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JOURNAL ARTICLE
Sivakumar Muthu, Gopinath Mudhana
AIM: This study comprehensively investigated pre-treatment quality assurance (QA) for 100 cancer patients undergoing stereotactic treatments (SRS/SRT) using various detectors. METHODS: The study conducted QA for SRS/SRT treatments planned with a 6MV SRS beam at a dose rate of 1,000 MU/min, utilizing Eclipse v13.6 Treatment Planning System (TPS). Point dose measurements employed 0.01cm3 and 0.13cm3 cylindrical ionization chambers, while planar dose verification utilized Gafchromic EBT-XD Film and Portal Imager (aS1000)...
April 1, 2024: Asian Pacific Journal of Cancer Prevention: APJCP
#2
JOURNAL ARTICLE
Yousif A M Yousif, John Daniel, Brendan Healy, Robin Hill
BACKGROUND: Ionization chambers play an essential role in dosimetry measurements for kilovoltage (kV) x-ray beams. Despite their widespread use, there is limited data on the absolute values for the polarity correction factors across a range of commonly employed ionization chambers. PURPOSE: This study aimed to investigate the polarity effects for five different ionization chambers in kV x-ray beams. METHODS: Two plane-parallel chambers being the Advanced Markus and Roos and three cylindrical chambers; 3D PinPoint, Semiflex and Farmer chamber (PTW, Freiburg, Germany), were employed to measure the polarity correction factors...
April 26, 2024: Medical Physics
#3
JOURNAL ARTICLE
Mark D'Souza, Arman Sarfehnia
BACKGROUND: In water calorimetry, absolute dose to water is determined by measuring radiation-induced temperature rises. In conventional water calorimeters, temperature detectors are housed in handmade glass vessels that are filled with high-purity water, thus mitigating radiation-induced exo/endothermic chemical reactions of impurities that would otherwise introduce additional heat gain/loss, known as heat defect. Being hand-crafted, these glass vessels may suffer from imperfections, have shape and design constraints, are often backordered, and can be prohibitively expensive...
April 24, 2024: Medical Physics
#4
JOURNAL ARTICLE
Pearl Abue, Nirvan Bhattacharyya, Mengjia Tang, Leif G Jahn, Daniel Blomdahl, David T Allen, Richard L Corsi, Atila Novoselac, Pawel K Mistzal, Lea Hildebrandt Ruiz
A rise in the disinfection of spaces occurred as a result of the COVID-19 pandemic as well as an increase in people wearing facial coverings. Hydrogen peroxide was among the recommended disinfectants for use against the virus. Previous studies have investigated the emissions of hydrogen peroxide associated with the disinfection of spaces and masks; however, those studies did not focus on the emitted byproducts from these processes. Here, we simulate the disinfection of an indoor space with H2 O2 while a person wearing a face mask is present in the space by using an environmental chamber with a thermal manikin wearing a face mask over its breathing zone...
April 17, 2024: ACS Eng Au
#5
JOURNAL ARTICLE
Gloria Vilches-Freixas, Geert Bosmans, Alexandros Douralis, Jonathan Martens, Arturs Meijers, Ilaria Rinaldi, Koen Salvo, Russell A S Thomas, Hugo Palmans, Ana Lourenço
Objective 
In this experimental work we compared the determination of absorbed dose to water using four ionization chambers (ICs), a PTW-34045 Advanced Markus, a PTW-34001 Roos, an IBA-PPC05 and a PTW-30012 Farmer, irradiated under the same conditions in one continuous- and in two pulsed-scanned proton beams. 
Approach
The ICs were positioned at 2 cm depth in a water phantom in four square-field single-energy scanned-proton beams with nominal energies between 80 MeV and 220 MeV and in the middle of 10x10x10 cm3 dose cubes centered at 10 cm or 12...
April 19, 2024: Physics in Medicine and Biology
#6
JOURNAL ARTICLE
Michaël Claessens, Verdi Vanreusel, Alessia Gasparini, Luana de Freitas Nascimento, Burak Yalvec, Brigitte Reniers, Dirk Verellen
BACKGROUND: Plane-parallel ionization chambers are the recommended secondary standard systems for clinical reference dosimetry of electrons. Dosimetry in high dose rate and dose-per-pulse (DPP) is challenging as ionization chambers are subject to ion recombination, especially when dose rate and/or DPP is increased beyond the range of conventional radiotherapy. The lack of universally accepted models for correction of ion recombination in UDHR is still an issue as it is, especially in FLASH-RT research, which is crucial in order to be able to accurately measure the dose for a wide range of dose rates and DPPs...
April 19, 2024: Medical Physics
#7
JOURNAL ARTICLE
A Talbi, T Zidouz, A Abarane, A Mekkioui, A Allach, M Zaryah, M El Harchaoui
The present study aimed to validate the different radiodiagnostic beam qualities (RQT, WAH and WAV) by the measurements of the X-ray beams HVL of a HOPEWELL generator, X80-225 kV from a high voltage range of 10 at 200 kV, at CNESTEN Gamma and X Calibration Laboratory. The experiments were carried out using the PTW TN 32005 ionization chamber, established at 100 cm from the center of the X-ray tube and connected to a SUPERMAX electrometer. The HVL values were measured by applying the attenuation law to the flow of Kair air kerma, including their uncertainties...
April 15, 2024: Applied Radiation and Isotopes
#8
JOURNAL ARTICLE
Qingxin Wang, Qifeng Li, Zhongqiu Wang, Chengwen Yang, Daguang Zhang, Jun Wang, Ping Wang, Wei Wang
PURPOSE: To investigate and characterize the performance of a novel orthogonal dual-layer alpha multileaf collimator (αMLC) mounted on the LinaTech VenusX linac. METHODS: We evaluated leaf positioning accuracy and reproducibility using an electronic portal imaging device through the picket fence test. The average, interleaf, intraleaf, and leaf tip transmissions of the single and dual layers were measured using an ionization chamber. Square and rhombus fields were used to evaluate the leaf penumbra of αMLC...
April 15, 2024: Journal of Applied Clinical Medical Physics
#9
JOURNAL ARTICLE
Dixin Chen, Seyyedeh Azar Oliaei Motlagh, François Vander Stappen, Rudi Labarbe, Beryl Bell, Michele Kim, Boon-Keng Kevin Teo, Lei Dong, Wei Zou, Eric Stanton Diffenderfer
BACKGROUND: Cyclotron-based proton therapy systems utilize the highest proton energies to achieve an ultra-high dose rate (UHDR) for FLASH radiotherapy. The deep-penetrating range associated with this high energy can be modulated by inserting a uniform plate of proton-stopping material, known as a range shifter, in the beam path at the nozzle to bring the Bragg peak within the target while ensuring high proton transport efficiency for UHDR. Aluminum has been recently proposed as a range shifter material mainly due to its high compactness and its mechanical properties...
April 10, 2024: Medical Physics
#10
JOURNAL ARTICLE
Henning Manke, Dirk Flühs, Michelle Stroth, Nikolaos E Bechrakis, Andreas M H Foerster, Johannes Albrecht
Objective
We present a novel concept to treat ophthalmic tumors which combines brachytherapy and low-energy x-ray therapy. Brachytherapy with106 Ru applicators applicators is inadequate for intraocular tumors with a height of 7 mm and more. This results from a steep dose gradient, and it is unfeasible to deliver the required dose at the tumor apex without exceeding the maximum tolerable sclera dose of usually 1000 to 1500 Gy. Other modalities, such as irradiation with charged particles, may be individually contraindicated...
April 8, 2024: Biomedical Physics & Engineering Express
#11
JOURNAL ARTICLE
Sana Choudhary, Towseef Mohsin Bhat, Khairiah Mubarak Alwutayd, Diaa Abd El-Moneim, Neha Naaz
Plants possess various defense mechanisms to cope with genotoxic and environmental challenges, with high temperatures posing a significant threat due to global warming. In this investigation, ten-day-old Trigonella foenum-graecum (fenugreek) seedlings were cultivated in a controlled environment chamber with conditions set at 70-80% relative humidity, a day/night cycle of 25/18 °C, and a photosynthetically active radiation (PAR) of 1000 μmol m-2 s-1 . Other groups of seedlings were subjected to temperatures of 30, 35, or 40 °C...
March 30, 2024: Heliyon
#12
JOURNAL ARTICLE
Marie-Luise Kuhlmann, Stefan Pojtinger
Personalized dose monitoring and risk management are of increasing significance with the growing number of computer tomography (CT) examinations. These require high-quality Monte Carlo (MC) simulations that are of the utmost importance for the new developments in personalized CT dosimetry. 
This work aims to extend the MC framework EGSnrc source code with a new particle source. This, in turn, allows CT-scanner-specific dose and image calculations for any CT scanner. The novel method can be used with all modern EGSnrc user codes, particularly for the simulation of the effective dose based on DICOM images and the calculation of CT images...
March 27, 2024: Physics in Medicine and Biology
#13
JOURNAL ARTICLE
Michel Chea, Mathilde Croisé, Christelle Huet, Céline Bassinet, Mohamed-Amine Benadjaoud, Catherine Jenny
PURPOSE: To assess a large panel of MR compatible detectors on the full range of measurements required for a 0.35 T MR-linac commissioning by using a specific statistical method represented as a continuum of comparison with the Monte Carlo (MC) TPS calculations. This study also describes the commissioning tests and the secondary MC dose calculation validation. MATERIAL AND METHODS: Plans were created on the Viewray TPS to generate MC reference data. Absolute dose points, PDD, profiles and output factors were extracted and compared to measurements performed with ten different detectors: PTW 31010, 31021, 31022, Markus 34045 and Exradin A28 MR ionization chambers, SN Edge shielded diode, PTW 60019 microdiamond, PTW 60023 unshielded diode, EBT3 radiochromic films and LiF µcubes...
March 20, 2024: Radiation Oncology
#14
JOURNAL ARTICLE
Douglas Batista da Silva, Ademir Xavier da Silva Xavier da Silva, Carlos Frederico Estrada Alves, Luis Alexandre Gonçalves Magalhaes
The aim of this study was to use computer simulation to analyze the impact of the aluminum fixing support on the Reference Air Kerma (RAK), a physical quantity obtained in a calibration system that was experimentally developed in the Laboratory of Radiological Sciences of the University of the State of Rio de Janeiro (LCR-UERJ). Correction factors due to scattered radiation and the geometry of the 192Ir sources were also sought to be determined. The computational simulation was validated by comparing some parameters of the experimental results with the computational results...
March 20, 2024: Biomedical Physics & Engineering Express
#15
JOURNAL ARTICLE
Stephan Frick, Moritz Schneider, Ralf-Peter Kapsch, Daniela Thorwarth
BACKGROUND AND PURPOSE: For dosimetry in magnetic resonance (MR) guided radiotherapy, assessing the magnetic field correction factors of air-vented ionization chambers is crucial. Novel MR-optimized chambers reduce MR-imaging artefacts, enhancing their quality assurance utility. This study aimed to characterize two new MR-optimized ionization chambers with sensitive volumes of 0.07 and 0.016 cm3 regarding magnetic field correction factors and intra-type variation and compare them to their conventional counterparts...
January 2024: Physics and Imaging in Radiation Oncology
#16
JOURNAL ARTICLE
Tadahiro Mizoguchi, Yuji Tameshige, Tatsuya Kaneda, Yoshiji Ogawa, Yoshiyuki Muranaka, Hiroyasu Tamamura
PURPOSE: When performing single-point dose verification in VMAT, it is necessary to avoid the regions with steep dose gradient. We propose a method to obtain the estimated value ( Uplan ) of uncertainty of the absolute dose measurement due to the phantom setup error by using dose gradient calculated from treatment planning system (TPS), for evaluating the appropriate measurement points. METHODS: The dose gradient was calculated from the planned dose values in the vicinity of the isocenter point using TPS...
March 5, 2024: Nihon Hoshasen Gijutsu Gakkai Zasshi
#17
JOURNAL ARTICLE
Matthew James Large, Aishah Bashiri, Yashiv Dookie, Joanne McNamara, Luca Antognini, Saba Aziz, Lucio Calcagnile, Anna Paola Caricato, Roberto Catalano, Deborah Chila, Giuseppe Antonio Pablo Cirrone, Tomasso Croci, Giacomo Cuttone, Sylvain Dunand, Michele Fabi, Luca Frontini, Catia Grimani, Maria Ionica, Keida Kanxheri, Valentino Liberali, Martino Maurizio, Giuseppe Maruccio, Giovanni Mazza, Mauro Menichelli, Anna Grazia Monteduro, Arianna Morozzi, Francesco Moscatelli, Stefania Pallotta, Daniele Passeri, Maddalena Pedio, Giada Petringa, Francesca Peverini, Lorenzo Piccolo, Pisana Placidi, Gianluca Quarta, Silvia Rizzato, Federico Sabbatini, Leonello Servoli, Alberto Stabile, Cinzia Talamonti, Jonathan Emanuel Thomet, Luca Tosti, Mattia Villani, Richard James Wheadon, Nicolas Wyrsch, Nicola Zema, Marco Petasecca
BACKGROUND: The increasing use of complex and high dose-rate treatments in radiation therapy necessitates advanced detectors to provide accurate dosimetry. Rather than relying on pre-treatment quality assurance (QA) measurements alone, many countries are now mandating the use of in vivo dosimetry, whereby a dosimeter is placed on the surface of the patient during treatment. Ideally, in vivo detectors should be flexible to conform to a patient's irregular surfaces. PURPOSE: This study aims to characterize a novel hydrogenated amorphous silicon (a-Si:H) radiation detector for the dosimetry of therapeutic x-ray beams...
March 3, 2024: Medical Physics
#18
JOURNAL ARTICLE
Xinhua Li, Theodore A Marschall, Kai Yang, Bob Liu
BACKGROUND: Mobile C-arms may be used in fixed locations, and it is recommended that qualified experts evaluate structural shielding. PURPOSE: To assess clinical workload distributions for mobile C-arms used in gastrointestinal endoscopy and determine the Archer equation parameters for the C-arm beam spectra. METHODS: Consecutive (30 months) gastrointestinal endoscopic procedures on two Cios Alpha systems (Siemens) were retrospectively analyzed...
February 29, 2024: Medical Physics
#19
JOURNAL ARTICLE
Chris Heintz, Lisa Schnödewind, Oliver Braubach, Hendrik Kersten, Thorsten Benter, Walter Wißdorf
Electrospray ionization (ESI) is one of the most prominent atmospheric pressure ionization techniques in modern mass spectrometry. It generates charged droplets from an analyte-containing solution as an initial step in the ionization process. Textbooks and the majority of the articles assume the entire droplet evaporation and release of bare analyte ions within the ionization chamber. However, non-mass-spectrometry-related literature and recent reports demonstrate droplet observation in regions of the vacuum systems of a variety of mass spectrometers...
February 26, 2024: Journal of the American Society for Mass Spectrometry
#20
JOURNAL ARTICLE
Hideyuki Mizuno, Taku Nakaji, Shigekazu Fukuda, Shingo Kato
BACKGROUND: End-to-end dosimetry audit for brachytherapy is challenging due to the steep dose gradient. However, it is an efficient method to detect unintended errors in actual clinical practice. PURPOSE: We aimed to develop an on-site end-to-end test phantom for three-dimensional image-guided brachytherapy (IGBT) for cervical cancer. METHODS: The test phantom we developed consisted of a water tank with an applicator/detector holder. The holder was designed to accommodate the applicator and insert an ionization chamber (PinPoint; PTW, Freiburg, Germany) to measure the dose at point A...
February 22, 2024: Physica Medica: PM
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