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A special issue of Applied Sciences (ISSN 2076-3417).

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 25412

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Special Issue Editors

Prof. Dr. Cinzia Talamonti

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Guest Editor

Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, University of Florence, 35632 Florence, Italy
Interests: dosimetric characterisation of Portal imaging systems; silicon and CVD diamond dosimeter; imaging with charged particles

Dr. Marco Petasecca

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Guest Editor

Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia
Interests: radiation dosimetry instrumentation; silicon and organic electronics; small field dosimetry

Dr. Simona Giordanengo

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Guest Editor

National Institute for Nuclear Physics - INFN, 10125 Torino, Italy
Interests: radiation detectors for particle therapy; beam monitoring; dose delivery systems; detector readout systems; applied physics in medicine

Special Issue Information

Dear Colleagues,

Physics principles applied to medical physics are well known, and ionizing and non-ionizing radiations have been in use for many years for medical imaging and therapy purposes.

Thanks to the rapid technological development, in recent years, we have witnessed tremendous progress in instrumentation for clinical applications especially in the direction of a personalized medicine, with new and more performant detectors, imaging modalities, new particle beams for therapy, and medical accelerators becoming available.

In this scenario, it is of paramount importance to understand what the new trends in the development of detectors are and which new methods, materials, and technologies are now available in medical physics.

The scope of this Special Issue is to collect original research works on cutting-edge detectors developed for medicine. The main topics covered include medical imaging detectors, detectors used in radiation therapy and hadron therapy, radiation protection and dosimetry, microdosimetry, and nanodosimetry, with special emphasis on interdisciplinary works.

Manuscripts regarding advanced detectors, novel approaches for characterizing and modeling materials, dedicated frontend readout and data acquisitions systems, as well as review articles on detector applications in medical physics, are welcome in this Special Issue.

Prof. Dr. Cinzia Talamonti
Prof. Marco Petasecca
Dr. Simona Giordandengo
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

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Published Papers (13 papers)

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12 pages, 1806 KiB

Open AccessArticle

First Characterization of Novel Silicon Carbide Detectors with Ultra-High Dose Rate Electron Beams for FLASH Radiotherapy

by Francesco Romano, Giuliana Milluzzo, Fabio Di Martino, Maria Cristina D’Oca, Giuseppe Felici, Federica Galante, Alessia Gasparini, Giulia Mariani, Maurizio Marrale, Elisabetta Medina, Matteo Pacitti, Enrico Sangregorio, Verdi Vanreusel, Dirk Verellen, Anna Vignati and Massimo Camarda

Appl. Sci. 2023, 13(5), 2986; https://doi.org/10.3390/app13052986 - 25 Feb 2023

Cited by 10 | Viewed by 2122

Abstract

Ultra-high dose rate (UHDR) beams for FLASH radiotherapy present significant dosimetric challenges. Although novel approaches for decreasing or correcting ion recombination in ionization chambers are being proposed, applicability of ionimetric dosimetry to UHDR beams is still under investigation. Solid-state sensors have been recently investigated as a valuable alternative for real-time measurements, especially for relative dosimetry and beam monitoring. Among them, Silicon Carbide (SiC) represents a very promising candidate, compromising between the maturity of Silicon and the robustness of diamond. Its features allow for large area sensors and high electric fields, required to avoid ion recombination in UHDR beams. In this study, we present simulations and experimental measurements with the low energy UHDR electron beams accelerated with the ElectronFLASH machine developed by the SIT Sordina company (IT). The response of a newly developed 1 × 1 cm² SiC sensor in charge as a function of the dose-per-pulse and its radiation hardness up to a total delivered dose of 90 kGy, was investigated during a dedicated experimental campaign, which is, to our knowledge, the first characterization ever done of SiC with UHDR-pulsed beams accelerated by a dedicated ElectronFLASH LINAC. Results are encouraging and show a linear response of the SiC detector up to 2 Gy/pulse and a variation in the charge per pulse measured for a cumulative delivered dose of 90 kGy, within ±0.75%. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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15 pages, 5501 KiB

Open AccessArticle

Fluence Beam Monitor for High-Intensity Particle Beams Based on a Multi-Gap Ionization Chamber and a Method for Ion Recombination Correction

by Simona Giordanengo, Leslie Fanola Guarachi, Saverio Braccini, Giuseppe A. P. Cirrone, Marco Donetti, Federico Fausti, Felix Mas Milian, Francesco Romano, Anna Vignati, Vincenzo Monaco, Roberto Cirio and Roberto Sacchi

Appl. Sci. 2022, 12(23), 12160; https://doi.org/10.3390/app122312160 - 28 Nov 2022

Cited by 4 | Viewed by 1222

Abstract

This work presents the tests of a multi-gap detector (MGD), composed of three parallel-plate ionization chambers (ICs) with different gap widths, assembled to prove the capability of correcting for charge volume recombination which is expected to occur when high fluence rates are delivered. Such beam conditions occur with a compact accelerator for charged particle therapy developed to reduce the costs, to accomplish faster treatments and to exploit different beam delivery techniques and dose rates as needed, for example, for range modulation and FLASH irradiations, respectively. The MGD was tested with carbon ions at the Centro Nazionale di Adroterapia Oncologica (CNAO Pavia, Italy), and with protons in two different beam lines: at Bern University Hospital with continuous beams and at the Laboratori Nazionale del Sud (Catania, Italy) of the Italian National Center of Nuclear Physics (INFN) with pulsed beams. For each accelerator, we took measurements with different beam intensities (up to the maximum rate of ionization achievable) and changed the detector bias voltage (V) in order to study the charge collection efficiency. Charge recombination models were used to evaluate the expected collected charge and to measure the linearity of the rate of ionization with the beam fluence rate. A phenomenological approach was used to determine the collection efficiency (f₁) of the chamber with thinnest gap from the relative efficiencies, f₁/f₂ and f₁/f₃, exploiting the condition that, for each measurement, the three chambers were exposed to the same rate of ionization. Results prove that two calibration curves can be determined and used to correct the online measurements for the charge losses in the ICs for recombination. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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17 pages, 3906 KiB

Open AccessArticle

IBA myQA SRS Detector for CyberKnife Robotic Radiosurgery Quality Assurance

by Francesco Padelli, Domenico Aquino, Laura Fariselli and Elena De Martin

Appl. Sci. 2022, 12(15), 7791; https://doi.org/10.3390/app12157791 - 2 Aug 2022

Cited by 10 | Viewed by 2791

Abstract

The IBA myQA^® SRS high-resolution solid-state detector was evaluated in the context of robotic radiosurgery delivered using CyberKnife^®. The performance was investigated for periodic machine delivery quality assurance (DQA) and patient-specific treatment verification. myQA^® SRS is a 140 × 120 mm CMOS matrix with 400 µm resolution, allocated in a cylindrical ABS phantom topped by a hemispheric cap. Evaluations included: periodic DQA tests, angular response, dose-rate dependence and Iris variable aperture collimator field size measurements. For patient-specific QA various intracranial targets were studied (Gamma Index, 3%/1 mm agreement criteria), taking into account also the detector’s angular response. Results for periodic DQA were in accordance with the machine commissioning data. Dose-rate dependence was confirmed, and angular response tests resulted in a signal decay >5% when beams were delivered outside a ±50° amplitude cone with respect to the vertical direction. Concerning patient-specific QA, >50° angled beams elimination led to a Gamma Index passing rates improvement ranging between +3% and +115%. IBA myQA^® SRS proved to be a suitable device for many CyberKnife^® constancy DQA checks, providing high-resolution real-time results. Patient-specific Gamma tests showed high passing rates once angular dependence corrections were performed, even in high complexity treatments such as those for trigeminal neuralgia targets. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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14 pages, 2878 KiB

Open AccessArticle

Predicting the Biological Effects of Human Salivary Gland Tumour Cells for Scanned ⁴He-, ¹²C-, ¹⁶O-, and ²⁰Ne-Ion Beams Using an SOI Microdosimeter

by Sung Hyun Lee, Kota Mizushima, Shunsuke Yonai, Shinnosuke Matsumoto, Hideyuki Mizuno, Taku Nakaji, Ryosuke Kohno, Yoshiyuki Iwata, Toshiyuki Shirai, Vladimir Pan, Angela Kok, Marco Povoli, Linh T. Tran, Anatoly B. Rosenfeld, Masao Suzuki and Taku Inaniwa

Appl. Sci. 2022, 12(12), 6148; https://doi.org/10.3390/app12126148 - 16 Jun 2022

Cited by 2 | Viewed by 1448

Abstract

Experimental microdosimetry along with the microdosimetric kinetic (MK) model can be utilized to predict the biological effects of ions. To predict the relative biological effectiveness (RBE) of ions and the survival fraction (SF) of human salivary gland tumour (HSGc-C5) cells, microdosimetric quantities measured by a silicon-on-insulator (SOI) MicroPlus-mushroom microdosimeter along the spread-out Bragg peak (SOBP) delivered by pencil beam scanning of ⁴He, ¹²C, ¹⁶O, and ²⁰Ne ions were used. The MK model parameters of HSGc-C5 cells were obtained from the best fit of the calculated SF for the different linear energy transfer (LET) of these ions and the formerly reported in vitro SF for the same LET and ions used for calculations. For a cube-shaped target of 10 × 10 × 6 cm³, treatment plans for ⁴He, ¹²C, ¹⁶O, and ²⁰Ne ions were produced with proprietary treatment planning software (TPS) aiming for 10% SF of HSGc-C5 cells over the target volume and were delivered to a polymethyl methacrylate (PMMA) phantom. Afterwards, the saturation-corrected dose-mean lineal energy derived based on the measured microdosimetry spectra, along with the physical dose at various depths in PMMA phantoms, was used for the estimation of the SF, RBE, and RBE-weighted dose using the MK model. The predicted SF, RBE, and the RBE-weighted dose agreed with what was planned by the TPS within 3% at most depths for these ions. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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10 pages, 1414 KiB

Open AccessArticle

Dose-Area Product Determination and Beam Monitor Calibration for the Fixed Beam of the Shanghai Advanced Proton Therapy Facility

by Libing Zhu, Manzhou Zhang, Xincheng Xiang and Xiangang Wang

Appl. Sci. 2022, 12(9), 4111; https://doi.org/10.3390/app12094111 - 19 Apr 2022

Cited by 2 | Viewed by 1658

Abstract

Research conducted to-date, makes use of the IBA-Lynx scintillating screen and radiochromic film to analyze the proton field uniformity for dose-area product (DAP) determination. In this paper, the machine log file based reconstruction is proposed to calculate the field uniformity to simplify the measurement. In order to calculate the field uniformity, the dose distribution is reconstructed based on the machine log file with matRad (an open source software for analytical dose calculation in MATLAB). After acquisition of the dose distribution, the field flatness and symmetry are calculated automatically for different proton energies. A comprehensive comparison of DAP determined with Bragg peak chamber (BPC) and Markus chamber (MC) is presented. The actual delivered dose is reconstructed with the log file to analyze the lateral dose distribution of the scanned field. DAP of different energies are calculated ranging from 70.6 MeV to 235 MeV. The percentage difference is calculated, illustrating the DAP discrepancy between the MC and BPC to the mean value. The percentage difference ranges from −0.19% to 1.26%. The variation between DAP measured with the BPC and MC peaks at −2.5%. The log file based reconstruction to calculate field uniformity can be an alternative for DAP determination. The direct method using a large-area Bragg peak chamber is investigated. The two methods to determine DAP and calibrate beam monitor illustrate consistent results. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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12 pages, 1063 KiB

Open AccessArticle

Dosimetric Characterization of Small Radiotherapy Electron Beams Collimated by Circular Applicators with the New Microsilicon Detector

by Serenella Russo, Silvia Bettarini, Barbara Grilli Leonulli, Marco Esposito, Paolo Alpi, Alessandro Ghirelli, Raffaella Barca, Simona Fondelli, Lisa Paoletti, Silvia Pini and Silvia Scoccianti

Appl. Sci. 2022, 12(2), 600; https://doi.org/10.3390/app12020600 - 8 Jan 2022

Cited by 1 | Viewed by 2048

Abstract

High-energy small electron beams, generated by linear accelerators, are used for radiotherapy of localized superficial tumours. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector compared to other available dosimeters. Relative dose measurements of circular fields with 20, 30, 40, and 50 mm aperture diameters were performed for electron beams generated by an Elekta Synergy linac, with energy between 4 and 12 MeV. Percentage depth dose, transverse profiles, and output factors, normalized to the 10 × 10 cm² reference field, were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom, at SSD of 100 cm, by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam apertures for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber. Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by circular applicators. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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14 pages, 1998 KiB

Open AccessArticle

A Large Area Pixelated Silicon Array Detector for Independent Transit In Vivo Dosimetry

by Owen J. Brace, Iolanda Fuduli, Saree Alnaghy, Albert T. Le, Jeremy A. Davis, Trent Causer, Dean Wilkinson, Aleksandr Perevertaylo, Anatoly B. Rosenfeld and Marco Petasecca

Appl. Sci. 2022, 12(2), 537; https://doi.org/10.3390/app12020537 - 6 Jan 2022

Cited by 2 | Viewed by 1358

Abstract

A large area pixelated silicon array detector named “MP987” has been developed for in vivo dosimetry. The detector was developed to overcome the non-water equivalent response of EPID (Electronic Portal Imaging Device) dosimetry systems, due to the shortfalls of the extensive corrections required. The detector, readout system and software have all been custom designed to be operated independently from the linac with the array secured directly above the EPID, to be used in combination with the 6 MV imaging system. Dosimetry characterisation measurements of percentage depth dose (PDD), dose rate dependence, radiation damage, output factors (OF), profile measurements, linearity and uniformity were performed. Additionally, the first pre-clinical tests with this novel detector of a transit dosimetry characterization and a collapsed IMRT (intensity-modulated radiation therapy) study are presented. Both PDD and OF measurements had a percentage difference of less than 2.5% to the reference detector. A maximum change in sensitivity of 4.3 ± 0.3% was observed after 30 kGy of gamma accumulated dose. Transit dosimetry measurements through a homogeneous Solid Water phantom had a measured dose within error of the TPS calculations, for field sizes between 3 × 3 cm² and 10 × 10 cm². A four-fraction collapsed IMRT plan on a lung phantom had absolute dose pass fractions between the MP987 and TPS (treatment planning system) from 94.2% to 97.4%, with a 5%/5 mm criteria. The ability to accurately measure dose at a transit level, without the need for correction factors derived from extensive commissioning data collection procedures, makes the MP987 a viable alternative to the EPID for in vivo dosimetry. This MP987 is this first of its kind to be successfully developed specifically for a dual detector application. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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11 pages, 2593 KiB

Open AccessArticle

Preliminary Evaluation of Pentacene Field Effect Transistors with Polymer Gate Electret as Ionizing Radiation Dosimeters

by Irina Valitova, Alexandria Mitchell, Michael A. Hupman, Ian G. Hill and Alasdair Syme

Appl. Sci. 2021, 11(23), 11368; https://doi.org/10.3390/app112311368 - 1 Dec 2021

Cited by 1 | Viewed by 1560

Abstract

Interest in the use of organic electronic devices in radiation sensing applications has grown in recent years. The numerous device configurations (e.g., diodes, thin film transistors) and potential for improved tissue equivalence compared to their silicon-based analogues make them attractive candidates for various radiation dosimetry measurements. In this work, a variation of the organic thin film transistor (OTFT) is studied, in which a polymer electret is added. An OTFT electret design can be used in either a wired or wireless configuration for in vivo dosimetry with the possibility of real-time detection. The linearity, reproducibility, and dependence on energy of these devices were measured through exposure to 100 kVp photons from an orthovoltage treatment unit (Xstrahl 300) and 6 MV photons from a Varian TrueBeam medical linear accelerator. Prior to irradiation, all transistors were programmed with a −80 V bias applied to the Gate electrode (V_g) for 3 s. In the wireless configuration, after each delivered dose, the transfer characteristic was scanned to readout the amount of erased charges by monitoring the drain current change. When the programmed charge was sufficiently depleted by radiation, transistors were reprogrammed for repeated use. The real-time readout in a wired configuration was performed by measuring the drain current with V_g = −15 V; V_d = −15 V. The 6 MV photon beam was turned on and off at different dose rates of 600, 400, 300, 200, and 60 cGy/min to quantify the sensitivity of the device to changes in dose rate. The wireless transistors showed a linear increase in current with increasing dose. The sensitivities for different energies were 60 ± 5 nA/Gy at 6 MV at a dose rate of 600 cGy/min and 80 ± 10 nA/Gy at 100 kVp at a dose rate of 200 cGy/min. The sensitivity of detectors tested in a wired configuration at V_d = −15 V; V_g = −15 V was 8.1 nA/s at a dose rate of 600 cGy/min. The principle of pentacene OTFTs with polymer electret as radiation detectors was demonstrated. Devices had excellent linearity, reproducibility, and were able to be reprogrammed for multiple uses as wireless detectors. The wired transistors demonstrated an effective response as real-time detectors. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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10 pages, 2130 KiB

Open AccessArticle

A Validation Method for EPID In Vivo Dosimetry Algorithms

by Marco Esposito, Livia Marrazzo, Eleonora Vanzi, Serenella Russo, Stefania Pallotta and Cinzia Talamonti

Appl. Sci. 2021, 11(22), 10715; https://doi.org/10.3390/app112210715 - 13 Nov 2021

Cited by 5 | Viewed by 1855

Abstract

The aim of this study was to develop and apply an evaluation method for assessing the accuracy of a novel 3D EPID back-projection algorithm for in vivo dosimetry. The novel algorithm of Dosimetry Check (DC) 5.8 was evaluated. A slab phantom homogeneously filled, or with air and bone inserts, was used for fluence reconstruction of different squared fields. VMAT plans in different anatomical sites were delivered on an anthropomorphic phantom. Dose distributions were measured with radiochromic films. The 2D Gamma Agreement Index (GAI) between the DC and the film dose distributions (3%, 3 mm) was computed for assessing the accuracy of the algorithm. GAIs between films and TPS and between DC and TPS were also computed. The fluence reconstruction accuracy was within 2% for all squared fields in the three slabs’ configurations. The GAI between the DC and the film was 92.7% in the prostate, 92.9% in the lung, 96.6% in the head and the neck, and 94.6% in the brain. An evaluation method for assessing the accuracy of a novel EPID algorithm was developed. The DC algorithm was shown to be able to accurately reconstruct doses in all anatomic sites, including the lung. The methodology described in the present study can be applied to any EPID back-projection in vivo algorithm. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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15 pages, 936 KiB

Open AccessArticle

Online Recombination Correction in Dosimetry with Arrays of Ionization Chambers: Application to FFF and UHDR Radiotherapy

by Juan Pardo-Montero, Jose Paz-Martín, Luis Brualla-Gónzalez and Faustino Gómez

Appl. Sci. 2021, 11(21), 10083; https://doi.org/10.3390/app112110083 - 28 Oct 2021

Cited by 2 | Viewed by 1451

Abstract

Recombination of charge carriers can affect the response of ionization detectors used for the dosimetry of radiotherapy fields. In this work, we present a method for correcting online the recombination effects in arrays of ionization chambers irradiated with time-varying dose rates. The method is based on the characterization of the dose rate/recombination response of the detector, and the measurement of the instant ionization current in the detector, rather than the integrated charge. The proposed method was investigated with simulations of the response of different air and liquid ionization chambers in situations where recombination can be large. In addition, we experimentally investigated the application of the method with an in-house-developed liquid-filled ionization chamber. The proposed online correction method can compensate for recombination losses and seems feasible to implement in the software of ionization arrays/detectors used for the dosimetry of radiotherapy fields. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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11 pages, 5743 KiB

Open AccessFeature PaperArticle

Feasibility of a Reusable Radiochromic Dosimeter

by Joseph R. Newton, Maxwell Recht, Joseph A. Hauger, Gabriel Segarra, Chase Inglett, Pedro A. Romo and John Adamovics

Appl. Sci. 2021, 11(21), 9906; https://doi.org/10.3390/app11219906 - 23 Oct 2021

Cited by 3 | Viewed by 1666

Abstract

The current practice for patient-specific quality assurance (QA) uses ion chambers or diode arrays primarily because of their ease of use and reliability. A standard routine compares the dose distribution measured in a phantom with the dose distribution calculated by the treatment planning system for the same experimental conditions. For the particular problems encountered in the treatment planning of complex radiotherapy techniques, such as small fields/segments and dynamic delivery systems, additional tests are required to verify the accuracy of dose calculations. The dose distribution verification should be throughout the total 3D dose distribution for a high dose gradient in a small, irradiated volume, instead of the standard practice of one to several planes with 2D radiochromic (GAFChromic) film. To address this issue, we have developed a 3D radiochromic dosimeter that improves the rigor of current QA techniques by providing high-resolution, complete 3D verification for a wide range of clinical applications. The dosimeter is composed of polyurethane, a radical initiator, and a leuco dye, which is radiolytically oxidized to a dye absorbing at 633 nm. Since this chemical dosimeter is single-use, it represents a significant expense. The purpose of this research is to develop a cost-effective reusable dosimeter formulation. Based on prior reusability studies, three promising dosimeter formulations were studied using small volume optical cuvettes and irradiated to known clinically relevant doses of 0.5–10 Gy. After irradiation, the change in optical density was measured in a spectrophotometer. All three formulations retained linearity of optical density response to radiation upon re-irradiations. However, only one formulation retained dose sensitivity upon at least five re-irradiations, making it ideal for further evaluation as a 3D dosimeter. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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20 pages, 8068 KiB

Open AccessArticle

Characterization with X-rays of a Large-Area GEMPix Detector with Optical Readout for QA in Hadron Therapy

by Andreia Maia Oliveira, Hylke B. Akkerman, Saverio Braccini, Albert J. J. M. van Breemen, Lucia Gallego Manzano, Natalie Heracleous, Ilias Katsouras, Johannes Leidner, Fabrizio Murtas, Bart Peeters and Marco Silari

Appl. Sci. 2021, 11(14), 6459; https://doi.org/10.3390/app11146459 - 13 Jul 2021

Viewed by 2208

Abstract

Quality Assurance (QA) in hadron therapy is crucial to ensure safe and accurate dose delivery to patients. This can be achieved with fast, reliable and high-resolution detectors. In this paper, we present a novel solution that combines a triple Gas Electron Multiplier (GEM) and a highly pixelated readout based on a matrix of organic photodiodes fabricated on top of an oxide-based thin-film transistor backplane. The first LaGEMPix prototype with an active area of 60 × 80 mm² was developed and characterized using low energy X-rays. The detector comprises a drift gap of 3.5 mm, a triple-GEM stack for electron amplification, and a readout featuring 480 × 640 pixels at a 126 µm pitch. Here, we describe the measurements and results in terms of spatial resolution for various experimental configurations. A comparison with GAFCHROMIC^® films and the GEMPix detector used in the charge readout mode was performed to better understand the contribution to the spatial resolution from both the electron diffusion and the isotropic emission of photons. The measurements were compared to Monte Carlo simulations, using the FLUKA code. The simulation predictions are in good agreement with the GEMPix results. Future plans with respect to applications in hadron therapy are discussed. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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Review

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18 pages, 6649 KiB

Open AccessFeature PaperReview

Silicon 3D Microdosimeters for Advanced Quality Assurance in Particle Therapy

by Linh T. Tran, David Bolst, Benjamin James, Vladimir Pan, James Vohradsky, Stefania Peracchi, Lachlan Chartier, Emily Debrot, Susana Guatelli, Marco Petasecca, Michael Lerch, Dale Prokopovich, Željko Pastuović, Marco Povoli, Angela Kok, Taku Inaniwa, Sung Hyun Lee, Naruhiro Matsufuji and Anatoly B. Rosenfeld

Appl. Sci. 2022, 12(1), 328; https://doi.org/10.3390/app12010328 - 30 Dec 2021

Cited by 11 | Viewed by 2288

Abstract

The Centre for Medical Radiation Physics introduced the concept of Silicon On Insulator (SOI) microdosimeters with 3-Dimensional (3D) cylindrical sensitive volumes (SVs) mimicking the dimensions of cells in an array. Several designs of high-definition 3D SVs fabricated using 3D MEMS technology were implemented. 3D SVs were fabricated in different sizes and configurations with diameters between 18 and 30 µm, thicknesses of 2–50 µm and at a pitch of 50 µm in matrices with volumes of 20 × 20 and 50 × 50. SVs were segmented into sub-arrays to reduce capacitance and avoid pile up in high-dose rate pencil beam scanning applications. Detailed TCAD simulations and charge collection studies in individual SVs have been performed. The microdosimetry probe (MicroPlus) is composed of the silicon microdosimeter and low-noise front–end readout electronics housed in a PMMA waterproof sheath that allows measurements of lineal energies as low as 0.4 keV/µm in water or PMMA. Microdosimetric quantities measured with SOI microdosimeters and the MicroPlus probe were used to evaluate the relative biological effectiveness (RBE) of heavy ions and protons delivered by pencil-beam scanning and passive scattering systems in different particle therapy centres. The 3D detectors and MicroPlus probe developed for microdosimetry have the potential to provide confidence in the delivery of RBE optimized particle therapy when introduced into routine clinical practice. Full article

(This article belongs to the Special Issue Detectors for Medical Physics)

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