoride (PbF2) crystals were used instead of a scintillator. In this work, a whole-body PbF2Cherenkov TOF-PET scanner was simulated and optimized. Different config...
Source: Physics in Medicine and Biology - January 24, 2020 Category: Physics Authors: Consuegra D, Korpar S, Krizan P, Pestotnik R, Razdevšek G, Dolenec R Tags: Phys Med Biol Source Type: research

Interactive 3D U-net for the segmentation of the pancreas in computed tomography scans.
Abstract The increasing incidence of pancreatic cancer will make it the second deadliest cancer in 2030. Artificial intelligence can help provide and improve widespread diagnostic expertise and accurate interventional image interpretation. Accurate segmentation of the pancreas is essential to create annotated data sets to train AI, and for computer assisted interventional guidance. Automated deep learning segmentation performance in pancreas CT imaging is low due to poor grey value contrast and complex anatomy. A good solution seemed a recent interactive deep learning segmentation framework for brain CT that helpe...
Source: Physics in Medicine and Biology - January 24, 2020 Category: Physics Authors: Boers TGW, Hu Y, Gibson E, Barratt DC, Bonmati E, Krdzalic J, van der Heijden F, Hermans JJ, Huisman H Tags: Phys Med Biol Source Type: research

An introduction to deep learning in medical physics: advantages, potential, and challenges.
Abstract As one of the most popular approaches in artificial intelligence, deep learning (DL) has attracted a lot of attention in the medical physics field over the past few years. The goals of this topical review article are twofold. First, we will provide an overview of the method to medical physics researchers interested in DL to help them start the endeavor. Second, we will give in-depth discussions on the DL technology to make researchers aware of its potential challenges and possible solutions. As such, we divide the article into two major parts. The first part introduces general concepts and principles of D...
Source: Physics in Medicine and Biology - January 23, 2020 Category: Physics Authors: Shen C, Nguyen D, Zhou Z, Jiang SB, Dong B, Jia X Tags: Phys Med Biol Source Type: research

Experimental validation of stochastic microdosimetric kinetic model for multi-ion therapy treatment planning with helium-, carbon-, oxygen-, and neon-ion beams.
In this study, we verified the SMK model in treatment planning of scanned helium-, carbon-, oxygen-, and neon-ion beams as well as their combinations through the irradiations of human undifferentiated carcinoma and human pancreatic cancer cells. Treatment plans were made with the ion-species beams to achieve a uniform 10% survival of the cells within a cuboid target. The planned survival fractions were reasonably reproduced by the measured survival fractions in the whole region from the plateau to the fragment tail for all planned irradiations. The SMK model offers the accuracy and simplicity required in hypo-fractionated ...
Source: Physics in Medicine and Biology - January 22, 2020 Category: Physics Authors: Inaniwa T, Suzuki M, Lee SH, Mizushima K, Iwata Y, Kanematsu N, Shirai T Tags: Phys Med Biol Source Type: research

On-beam computed tomography reconstruction for radiotherapy verification from projection image differences caused by motion during treatment.
Abstract The purpose of this study is to propose a reconstruction method of a target and its neighborhood, representative of the moment of radiotherapy delivery, based on differences in its transit images between the time of planning computed tomography (pCT) and the time of treatment beam delivery. To validate the method, a lung phantom with a target object was constructed, and CT-scanned before and after making a shift of the target. The latter scan was intended to simulate a potential organ movement at the time of treatment, and to serve as ground-truth images. Treatment planning using arc-beam delivery was don...
Source: Physics in Medicine and Biology - January 22, 2020 Category: Physics Authors: Lee H, Cheong KH, Jung JW, Cho BC, Cho S, Yeo IJ Tags: Phys Med Biol Source Type: research

Data clustering to select clinically-relevant test cases for algorithm benchmarking and characterization.
This study proposes a framework for selecting test cases to assess algorithm and workflow equivalence. Effective test case selection may minimize the number of ground-truth comparisons required to establish robust and clinically relevant benchmarking and characterization results. METHODS: To demonstrate the proposed framework, we clustered differences between two independent workflows estimating during-treatment dose objective violations for 15 head and neck cancer patients (15 planning CTs, 105 on-unit CBCTs). Each workflow used a different deformable image registration algorithm to estimate inter-fractional anatomy ...
Source: Physics in Medicine and Biology - January 21, 2020 Category: Physics Authors: Weppler S, Schinkel C, Kirkby C, Smith WL Tags: Phys Med Biol Source Type: research

A prognostic analysis method for non-small cell lung cancer based on the computed tomography radiomics.
CONCLUSIONS: This study proved that CT radiomics features could effectively assist doctors to make more accurate prognosis survival prediction for NSCLC patients, so as to help doctors to optimize treatment and re-examination for NSCLC patients to extend their survival time. PMID: 31962301 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 21, 2020 Category: Physics Authors: Wang X, Duan H, Li X, Ye X, Huang G, Nie SD Tags: Phys Med Biol Source Type: research

Experimental exploration of a mixed helium/carbon beam for online treatment monitoring in carbon ion beam therapy.
o J Abstract Recently, it has been proposed that a mixed helium/carbon beam could be used for online monitoring in carbon ion beam therapy. Fully stripped, the two ion species exhibit approximately the same mass/charge ratio and hence could potentially be accelerated simultaneously in a synchrotron to the same energy per nucleon. At the same energy per nucleon, helium ions have about three times the range of carbon ions, which could allow for simultaneous use of the carbon ion beam for treatment and the helium ion beam for imaging. In this work, measurements and simulations of PMMA phantoms as well as anthropomorp...
Source: Physics in Medicine and Biology - January 21, 2020 Category: Physics Authors: Volz L, Kelleter L, Brons S, Burigo LN, Graeff C, Niebuhr NI, Radogna R, Scheloske S, Schömers C, Jolly S, Seco J Tags: Phys Med Biol Source Type: research

Monte Carlo calculation of beam quality correction factors in proton beams using TOPAS/GEANT4.
CONCLUSION: TOPAS/GEANT4 can be used to calculatekQfactors in clinical proton beams.kQfactors for six plane-parallel and four cylindrical ionization chambers were calculated and provided for the update of the IAEA TRS-398 CoP. PMID: 31962306 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 21, 2020 Category: Physics Authors: Baumann KS, Kaupa S, Bach C, Engenhart-Cabillic R, Zink K Tags: Phys Med Biol Source Type: research

Microdosimetric calculations of the direct DNA damage induced by low energy electrons using the Geant4-DNA Monte Carlo code.
CONCLUSIONS: The yields of electron-induced simple and clustered DSB exhibit a strong energy dependence over the 100 eV - 100 keV range with implications to radiation quality issues. It is shown that a classical microdosimetry approach for the calculation of DNA damage based on lineal energy spectra in nanometer-size targets predicts comparable results to computationally intensive mechanistic approaches which use detailed atomistic DNA geometries, thus, offering a relatively simple and robust alternative for some practical applications. PMID: 31935692 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Margis S, Magouni M, Kyriakou I, Georgakilas AG, Incerti S, Emfietzoglou D Tags: Phys Med Biol Source Type: research

Performance evaluation of HiPET, a high sensitivity and high resolution preclinical PET tomograph.
CONCLUSION: These results and in vivo evaluation demonstrate that the HiPET can achieve high quality molecular imaging for biomedical applications. PMID: 31935693 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Gu Z, Taschereau R, Vu NT, Prout DL, Lee J, Chatziioannou AF Tags: Phys Med Biol Source Type: research

Iterative image reconstruction in transcranial photoacoustic tomography based on the elastic wave equation.
In this study, an optimization-based image reconstruction method for 3D transcranial PACT is developed based on the elastic wave equation. To accomplish this, a forward-adjoint operator pair based on a finite-difference time-domain discretization of the elastic wave equation is utilized to compute penalized least squares estimates of the initial pressure distribution. Computer-simulation and experimental studies are conducted to investigate the robustness of the reconstruction method to model mismatch and its ability to effectively resolve cortical and superficial brain structures. PMID: 31935694 [PubMed - as supplied...
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Poudel J, Na S, Wang LV, Anastasio MA Tags: Phys Med Biol Source Type: research

A cell-based dosimetry model for radium-223 dichloride therapy using bone micro-CT images and GATE simulations.
CONCLUSION: The absorbed dose distribution in images of mouse trabecular bone was compatible with simple geometric models, with absorbed doses capable of deterministic effects near the bone surface. The interaction distributions need to be correlated with in vivo studies for better interpretation. PMID: 31935695 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Pinto GM, Bonifacio DAB, de Sá LV, Lima LFC, Vieira IF, Lopes RT Tags: Phys Med Biol Source Type: research

Heuristic tree searching for pose-independent 3D/2D rigid registration of vessel structures.
In this study, 3D/2D vascular registration is formulated as a search tree problem on the basis of the topological continuity of vessels and the fact that matching can be decomposed into continuous states. In each node of the tree, a closed-solution of 3D/2D transfor-mation is used to obtain the registration results based on the dense correspondences of vessel points, and the results of match-ing and registration are calculated and recorded. Then, a hand-crafted score that quantifies the qualities of matching and regis-tration of vessels is used, and the remaining problem focuses on finding the highest score in the search t...
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Zhu J, Fan J, Guo S, Ai D, Song H, Wang C, Zhou S, Yang J Tags: Phys Med Biol Source Type: research

Assessment of uncertainties associated with Monte Carlo-based personalized dosimetry in clinical CT examinations.
Abstract The clinical value of x-ray Computed Tomography (CT) has skyrocketed in the last decade while at the same time accounting as the main source of medical exposure to the population. Concerns regarding the potential health hazards associated with the use of ionizing radiation were raised and an appropriate estimation of absorbed dose to patients is highly desired. In this work, we aim to validate our developed Monte Carlo CT simulator using in-phantom dose measurements and further assess the impact of personalized scan-related parameters on dosimetric calculations. We developed a Monte Carlo-based CT simulat...
Source: Physics in Medicine and Biology - January 14, 2020 Category: Physics Authors: Akhavanallaf A, Xie T, Zaidi H Tags: Phys Med Biol Source Type: research

Experimental validation of recommended < i > msr < /i > -correction factors for the calibration of Leksell Gamma Knife < sup > ® < /sup > Icon ™ unit following IAEA TRS-483.
Experimental validation of recommended msr-correction factors for the calibration of Leksell Gamma Knife® Icon™ unit following IAEA TRS-483. Phys Med Biol. 2020 Jan 08;: Authors: Mirzakhanian L, Sarfehnia A, Seuntjens J Abstract Currently, the American Association of Physicists in Medicine (AAPM) TG-21 is the conventional protocol currently used for the calibration of the Leksell Gamma Knife (LGK) (despite the publication of the AAPM TG-51 protocol). However, this protocol is based on the air-kerma standards requiring an elaborate conversion process resulting in an increase in the possibilit...
Source: Physics in Medicine and Biology - January 8, 2020 Category: Physics Authors: Mirzakhanian L, Sarfehnia A, Seuntjens J Tags: Phys Med Biol Source Type: research

Real-time tumor localization with single x-ray projection at arbitrary gantry angle using convolutional neural network (CNN).
CONCLUSION: A tumor localization method for single x-ray projection at arbitrary angle based on novel CNN was developed and validated in this study for real time operation. This greatly expanded the applicability of the tumor localization framework to the rotation therapy. PMID: 31896093 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 2, 2020 Category: Physics Authors: Wei R, Zhou F, Liu B, Bai X, Fu D, Liang B, Wu Q Tags: Phys Med Biol Source Type: research

A partial-dithering strategy for edge-illumination X-ray phase-contrast tomography enabled by a joint reconstruction method.
Abstract Edge-illumination X-ray phase-contrast tomography (EIXPCT) is a promising imaging technology where partially opaque masks are utilized with laboratory-based X-ray sources to estimate the distribution of the complex-valued refractive index. EIXPCT resolution is mainly determined by the period of a sample mask, but can be significantly improved by a dithering technique. Here, dithering means that multiple images per tomographic view angle are acquired as the object is moved over sub-pixel distances. Drawbacks of dithering include increased data-acquisition times and radiation doses. Motivated by the flexibi...
Source: Physics in Medicine and Biology - January 2, 2020 Category: Physics Authors: Chen Y, Hagen CK, Olivo A, Anastasio MA Tags: Phys Med Biol Source Type: research

Comparison of different kinetic models for dynamic 18F-FDG PET/CT imaging of hepatocellular carcinoma with various, also dual-blood input function.
Abstract A kinetic modeling analysis was performed on hepatocellular carcinoma (HCC) as well as healthy liver tissue regions from dynamic FDG positron emission tomography s/ computer tomography (PET/CT) cans. On basis of image derived input function from hepatic artery and portal vein, various kinetic models were compared among each other in order to check whether HCC can be classified and differ from healthy tissue within the kinetic parameters. 14 HCC and 10 healthy liver regions from FDG PET/CT scans of 10 patients were analyzed from their time activity curves (TACs) were extracted from the PET dynamic images. ...
Source: Physics in Medicine and Biology - January 2, 2020 Category: Physics Authors: Geist BK, Wang J, Wang X, Lin J, Yang X, Zhang H, Li F, Zhao H, Hacker M, Huo L, Li X Tags: Phys Med Biol Source Type: research

Validation of the proton range accuracy and optimization of CT calibration curves utilizing range probing.
CONCLUSIONS: The feasibility of using range probing to assess range errors was demonstrated. The theoretical uncertainty margins in the institution-specific setting potentially may be reduced by ∼25%. PMID: 31896099 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - January 2, 2020 Category: Physics Authors: Meijers A, Free J, Wagenaar D, Deffet S, Knopf AC, Langendijk JA, Both S Tags: Phys Med Biol Source Type: research

Predicting Outcome using Genomic-Based Liquid Biomarkers.
PMID: 31836074 [PubMed - in process] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - December 16, 2019 Category: Physics Authors: Marples B, Wilson GD Tags: Int J Radiat Oncol Biol Phys Source Type: research

ComBat harmonization for radiomic features in independent phantom and lung cancer patient computed tomography datasets.
CONCLUSION: This work verifies previously published results and demonstrates that ComBat harmonization is an effective means to harmonize radiomic features extracted from different imaging protocols to allow comparisons in large multi-institution datasets. Biological variation can be explicitly preserved by providing the ComBat algorithm with clinical or biological variables to protect. ComBat harmonization should be tested for its effect on predictive models. PMID: 31835261 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - December 13, 2019 Category: Physics Authors: Mahon RN, Ghita M, Hugo GD, Weiss E Tags: Phys Med Biol Source Type: research

Modelling of the focal spot intensity distribution and the off-focal spot radiation in kilovoltage X-ray tubes for imaging.
In conclusion, an X-ray tube, Monte Carlo simulation model was developed to simulate focal spot intensity distributions and to evaluate off-focal radiation characteristics at several energies. This model can be further employed to investigate focal spot corrections methods and improve cone-beam CT image quality. PMID: 31835265 [PubMed - as supplied by publisher] (Source: Physics in Medicine and Biology)
Source: Physics in Medicine and Biology - December 13, 2019 Category: Physics Authors: van der Heyden B, Fonseca GP, Podesta M, Messner I, Reisz N, Vaniqui A, Deutschmann H, Steininger P, Verhaegen F Tags: Phys Med Biol Source Type: research

Validation of the analytical irradiator model and Monte Carlo dose engine in the small animal irradiation treatment planning system µ-RayStation 8B.
Validation of the analytical irradiator model and Monte Carlo dose engine in the small animal irradiation treatment planning system µ-RayStation 8B. Phys Med Biol. 2019 Dec 12;: Authors: Chiavassa S, Nilsson R, Clement-Colmou K, Potiron V, Delpon G, Traneus E Abstract Dose calculation in preclinical context with a clinical level of accuracy is a challenge due to the small animal scale and the medium photon energy range. In this work, we evaluate the effectiveness and accuracy of an analytical irradiator model combined with Monte Carlo (MC) calculations in the irradiated volume to calculate the d...
Source: Physics in Medicine and Biology - December 12, 2019 Category: Physics Authors: Chiavassa S, Nilsson R, Clement-Colmou K, Potiron V, Delpon G, Traneus E Tags: Phys Med Biol Source Type: research

Small field dosimetry correction factors for circular and MLC shaped fields with the CyberKnife M6 System: evaluation of the PTW 60023 microSilicon detector.
In this study we evaluated the correction factors relevant to commissioning a CyberKnife System with this detector by Monte Carlo simulation and verified this data by multi-detector measurement comparison. The correction factors required for output factor determination were substantially closer to unity at small field sizes than for previous diode versions (e.g. k_(Q_clin,Q_msr)^(f_clin,f_msr ) = 0.981 at 5 mm field size which compares with corrections of 5% - 6% with other stereotactic diodes). Because of these differences we recommend that corrections to small field output factor measurements generated specifically for t...
Source: Physics in Medicine and Biology - December 12, 2019 Category: Physics Authors: Francescon P, Kilby W, Noll JM, Satariano N, Orlandi C Tags: Phys Med Biol Source Type: research

The convolutional interpretation of registration-based plane wave steered pulse-echo local sound speed estimators.
Abstract Pulse-echo reconstruction of sound speed has long been considered a difficult problem within the domain of quantitative biomedical ultrasound. However, recent results [1-3] have demonstrated that pulse-echo reconstructions of sound speed are achievable by exploiting correlations in post-beamformed data from steered, plane-wave excitations in the presence of diffuse scatterers. Despite these recent advances, a coherent theoretical imaging framework for describing the approach and results is lacking in the literature. In this work, the problem of sound speed reconstruction using steered, plane-wave excitati...
Source: Physics in Medicine and Biology - December 11, 2019 Category: Physics Authors: Podkowa AS, Oelze ML Tags: Phys Med Biol Source Type: research

Nuclear-interaction correction for patient dose calculations in treatment planning of helium-, carbon-, oxygen-, and neon-ion beams.
Abstract In charged-particle therapy treatment planning, the patient is conventionally modeled as variable-density water, i.e., stopping effective density ρS, and the planar integrated dose distribution measured in water (PID) is applied for patient dose calculation based on path length scaling with the ρS. This approximation assures the range accuracy of charged-particle beams. However, it causes dose calculation errors due to water nonequivalence of body tissues in nuclear interactions originating from compositional differences. We had previously proposed a PID correction method for the errors in carbon-...
Source: Physics in Medicine and Biology - December 9, 2019 Category: Physics Authors: Inaniwa T, Lee SH, Mizushima K, Sakata D, Iwata Y, Kanematsu N, Shirai T Tags: Phys Med Biol Source Type: research

Novel computed tomography image synthesis method for correcting the spectrum dependence of CT numbers.
This study proposed a novel CT image synthesis method to correct the spectrum dependence of CT numbers by normalizing them to the same spectrum condition. Stoichiometric calibration was performed to derive the spectrum characteristic parameters (SCPs) of six spectra from two CT scanners with different applied tube voltages. Subsequently, conversion relationships between CT numbers and tissue parameters (TPs) were determined using the SCPs and standard tissue data. The CT number of a tissue measured from a spectrum condition was converted to TPs using these relationships, and the results were used to estimate the CT number ...
Source: Physics in Medicine and Biology - December 9, 2019 Category: Physics Authors: Chen Y, Fang HY, Wang YC, Peng SL, Shih CT Tags: Phys Med Biol Source Type: research

Numerical observer study of lesion detectability for a long axial field-of-view whole-body PET imager using the PennPET Explorer.
Abstract This work uses lesion detectability to characterize the performance of long axial field of view (AFOV) PET scanners which have increased sensitivity compared to clinical scanners. Studies were performed using the PennPET Explorer, a 70-cm long AFOV scanner built at the University of Pennsylvania, for small lesions distributed in a uniform water-filled cylinder (simulations and measurements), an anthropomorphic torso phantom (measurement), and a human subject (measurement). The lesion localization and detection task was quantified numerically using a generalized scan statistics methodology. Detectability w...
Source: Physics in Medicine and Biology - December 9, 2019 Category: Physics Authors: Viswanath V, Daube-Witherspoon ME, Karp JS, Surti S Tags: Phys Med Biol Source Type: research

Reconstruction method for DECT with one half-scan plus a second limited-angle scan using prior knowledge of complementary support set (Pri-CSS).
In this study, using one half-scan and a second limited-angle scan, we propose a DECT reconstruction method by exploiting the consistent information of gradient images at high- and low-energy spectra, which relaxes the requirement of data acquisition of DECT. Based on the theory of sampling condition analysis, the complementary support set of gradient images plays an important role in image reconstruction because it constitutes the sufficient and necessary condition for accurate CT reconstruction. For DECT, the gradient images of high- and low-energy CT images ideally share the same complementary support set for the same o...
Source: Physics in Medicine and Biology - December 6, 2019 Category: Physics Authors: Zhang W, Wang L, Li L, Li Z, Liang N, Yan B, Hu G Tags: Phys Med Biol Source Type: research

Group-level analysis of induced electric field in deep brain regions by different TMS coils.
In this study, we computationally evaluated group-level dosage for dTMS to characterize the targeted deep brain regions to overcome the limitations of using individualized head models to characterize coil performance in a population. We used an inter-subject registration method adapted to the deep brain regions that enable projection of computed electric fields (EFs) from individual realistic head models (n = 18) to the average space of deep brain regions. The computational results showed consistent group-level hotspots of the EF in the deep brain regions. The halo circular assembly coils induced the highest EFs in deep br...
Source: Physics in Medicine and Biology - December 4, 2019 Category: Physics Authors: Gomez-Tames J, Hamasaka A, Hirata A, Laakso I, Lu M, Ueno S Tags: Phys Med Biol Source Type: research