Medical Physics Mishkat Ali Jafri; Intikhab Ulfat
International journal of endorsing health science research,
12/2023, Volume:
11, Issue:
4
Journal Article
Peer reviewed
Open access
Medical physics is a branch of applied physics that is dedicated to the application of physics principles and techniques to the field of medicine. It plays a crucial role in ensuring the safety and ...effectiveness of medical procedures and contributes to advancements in the diagnosis and treatment of various medical conditions. Medical physics has its roots in the early discoveries of X-rays by Wilhelm Roentgen and the radioactive properties of certain elements, notably those discovered by Marie Curie.
Purpose: Very high energy electrons (VHEEs) present promising clinical advantages over conventional beams. They are able to target deep-seated tumors due to their increased range and improved ...penumbra compared to low energy electrons. VHEEs are also relatively insensitive to tissue heterogeneities, and are able to be electromagnetically scanned. These advantages facilitate their use in conjunction with spatial fractionation techniques or FLASH irradiations. However, the lack of radiobiological data concerning their biological efficacy is a limiting factor. This study aims to characterize different VHEE beams against clinically available beams by making use of Monte Carlo (MC) based numerical simulations to compare their macroand microdosimetric properties.Methods: All simulations were performed on GATE version 8.2. A solid water phantom was irradiated by the following beams: 5, 20, 100, and 300 MeV electrons, a 60Co source (1.25 MeV photons), 105 MeV protons, 194.2 MeV/nucleon 12C ions, and 262 MeV/nucleon 20Ne ions. The dose-averaged linear energy transfer (¯(L_d )) was evaluated as the macrodosimetric quantity of interest. On a microscopic scale, the lineal energy y was used in order to account for the stochasticity of irradiations. The dose-mean lineal energy ¯(y_d ) and the lineal energy distribution described as a function of its dose density, d(y), were calculated. A tissue equivalent proportional counter (TEPC) was implemented in GATE to record the lineal energy spectra. Finally, the modified microdosimetric kinetic model (MKM) was used to calculate the respective cell survival curves using biological parameters of HSG cell line and the lineal energy spectra as inputs.Results: From the macrodosimetric point of view, VHEEs present a potential improved biological efficacy over clinical photon/electron beams due to their increased ¯(L_d ). At a depth of 4 cm in water, the ratio of 300 MeV ¯(L_d ) values to other particles is 0.2, 1.9, 3.2, and 2.4 for protons, 100 MeV electrons, 20 MeV electrons, and photons respectively. The microdosimetric data, however, suggests no increased biological effectiveness of VHEEs over clinical electron beams, as seen in Figure 1 and Table 1. No significant differences were found between their lineal energy spectra nor their ¯(y_d ) depth profiles. Correspondingly, application of the MKM yielded similar cell survival curves, resulting in relative biological effectiveness (RBE10) values for VHEEs of approximately 1. Furthermore, RBE values of 1.2, 2.9 and 3.3 were obtained for proton, carbon-ion and neon-ion beams respectively, while ¯(L_d ) values above 200 keV/µm and lineal energies as high as 2000 keV/µm were obtained in the Bragg peak region for neon-ions.Conclusion: This study represents a first step towards a full evaluation of the biological efficacy of VHEE beams. The biologically relevant information obtained from these theoretical MC simulations could be used to complement further experiments which explore the radiobiological response to VHEE treatment.
BackgroundNot all patients with severe aortic valve stenosis are eligible for open-heart surgery or TAVR. CARDIAWAVE (Paris, France) has developed Valvosoft, a unique non-invasive ultrasound therapy ...device to treat aortic stenosis. The therapy aims to improve the opening of severely calcified aortic valves by cracking the calcium and reducing the stiffness in the aortic valve tissue by delivering transthoracically local shock waves on the valve leaflets. This study assesses the safety, feasibility and performance of this novel technique.MethodsThis is a multi-center, prospective, first-in-man study designed to evaluate the safety and feasibility of the Valvosoft device. Ten patients with severe symptomatic calcific aortic stenosis and not eligible for SAVR/TAVR underwent a Valvosoft ultrasound therapy. Echocardiographic evaluation was performed by an independent core lab at baseline, discharge, and at 1, 3, 6 and 12 months along with clinical follow up.ResultsEnrolled patients were advanced in age (84.1±6.5 yrs) with severe comorbidities (8 with heart failure, 5 with coronary heart disease and 5 with kidney failure). All had extensive aortic valve calcification with mean AVA of 0.61±0.17 cm2 and mean pressure gradient of 37.5±10.5 mmHg. At one-month follow-up, six patients had significantly improved their AVA with increase of 27.5% (p=0.03) and mean pressure gradient decrease of 23.2 % (p=0.025). These patients also received the highest dose and longest treatment duration. During one year follow up, 4 patients died due to progression of end stage heart failure not linked to the procedure and one patient had undergone a TAVR procedure. At 12 months, the five remaining patients has no device or procedure related major adverse events nor deterioration of neurological status. Echo, brain-MRI and clinical follow up will be presented.ConclusionsNon-invasive ultrasound therapy is feasible and safe in patients with severe aortic valve stenosis and can improve AVA and hemodynamic parameters. NIUT can be an important tool complementary to TAVI in treating patients with aortic valve stenosis.
Purpose:
To investigate behaviors that may be in conflict with ethical standards of the Medical Physics Residency (MedPhys) Match process and with best practices for adhering to non-discrimination ...regulations of the Equal Employment Opportunity Commission (EEOC).
Methods:
A confidential survey was sent to registered applicants and program directors for the 2014/2015 MedPhys Match. Survey questions included demographics, application, interview and post-interview experiences, match results, and overall satisfaction with the process.
Results:
Of the 402 candidates emailed, 109 completed the survey. 48% of the respondents did match with a residency position in 2015. Of the 77 program directors emailed, 42 completed the survey. Selected results of the surveys are included. 69% of candidate respondents indicated that they were asked during interviews where else they were interviewing; 31.7% of those respondents indicated that they were uncomfortable or very uncomfortable answering. 40% of candidate respondents (39% of males, 41% of females) indicated that they were asked about their marital or relationship status. 23% of the respondents (19% of males, 33% of females) indicated that they were asked about children or plans to have children. 57% who were asked this question (27% of males, 89% of females) indicated that they were uncomfortable/very uncomfortable answering. 29% were told by a program that they were “ranked to match” or told their rank prior to the match deadline. Only 13% indicated that they were asked by a program how highly they were going to rank that program or asked which program they would rank number one. Among that 13%, 64% indicated that they were uncomfortable/very uncomfortable answering.
Conclusion:
In the inaugural year of the MedPhys Match, there were instances of ethical violations and discriminatory interviewing. Training on the Match rules and EEOC guidelines can decrease these instances and thereby increase the fairness of the residency selection process.
Brachytherapy is a well-established therapeutic technique for treating tumours involving the placement of radioactive encapsulated sources close to or in direct contact with a tumour. Considering ...this type of treatments, the purpose of this work is to incorporate Monte Carlo (MC) simulation into brachytherapy treatment planning. This approach allows for precise estimation of dose distribution in target organs as well as in Organs At Risk (OAR), due to the accuracy of the MC methods in describing dose deposition.
To carry out this work, the medical image visualization and dose analysis tools provided by the open-source planner PlanUNC (PLUNC) were utilized. Additionally, a set of programs was developed which automatize the main steps of a treatment planning segmentation, from DICOM images, exporting geometries determining materials and seeds positions, creating an input file for the simulation code (MCNP6.2) and, finally, reading and visualization of the simulation results in the format of the used planning software. With this methodology, results of 3D dose distribution, isodoses curves, Dose-Volume Histograms (DVH), and absorbed dose in OAR were obtained. Thus, the integration of the MC simulation into PLUNC for brachytherapy treatments, has demonstrate its utility for this purpose, showing adaptability to different anatomical geometries and extensibility to various types of treatments.
•More accuracy in patient dose estimation when using Monte Carlo simulation.•Methodology has been designed to incorporate Monte Carlo into brachytherapy planning.•Realistic simulations with patient CT images allows calculating dose distribution.•Adequate accuracies and computing times compared to real planning treatment.•In-depth analysis of medically valid outcome data for brachytherapy treatments.
Psychoacoustics - Facts and Models offers a unique, comprehensive summary of information describing the processing of sound by the human hearing system. It includes quantitative relations between ...sound stimuli and auditory perception in terms of hearing sensations, for which quantitative models are given, as well as an unequalled collection of data on the human hearing system as a receiver of acoustic information. In addition, many examples of the practical application of the results of basic research in fields such as noise control, audiology, or sound quality engineering are detailed. The third edition includes an additional chapter on audio-visual interactions and applications, plus more on applications throughout. Reviews of previous editions have characterized it as "an essential source of psychoacoustic knowledge," "a major landmark ," and a book that "without doubt will have a long-lasting effect on the standing and future evolution of this scientific domain.".
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