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Georgi PD, Nielsen SK, Hansen AT, Spejlborg H, Rylander S, Lindegaard J, Buus S, Wulff C, Petric P, Tanderup K, Johansen JG. In vivo dosimetry with an inorganic scintillation detector during multi-channel vaginal cylinder pulsed dose-rate brachytherapy: Dosimetry for pulsed dose-rate brachytherapy. Phys Imaging Radiat Oncol 2024; 32:100638. [PMID: 39310220 PMCID: PMC11413746 DOI: 10.1016/j.phro.2024.100638] [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: 01/31/2024] [Revised: 08/21/2024] [Accepted: 08/22/2024] [Indexed: 09/25/2024] Open
Abstract
Background and purpose In vivo dosimetry is not standard in brachytherapy and some errors go undetected. The aim of this study was to evaluate the accuracy of multi-channel vaginal cylinder pulsed dose-rate brachytherapy using in vivo dosimetry. Materials and methods In vivo dosimetry data was collected during the years 2019-2022 for 22 patients (32 fractions) receiving multi-channel cylinder pulsed dose-rate brachytherapy. An inorganic scintillation detector was inserted in a cylinder channel. Each fraction was analysed as independent data sets. In vivo dosimetry-based source-tracking was used to determine the relative source-to-detector position. Measured dose was compared to planned and re-calculated source-tracking based doses. Assuming no change in organ and applicator geometry throughout treatment, the planned and source-tracking based dose distributions were compared in select volumes via γ-index analysis and dose-volume-histograms. Results The mean ± SD planned vs. measured dose deviations in the first pulse were 0.8 ± 5.9 %. In 31/32 fractions the deviation was within the combined in vivo dosimetry uncertainty (averaging 9.7 %, k = 2) and planning dose calculation uncertainty (1.6 %, k = 2). The dwell-position offsets were < 2 mm for 88 % of channels, with the largest being 5.1 mm (4.0 mm uncertainty, k = 2). 3 %/2 mm γ pass-rates averaged 97.0 % (clinical target volume (CTV)), 100.0 % (rectum), 99.9 % (bladder). The mean ± SD deviation was -1. 1 ± 2.9 % for CTV D98, and -0.2 ± 0.9 % and -1.2 ± 2.5 %, for bladder and rectum D2cm3 respectively, indicating good agreement between intended and delivered dose. Conclusions In vivo dosimetry verified accurate and stable dose delivery in multi-channel vaginal cylinder based pulsed dose-rate brachytherapy.
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Affiliation(s)
- Peter D. Georgi
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Søren K. Nielsen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Anders T. Hansen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Harald Spejlborg
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Susanne Rylander
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Jacob Lindegaard
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Simon Buus
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Christian Wulff
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Primoz Petric
- Department of Oncology, Aarhus University Hospital, 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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Gonod M, Suarez MA, Avila CC, Karakhanyan V, Eustache C, Laskri S, Crouzilles J, Vinchant JF, Aubignac L, Grosjean T. Six-probe scintillator dosimeter for treatment verification in HDR-brachytherapy. Med Phys 2023; 50:7192-7202. [PMID: 37738612 DOI: 10.1002/mp.16745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 09/24/2023] Open
Abstract
BACKGROUND In vivo dosimetry (IVD) is gaining interest for treatment delivery verification in HDR-brachytherapy. Time resolved methods, including source tracking, have the ability both to detect treatment errors in real time and to minimize experimental uncertainties. Multiprobe IVD architectures holds promise for simultaneous dose determinations at the targeted tumor and surrounding healthy tissues while enhancing measurement accuracy. However, most of the multiprobe dosimeters developed so far either suffer from compactness issues or rely on complex data post-treatment. PURPOSE We introduce a novel concept of a compact multiprobe scintillator detector and demonstrate its applicability in HDR-brachytherapy. Our fabricated seven-fiber probing system is sufficiently narrow to be inserted in a brachytherapy needle or in a catheter. METHODS Our multiprobe detection system results from the parallel implementation of six miniaturized inorganic Gd2 O2 S:Tb scintillator detectors at the end of a bundle of seven fibers, one fiber is kept bare to assess the stem effect. The resulting system, which is narrower than 320 microns, is tested with a MicroSelectron 9.14 Ci Ir-192 HDR afterloader, in a water phantom. The detection signals from all six probes are simultaneously read with a sCMOS camera (at a rate of 0.06 s). The camera is coupled to a chromatic filter to cancel Cerenkov signal induced within the fibers upon exposure. By implementing an aperiodic array of six scintillating cells along the bundle axis, we first determine the range of inter-probe spacings leading to optimal source tracking accuracy (first tracking method). Then, three different source tracking algorithms involving all the scintillating probes are tested and compared. In each of these four methods, dwell positions are assessed from dose measurements and compared to the treatment plan. Dwell time is also determined and compared to the treatment plan. RESULTS The optimum inter-probe spacing for an accurate source tracking ranges from 15 to 35 mm. The optimum detection algorithm consists of adding the readout signals from all detector probes. In that case, the error to the planned dwell positions is of 0.01 ± 0.14 mm and 0.02 ± 0.29 mm at spacings between the source and detector axes of 5.5 and 40 mm, respectively. Using this approach, the average deviations to the expected dwell time are of- 0.006 ± 0.009 $-0.006\,\pm \,0.009$ s and- 0.008 ± 0.058 $-0.008\, \pm 0.058$ s, at spacings between source and probe axes of 5.5 and 20 mm, respectively. CONCLUSIONS Our six-probe Gd2 O2 S:Tb dosimeter coupled to a sCMOS camera can perform time-resolved treatment verification in HDR brachytherapy. This detection system of high spatial and temporal resolutions (0.25 mm and 0.06 s, respectively) provides a precise information on the treatment delivery via a dwell time and position verification of unmatched accuracy.
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Affiliation(s)
- Mathieu Gonod
- Medical Physics Department, Centre Georges François Leclerc (CGFL), Dijon, France
| | | | | | - Vage Karakhanyan
- FEMTO-ST Institute, CNRS, University of Franche-Comté, Besançon, France
| | - Clément Eustache
- FEMTO-ST Institute, CNRS, University of Franche-Comté, Besançon, France
| | - Samir Laskri
- SEDI-ATI Fibres Optiques, Évry-Courcouronnes, France
| | | | | | - Léone Aubignac
- Medical Physics Department, Centre Georges François Leclerc (CGFL), Dijon, France
| | - Thierry Grosjean
- FEMTO-ST Institute, CNRS, University of Franche-Comté, Besançon, France
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Sung S, Lee M, Choi HJ, Park H, Cheon BW, Min CH, Yeom YS, Kim H, You SH, Choi HJ. Feasibility of internal-source tracking with C-arm CT/SPECT imaging with limited-angle projection data for online in vivo dose verification in brachytherapy: A Monte Carlo simulation study. Brachytherapy 2023; 22:673-685. [PMID: 37301703 DOI: 10.1016/j.brachy.2023.05.003] [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: 10/01/2022] [Revised: 03/13/2023] [Accepted: 05/07/2023] [Indexed: 06/12/2023]
Abstract
PURPOSE The current protocol for use of the image-guided adaptive brachytherapy (IGABT) procedure entails transport of a patient between the treatment room and the 3-D tomographic imaging room after implantation of the applicators in the body, which movement can cause position displacement of the applicator. Moreover, it is not possible to track 3-D radioactive source movement inside the body, even though there can be significant inter- and intra-fractional patient-setup changes. In this paper, therefore, we propose an online single-photon emission computed tomography (SPECT) imaging technique with a combined C-arm fluoroscopy X-ray system and attachable parallel-hole collimator for internal radioactive source tracking of every source position in the applicator. METHODS AND MATERIALS In the present study, using Geant4 Monte Carlo (MC) simulation, the feasibility of high-energy gamma detection with a flat-panel detector for X-ray imaging was assessed. Further, a parallel-hole collimator geometry was designed based on an evaluation of projection image quality for a 192Ir point source, and 3-D limited-angle SPECT-image-based source-tracking performances were evaluated for various source intensities and positions. RESULTS The detector module attached to the collimator could discriminate the 192Ir point source with about 3.4% detection efficiency when including the total counts in the entire deposited energy region. As the result of collimator optimization, hole size, thickness, and length were determined to be 0.5, 0.2, and 45 mm, respectively. Accordingly, the source intensities and positions also were successfully tracked with the 3-D SPECT imaging system when the C-arm was rotated within 110° in 2 seconds. CONCLUSIONS We expect that this system can be effectively implemented for online IGABT and in vivo patient dose verification.
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Affiliation(s)
- Saerom Sung
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Minjae Lee
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Hyung-Joo Choi
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Hyojun Park
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Bo-Wi Cheon
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Chul Hee Min
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Yeon Soo Yeom
- Department of Radiation Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Hyemi Kim
- Department of Radiation Oncology, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju-si, Gangwon-do, Republic of Korea
| | - Sei Hwan You
- Department of Radiation Oncology, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju-si, Gangwon-do, Republic of Korea
| | - Hyun Joon Choi
- Department of Radiation Oncology, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju-si, Gangwon-do, Republic of Korea.
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Gonod M, Suarez MA, Chacon Avila C, Karakhanyan V, Eustache C, Crouzilles J, Laskri S, Vinchant JF, Aubignac L, Grosjean T. Characterization of a miniaturized scintillator detector for time-resolved treatment monitoring in HDR-brachytherapy. Phys Med Biol 2022; 67. [PMID: 36240766 DOI: 10.1088/1361-6560/ac9a9b] [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: 07/13/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022]
Abstract
Purpose.HDR brachytherapy combines steep dose gradients in space and time, thereby requiring detectors of high spatial and temporal resolution to perform accurate treatment monitoring. We demonstrate a miniaturized fiber-integrated scintillator detector (MSD) of unmatched compactness which fulfills these conditions.Methods.The MSD consists of a 0.28 mm large and 0.43 mm long detection cell (Gd2O2S:Tb) coupled to a 110 micron outer diameter silica optical fiber. The fiber probe is tested in a phantom using a MicroSelectron 9.1 Ci Ir-192 HDR afterloader. The detection signal is acquired at a rate of 0.08 s with a standard sCMOS camera coupled to a chromatic filter (to cancel spurious Cerenkov signal). The dwell position and time monitoring are analyzed over prostate treatment sequences with dwell times spanning from 0.1 to 11 s. The dose rate at the probe position is both evaluated from a direct measurement and by reconstruction from the measured dwell position using the AAPM TG-43 formalism.Results.A total number of 1384 dwell positions are analyzed. In average, the measured dwell positions differ by 0.023 ± 0.077 mm from planned values over a 6-54 mm source-probe distance range. The standard deviation of the measured dwell positions is below 0.8 mm. 94% of the 966 dwell positions occurring at a source-probe inter-catheter spacing below 20 mm are successfully identified, with a 100% detection rate for dwell times exceeding 0.5 s. The average deviation to the planned dwell times is of 0.005 ± 0.060 s. The instant dose retrieval from dwell position monitoring leads to a relative mismatch to planned values of 0.14% ± 0.7%.Conclusion.A miniaturized Gd2O2S:Tb detector coupled to a standard sCMOS camera can be used for time-resolved treatment monitoring in HDR Brachytherapy.
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Affiliation(s)
- Mathieu Gonod
- Centre Georges François Leclerc (CGFL)-Dijon, France
| | - Miguel Angel Suarez
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Franche-Comté-CNRS-Besançon, France
| | - Carlos Chacon Avila
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Franche-Comté-CNRS-Besançon, France
| | - Vage Karakhanyan
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Franche-Comté-CNRS-Besançon, France
| | - Clément Eustache
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Franche-Comté-CNRS-Besançon, France
| | - Julien Crouzilles
- SEDI-ATI Fibres Optiques, 8 Rue Jean Mermoz, F-91080 Évry-Courcouronnes, France
| | - Samir Laskri
- SEDI-ATI Fibres Optiques, 8 Rue Jean Mermoz, F-91080 Évry-Courcouronnes, France
| | | | | | - Thierry Grosjean
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Franche-Comté-CNRS-Besançon, France
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Houlihan OA, Workman G, Hounsell AR, Prise KM, Jain S. In vivo dosimetry in pelvic brachytherapy. Br J Radiol 2022; 95:20220046. [PMID: 35635803 PMCID: PMC10996950 DOI: 10.1259/bjr.20220046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 11/05/2022] Open
Abstract
ADVANCES IN KNOWLEDGE This paper describes the potential role for in vivo dosimetry in the reduction of uncertainties in pelvic brachytherapy, the pertinent factors for consideration in clinical practice, and the future potential for in vivo dosimetry in the personalisation of brachytherapy.
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Affiliation(s)
- Orla Anne Houlihan
- Department of Clinical Oncology, Northern Ireland Cancer
Centre, Belfast Health and Social Care Trust,
Belfast, UK
- Patrick G. Johnston Centre for Cancer Research, Queen's
University Belfast, Belfast,
UK
| | - Geraldine Workman
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast
Health and Social Care Trust,
Belfast, UK
| | - Alan R Hounsell
- Patrick G. Johnston Centre for Cancer Research, Queen's
University Belfast, Belfast,
UK
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast
Health and Social Care Trust,
Belfast, UK
| | - Kevin M Prise
- Patrick G. Johnston Centre for Cancer Research, Queen's
University Belfast, Belfast,
UK
| | - Suneil Jain
- Department of Clinical Oncology, Northern Ireland Cancer
Centre, Belfast Health and Social Care Trust,
Belfast, UK
- Patrick G. Johnston Centre for Cancer Research, Queen's
University Belfast, Belfast,
UK
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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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Zhang J, Xiang Y, Wang C, Chen Y, Tjin SC, Wei L. Recent Advances in Optical Fiber Enabled Radiation Sensors. SENSORS 2022; 22:s22031126. [PMID: 35161870 PMCID: PMC8840197 DOI: 10.3390/s22031126] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/23/2022] [Accepted: 01/27/2022] [Indexed: 02/07/2023]
Abstract
Optical fibers are being widely utilized as radiation sensors and dosimeters. Benefiting from the rapidly growing optical fiber manufacturing and material engineering, advanced optical fibers have evolved significantly by using functional structures and materials, promoting their detection accuracy and usage scenarios as radiation sensors. This paper summarizes the current development of optical fiber-based radiation sensors. The sensing principles of both extrinsic and intrinsic optical fiber radiation sensors, including radiation-induced attenuation (RIA), radiation-induced luminescence (RIL), and fiber grating wavelength shifting (RI-GWS), were analyzed. The relevant advanced fiber materials and structures, including silica glass, doped silica glasses, polymers, fluorescent and scintillator materials, were also categorized and summarized based on their characteristics. The fabrication methods of intrinsic all-fiber radiation sensors were introduced, as well. Moreover, the applicable scenarios from medical dosimetry to industrial environmental monitoring were discussed. In the end, both challenges and perspectives of fiber-based radiation sensors and fiber-shaped radiation dosimeters were presented.
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Affiliation(s)
- Jing Zhang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China; (Y.X.); (C.W.); (Y.C.)
- Correspondence: (J.Z.); (L.W.)
| | - Yudiao Xiang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China; (Y.X.); (C.W.); (Y.C.)
| | - Chen Wang
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China; (Y.X.); (C.W.); (Y.C.)
| | - Yunkang Chen
- School of Mechanical Engineering and Electronic Information, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China; (Y.X.); (C.W.); (Y.C.)
| | - Swee Chuan Tjin
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;
| | - Lei Wei
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;
- Correspondence: (J.Z.); (L.W.)
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Isikawa M, Guidelli E. Microfluidic Synthesis of Theranostic Nanoparticles with Near-Infrared Scintillation: Toward Next-Generation Dosimetry in X-ray-Induced Photodynamic Therapy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:324-336. [PMID: 34963048 DOI: 10.1021/acsami.1c20689] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We developed a microfluidic synthesis to grow GdF3:Eu theranostic scintillating nanoparticles to simultaneously monitor the X-ray dose delivered to tumors during treatments with X-ray activated photodynamic therapy (X-PDT). The flow reaction was optimized to enhance scintillation emission from the Eu3+ ions. The as-prepared ∼15 nm rhombohedral-shaped nanoparticles self-assembled into ∼100 nm mesoporous flower-like nanostructures, but the rhombohedral units remained intact and the scintillation spectra unaltered. The conjugation of the ScNPs with multilayers of methylene blue (MB) in a core-shell structure (GdF@MB) resulted in enhanced singlet oxygen (1O2) generation under X-ray irradiation, with maximum 1O2 production for nanoparticles with 4 MB layers (GdF@4MB). High 1O2 yield was further evidenced in cytotoxicity assays, demonstrating complete cell death only for the association of ScNPs with MB and X-rays. Because the scintillating Eu3+ emission at 694 nm is within the therapeutic window and was only partially absorbed by the MB molecules, it was explored for getting in vivo dosimetric information. Using porcine skin and fat to simulate the optical and radiological properties of the human tissues, we showed that the scintillation light can be detected for a tissue layer of ∼16 mm, thick enough to be employed in radiotherapy treatments of breast cancers, for instance. Therefore, the GdF3:Eu ScNPs and the GdF@4MB nanoconjugates are strong candidates for treating cancer with X-PDT while monitoring the treatment and the radiation dose delivered, opening new avenues to develop a next-generation modality of real-time in vivo dosimetry.
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Affiliation(s)
- Mileni Isikawa
- Departamento de Física. FFCLRP- Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
| | - Eder Guidelli
- Departamento de Física. FFCLRP- Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
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Biological Planning of Radiation Dose Based on In Vivo Dosimetry for Postoperative Vaginal-Cuff HDR Interventional Radiotherapy (Brachytherapy). Biomedicines 2021; 9:biomedicines9111629. [PMID: 34829858 PMCID: PMC8615499 DOI: 10.3390/biomedicines9111629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 10/28/2021] [Accepted: 11/04/2021] [Indexed: 12/24/2022] Open
Abstract
(1) Background: Postoperative vaginal-cuff HDR interventional radiotherapy (brachytherapy) is a standard treatment in early-stage endometrial cancer. This study reports the effect of in vivo dosimetry-based biological planning for two different fractionation schedules on the treatment-related toxicities. (2) Methods: 121 patients were treated. Group A (82) received 21 Gy in three fractions. Group B (39) received 20 Gy in four fractions. The dose was prescribed at a 5 mm depth or to the applicator surface according to the distance between the applicator and the rectum. In vivo dosimetry measured the dose of the rectum and/or urinary bladder. With a high measured dose, the dose prescription was changed from a 5 mm depth to the applicator surface. (3) Results: The median age was 66 years with 58.8 months mean follow-up. The dose prescription was changed in 20.7% of group A and in 41% of group B. Most toxicities were grade 1–2. Acute urinary toxicities were significantly higher in group A. The rates of acute and late urinary toxicities were significantly higher with a mean bladder dose/fraction of >2.5 Gy and a total bladder dose of >7.5 Gy. One patient had a vaginal recurrence. (4) Conclusions: Both schedules have excellent local control and acceptable rates of toxicities. Using in vivo dosimetry-based biological planning yielded an acceptable dose to the bladder and rectum.
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Hayashi H, Kimoto N, Maeda T, Tomita E, Asahara T, Goto S, Kanazawa Y, Shitakubo Y, Sakuragawa K, Ikushima H, Okazaki T, Hashizume T. A disposable OSL dosimeter for in vivo measurement of rectum dose during brachytherapy. Med Phys 2021; 48:4621-4635. [PMID: 33760234 DOI: 10.1002/mp.14857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/26/2021] [Accepted: 03/15/2021] [Indexed: 12/31/2022] Open
Abstract
PURPOSE We aimed to develop a disposable rectum dosimeter and to demonstrate its ability to measure exposure dose to the rectum during brachytherapy for cervical cancer treatment using high-dose rate 192 Ir. Our rectum dosimeter measures the dose with an optically stimulated luminescence (OSL) sheet which was furled to a catheter. The catheter we used is 6 mm in diameter; therefore, it is much less invasive than other rectum dosimeters. The rectum dosimeter developed in this study has the characteristics of being inexpensive and disposable. It is also an easy-to-use detector that can be individually sterilized, making it suitable for clinical use. METHODS To obtain a dose calibration curve, phantom experiments were performed. Irradiation was performed using a cubical acrylic phantom, and the response of the OSL dosimeter was calibrated with the calculation value predicted by the treatment planning system (TPS). Additionally, the dependence of catheter angle on the dosimeter position and repeatability were evaluated. We also measured the absorbed dose to the rectum of patients who were undergoing brachytherapy for cervical cancer (n = 64). The doses measured with our dosimeters were compared with the doses calculated by the TPS. In order to examine the causes of large differences between measured and planned doses, we classified the data into common and specific cases when performing this clinical study. For specific cases, the following three categories were considered: (a) patient movement, (b) gas in the vagina and/or rectum, and (c) artifacts in the X-ray image caused by applicators. RESULTS A dose calibration curve was obtained in the range of 0.1 Gy-10.0 Gy. From the evaluation of the dependence of catheter angle on the dosimeter position and repeatability, we determined that our dosimeter can measure rectum dose with an accuracy of 3.1% (k = 1). In this clinical study, we succeeded in measuring actual doses using our rectum dosimeter. We found that the deviation of the measured dose from the planned dose was derived to be 12.7% (k = 1); this result shows that the clinical study included large elements of uncertainty. The discrepancies were found to be due to patient motion during treatment, applicator movement after planning images were taken, and artifacts in the planning images. CONCLUSIONS We present the idea that a minimally invasive rectum dosimeter can be fabricated using an OSL sheet. Our clinical study demonstrates that a rectum dosimeter made from an OSL sheet has sufficient ability to evaluate rectum dose. Using this dosimeter, valuable information concerning organs at risk can be obtained during brachytherapy.
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Affiliation(s)
- Hiroaki Hayashi
- College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Natsumi Kimoto
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Tatsuya Maeda
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Emi Tomita
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Takashi Asahara
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan.,Okayama University Hospital, Kitaku, Okayama, Japan
| | - Sota Goto
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Yuki Kanazawa
- Graduate School of Health Sciences, Tokushima University, Tokushima, Japan
| | | | | | - Hitoshi Ikushima
- Graduate School of Health Sciences, Tokushima University, Tokushima, Japan.,Tokushima University Hospital, Tokushima, Japan
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Fonseca GP, van Wagenberg T, Voncken R, Podesta M, van Beveren C, van Limbergen E, Lutgens L, Vanneste B, Berbee M, Reniers B, Verhaegen F. Brachytherapy treatment verification using gamma radiation from the internal treatment source combined with an imaging panel-a phantom study. Phys Med Biol 2021; 66. [PMID: 33831856 DOI: 10.1088/1361-6560/abf605] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 04/08/2021] [Indexed: 12/15/2022]
Abstract
Brachytherapy has an excellent clinical outcome for different treatment sites. However,in vivotreatment verification is not performed in the majority of hospitals due to the lack of proper monitoring systems. This study investigates the use of an imaging panel (IP) and the photons emitted by a high dose rate (HDR)192Ir source to track source motion and obtain some information related to the patient anatomy. The feasibility of this approach was studied by monitoring the treatment delivery to a 3D printed phantom that mimicks a prostate patient. A 3D printed phantom was designed with a template for needle insertion, a cavity ('rectum') to insert an ultrasound probe, and lateral cavities used to place tissue-equivalent materials. CT images were acquired to create HDR192Ir treatment plans with a range of dwell times, interdwell distances and needle arrangements. Treatment delivery was verified with an IP placed at several positions around the phantom using radiopaque markers on the outer surface to register acquired IP images with the planning CT. All dwell positions were identified using acquisition times ≤0.11 s (frame rates ≥ 9 fps). Interdwell distances and dwell positions (in relation to the IP) were verified with accuracy better than 0.1 cm. Radiopaque markers were visible in the acquired images and could be used for registration with CT images. Uncertainties for image registration (IP and planning CT) between 0.1 and 0.4 cm. The IP is sensitive to tissue-mimicking insert composition and showed phantom boundaries that could be used to improve treatment verification. The IP provided sufficient time and spatial resolution for real-time source tracking and allows for the registration of the planning CT and IP images. The results obtained in this study indicate that several treatment errors could be detected including swapped catheters, incorrect dwell times and dwell positions.
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Affiliation(s)
- G P Fonseca
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - T van Wagenberg
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - R Voncken
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - M Podesta
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - C van Beveren
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - E van Limbergen
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - L Lutgens
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - B Vanneste
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - M Berbee
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
| | - B Reniers
- Research group NuTeC, Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - F Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Doctor Tanslaan 12, 6229 ET Maastricht, The Netherlands
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12
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Majdaeen M, Dorri-Giv M, Olfat S, Ataei G, Abedi-Firouzjah R, Banaei A, Ranjbar S. Skin dose measurement and estimating the dosimetric effect of applicator misplacement in gynecological brachytherapy: A patient and phantom study. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2021; 29:917-929. [PMID: 34180462 DOI: 10.3233/xst-210911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
OBJECTIVES To evaluate skin dose differences between TPS (treatment planning system) calculations and TLD (thermo-luminescent dosimeters) measurements along with the dosimetric effect of applicator misplacement for patients diagnosed with gynecological (GYN) cancers undergoing brachytherapy. METHODS The skin doses were measured using TLDs attached in different locations on patients' skin in pelvic regions (anterior, left, and right) for 20 patients, as well as on a phantom. In addition, the applicator surface dose was calculated with TLDs attached to the applicator. The measured doses were compared with TPS calculations to find TPS accuracy. For the phantom, different applicator shifts were applied to find the effect of applicator misplacement on the surface dose. RESULTS The mean absolute dose differences between the TPS and TLDs results for anterior, left, and right points were 3.14±1.03, 6.25±1.88, and 6.20±1.97 %, respectively. The mean difference on the applicator surface was obtained 1.92±0.46 %. Applicator misplacements of 0.5, 2, and 4 cm (average of three locations) resulted in 9, 36, and 61%, dose errors respectively. CONCLUSIONS The surface/skin differences between the calculations and measurements are higher in the left and right regions, which relate to the higher uncertainty of TPS dose calculation in these regions. Furthermore, applicator misplacements can result in high skin dose variations, therefore it can be an appropriate quality assurance method for future research.
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Affiliation(s)
- Mehrsa Majdaeen
- Department of Radiotherapy and Oncology, Razi Hospital, Guilan University of Medical Sciences, Rasht, Iran
| | - Masoumeh Dorri-Giv
- Nuclear Medicine Research Center, Department of Nuclear Medicine, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Shaghayegh Olfat
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Gholamreza Ataei
- Department of Radiology Technology, Faculty of Paramedical Sciences, Babol University of Medical Science, Babol, Iran
| | | | - Amin Banaei
- Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Sahar Ranjbar
- Department of Medical Physics and Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
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13
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Muenkel J, Xu Z, Traughber BJ, Baig T, Xu K, Langmack C, Harris E, Podder TK. Feasibility of improving patient's safety with in vivo dose tracking in intracavitary and interstitial HDR brachytherapy. Brachytherapy 2020; 20:353-360. [PMID: 33187822 DOI: 10.1016/j.brachy.2020.09.010] [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: 04/17/2020] [Revised: 08/29/2020] [Accepted: 09/14/2020] [Indexed: 11/19/2022]
Abstract
PURPOSE The in vivo dosimetric monitoring in HDR brachytherapy is important for improving patient safety. However, there are very limited options available for clinical application. In this study, we present a new in vivo dose measurement system with a plastic scintillating detector (PSD) for GYN HDR brachytherapy. METHODS An FDA approved PSD system, called OARtrac (AngioDynamics, Latham, NY), was used with various applicators for in vivo dose measurements for GYN patients. An institutional workflow was established for the clinical implementation of the dosimetric system. Action levels were proposed based on the measurement and system uncertainty for measurement deviations. From October 2018 to September 2019, a total of 75 measurements (48 fractions) were acquired from 14 patients who underwent HDR brachytherapy using either a multichannel cylinder, Venezia applicator, or Syed-Neblett template. The PSDs were placed in predetermined catheters/channels. A planning CT was acquired for treatment planning in Oncentra (Elekta, Version-4.5.2) TPS. The PSDs were contoured on the CT images, and the PSD D90% values were used as the expected doses for comparison with the measured doses. RESULTS The mean difference from patient measurements was -0.22% ± 5.98%, with 26% being the largest deviation from the expected value (Syed case). Large deviations were observed when detectors were placed in the area where dose rates were less than 1 cGy/s. CONCLUSIONS The establishment of clinical workflow for the in vivo dosimetry for both the intracavitary and interstitial GYN HDR brachytherapy will potentially improve the safety of the patient treatment.
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Affiliation(s)
- Jessica Muenkel
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Zhengzheng Xu
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH.
| | - Bryan J Traughber
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH; School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Tanvir Baig
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Keying Xu
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Christian Langmack
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Eleanor Harris
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH; School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Tarun K Podder
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH; School of Medicine, Case Western Reserve University, Cleveland, OH
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14
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Ding L, Wu Q, Wang Q, Li Y, Perks RM, Zhao L. Advances on inorganic scintillator-based optic fiber dosimeters. EJNMMI Phys 2020; 7:60. [PMID: 33025267 PMCID: PMC7538482 DOI: 10.1186/s40658-020-00327-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 09/03/2020] [Indexed: 12/19/2022] Open
Abstract
This article presents a new perspective on the development of inorganic scintillator-based fiber dosimeters (IOSFDs) for medical radiotherapy dosimetry (RTD) focusing on real-time in vivo dosimetry. The scintillator-based optical fiber dosimeters (SFD) are compact, free of electromagnetic interference, radiation-resistant, and robust. They have shown great potential for real-time in vivo RTD. Compared with organic scintillators (OSs), inorganic scintillators (IOSs) have larger X-ray absorption and higher light output. Variable IOSs with maximum emission peaks in the red part of the spectrum offer convenient stem effect removal. This article outlines the main advantages and disadvantages of utilizing IOSs for SFD fabrication. IOSFDs with different configurations are presented, and their use for dosimetry in X-ray RT, brachytherapy (BT), proton therapy (PT), and boron neutron capture therapy (BNCT) is reviewed. Challenges including the percentage depth dose (PDD) deviation from the standard ion chamber (IC) measurement, the angular dependence, and the Cherenkov effect are discussed in detail; methods to overcome these problems are also presented.
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Affiliation(s)
- Liang Ding
- School of Engineering, Cardiff University, Cardiff, UK
| | - Qiong Wu
- Department of Pharmacy, General Hospital of Southern Theatre Command, Guangzhou, China
| | - Qun Wang
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
| | - Yamei Li
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
| | | | - Liang Zhao
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
- Institute for Translational Medicine Research, Shanghai University, Shanghai, China
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15
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Fonseca GP, Johansen JG, Smith RL, Beaulieu L, Beddar S, Kertzscher G, Verhaegen F, Tanderup K. In vivo dosimetry in brachytherapy: Requirements and future directions for research, development, and clinical practice. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2020; 16:1-11. [PMID: 33458336 PMCID: PMC7807583 DOI: 10.1016/j.phro.2020.09.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/24/2020] [Accepted: 09/17/2020] [Indexed: 12/19/2022]
Abstract
Brachytherapy can deliver high doses to the target while sparing healthy tissues due to its steep dose gradient leading to excellent clinical outcome. Treatment accuracy depends on several manual steps making brachytherapy susceptible to operational mistakes. Currently, treatment delivery verification is not routinely available and has led, in some cases, to systematic errors going unnoticed for years. The brachytherapy community promoted developments in in vivo dosimetry (IVD) through research groups and small companies. Although very few of the systems have been used clinically, it was demonstrated that the likelihood of detecting deviations from the treatment plan increases significantly with time-resolved methods. Time–resolved methods could interrupt a treatment avoiding gross errors which is not possible with time-integrated dosimetry. In addition, lower experimental uncertainties can be achieved by using source-tracking instead of direct dose measurements. However, the detector position in relation to the patient anatomy remains a main source of uncertainty. The next steps towards clinical implementation will require clinical trials and systematic reporting of errors and near-misses. It is of utmost importance for each IVD system that its sensitivity to different types of errors is well understood, so that end-users can select the most suitable method for their needs. This report aims to formulate requirements for the stakeholders (clinics, vendors, and researchers) to facilitate increased clinical use of IVD in brachytherapy. The report focuses on high dose-rate IVD in brachytherapy providing an overview and outlining the need for further development and research.
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Affiliation(s)
- Gabriel P Fonseca
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, Doctor Tanslaan 12, 6229 ET Maastricht, the Netherlands
| | - Jacob G Johansen
- Department of Oncology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus, Denmark
| | - Ryan L Smith
- Alfred Health Radiation Oncology, Alfred Health, 55 Commercial Rd, Melbourne, VIC 3004, Australia
| | - Luc Beaulieu
- Department of Physics, Engineering Physics & Optics and Cancer Research Center, Université Laval, Quebec City, QC, Canada.,Department of Radiation Oncology, Research Center of CHU de Québec, Université Laval, Quebec City, QC, Canada
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Unit 1420, Houston, TX 77030, United States
| | - Gustavo Kertzscher
- Department of Oncology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus, Denmark
| | - Frank Verhaegen
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, Doctor Tanslaan 12, 6229 ET Maastricht, the Netherlands
| | - Kari Tanderup
- Department of Oncology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus, Denmark
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16
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Subashi E, Jacobs C, Hood R, Kirsch DG, Craciunescu O. A design process for a 3D printed patient-specific applicator for HDR brachytherapy of the orbit. 3D Print Med 2020; 6:15. [PMID: 32601842 PMCID: PMC7322888 DOI: 10.1186/s41205-020-00068-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/15/2020] [Indexed: 11/10/2022] Open
Abstract
Background This report describes a process for designing a 3D printed patient-specific applicator for HDR brachytherapy of the orbit. Case presentation A 34-year-old man with recurrent melanoma of the orbit was referred for consideration of re-irradiation. An applicator for HDR brachytherapy was designed based on the computed tomography (CT) of patient anatomy. The body contour was used to generate an applicator with a flush fit against the patient’s skin while the planning target volume (PTV) was used to devise channels that allow for access and coverage of the tumor bed. An end-to-end dosimetric test was devised to determine feasibility for clinical use. The applicator was designed to conform to the volume and contours inside the orbital cavity. Support wings placed flush with the patient skin provided stability and reproducibility, while 16 source channels of varying length were needed for sufficient access to the target. A solid sheath, printed as an outer support-wall for each channel, prevented bending or accidental puncturing of the surface of the applicator. Conclusions Quality assurance tests demonstrated feasibility for clinical use. Our experience with available 3D printing technology used to generate an applicator for the orbit may provide guidance for how materials of suitable biomechanical and radiation properties can be used in brachytherapy.
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Affiliation(s)
- Ergys Subashi
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Corbin Jacobs
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Rodney Hood
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - David G Kirsch
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Oana Craciunescu
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.,Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, USA
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17
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Abstract
Many brachytherapy (BT) errors could be detected with real-time in vivo dosimetry technology. Inorganic scintillation detectors (ISDs) have demonstrated promising capabilities for BT, because some ISD materials can generate scintillation signals large enough that (a) the background signal emitted in the fiber-optic cable (stem signal) is insignificant, and (b) small detector volumes can be used to avoid volume averaging effects in steep dose gradients near BT sources. We investigated the characteristics of five ISD materials to identify one that is appropriate for BT. ISDs consisting of a 0.26 to 1.0 mm3 volume of ruby (Al2O3:Cr), a mixture of Y2O3:Eu and YVO4:Eu, ZnSe:O, or CsI:Tl coupled to a fiber-optic cable were irradiated in a water-equivalent phantom using a high-dose-rate 192Ir BT source. Detectors based on plastic scintillators BCF-12 and BCF-60 (0.8 mm3 volume) were used as a reference. Measurements demonstrated that the ruby, Y2O3:Eu+YVO4:Eu, ZnSe:O, and CsI:Tl ISDs emitted scintillation signals that were up to 19, 19, 250, and 880 times greater, respectively, than that of the BCF-12 detector. While the total signals of the plastic scintillation detectors were dominated by the stem signal for source positions 0.5 cm from the fiber-optic cable and >3.5 cm from the scintillator volume, the stem signal for the ruby and Y2O3:Eu+YVO4:Eu ISDs were <1% of the total signal for source positions <3.4 and <4.4 cm from the scintillator, respectively, and <0.7% and <0.5% for the ZnSe:O and CsI:Tl ISDs, respectively, for positions ⩽8.0 cm. In contrast to the other ISDs, the Y2O3:Eu+YVO4:Eu ISD exhibited unstable scintillation and significant afterglow. All ISDs exhibited significant energy dependence, i.e. their dose response to distance-dependent 192Ir energy spectra differed significantly from the absorbed dose in water. Provided that energy dependence is accounted for, ZnSe:O ISDs are promising for use in error detection and patient safety monitoring during BT.
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Affiliation(s)
- Gustavo Kertzscher
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
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18
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Madden L, Archer J, Li E, Jelen U, Dong B, Roberts N, Holloway L, Rosenfeld A. First measurements with a plastic scintillation dosimeter at the Australian MRI-LINAC. ACTA ACUST UNITED AC 2019; 64:175015. [DOI: 10.1088/1361-6560/ab324b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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