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Debnath SBC, Tonneau D, Fauquet C, Tallet A, Darréon J. Cerenkov free micro-dosimetry in small-field radiation therapy technique. Phys Med Biol 2024; 69:125018. [PMID: 38810619 DOI: 10.1088/1361-6560/ad51c6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 05/29/2024] [Indexed: 05/31/2024]
Abstract
Objective. Optical fiber-based scintillating dosimetry is a recent promising technique owing to the miniature size dosimeter and quality measurement in modern radiation therapy treatment. Despite several advantages, the major issue of using scintillating dosimeters is the Cerenkov effect and predominantly requires extra measurement corrections. Therefore, this work highlighted a novel micro-dosimetry technique to ensure Cerenkov-free measurement in radiation therapy treatment protocol by investigating several dosimetric characteristics.Approach.A micro-dosimetry technique was proposed with the performance evaluation of a novel infrared inorganic scintillator detector (IR-ISD). The detector essentially consists of a micro-scintillating head based on IR-emitting micro-clusters with a sensitive volume of 1.5 × 10-6mm3. The proposed system was evaluated under the 6 MV LINAC beam used in patient treatment. Overall measurements were performed using IBATMwater tank phantoms by following TRS-398 protocol for radiotherapy. Cerenkov measurements were performed for different small fields from 0.5 × 0.5 cm2to 10 × 10 cm2under LINAC. In addition, several dosimetric parameters such as percentage depth dose (PDD), high lateral resolution beam profiling, dose linearity, dose rate linearity, repeatability, reproducibility, and field output factor were investigated to realize the performance of the novel detector.Main results. This study highlighted a complete removal of the Cerenkov effect using a point-like miniature detector, especially for small field radiation therapy treatment. Measurements demonstrated that IR-ISD has acceptable behavior with dose rate variability (maximum standard deviation ∼0.18%) for the dose rate of 20-1000 cGy s-1. An entire linear response (R2= 1) was obtained for the dose delivered within the range of 4-1000 cGy, using a selected field size of 1 × 1 cm2. Perfect repeatability (max 0.06% variation from average) with day-to-day reproducibility (0.10% average variation) was observed. PDD profiles obtained in the water tank present almost identical behavior to the reference dosimeter with a build-up maximum depth dose at 1.5 cm. The small field of 0.5 × 0.5 cm2profiles have been characterized with a high lateral resolution of 100µm.Significance. Unlike recent plastic scintillation detector systems, the proposed micro-dosimetry system in this study requires no Cerenkov corrections and showed efficient performance for several dosimetric parameters. Therefore, it is expected that considering the detector correction factors, the IR-ISD system can be a suitable dose measurement tool, such as in small-field dose measurements, high and low gradient dose verification, and, by extension, in microbeam radiation and FLASH radiation therapy.
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Affiliation(s)
- Sree Bash Chandra Debnath
- Aix-Marseille University, CNRS, LP3 UMR 7341, 13288 Marseille, France
- Aix Marseille University, CNRS, CINaM UMR 7325, Marseille, 13288, France
| | - Didier Tonneau
- Aix Marseille University, CNRS, CINaM UMR 7325, Marseille, 13288, France
| | - Carole Fauquet
- Aix Marseille University, CNRS, CINaM UMR 7325, Marseille, 13288, France
| | - Agnes Tallet
- Institut Paoli-Calmettes, 13009 Marseille, France
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Das IJ, Sohn JJ, Lim SN, Sengupta B, Feijoo M, Yadav P. Characteristics of a plastic scintillation detector in photon beam dosimetry. J Appl Clin Med Phys 2024; 25:e14209. [PMID: 37983685 PMCID: PMC10795454 DOI: 10.1002/acm2.14209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/24/2023] [Accepted: 11/04/2023] [Indexed: 11/22/2023] Open
Abstract
BACKGROUND Plastic scintillating detectors (PSD) have gained popularity due to small size and are ideally suited in small-field dosimetry due to no correction needed and hence detector reading can be compared to dose. Likewise, these detectors are active and water equivalent. A new PSD from Blue Physics is characterized in photon beam. PURPOSE Innovation in small-field dosimetry detector has led us to examine Blue Physics PSD (BP-PSD) for use in photon beams from linear accelerator. METHODS BP-PSD was acquired and its characteristics were evaluated in photon beams from a Varian TrueBeam. Data were collected in a 3D water tank. Standard parameters; dose, dose rate, energy, angular dependence and temperature dependence were studied. Depth dose, profiles and output in a reference condition as well as small fields were measured. RESULTS BP-PSD is versatile and provides data very similar to an ion chamber when Cerenkov radiation is properly accounted. This device measures data pulse by pulse which very few detectors can perform. The differences between ion chamber data and PSD are < 2% in most cases. The angular dependence is a bit pronounces to 1.5% which is due to PSD housing. Depth dose and profiles are comparable within < 1% to an ion chamber. For small fields this detector provides suitable field output factor compared to other detectors and Monte Carlo (MC) simulated data without any added correction factor. CONCLUSIONS The characteristics of Blue Physics PSD is uniquely suitable in photon beam and more so in small fields. The data are reproducible compared to ion chamber for most parameters and ideally suitable for small-field dosimetry without any correction factor.
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Affiliation(s)
- Indra J. Das
- Department of Radiation OncologyNorthwest Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | - Jooyoung J. Sohn
- Department of Radiation OncologyNorthwest Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | - Sara N. Lim
- Department of Radiation OncologyNorthwest Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | - Bishwambhar Sengupta
- Department of Radiation OncologyNorthwest Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | | | - Poonam Yadav
- Department of Radiation OncologyNorthwest Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
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Yasui K, Nakajima Y, Suda Y, Arai Y, Takizawa T, Sakai K, Fujita Y. Experimental investigation of the effective point of measurement for plane-parallel chambers used in electron beam dosimetry. J Appl Clin Med Phys 2023:e14059. [PMID: 37307247 DOI: 10.1002/acm2.14059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/07/2023] [Accepted: 05/18/2023] [Indexed: 06/14/2023] Open
Abstract
In this study, the effective point of measurement (EPOM) for plane-parallel ionization chambers in clinical high-energy electron beams was determined experimentally. Previous studies have reported that the EPOM of plane-parallel chambers is shifted several tens of millimeters downstream from the inner surface of the entrance window to the cavity. These findings were based on the Monte Carlo (MC) simulation, and few experimental studies have been performed. Thus, additional experimental validations of the reported EPOMs were required. In this study, we investigated the EPOMs of three plane-parallel chambers (NACP-02, Roos and Advanced Markus) for clinical electron beams. The EPOMs were determined by comparing the measured percentage depth-dose (PDD) of the plane-parallel chambers and the PDD obtained using the microDiamond detector. The optimal shift to the EPOM was energy-dependent. The determined EPOM showed no chamber-to-chamber variation, thereby allowing the use of a single value. The mean optimal shifts were 0.104 ± 0.011, 0.040 ± 0.012, and 0.012 ± 0.009 cm for NACP-02, Roos, and Advanced Markus, respectively. These values are valid in the R50 range from 2.40 to 8.82 cm, which correspond to 6-22 MeV. Roos and Advanced Markus exhibited similar results to those of the previous studies, but NACP-02 showed a larger shift. This is probably due to the uncertainty of the entrance window of NACP-02. Therefore, it is necessary to carefully consider where the optimal EPOM is located when using this chamber.
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Affiliation(s)
- Kohki Yasui
- Department of Radiological Sciences, Komazawa University Graduate School, Setagaya-ku, Tokyo, Japan
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
| | - Yujiro Nakajima
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
- Department of Radiological Sciences, Komazawa University, Setagaya-ku, Tokyo, Japan
| | - Yuhi Suda
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
| | - Yu Arai
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
| | - Takuto Takizawa
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
| | - Kaito Sakai
- Department of Radiological Sciences, Komazawa University Graduate School, Setagaya-ku, Tokyo, Japan
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Bunkyo-ku, Tokyo, Japan
| | - Yukio Fujita
- Department of Radiological Sciences, Komazawa University, Setagaya-ku, Tokyo, Japan
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Momeni Harzanji Z, Larizadeh MH, Namiranian N, Nickfarjam A. Evaluation and Comparison of Dosimetric Characteristics of Semiflex ®3D and Microdiamond in Relative Dosimetry under 6 and 15 MV Photon Beams in Small Fields. J Biomed Phys Eng 2022; 12:477-488. [PMID: 36313410 PMCID: PMC9589081 DOI: 10.31661/jbpe.v0i0.2008-1160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 01/14/2021] [Indexed: 06/16/2023]
Abstract
BACKGROUND In modern radiotherapy techniques, the frequently small and non-uniformed fields can increase treatment efficiency due to their highly conformal dose distribution. Particular features including lack of Lateral Charge Particle Equilibrium (LCPE) lead to detectors with high resolution since any error in obtained dosimetric data could cause patient mistreatments. OBJECTIVE This study aims to evaluate and compare two small detectors (Semiflex®3D and microdiamond) dosimetric characteristics in small field relative dosimetry. MATERIAL AND METHODS In this experimental study, the dosimetric properties of Semiflex®3D and microdiamond were assessed under 6 and 15 MV photon beams. The linearity and stability of the detector's response and dose rate were measured. Square-field sizes ranging from 0.6×0.6 - 5×5 cm2 were used for obtaining percentage depth dose curves (PDDs) and in-plane profiles. The angular and temperature dependence of both detectors' responses were also studied. RESULTS The detector response shows good stability, no deviation from linearity, and low dose rate dependence (≤1.6%). PDDs and in-plan profiles of both detectors are in good agreement and no significant difference was observed except for the high dose gradient regions (P-value≤0.017). Both detectors demonstrated low angular dependence (<0.3%) with temperature dependence lower than 1% for both detectors. CONCLUSION The results indicate both investigated detectors were well performed in small field relative dosimetry and for measuring penumbra, it is better to use microdiamond detector.
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Affiliation(s)
- Zahra Momeni Harzanji
- MSc, Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Mohammad Hassan Larizadeh
- MD, Department of Radiation Oncology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | - Nasim Namiranian
- MD, Yazd Diabetes Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Abolfazl Nickfarjam
- PhD, Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
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Klimanov VA, Kirpichev YS, Serikbekova ZK, Belousov AV, Krusanov GA, Walwyn‐Salas G, Morozov VN, Kolyvanova MA. Monte-Carlo calculation of output correction factors for ionization chambers, solid-state detectors, and EBT3 film in small fields of high-energy photons. J Appl Clin Med Phys 2022; 24:e13753. [PMID: 35998153 PMCID: PMC9860002 DOI: 10.1002/acm2.13753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 07/13/2022] [Accepted: 07/25/2022] [Indexed: 01/26/2023] Open
Abstract
High-energy accelerators are often used in oncological practice, but the information on the small-field dosimetry for the photon beams with nominal energy above 10 MV is limited. The goal of the present work was to determine the values of the output correction factor ( k Q clin , Q ref f clin , f ref $k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ ) for solid-state detectors (Diode E, PTW 60017; microDiamond, PTW 60019), EBT3 film, and ionization chambers (Semiflex, PTW 31010; Semiflex 3D, PTW 31021; PinPoint, PTW 31015; PinPoint 3D, PTW 31016) in the small fields formed by 10, 15, 18, and 20 MV photon beams. The output correction factors were calculated by Monte-Carlo method using EGSnrc toolkit for six field sizes (from 0.5 × 0.5 cm 2 $0.5 \times 0.5\ {\rm{cm}}^2$ to 10 × 10 cm 2 $10 \times 10\ {\rm{cm}}^2$ ) for isocentric and constant source-to-surface distance (SSD) techniques. The decrease in the field size led to an increase in k Q clin , Q ref f clin , f ref $k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ for ionization chambers, while for solid-state detectors and radiochromic film, k Q clin , Q ref f clin , f ref $k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ were less than unity at the smallest field size. A larger sensitive volume of ionization chamber corresponded to a stronger deviation of output correction factor from unity: 1.847 (125 mm3 PTW 31010) versus up to 1.183 (16 mm3 PTW 31016) at the smallest field of 10 MV beam. The calculated output correction factors were used to correct the output factors for PTW 60017, PTW 60019, and EBT3. The deviation of the corrected output factor from the results of Monte-Carlo simulation did not exceed 3% in the fields from 1.0 × 1.0 cm 2 $1.0 \times 1.0\ {\rm{cm}}^2$ to 4.0 × 4.0 cm 2 $4.0 \times 4.0\ {\rm{cm}}^2$ for 10 and 18 MV beams. Thus, Diode E, microDiamond, and EBT3 film can be recommended for small-field dosimetry of high-energy photons.
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Affiliation(s)
- Vladimir A. Klimanov
- State Research Center—Burnazyan Federal Medical Biophysical CenterFederal Medical Biological Agency of the Russian FederationMoscowRussia,National Research Nuclear University MEPhIMoscowRussia
| | | | | | - Alexandr V. Belousov
- State Research Center—Burnazyan Federal Medical Biophysical CenterFederal Medical Biological Agency of the Russian FederationMoscowRussia
| | - Grigorii A. Krusanov
- State Research Center—Burnazyan Federal Medical Biophysical CenterFederal Medical Biological Agency of the Russian FederationMoscowRussia
| | | | - Vladimir N. Morozov
- Emanuel Institute of Biochemical PhysicsRussian Academy of SciencesMoscowRussia
| | - Maria A. Kolyvanova
- State Research Center—Burnazyan Federal Medical Biophysical CenterFederal Medical Biological Agency of the Russian FederationMoscowRussia,Emanuel Institute of Biochemical PhysicsRussian Academy of SciencesMoscowRussia
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Experimental determination of the effective point of measurement for cylindrical ionization chambers in megavoltage photon beams. Radiol Phys Technol 2022; 15:291-297. [PMID: 35932415 DOI: 10.1007/s12194-022-00669-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/27/2022] [Accepted: 07/27/2022] [Indexed: 10/15/2022]
Abstract
Current dosimetry protocols specify an effective point of measurement (EPOM) shift of 0.6r for a cylindrical ionization chamber in photon beams. However, prior studies have reported that this shift was excessively large. The objective of this study was to experimentally evaluate the EPOM shifts in photon beams for cylindrical ionization chambers, which are widely used in clinical practice, and thus determine the appropriate EPOM shift. A microdiamond detector, which is a semiconductor detector with a small sensitive volume, was used as a reference detector, and the EPOM shifts of 11 types of cylindrical ionization chambers were evaluated at 6 MV and 10 MV. The depth shift from the percent depth dose (PDD) of the reference detector to that of the evaluated chamber was calculated using the least-squares method and was defined as the EPOM shift. The EPOM shift of the 10 MV condition was slightly larger than that of the 6 MV condition. However, because this trend was not observed for all chambers, the results of the two energies were averaged, and the EPOM shifts were determined to be 0.33r-0.43r (± 0.05) for 10 types of ionization chambers, and 0.03r (± 0.03) for the A1SL chamber. The shifts for all ionization chambers were smaller than 0.6r, indicating that the recommended EPOM shifts were overestimated and the absorbed dose was underestimated at the calibration depth. Hence, the appropriate EPOM shift of the 10 types of ionization chambers was 0.4r (the geometric center of the A1SL chamber), with a dose uncertainty of 0.05%.
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7
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Rinati GV, Felici G, Galante F, Gasparini A, Kranzer R, Mariani G, Pacitti M, Prestopino G, Schüller A, Vanreusel V, Verellen D, Verona C, Marinelli M. Application of a novel diamond detector for commissioning of FLASH radiotherapy electron beams. Med Phys 2022; 49:5513-5522. [PMID: 35652248 PMCID: PMC9543846 DOI: 10.1002/mp.15782] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/18/2022] [Accepted: 05/23/2022] [Indexed: 11/06/2022] Open
Abstract
Purpose A diamond detector prototype was recently proposed by Marinelli et al. (Medical Physics 2022, https://doi.org/10.1002/mp.15473) for applications in ultrahigh‐dose‐per‐pulse (UH‐DPP) and ultrahigh‐dose‐rate (UH‐DR) beams, as used in FLASH radiotherapy (FLASH‐RT). In the present study, such so‐called flashDiamond (fD) was investigated from the dosimetric point of view, under pulsed electron beam irradiation. It was then used for the commissioning of an ElectronFlash linac (SIT S.p.A., Italy) both in conventional and UH‐DPP modalities. Methods Detector calibration was performed in reference conditions, under 60Co and electron beam irradiation. Its response linearity was investigated in UH‐DPP conditions. For this purpose, the DPP was varied in the 1.2–11.9 Gy range, by changing either the beam applicator or the pulse duration from 1 to 4 μs. Dosimetric validation of the fD detector prototype was then performed in conventional modality, by measuring percentage depth dose (PDD) curves, beam profiles, and output factors (OFs). All such measurements were carried out in a motorized water phantom. The obtained results were compared with the ones from commercially available dosimeters, namely, a microDiamond, an Advanced Markus ionization chamber, a silicon diode detector, and EBT‐XD GAFchromic films. Finally, the fD detector was used to fully characterize the 7 and 9 MeV UH‐DPP electron beams delivered by the ElectronFlash linac. In particular, PDDs, beam profiles, and OFs were measured, for both energies and all the applicators, and compared with the ones from EBT‐XD films irradiated in the same experimental conditions. Results The fD calibration coefficient resulted to be independent from the investigated beam qualities. The detector response was found to be linear in the whole investigated DPP range. A very good agreement was observed among PDDs, beam profiles, and OFs measured by the fD prototype and reference detectors, both in conventional and UH‐DPP irradiation modalities. Conclusions The fD detector prototype was validated from the dosimetric point of view against several commercial dosimeters in conventional beams. It was proved to be suitable in UH‐DPP and UH‐DR conditions, for which no other commercial real‐time active detector is available to date. It was shown to be a very useful tool to perform fast and reproducible beam characterizations in standard clinical motorized water phantom setups. All of the previously mentioned demonstrate the suitability of the proposed detector for the commissioning of UH‐DR linac beams for preclinical FLASH‐RT applications.
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Affiliation(s)
- Gianluca Verona Rinati
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata,", Roma, 00133, Italy
| | | | | | - Alessia Gasparini
- Iridium Kankernetwerk, Antwerp, 2610, Belgium.,Antwerp University, Faculty of Medicine and Health Sciences, Antwerp, 2610, Belgium
| | - Rafael Kranzer
- PTW-Freiburg, Freiburg, 79115, Germany.,University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, 26121, Germany
| | | | | | - Giuseppe Prestopino
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata,", Roma, 00133, Italy
| | - Andreas Schüller
- Physikalisch-Technische Bundesanstalt, Braunschweig, 38116, Germany
| | - Verdi Vanreusel
- Iridium Kankernetwerk, Antwerp, 2610, Belgium.,Antwerp University, Faculty of Medicine and Health Sciences, Antwerp, 2610, Belgium
| | - Dirk Verellen
- Iridium Kankernetwerk, Antwerp, 2610, Belgium.,Antwerp University, Faculty of Medicine and Health Sciences, Antwerp, 2610, Belgium
| | - Claudio Verona
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata,", Roma, 00133, Italy
| | - Marco Marinelli
- Dipartimento di Ingegneria Industriale, Università di Roma "Tor Vergata,", Roma, 00133, Italy
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López-Sánchez M, Pérez-Fernández M, Pardo E, Fandiño JM, Teijeiro A, Gómez-Fernández N, Gómez F, González-Castaño DM. Small static radiosurgery field dosimetry with small volume ionization chambers. Phys Med 2022; 97:66-72. [DOI: 10.1016/j.ejmp.2022.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/15/2022] [Accepted: 04/09/2022] [Indexed: 11/28/2022] Open
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Dose area product primary standards established by graphite calorimetry at the LNE-LNHB for small radiation fields in radiotherapy. Phys Med 2022; 98:18-27. [PMID: 35489128 DOI: 10.1016/j.ejmp.2022.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 03/10/2022] [Accepted: 03/19/2022] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To present primary standards establishment in terms of Dose Area Product (DAP) for small field sizes. METHODS A large section graphite calorimeter and two plane-parallel ionization chambers were designed and built in-house. These chambers were calibrated in a 6MV FFF beam at the maximum dose rate of 1400 UM/min for fields defined by specifically designed circular collimators of 5, 7.5, 10, 13 and 15 mm diameter and jaws of 5, 7, 10, 13 and 15 mm side length on a Varian TrueBeam linac. RESULTS The two chambers show the same behaviour regardless of field shape and size. From 5 to 15 mm, calibration coefficients slightly increase with the field size with a magnitude of 1.8% and 1.1% respectively for the two chambers, and are independent of the field shape. This tendency was confirmed by Monte Carlo calculations. The average associated uncertainty of the calibration coefficients is around 0.6% at k=1. CONCLUSIONS For the first time, primary standards in terms of DAP were established by graphite calorimetry for an extended range of small field sizes. These promising results open the door for an alternative approach in small fields dosimetry.
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Marinelli M, Felici G, Galante F, Gasparini A, Giuliano L, Heinrich S, Pacitti M, Prestopino G, Vanreusel V, Verellen D, Verona C, Rinati GV. Design, realization and characterization of a novel diamond detector prototype for flash radiotherapy dosimetry. Med Phys 2022; 49:1902-1910. [PMID: 35064594 PMCID: PMC9306529 DOI: 10.1002/mp.15473] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 11/28/2022] Open
Abstract
Purpose FLASH radiotherapy (RT) is an emerging technique in which beams with ultra‐high dose rates (UH‐DR) and dose per pulse (UH‐DPP) are used. Commercially available active real‐time dosimeters have been shown to be unsuitable in such conditions, due to severe response nonlinearities. In the present study, a novel diamond‐based Schottky diode detector was specifically designed and realized to match the stringent requirements of FLASH‐RT. Methods A systematic investigation of the main features affecting the diamond response in UH‐DPP conditions was carried out. Several diamond Schottky diode detector prototypes with different layouts were produced at Rome Tor Vergata University in cooperation with PTW‐Freiburg. Such devices were tested under electron UH‐DPP beams. The linearity of the prototypes was investigated up to DPPs of about 26 Gy/pulse and dose rates of approximately 1 kGy/s. In addition, percentage depth dose (PDD) measurements were performed in different irradiation conditions. Radiochromic films were used for reference dosimetry. Results The response linearity of the diamond prototypes was shown to be strongly affected by the size of their active volume as well as by their series resistance. By properly tuning the design layout, the detector response was found to be linear up to at least 20 Gy/pulse, well into the UH‐DPP range conditions. PDD measurements were performed by three different linac applicators, characterized by DPP values at the point of maximum dose of 3.5, 17.2, and 20.6 Gy/pulse, respectively. The very good superimposition of three curves confirmed the diamond response linearity. It is worth mentioning that UH‐DPP irradiation conditions may lead to instantaneous detector currents as high as several mA, thus possibly exceeding the electrometer specifications. This issue was properly addressed in the case of the PTW UNIDOS electrometers. Conclusions The results of the present study clearly demonstrate the feasibility of a diamond detector for FLASH‐RT applications.
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Affiliation(s)
- Marco Marinelli
- Industrial Engineering Dept., University of Rome Tor Vergata, Rome, Italy
| | | | | | - Alessia Gasparini
- Iridium Kankernetwerk, Antwerp, Belgium and University of Antwerp, Antwerp, Belgium
| | - Lucia Giuliano
- Institut Curie, Inserm U 1021-CNRS UMR 3347, University Paris-Saclay, PSL Research University, Orsay, France
| | - Sophie Heinrich
- Institut Curie, Inserm U 1021-CNRS UMR 3347, University Paris-Saclay, PSL Research University, Orsay, France
| | | | | | - Verdi Vanreusel
- Iridium Kankernetwerk, Antwerp, Belgium and University of Antwerp, Antwerp, Belgium
| | - Dirk Verellen
- Iridium Kankernetwerk, Antwerp, Belgium and University of Antwerp, Antwerp, Belgium
| | - Claudio Verona
- Industrial Engineering Dept., University of Rome Tor Vergata, Rome, Italy
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Torres Valderrama A, Olaciregui-Ruiz I, González P, Perik T, Mijnheer B, Mans A. Portal dosimetry of small unflattened beams. Phys Med Biol 2021; 66. [PMID: 32217828 DOI: 10.1088/1361-6560/ab843d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 03/27/2020] [Indexed: 11/12/2022]
Abstract
We developed and validated a dedicated small field back-projection portal dosimetry model for pretreatment andin vivoverification of stereotactic plans entailing small unflattened photon beams. For this purpose an aSi-EPID was commissioned as a small field dosimeter. Small field output factors for 6 MV FFF beams were measured using the PTW microDiamond detector and the Agility 160-leaf MLC from Elekta. The back-projection algorithm developed in our department was modified to better model the small field physics. The feasibility of small field portal dosimetry was validated via absolute point dose differences w.r.t. small static beams, and 5 hypofractionated stereotactic VMAT clinical plans measured with the OCTAVIUS 1000 SRS array dosimeter and computed with the treatment planning system Pinnacle v16.2. Dose reconstructions using the currently clinically applied back-projection model were also computed for comparison. We found that the latter yields underdosage of about -8% for square beams with cross section near 10 mm x 10 mm and about -6% for VMAT treatments with PTV volumes smaller than about 2cm3. With the methods described in this work such errors can be reduced to less than the ±3.0% recommendations for clinical use. Our results indicate that aSi-EPIDs can be used as accurate small field radiation dosimeters, offering advantages over point dose detectors, the correct positioning and orientation of which is challenging for routine clinical QA.
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Affiliation(s)
- Aldemar Torres Valderrama
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Igor Olaciregui-Ruiz
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Patrick González
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Thijs Perik
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Ben Mijnheer
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Anton Mans
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
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13
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Ayala Alvarez DS, G F Watson P, Popovic M, Jean Heng V, Evans MDC, Seuntjens J. Monte Carlo calculation of the relative TG-43 dosimetry parameters for the INTRABEAM electronic brachytherapy source. Phys Med Biol 2020; 65:245041. [PMID: 33137796 DOI: 10.1088/1361-6560/abc6f1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The INTRABEAM system (Carl Zeiss Meditec AG, Jena, Germany) is an electronic brachytherapy (eBT) device designed for intraoperative radiotherapy applications. To date, the INTRABEAM x-ray source has not been characterized according to the AAPM TG-43 specifications for brachytherapy sources. This restricts its modelling in commercial treatment planning systems (TPSs), with the consequence that the doses to organs at risk are unknown. The aim of this work is to characterize the INTRABEAM source according to the TG-43 brachytherapy dosimetry protocol. The dose distribution in water around the source was determined with Monte Carlo (MC) calculations. For the validation of the MC model, depth dose calculations along the source longitudinal axis were compared with measurements using a soft x-ray ionization chamber (PTW 34013) and two synthetic diamond detectors (microDiamond PTW TN60019). In our results, the measurements in water agreed with the MC model calculations within uncertainties. The use of the microDiamond detector yielded better agreement with MC calculations, within estimated uncertainties, compared to the ionization chamber at points of steeper dose gradients. The radial dose function showed a steep fall-off close to the INTRABEAM source ([Formula: see text]10 mm) with a gradient higher than that of commonly used brachytherapy radionuclides (192Ir, 125I and 103Pd), with values of 2.510, 1.645 and 1.232 at 4, 6 and 8 mm, respectively. The radial dose function partially flattens at larger distances with a fall-off comparable to that of the Xoft Axxent® (iCAD, Inc., Nashua, NH) eBT system. The simulated 2D polar anisotropy close to the bare probe walls showed deviations from unity of up to 55% at 10 mm and 155°. This work presents the MC calculated TG-43 parameters for the INTRABEAM, which constitute the necessary data for the characterization of the source as required by a TPS used in clinical dose calculations.
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Affiliation(s)
| | - Peter G F Watson
- Medical Physics Unit, McGill University and Cedars Cancer Center, Montreal, Canada
| | - Marija Popovic
- Medical Physics Unit, McGill University and Cedars Cancer Center, Montreal, Canada
| | - Veng Jean Heng
- Medical Physics Unit, McGill University and Cedars Cancer Center, Montreal, Canada
| | - Michael D C Evans
- Medical Physics Unit, McGill University and Cedars Cancer Center, Montreal, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University and Cedars Cancer Center, Montreal, Canada
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Tekin T, Blum I, Delfs B, Schönfeld A, Kapsch R, Poppe B, Looe HK. The dose response of high‐resolution diode‐type detectors and the role of their structural components in strong magnetic field. Med Phys 2020; 47:6509-6518. [DOI: 10.1002/mp.14535] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/09/2020] [Accepted: 10/01/2020] [Indexed: 11/05/2022] Open
Affiliation(s)
- Tuba Tekin
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
| | - Isabel Blum
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
| | - Björn Delfs
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
| | - Ann‐Britt Schönfeld
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
| | | | - Björn Poppe
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
| | - Hui Khee Looe
- University Clinic for Medical Radiation Physics Medical Campus Pius HospitalCarl von Ossietzky University Oldenburg26121Germany
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Rossi G, Gainey M, Kollefrath M, Hofmann E, Baltas D. Suitability of the microDiamond detector for experimental determination of the anisotropy function of High Dose Rate 192 Ir brachytherapy sources. Med Phys 2020; 47:5838-5851. [PMID: 32970875 DOI: 10.1002/mp.14488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 09/07/2020] [Accepted: 09/13/2020] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To investigate the suitability of the microDiamond detector (mDD) type 60019 (PTW-Freiburg, Germany) to measure the anisotropy function F(r,θ) of High Dose Rate (HDR) 192 Ir brachytherapy sources. METHODS The HDR 192 Ir brachytherapy source, model mHDR-v2r (Elekta AB, Sweden), was placed inside a water tank within a 4F plastic needle. Four mDDs (mDD1, mDD2, mDD3, and mDD4) were investigated. Each mDD was placed laterally with respect to the source, and measurements were performed at radial distances r = 1 cm, 3 and 5 cm, and polar angles θ from 0° to 168°. The Monte Carlo (MC) system EGSnrc was used to simulate the measurements and to calculate phantom effect, energy dependence and volume-averaging correction factors. F(r,θ) was determined according to TG-43 formalism from the detector reading corrected with the MC-based factors and compared to the consensus anisotropy function CON F(r,θ). RESULTS At 1 cm, the differences between measurements and MC simulations ranged from -0.8% to +0.8% for θ = 0° and from -2.1% to + 2.3% for θ ≠ 0°. At 3 and 5 cm, the differences ranged from +1.4% to +3.9% for θ = 0°, and from -0.4% to +2.9% for θ ≠ 0°. All differences were within the uncertainties (k = 2). At small angles, the phantom effect correction was up to -1.9%. This effect was mainly caused by the air between source and needle tip. The energy correction was angle-independent everywhere. For small angles at 1 cm, the volume-averaging correction was up to -2.9% and became less important for larger angles and distances. The differences of the measured F(r,θ) corrected with the MC-based factors to CON F(r,θ) ranged from -1.0% to +3.4% for mDD1, -2.2% to +4.2% for mDD2, -2.5% to +4.0% for mDD3, and -2.6% to +3.4% for mDD4. All differences were within the uncertainties (k = 2) except one at (3 cm, 0°). For all the mDDs, F(r,0°) was always higher than CON F(r,0°), with average differences of +3.1% (1 cm), +3.6% (3 cm), and +1.9% (5 cm). The inter-detector variability was within 2.9% (1 cm), 1.8% (3 cm), and 3.4% (5 cm). CONCLUSIONS A reproducible method and experimental setup were presented for measuring and validating F(r,θ) of an HDR 192 Ir brachytherapy source in a water phantom using the mDD. The phantom effect and the volume-averaging need to be taken into account, especially for the smaller distances and angles. Good agreement to CON F(r,θ) was obtained. The discrepancies at (1 cm, 0°), accurately predicted by the MC results, may suggest a reconsideration of CON F(r,θ), at least for this position. The slight overestimations at (3 cm,0°) and (5 cm,0°), both in comparison to CON F(r,θ) and MC results, may be due to an underestimation of the air volume between source and needle tip, dark current, intrinsic over-response of the mDDs, or radiation-induced charge imbalance in the detector's components. The results indicate that the mDD is a valuable tool for measurements with HDR 192 Ir brachytherapy sources and support its employment for the determination and validation of TG-43 parameters of such sources.
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Affiliation(s)
- Giulio Rossi
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mark Gainey
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Michael Kollefrath
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Elena Hofmann
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Rosenfeld AB, Biasi G, Petasecca M, Lerch MLF, Villani G, Feygelman V. Semiconductor dosimetry in modern external-beam radiation therapy. Phys Med Biol 2020; 65:16TR01. [PMID: 32604077 DOI: 10.1088/1361-6560/aba163] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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17
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Brace OJ, Alhujaili SF, Paino JR, Butler DJ, Wilkinson D, Oborn BM, Rosenfeld AB, Lerch MLF, Petasecca M, Davis JA. Evaluation of the PTW microDiamond in edge-on orientation for dosimetry in small fields. J Appl Clin Med Phys 2020; 21:278-288. [PMID: 32441884 PMCID: PMC7484886 DOI: 10.1002/acm2.12906] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/16/2020] [Accepted: 04/20/2020] [Indexed: 12/11/2022] Open
Abstract
Purpose The PTW microDiamond has an enhanced spatial resolution when operated in an edge‐on orientation but is not typically utilized in this orientation due to the specifications of the IAEA TRS‐483 code of practice for small field dosimetry. In this work the suitability of an edge‐on orientation and advantages over the recommended face‐on orientation will be presented. Methods The PTW microDiamond in both orientations was compared on a Varian TrueBeam linac for: machine output factor (OF), percentage depth dose (PDD), and beam profile measurements from 10 × 10 cm2 to a 0.5 × 0.5 cm2 field size for 6X and 6FFF beam energies in a water tank. A quantification of the stem effect was performed in edge‐on orientation along with tissue to phantom ratio (TPR) measurements. An extensive angular dependence study for the two orientations was also undertaken within two custom PMMA plastic cylindrical phantoms. Results The OF of the PTW microDiamond in both orientations agrees within 1% down to the 2 × 2 cm2 field size. The edge‐on orientation overresponds in the build‐up region but provides improved penumbra and has a maximum observed stem effect of 1%. In the edge‐on orientation there is an angular independent response with a maximum of 2% variation down to a 2 × 2 cm2 field. The PTW microDiamond in edge‐on orientation for TPR measurements agreed to the CC01 ionization chamber within 1% for all field sizes. Conclusions The microDiamond was shown to be suitable for small field dosimetry when operated in edge‐on orientation. When edge‐on, a significantly reduced angular dependence is observed with no significant stem effect, making it a more versatile QA instrument for rotational delivery techniques.
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Affiliation(s)
- Owen J Brace
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Sultan F Alhujaili
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Jason R Paino
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Duncan J Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, VIC, UK
| | - Dean Wilkinson
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Cancer Care Centre Wollongong Hospital Wollongong, Wollongong, NSW, Australia
| | - Brad M Oborn
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Cancer Care Centre Wollongong Hospital Wollongong, Wollongong, NSW, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Michael L F Lerch
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Jeremy A Davis
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
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Bartzsch S, Corde S, Crosbie JC, Day L, Donzelli M, Krisch M, Lerch M, Pellicioli P, Smyth LML, Tehei M. Technical advances in x-ray microbeam radiation therapy. Phys Med Biol 2020; 65:02TR01. [PMID: 31694009 DOI: 10.1088/1361-6560/ab5507] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the last 25 years microbeam radiation therapy (MRT) has emerged as a promising alternative to conventional radiation therapy at large, third generation synchrotrons. In MRT, a multi-slit collimator modulates a kilovoltage x-ray beam on a micrometer scale, creating peak dose areas with unconventionally high doses of several hundred Grays separated by low dose valley regions, where the dose remains well below the tissue tolerance level. Pre-clinical evidence demonstrates that such beam geometries lead to substantially reduced damage to normal tissue at equal tumour control rates and hence drastically increase the therapeutic window. Although the mechanisms behind MRT are still to be elucidated, previous studies indicate that immune response, tumour microenvironment, and the microvasculature may play a crucial role. Beyond tumour therapy, MRT has also been suggested as a microsurgical tool in neurological disorders and as a primer for drug delivery. The physical properties of MRT demand innovative medical physics and engineering solutions for safe treatment delivery. This article reviews technical developments in MRT and discusses existing solutions for dosimetric validation, reliable treatment planning and safety. Instrumentation at synchrotron facilities, including beam production, collimators and patient positioning systems, is also discussed. Specific solutions reviewed in this article include: dosimetry techniques that can cope with high spatial resolution, low photon energies and extremely high dose rates of up to 15 000 Gy s-1, dose calculation algorithms-apart from pure Monte Carlo Simulations-to overcome the challenge of small voxel sizes and a wide dynamic dose-range, and the use of dose-enhancing nanoparticles to combat the limited penetrability of a kilovoltage energy spectrum. Finally, concepts for alternative compact microbeam sources are presented, such as inverse Compton scattering set-ups and carbon nanotube x-ray tubes, that may facilitate the transfer of MRT into a hospital-based clinical environment. Intensive research in recent years has resulted in practical solutions to most of the technical challenges in MRT. Treatment planning, dosimetry and patient safety systems at synchrotrons have matured to a point that first veterinary and clinical studies in MRT are within reach. Should these studies confirm the promising results of pre-clinical studies, the authors are confident that MRT will become an effective new radiotherapy option for certain patients.
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Affiliation(s)
- Stefan Bartzsch
- Department of Radiation Oncology, School of Medicine, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany. Helmholtz Centre Munich, Institute for Radiation Medicine, Munich, Germany
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Kaveckyte V, Persson L, Malusek A, Benmakhlouf H, Alm Carlsson G, Carlsson Tedgren Å. Investigation of a synthetic diamond detector response in kilovoltage photon beams. Med Phys 2019; 47:1268-1279. [PMID: 31880809 DOI: 10.1002/mp.13988] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/04/2019] [Accepted: 12/01/2019] [Indexed: 12/28/2022] Open
Abstract
PURPOSE An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed-dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low-energy brachytherapy (BT) beams, we determined their intrinsic and absorbed-dose energy responses in 25-250 kV beams relative to a 60 Co beam, which is usually the reference beam quality for detector calibration in radiotherapy. MATERIAL AND METHODS Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air-kerma free in air in six x-ray beam qualities (from 25 to 250 kV) and in terms of absorbed dose to water in a 60 Co beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed-dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 125 I BT seed (effective photon energy of 28 keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra-cameral components on the absorbed-dose energy response of a microDiamond detector was studied using MC simulations. RESULTS The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50 kV beams compared to the 60 Co beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG-43 formalism-based calculations for the 125 I seed. MC study of microDiamond detector design features provided a possible explanation for inter-detector response variation at low-energy photon beams by differences in the effective thickness of the active volume. CONCLUSIONS MicroDiamond detectors had a non-negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed-dose energy response relative to water at low-energy photon beams. Silicon diodes, in contrast, had an absorbed-dose energy dependence on photon energy that varied by a factor of 6, whereas the intrinsic energy dependence on beam quality was within 10%. It is important to decouple these two responses for a full characterization of detector energy response especially when the user and reference beam qualities differ significantly, and MC alone is not enough.
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Affiliation(s)
- Vaiva Kaveckyte
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Linda Persson
- Swedish Radiation Safety Authority, SE-171 16, Stockholm, Sweden
| | - Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
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Hartmann GH, Zink K. A Monte Carlo study on the PTW 60019 microDiamond detector. Med Phys 2019; 46:5159-5172. [DOI: 10.1002/mp.13721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Klemens Zink
- Institute of Medical Physics and Radiation Protection (IMPS) University of Applied Sciences Giessen 35390Giessen Germany
- Department for Radiotherapy and Radiooncology University Medical Center Giessen‐Marburg 35043Marburg Germany
- Frankfurt Institute for Advanced Studies (FIAS), Goethe‐University 60438Frankfurt Germany
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Palmans H, Andreo P, Huq MS, Seuntjens J, Christaki KE, Meghzifene A. Reply to "Comments on the TRS-483 Protocol on Small field Dosimetry" [Med. Phys. 45(12), 5666-5668 (2018)]. Med Phys 2019; 45:5669-5671. [PMID: 30536943 DOI: 10.1002/mp.13235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/24/2018] [Accepted: 09/24/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Hugo Palmans
- Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, UK.,Department of Medical Physics, EBG MedAustron GmbH, A-2700, Wiener Neustadt, Austria
| | - Pedro Andreo
- Department of Medical Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - M Saiful Huq
- Department of Radiation Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15232, USA
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montréal, QC, H3A 0G4, Canada
| | - Karen E Christaki
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, A-1400, Vienna, Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, A-1400, Vienna, Austria
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Poppinga D, Kranzer R, Ulrichs AB, Delfs B, Giesen U, Langner F, Poppe B, Looe HK. Three-dimensional characterization of the active volumes of PTW microDiamond, microSilicon, and Diode E dosimetry detectors using a proton microbeam. Med Phys 2019; 46:4241-4245. [PMID: 31292964 PMCID: PMC6851623 DOI: 10.1002/mp.13705] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 06/28/2019] [Accepted: 06/28/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The purpose of this work is the three-dimensional characterization of the active volumes of commercial solid-state dosimetry detectors. Detailed knowledge of the dimensions of the detector's active volume as well as the detector housing is of particular interest for small-field photon dosimetry. As shown in previous publications from different groups, the design of the detector housing influences the detector signal for small photon fields. Therefore, detailed knowledge of the active volume dimension and the surrounding materials form the basis for accurate Monte Carlo simulations of the detector. METHODS A 10 MeV proton beam focused by the microbeam system of the Physikalisch-Technische Bundesanstalt was used to measure two-dimensional response maps of a synthetic diamond detector (microDiamond, type 60019, PTW Freiburg) and two silicon detectors (microSilicon, type 60023, PTW Freiburg and Diode E, type 60017, PTW Freiburg). In addition, the thickness of the active volume of the new microSilicon was measured using the method developed in a previous study. RESULTS The analysis of the response maps leads to active area of 1.18 mm2 for the Diode E, 1.75 mm2 for the microSilicon, and 3.91 mm2 for the microDiamond detector. The thickness of the active volume of the microSilicon detector was determined to be (17.8 ± 2) µm. CONCLUSIONS This study provides detailed geometrical data of the dosimetric active volume of three different solid-state detector types.
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Affiliation(s)
| | | | - Ann-Britt Ulrichs
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Björn Delfs
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Ulrich Giesen
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany
| | - Frank Langner
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany
| | - Björn Poppe
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Hui Khee Looe
- University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany
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Girardi A, Fiandra C, Giglioli FR, Gallio E, Ali OH, Ragona R. Small field correction factors determination for several active detectors using a Monte Carlo method in the Elekta Axesse linac equipped with circular cones. ACTA ACUST UNITED AC 2019; 64:11NT01. [DOI: 10.1088/1361-6560/ab1f26] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Looe HK, Poppinga D, Kranzer R, Büsing I, Tekin T, Ulrichs A, Delfs B, Vogt D, Würfel J, Poppe B. The role of radiation-induced charge imbalance on the dose-response of a commercial synthetic diamond detector in small field dosimetry. Med Phys 2019; 46:2752-2759. [PMID: 30972756 PMCID: PMC6849526 DOI: 10.1002/mp.13542] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE Discrepancy between experimental and Monte Carlo simulated dose-response of the microDiamond (mD) detector (type 60019, PTW Freiburg, Germany) at small field sizes has been reported. In this work, the radiation-induced charge imbalance in the structural components of the detector has been investigated as the possible cause of this discrepancy. MATERIALS AND METHODS Output ratio (OR) measurements have been performed using standard and modified versions of the mD detector at nominal field sizes from 6 mm × 6 mm to 40 mm × 40 mm. In the first modified mD detector (mD_reversed), the type of charge carriers collected is reversed by connecting the opposite contact to the electrometer. In the second modified mD detector (mD_shortened), the detector's contacts have been shortened. The third modified mD detector (mD_noChip) is the same as the standard version but the diamond chip with the sensitive volume has been removed. Output correction factors were calculated from the measured OR and simulated using the EGSnrc package. An adapted Monte Carlo user-code has been used to study the underlying mechanisms of the field size-dependent charge imbalance and to identify the detector's structural components contributing to this effect. RESULTS At the smallest field size investigated, the OR measured using the standard mD detector is >3% higher than the OR obtained using the modified mD detector with reversed contact (mD_reversed). Combining the results obtained with the different versions of the detector, the OR have been corrected for the effect of radiation imbalance. The OR obtained using the modified mD detector with shortened contacts (mD_shortened) agree with the corrected OR, all showing an over-response of less than 2% at the field sizes investigated. The discrepancy between the experimental and simulated output correction factors has been eliminated after accounting for the effect of charge imbalance. DISCUSSIONS AND CONCLUSIONS The role of radiation-induced charge imbalance on the dose-response of mD detector in small field dosimetry has been studied and quantified. It has been demonstrated that the effect is significant at small field sizes. Multiple methods were used to quantify the effect of charge imbalance with good agreement between Monte Carlo simulations and experimental results obtained with modified detectors. When this correction is applied to the Monte Carlo data, the discrepancy from experimental data is eliminated. Based on the detailed component analysis using an adapted Monte Carlo user-code, it has been demonstrated that the effect of charge imbalance can be minimized by modifying the design of the detector's contacts.
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Affiliation(s)
- Hui Khee Looe
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
| | | | | | - Isabel Büsing
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
| | - Tuba Tekin
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
| | - Ann‐Britt Ulrichs
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
| | - Björn Delfs
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
| | | | | | - Björn Poppe
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburgGermany
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Comments on the
TRS
‐483 protocol on small field dosimetry. Med Phys 2018; 45:5666-5668. [DOI: 10.1002/mp.13236] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/10/2018] [Accepted: 05/15/2018] [Indexed: 11/07/2022] Open
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Dosimetric characterization of a single crystal diamond detector in X-ray beams for preclinical research. Z Med Phys 2018; 28:303-309. [DOI: 10.1016/j.zemedi.2018.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 03/26/2018] [Accepted: 05/12/2018] [Indexed: 11/24/2022]
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Looe HK, Büsing I, Tekin T, Brant A, Delfs B, Poppinga D, Poppe B. The polarity effect of compact ionization chambers used for small field dosimetry. Med Phys 2018; 45:5608-5621. [DOI: 10.1002/mp.13227] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 09/24/2018] [Accepted: 09/28/2018] [Indexed: 11/07/2022] Open
Affiliation(s)
- Hui Khee Looe
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
| | - Isabel Büsing
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
| | - Tuba Tekin
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
| | - Andre Brant
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
| | - Björn Delfs
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
| | | | - Björn Poppe
- University Clinic for Medical Radiation Physics Medical Campus Pius Hospital Carl von Ossietzky University Oldenburg Germany
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Rossi G, Gainey M, Thomann B, Kollefrath M, Würfel J, Allgaier B, Baltas D. Monte Carlo and experimental high dose rate 192Ir brachytherapy dosimetry with microDiamond detectors. Z Med Phys 2018; 29:272-281. [PMID: 30340801 DOI: 10.1016/j.zemedi.2018.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/28/2018] [Accepted: 09/24/2018] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to investigate the suitability of the microDiamond detector (mDD) type 60019 (PTW-Freiburg, Germany) for radial dose function measurements with High Dose Rate (HDR) 192Ir brachytherapy sources. An HDR 192Ir source model mHDR v2r (Nucletron BV, an Elekta company, The Netherlands) was placed at the centre of a MP3 water phantom (PTW-Freiburg, Germany) within a 4F needle. Three mDDs were employed to measure the radial dose function of the source by acquiring profiles along the source transverse axis. Meanwhile, the experimental setup was simulated using the Monte Carlo (MC) code MCNP6.1™ (Los Alamos National Laboratory, USA) to calculate phantom-size, absorbed-dose energy dependence and volume averaging correction factors. After applying the correction factors, the radial dose function gL(r) for the line source approximation was calculated as defined in the TG-43 formalism at radial distances from 0.5cm to 10cm and compared to the consensus gL(r) (ESTRO and AAPM). The percentage differences to the consensus gL(r) for all the three mDDs were from -2.3% to +1.4% for distances r≤5cm and -6.2% to +2.6% for larger distances. These results indicate the suitability of the mDD for HDR brachytherapy measurements when all required corrections are applied.
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Affiliation(s)
- Giulio Rossi
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Mark Gainey
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Benedikt Thomann
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Michael Kollefrath
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | | | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, Medical Center, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Alhakeem E, Zavgorodni S. Output and ($k_{{{Q}_{{\rm clin},}}{{Q}_{{\rm msr}}}}^{{{\,f}_{{\rm clin},}}{{f}_{{\rm msr}}}}$ ) correction factors measured and calculated in very small circular fields for microDiamond and EFD-3G detectors. ACTA ACUST UNITED AC 2018; 63:155002. [DOI: 10.1088/1361-6560/aacfb2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Poppinga D, Delfs B, Meyners J, Langner F, Giesen U, Harder D, Poppe B, Looe HK. Determination of the active volumes of solid-state photon-beam dosimetry detectors using the PTB proton microbeam. Med Phys 2018; 45:3340-3348. [PMID: 29727482 DOI: 10.1002/mp.12948] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 03/12/2018] [Accepted: 04/14/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE This study aims at the experimental determination of the diameters and thicknesses of the active volumes of solid-state photon-beam detectors for clinical dosimetry. The 10 MeV proton microbeam of the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig) was used to examine two synthetic diamond detectors, type microDiamond (PTW Freiburg, Germany), and the silicon detectors Diode E (PTW Freiburg, Germany) and Razor Diode (Iba Dosimetry, Germany). The knowledge of the dimensions of their active volumes is essential for their Monte Carlo simulation and their applications in small-field photon-beam dosimetry. METHODS The diameter of the active detector volume was determined from the detector current profile recorded by radially scanning the proton microbeam across the detector. The thickness of the active detector volume was determined from the detector's electrical current, the number of protons incident per time interval and their mean stopping power in the active volume. The mean energy of the protons entering this volume was assessed by comparing the measured and the simulated influence of the thickness of a stack of aluminum preabsorber foils on the detector signal. RESULTS For all detector types investigated, the diameters measured for the active volume closely agreed with the manufacturers' data. For the silicon Diode E detector, the thickness determined for the active volume agreed with the manufacturer's data, while for the microDiamond detectors and the Razor Diode, the thicknesses measured slightly exceeded those stated by the manufacturers. DISCUSSION The PTB microbeam facility was used to analyze the diameters and thicknesses of the active volumes of photon dosimetry detectors for the first time. A new method of determining the thickness values with an uncertainty of ±10% was applied. The results appear useful for further consolidating detailed geometrical knowledge of the solid-state detectors investigated, which are used in clinical small-field photon-beam dosimetry.
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Affiliation(s)
- Daniela Poppinga
- University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Bjoern Delfs
- University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Jutta Meyners
- Radiotherapy Department, Imland Hospital, Rendsburg, Germany
| | - Frank Langner
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig, 38116, Germany
| | - Ulrich Giesen
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig, 38116, Germany
| | - Dietrich Harder
- Prof. em., Medical Physics and Biophysics, Georg August University, Göttingen, Germany
| | - Bjoern Poppe
- University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany
| | - Hui K Looe
- University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany
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Andreo P. The physics of small megavoltage photon beam dosimetry. Radiother Oncol 2018; 126:205-213. [DOI: 10.1016/j.radonc.2017.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/16/2017] [Accepted: 11/01/2017] [Indexed: 10/18/2022]
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Butler DJ, Beveridge T, Lehmann J, Oliver CP, Stevenson AW, Livingstone J. Spatial response of synthetic microDiamond and diode detectors measured with kilovoltage synchrotron radiation. Med Phys 2018; 45:943-952. [PMID: 29244899 DOI: 10.1002/mp.12733] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/16/2017] [Accepted: 11/30/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To map the spatial response of four solid-state radiation detectors of types commonly used for radiotherapy dosimetry. METHODS PTW model 60016 Diode P, 60017 Diode E, 60018 Diode SRS, and 60019 microDiamond detectors were radiographed using a high resolution conventional X-ray system. Their spatial response was then investigated using a 0.1 mm diameter beam of 95 keV average energy photons generated by a synchrotron. The detectors were scanned through the beam while their signal was recorded as a function of position, to map the response. These 2D response maps were created in both the end-on and side-on orientations. RESULTS The results show the location and size of the active region. End-on, the active area was determined to be centrally located and within 0.2 mm of the manufacturer's specified diameter. The active areas of the 60016 Diode P, 60017 Diode E, 60018 Diode SRS detectors are uniform to within approximately 5%. The 60019 microDiamond showed local variations up to 30%. The extra-cameral signal in the microDiamond was calculated from the side-on scan to be approximately 8% of the signal from the active element. CONCLUSIONS The spatial response of four solid-state detectors has been measured. The technique yielded information about the location and uniformity of the active area, and the extra-cameral signal, for the beam quality used.
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Affiliation(s)
- Duncan J Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Vict., 3085, Australia
| | - Toby Beveridge
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Vict., 3085, Australia
| | - Joerg Lehmann
- Institute of Medical Physics, University of Sydney, Physics Road A28, Sydney, NSW, 2006, Australia
| | - Christopher P Oliver
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Vict., 3085, Australia
| | - Andrew W Stevenson
- Australian Synchrotron, 800 Blackburn Road, Clayton, Vict., 3168, Australia.,CSIRO, Manufacturing, Clayton, Vict., 3168, Australia
| | - Jayde Livingstone
- Australian Synchrotron, 800 Blackburn Road, Clayton, Vict., 3168, Australia
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Pimpinella M, Caporali C, Guerra AS, Silvi L, De Coste V, Petrucci A, Delaunay F, Dufreneix S, Gouriou J, Ostrowsky A, Rapp B, Bordy JM, Daures J, Le Roy M, Sommier L, Vermesse D. Feasibility of using a dose-area product ratio as beam quality specifier for photon beams with small field sizes. Phys Med 2018; 45:106-116. [DOI: 10.1016/j.ejmp.2017.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 01/17/2023] Open
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Looe HK, Delfs B, Poppinga D, Jiang P, Harder D, Poppe B. The ‘cutting away’ of potential secondary electron tracks explains the effects of beam size and detector wall density in small-field photon dosimetry. ACTA ACUST UNITED AC 2017; 63:015001. [DOI: 10.1088/1361-6560/aa9b46] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Veselsky T, Novotny J, Pastykova V, Koniarova I. Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator. Phys Med 2017; 44:66-71. [DOI: 10.1016/j.ejmp.2017.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 10/09/2017] [Accepted: 11/09/2017] [Indexed: 10/18/2022] Open
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Kaveckyte V, Malusek A, Benmakhlouf H, Alm Carlsson G, Carlsson Tedgren Å. Suitability of microDiamond detectors for the determination of absorbed dose to water around high-dose-rate 192 Ir brachytherapy sources. Med Phys 2017; 45:429-437. [PMID: 29171060 DOI: 10.1002/mp.12694] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 10/26/2017] [Accepted: 10/29/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Experimental dosimetry of high-dose-rate (HDR) 192 Ir brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high sensitivity, direct readout, and nearly water-equivalent active volume. The purpose of this study was to evaluate the suitability of microDiamond detectors for the determination of absorbed dose to water around HDR 192 Ir BT sources. Three microDiamond detectors were used, allowing for the comparison of their properties. METHODS In-phantom measurements were performed using microSelectron and VariSource iX HDR 192 Ir BT treatment units. Their treatment planning systems (TPSs), Oncentra (v. 4.3) and BrachyVision (v. 13.6), respectively, were used to create irradiation plans for a cubic PMMA phantom with the microDiamond positioned at one of three source-to-detector distances (SDDs) (1.5, 2.5, and 5.5 cm) at a time. The source was stepped in increments of 0.5 cm over a total length of 6 cm to yield absorbed dose of 2 Gy at the nominal reference-point of the detector. Detectors were calibrated in 60 Co beam in terms of absorbed dose to water, and Monte Carlo (MC) calculated beam quality correction factors were applied to account for absorbed-dose energy dependence. Phantom correction factors were applied to account for differences in dimensions between the measurement phantom and a water phantom used for absorbed dose calculations made with a TPS. The same measurements were made with all three of the detectors. Additionally, dose-rate dependence and stability of the detectors were evaluated in 60 Co beam. RESULTS The percentage differences between experimentally determined and TPS-calculated absorbed doses to water were from -1.3% to +2.9%. The values agreed to within experimental uncertainties, which were from 1.9% to 4.3% (k = 2) depending on the detector, SDD and treatment delivery unit. No dose-rate or intrinsic energy dependence corrections were applied. All microDiamonds were comparable in terms of preirradiation dose, stability of the readings and energy response, and showed a good agreement. CONCLUSIONS The results indicate that the microDiamond is potentially suitable for the determination of absorbed dose to water around HDR 192 Ir BT sources and may be used for independent verification of TPS's calculations, as well as for QA measurements of HDR 192 Ir BT treatment delivery units at clinical sites.
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Affiliation(s)
- Vaiva Kaveckyte
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
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De Coste V, Francescon P, Marinelli M, Masi L, Paganini L, Pimpinella M, Prestopino G, Russo S, Stravato A, Verona C, Verona-Rinati G. Is the PTW 60019 microDiamond a suitable candidate for small field reference dosimetry? ACTA ACUST UNITED AC 2017; 62:7036-7055. [DOI: 10.1088/1361-6560/aa7e59] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Reggiori G, Stravato A, Pimpinella M, Lobefalo F, De Coste V, Fogliata A, Mancosu P, De Rose F, Palumbo V, Scorsetti M, Tomatis S. Use of PTW-microDiamond for relative dosimetry of unflattened photon beams. Phys Med 2017; 38:45-53. [PMID: 28610696 DOI: 10.1016/j.ejmp.2017.05.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 01/31/2017] [Accepted: 05/03/2017] [Indexed: 10/19/2022] Open
Abstract
PURPOSE The increasing interest in SBRT treatments encourages the use of flattening filter free (FFF) beams. Aim of this work was to evaluate the performance of the PTW60019 microDiamond detector under 6MV and 10MVFFF beams delivered with the EDGE accelerator (Varian Medical System, Palo Alto, USA). A flattened 6MV beam was also considered for comparison. METHODS Short term stability, dose linearity and dose rate dependence were evaluated. Dose per pulse dependence was investigated in the range 0.2-2.2mGy/pulse. MicroDiamond profiles and output factors (OFs) were compared to those obtained with other detectors for field sizes ranging from 40×40cm2 to 0.6×0.6cm2. In small fields, volume averaging effects were evaluated and the relevant correction factors were applied for each detector. RESULTS MicroDiamond short term stability, dose linearity and dependence on monitor unit rate were less than 0.8% for all energies. Response variations with dose per pulse were found within 1.8%. MicroDiamond output factors (OF) values differed from those measured with the reference ion-chamber for less than 1% up to 40×40cm2 fields where silicon diodes overestimate the dose of ≈3%. For small fields (<3×3cm2) microDiamond and the unshielded silicon diode were in good agreement. CONCLUSIONS MicroDiamond showed optimal characteristics for relative dosimetry even under high dose rate beams. The effects due to dose per pulse dependence up to 2.2mGy/pulse are negligible. Compared to other detectors, microDiamond provides accurate OF measurements in the whole range of field sizes. For fields <1cm correction factors accounting for fluence perturbation and volume averaging could be required.
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Affiliation(s)
- Giacomo Reggiori
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy.
| | - Antonella Stravato
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Maria Pimpinella
- Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA-INMRI C R Casaccia, Roma, Italy
| | - Francesca Lobefalo
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Vanessa De Coste
- Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA-INMRI C R Casaccia, Roma, Italy
| | - Antonella Fogliata
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Pietro Mancosu
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Fiorenza De Rose
- Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Valentina Palumbo
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
| | - Marta Scorsetti
- Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Milano, Italy
| | - Stefano Tomatis
- Physics Service of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Milan-Rozzano, Italy
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Wegener S, Sauer OA. Separation of scatter from small MV beams and its effect on detector response. Med Phys 2017; 44:1139-1148. [PMID: 28063164 DOI: 10.1002/mp.12091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/20/2016] [Accepted: 01/01/2017] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Separating the scatter from the primary component of a MV beam to study detector response separately in each case for a better understanding of the role of different effects influencing the response in nonstandard fields. METHODS Detector response in three different experimental setups was investigated for a variety of different types (diamond, shielded and unshielded diodes, ionization chamber and film): (a). Detectors positioned in water under a thin steel pole blocking the central part of the beam, yielding only the response to the scatter part of the beam. (b). Detectors positioned in air under a PMMA cap to approximate the contribution of the primary beam without scatter. (c). Detectors positioned in water in the standard open field configuration to obtain a superposition of both. RESULTS Detector differences became more clearly observable when the primary beam was blocked and detector behavior heavily depended on the construction type. It was possible to calculate the response in the open fields from the values measured in the blocked configuration with 1% accuracy for all studied field sizes between 0.8 and 10 cm and for all detectors. CONCLUSIONS The limitations of clinically used detectors in nonstandard situations were illustrated in the extreme situation of just scattered radiation reaching the detector. By experimentally separating scatter from the primary beam, the roles of different effects on the detector response were observed.
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Affiliation(s)
- Sonja Wegener
- Department of Radiation Oncology, University of Würzburg, 97080, Würzburg, Germany
| | - Otto A Sauer
- Department of Radiation Oncology, University of Würzburg, 97080, Würzburg, Germany
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Francescon P, Kilby W, Noll JM, Masi L, Satariano N, Russo S. Monte Carlo simulated corrections for beam commissioning measurements with circular and MLC shaped fields on the CyberKnife M6 System: a study including diode, microchamber, point scintillator, and synthetic microdiamond detectors. Phys Med Biol 2017; 62:1076-1095. [DOI: 10.1088/1361-6560/aa5610] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Andreo P, Palmans H. Comment on “Experimental determination of the PTW 60019 microDiamond dosimeter active area and volume” [Med. Phys. 43, 5205-5212 (2016)]. Med Phys 2016; 43:6667. [DOI: 10.1118/1.4966023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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