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Gierej A, Baghdasaryan T, Martyn M, Woulfe P, Mc Laughlin O, Prise K, Workman G, O'Keeffe S, Rochlitz K, Verlinski S, Giaz A, Santoro R, Caccia M, Berghmans F, Van Erps J. Mass-manufacturable scintillation-based optical fiber dosimeters for brachytherapy. Biosens Bioelectron 2024; 255:116237. [PMID: 38537429 DOI: 10.1016/j.bios.2024.116237] [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: 12/18/2023] [Revised: 03/08/2024] [Accepted: 03/20/2024] [Indexed: 04/15/2024]
Abstract
Scintillation-based fiber dosimeters are a powerful tool for minimally invasive localized real-time monitoring of the dose rate during Low Dose Rate (LDR) and High Dose Rate (HDR) brachytherapy (BT). This paper presents the design, fabrication, and characterization of such dosimeters, consisting of scintillating sensor tips attached to polymer optical fiber (POF). The sensor tips consist of inorganic scintillators, i.e. Gd2O2S:Tb for LDR-BT, and Y2O3:Eu+4YVO4:Eu for HDR-BT, dispersed in a polymer host. The shape and size of the tips are optimized using non-sequential ray tracing simulations towards maximizing the collection and coupling of the scintillation signal into the POF. They are then manufactured by means of a custom moulding process implemented on a commercial hot embossing machine, paving the way towards series production. Dosimetry experiments in water phantoms show that both the HDR-BT and LDR-BT sensors feature good consistency in the magnitude of the average photon count rate and that the photon count rate signal is not significantly affected by variations in sensor tip composition and geometry. Whilst individual calibration remains necessary, the proposed dosimeters show great potential for in-vivo dosimetry for brachytherapy.
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Affiliation(s)
- Agnieszka Gierej
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium
| | - Tigran Baghdasaryan
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium
| | - Michael Martyn
- Department of Medical Physics, Blackrock Health - Galway Clinic, Doughiska, Co. Galway, Ireland; Physics Unit, School of Natural Sciences, University of Galway, Galway, Ireland
| | - Peter Woulfe
- Department of Medical Physics, Blackrock Health - Galway Clinic, Doughiska, Co. Galway, Ireland
| | - Owen Mc Laughlin
- The Centre for Cancer Research & Cell Biology (CCRCB) at Queen's University, Belfast, UK
| | - Kevin Prise
- The Centre for Cancer Research & Cell Biology (CCRCB) at Queen's University, Belfast, UK
| | - Geraldine Workman
- The Centre for Cancer Research & Cell Biology (CCRCB) at Queen's University, Belfast, UK
| | - Sinead O'Keeffe
- Optical Fibre Sensors Research Centre, University of Limerick, Ireland
| | - Kurt Rochlitz
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium
| | - Sergey Verlinski
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium
| | - Agnese Giaz
- Università Degli Studi Dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Via Valleggio 11, Como, Italy
| | - Romualdo Santoro
- Università Degli Studi Dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Via Valleggio 11, Como, Italy
| | - Massimo Caccia
- Università Degli Studi Dell'Insubria, Dipartimento di Scienza e Alta Tecnologia, Via Valleggio 11, Como, Italy
| | - Francis Berghmans
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium
| | - Jürgen Van Erps
- Brussels Photonics (B-PHOT), Vrije Universiteit Brussel and Flanders Make, Dept. of Applied Physics and Photonics, Brussels, Belgium.
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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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Georgi PD, Jørgensen EB, Heidotting M, Tanderup K, Kertzscher G, Johansen JG. A simple calibration routine for small inorganic scintillation detectors for in vivo dosimetry during brachytherapy. Brachytherapy 2024:S1538-4721(24)00070-9. [PMID: 38853063 DOI: 10.1016/j.brachy.2024.05.001] [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: 09/22/2023] [Revised: 04/04/2024] [Accepted: 05/07/2024] [Indexed: 06/11/2024]
Abstract
BACKGROUND In vivo dosimetry (IVD) is rarely performed in brachytherapy (BT), allowing potential dose misadministration to go unnoticed. This study presents a clinical routine-calibration method of detectors for IVD in high (HDR) and pulsed dose rate (PDR) Ir-192 BT. PURPOSE To evaluate the dosimetric precision and feasibility of an in-clinic calibration routine of detectors for IVD in afterloading BT. METHODS Calibrations were performed in a PMMA phantom with two needles inserted 20 mm apart. The source was loaded in one of the needles at 15 dwells for 10 s. The detector was placed in the other needle, and its signal was recorded. The mean signal at each dwell position was fitted to the expected dose rate with the calibration factor and the detector's longitudinal position being free parameters. The method was tested with an inorganic scintillation detector using one Ir-192 FlexiSource HDR and two Ir-192 GammaMedPlus PDR sources and followed by validation measurements in water. RESULTS The standard measurement uncertainty (k = 1) of the calibration factor in absolute terms (Gy/s) was 3.2/3.4% for the HDR/PDR source. The uncertainty was dominated by source strength uncertainty, and the precision of the method was <1%. The mean ± 1SD of the difference in measured and expected dose rate during validation was 1.5 ± 4.7% (HDR) and 0.0 ± 4.1% (PDR) with a positional uncertainty in the setup of 0.33/0.23 mm (HDR/PDR) (k = 1). CONCLUSION A precise and feasible in-clinic calibration method for IVD and source strength consistency tests in BT was presented.
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Affiliation(s)
- Peter D Georgi
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
| | - Erik B Jørgensen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Kari Tanderup
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Jacob G Johansen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
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Strigari L, Marconi R, Solfaroli-Camillocci E. Evolution of Portable Sensors for In-Vivo Dose and Time-Activity Curve Monitoring as Tools for Personalized Dosimetry in Molecular Radiotherapy. SENSORS (BASEL, SWITZERLAND) 2023; 23:2599. [PMID: 36904802 PMCID: PMC10007630 DOI: 10.3390/s23052599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/19/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Treatment personalization in Molecular Radiotherapy (MRT) relies on pre- and post-treatment SPECT/ PET-based images and measurements to obtain a patient-specific absorbed dose-rate distribution map and its evolution over time. Unfortunately, the number of time points that are available per patient to investigate individual pharmacokinetics is often reduced by limited patient compliance or SPECT or PET/CT scanner availability for dosimetry in busy departments. The adoption of portable sensors for in-vivo dose monitoring during the entire treatment could improve the assessment of individual biokinetics in MRT and, thus, the treatment personalization. The evolution of portable devices, non-SPECT/PET-based options, already used for monitoring radionuclide activity transit and accumulation during therapy with radionuclides (i.e., MRT or brachytherapy), is presented to identify valuable ones, which combined with conventional nuclear medicine imaging systems could be effective in MRT. External probes, integration dosimeters and active detecting systems were included in the study. The devices and their technology, the range of applications, the features and limitations are discussed. Our overview of the available technologies encourages research and development of portable devices and dedicated algorithms for MRT patient-specific biokinetics study. This would represent a crucial advancement towards personalized treatment in MRT.
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Affiliation(s)
- Lidia Strigari
- Department of Medical Physics, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Via Giuseppe Massarenti 9, 40138 Bologna, Italy
| | - Raffaella Marconi
- Scientific Direction, IRCCS Regina Elena National Cancer Institute, Via Elio Chianesi 53, 00144 Rome, Italy
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In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility Study. J Pers Med 2022; 12:jpm12060911. [PMID: 35743696 PMCID: PMC9224704 DOI: 10.3390/jpm12060911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/24/2022] [Accepted: 05/28/2022] [Indexed: 11/17/2022] Open
Abstract
(1) Background: In brachytherapy, there are still many manual procedures that can cause adverse events which can be detected with in vivo dosimetry systems. Plastic scintillator dosimeters (PSD) have interesting properties to achieve this objective such as real-time reading, linearity, repeatability, and small size to fit inside brachytherapy catheters. The purpose of this study was to evaluate the performance of a PSD in postoperative endometrial brachytherapy in terms of source dwell time accuracy. (2) Methods: Measurements were carried out in a PMMA phantom to characterise the PSD. Patient measurements in 121 dwell positions were analysed to obtain the differences between planned and measured dwell times. (3) Results: The repeatability test showed a relative standard deviation below 1% for the measured dwell times. The relative standard deviation of the PSD sensitivity with accumulated absorbed dose was lower than 1.2%. The equipment operated linearly in total counts with respect to absorbed dose and also in count rate versus absorbed dose rate. The mean (standard deviation) of the absolute differences between planned and measured dwell times in patient treatments was 0.0 (0.2) seconds. (4) Conclusions: The PSD system is useful as a quality assurance tool for brachytherapy treatments.
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Kaveckyte V, Jørgensen EB, Kertzscher G, Johansen JG, Tedgren ÅC. Monte Carlo characterization of high atomic number inorganic scintillators for in vivo dosimetry in 192 Ir brachytherapy. Med Phys 2022; 49:4715-4730. [PMID: 35443079 DOI: 10.1002/mp.15674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/01/2022] [Accepted: 04/06/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND There is increased interest in vivo dosimetry for 192 Ir brachytherapy (BT) treatments using high atomic number (Z) inorganic scintillators. Their high light output enables construction of small detectors with negligible stem effect and simple readout electronics. Experimental determination of absorbed-dose energy dependence of detectors relative to water is prevalent, but it can be prone to high detector positioning uncertainties and does not allow for decoupling of absorbed-dose energy dependence from other factors affecting detector response. PURPOSE To investigate which measurement conditions and detector properties could affect their absorbed-dose energy dependence in BT in vivo dosimetry. METHODS We used a general-purpose MC code penelope for the characterization of high-Z inorganic scintillators with the focus on ZnSe (Z¯=32). Two other promising media CsI (Z¯=54) and Al2 O3 (Z¯=11) were included for comparison in selected scenarios. We determined absorbed-dose energy dependence of crystals relative to water under different scatter conditions (calibration phantom 12 × 12 × 30 cm3 , characterization phantoms 20 × 20 × 20 cm3 , 30 × 30 × 30 cm3 , 40 × 40 × 40 cm3 , and patient-like elliptic phantom 40 × 30 × 25 cm3 ). To mimic irradiation conditions during prostate treatments, we evaluated whether the presence of pelvic bones and calcifications affect ZnSe response. ZnSe detector design influence was also investigated. RESULTS In contrast to low-Z organic and medium-Z inorganic scintillators, ZnSe and CsI media have substantially greater absorbed-dose energy dependence relative to water. The response was phantom-size dependent and changed by 11 % between limited- and full-scatter conditions for ZnSe, but not for Al2 O3 . For a given phantom size, a part of the absorbed-dose energy dependence of ZnSe is caused not due to in-phantom scatter but due to source anisotropy. Thus, the absorbed-dose energy dependence of high-Z scintillators is a function of not only the radial distance but also the polar angle. Pelvic bones did not affect ZnSe response, whereas large and intermediate size calcifications reduced it by 9 % and 5 %, respectively, when placed midway between the source and the detector. CONCLUSIONS Unlike currently prevalent low- and medium-Z scintillators, high-Z crystals are sensitive to characterization and in vivo measurement conditions. However, good agreement between MC data for ZnSe in the present study and experimental data for ZnSe:O by Jørgensen et al (2021) suggest that detector signal is proportional to the average absorbed dose to the detector cavity. This enables an easy correction for non-TG43-like scenarios (e.g., patient sizes and calcifications) through MC simulations. Information that should be provided to the clinic by the detector vendors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Vaiva Kaveckyte
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, SE-581 85, Sweden
| | - Erik B Jørgensen
- Department of Clinical Medicine, Aarhus University, Aarhus, DK-8000, Denmark.,Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Gustavo Kertzscher
- Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Jacob G Johansen
- Department of Clinical Medicine, Aarhus University, Aarhus, DK-8000, Denmark.,Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Åsa Carlsson Tedgren
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, SE-581 85, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, SE-171 76, Sweden.,Department of Oncology-Pathology, Karolinska Institute, Stockholm, SE-171 76, Sweden
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Debnath SBC, Tonneau D, Fauquet C, Tallet A, Goncalves A, Darreon J. Dosimetric characterization of a small-scale (Zn,Cd)S:Ag inorganic scintillating detector to be used in radiotherapy. Phys Med 2021; 84:15-23. [PMID: 33813200 DOI: 10.1016/j.ejmp.2021.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/14/2021] [Accepted: 03/20/2021] [Indexed: 12/01/2022] Open
Abstract
PURPOSE In modern radiotherapy techniques, to ensure an accurate beam modeling process, dosimeters with high accuracy and spatial resolution are required. Therefore, this work aims to propose a simple, robust, and a small-scale fiber-integrated X-ray inorganic detector and investigate the dosimetric characteristics used in radiotherapy. METHODS The detector is based on red-emitting silver-activated zinc-cadmium sulfide (Zn,Cd)S:Ag nanoclusters and the proposed system has been tested under 6 MV photons with standard dose rate used in the patient treatment protocol. The article presents the performances of the detector in terms of dose linearity, repeatability, reproducibility, percentage depth dose distribution, and field output factor. A comparative study is shown using a microdiamond dosimeter and considering data from recent literature. RESULTS We accurately measured a small field beam profile of 0.5 × 0.5 cm2 at a spatial resolution of 100 µm using a LINAC system. The dose linearity at 400 MU/min has shown less than 0.53% and 1.10% deviations from perfect linearity for the regular and smallest field. Percentage depth dose measurement agrees with microdiamond measurements within 1.30% and 2.94%, respectively for regular to small field beams. Besides, the stem effect analysis shows a negligible contribution in the measurements for fields smaller than 3x3 cm2. This study highlights the drastic decrease of the convolution effect using a point-like detector, especially in small dimension beam characterization. Field output factor has shown a good agreement while comparing it with the microdiamond dosimeter. CONCLUSION All the results presented here anticipated that the developed detector can accurately measure delivered dose to the region of interest, claim accurate depth dose distribution hence it can be a suitable candidate for beam characterization and quality assurance of LINAC system.
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Affiliation(s)
| | - Didier Tonneau
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
| | - Carole Fauquet
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
| | - Agnes Tallet
- Institut Paoli-Calmettes, 13009 Marseille, France
| | - Anthony Goncalves
- Institut Paoli-Calmettes, 13009 Marseille, France; Aix Marseille Université, CNRS UMR 7258, INSERM UMR 1068, CRCM, 13009 Marseille, France
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