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Yamaguchi S, Ieko Y, Ariga H, Yoshioka K. Electron beam detection in radiotherapy using a capacitor dosimeter equipped with a silicon photodiode. Med Biol Eng Comput 2023:10.1007/s11517-023-02870-7. [PMID: 37380785 DOI: 10.1007/s11517-023-02870-7] [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: 11/25/2022] [Accepted: 06/16/2023] [Indexed: 06/30/2023]
Abstract
In this study, a newly developed capacitor dosimeter was evaluated using electron beams commonly utilized in radiotherapy. The capacitor dosimeter comprised a silicon photodiode, 0.47-μF capacitor, and dedicated terminal (dock). Before electron beam irradiation, the dosimeter was charged using the dock. The doses were measured without using a cable by reducing the charging voltages using the currents from the photodiode during irradiation. A commercially available parallel-plane-type ionization chamber and solid-water phantom were used for dose calibration with an electron energy of 6 MeV. In addition, the depth doses were measured using a solid-water phantom at electron energies of 6, 9, and 12 MeV. The doses were proportional to the discharging voltages, and the maximum dose difference in the calibrated doses measured using a two-point calibration was approximately 5% in the range of 0.25-1.98 Gy. The depth dependencies at energies of 6, 9, and 12 MeV corresponded to those measured using the ionization chamber.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Radiology, School of Medicine, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan.
| | - Yoshiro Ieko
- Department of Radiation Oncology, Iwate Medical University Hospital, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
| | - Hisanori Ariga
- Department of Radiation Oncology, Iwate Medical University Hospital, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
| | - Kunihiro Yoshioka
- Department of Radiology, School of Medicine, Iwate Medical University, 2-1-1, Idaidori, Yahaba, Iwate, 028-3695, Japan
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Anam C, Kusuma Dewi W, Masdi M, Haryanto F, Fujibuchi T, Dougherty G. Investigation of Eye Lens Dose Estimate based on AAPM Report 293 in Head Computed Tomography. J Biomed Phys Eng 2021; 11:563-572. [PMID: 34722401 PMCID: PMC8546161 DOI: 10.31661/jbpe.v0i0.2104-1304] [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: 04/09/2021] [Accepted: 06/22/2021] [Indexed: 11/17/2022]
Abstract
Background: Estimation of eye lens dose is important in head computed tomography (CT) examination since the eye lens is a sensitive organ to ionizing radiation. Objective: The purpose of this study is to compare estimations of eye lens dose in head CT examinations using local size-specific dose estimate (SSDE) based on size-conversion
factors of the American Association of Physicists in Medicine (AAPM) Report No. 293 with those based on size-conversion factors of the AAPM Report No. 220. Material and Methods: This experimental study is conducted on a group of patients who had undergone nasopharyngeal CT examination. Due to the longitudinal (z-axis) dose fluctuation,
the average global SSDE and average local SSDE (i.e. particular slices where the eyes are located) were investigated. All estimates were compared to the measurement
results using thermo-luminescent dosimeters (TLDs). The estimated and measured doses were implemented for 14 patients undergoing nasopharyngeal CT examination. Results: It was found that the percentage differences of the volume CT dose index (CTDIvol), average global SSDE based on AAPM No. 220 (SSDEo,g), average local SSDE based
on AAPM No. 220 (SSDEo,l), average global SSDE based on AAPM No. 293 (SSDEn,g) and average local SSDE based on AAPM No. 293 (SSDEn,l) against the measured TLD doses
were 22.5, 21.7, 15.0, 9.3, and 2.1%, respectively. All comparisons between dose estimates and TLD measurements gave p-values less than 0.001, except for SSDEn,l (p-value = 0.566). Conclusion: SSDE based on AAPM Report No. 293 can be used to accurately estimate eye lens radiation doses by performing the calculations on a number of specific slices containing the eyes.
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Affiliation(s)
- Choirul Anam
- PhD, Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Semarang 50275, Central Java, Indonesia
| | - Winda Kusuma Dewi
- MSc, Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Semarang 50275, Central Java, Indonesia
| | - Masdi Masdi
- BSc, Department of Radiology, Prof. Margono Hospital, Purwokerto, Indonesia
| | - Freddy Haryanto
- PhD, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10 Bandung 40132, Indonesia
| | - Toshioh Fujibuchi
- PhD, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Geoff Dougherty
- PhD, Department of Applied Physics and Medical Imaging, California State University Channel Islands, Camarillo, CA 93012, USA
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Irdawati Y, Sutanto H, Anam C, Fujibuchi T, Zahroh F, Dougherty G. Development of a novel artifact-free eye shield based on silicon rubber-lead composition in the CT examination of the head. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2019; 39:991-1005. [PMID: 31272094 DOI: 10.1088/1361-6498/ab2f3e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The aim of this work was to develop a novel artifact-free eye shield and evaluate its effect on the dose received by the eye lens and the resulting image quality in the CT examination of the head. A new material for an eye shield was synthesised from silicon rubber (SR) and lead (Pb) using a simple method. The percentage of Pb was varied from 0 to 5% wt. An anthropomorphic head phantom was scanned with and without the SR-Pb eye shield, and compared with a tungsten paper (WP) eye shield. The distance from the eye shield and head was varied from 0 to 5 cm. The dose to the eye lens was measured using photo-luminescence detectors (PLDs). The presence of artifacts was determined by measuring CT numbers at different eye lens locations and by subtracting images with and without the eye shield. The dose reduction increases with increasing Pb content in the SR-Pb eye shield. A 5% wt SR-Pb eye shield reduced the eye lens dose by up to 50%, whereas the WP eye shield reduced the dose by up to 86%. The CT numbers in images with the SR-Pb eye shield in the regions of both eyes and the center of the head phantom is similar to those without the eye shield, indicating that there is no artifact in the resulting image. Using the WP eye shield, there is considerable artifact with the CT number increasing by up to 700% in the regions of both eyes and the center of the head. It is found that the distance between the SR-Pb eye shield and the head does not affect either the dose or the resulting images. A SR-Pb-based eye shield can be applied in clinical environments and should be placed directly above the eye surface for dose optimisation.
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Affiliation(s)
- Yulia Irdawati
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
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Tendler II, Bruza P, Jermyn M, Cao X, Williams BB, Jarvis LA, Pogue BW, Gladstone DJ. Characterization of a non-contact imaging scintillator-based dosimetry system for total skin electron therapy. Phys Med Biol 2019; 64:125025. [PMID: 31035267 PMCID: PMC10653344 DOI: 10.1088/1361-6560/ab1d8a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Surface dosimetry is required for ensuring effective administration of total skin electron therapy (TSET); however, its use is often reduced due to the time consuming and complex nature of acquisition. A new surface dose imaging technique was characterized in this study and found to provide accurate, rapid and remote measurement of surface doses without the need for post-exposure processing. Disc-shaped plastic scintillators (1 mm thick × 15 mm [Formula: see text]) were chosen as optimal-sized samples and designed to attach to a flat-faced phantom for irradiation using electron beams. Scintillator dosimeter response to radiation damage, dose rate, and temperature were studied. The effect of varying scintillator diameter and thickness on light output was evaluated. Furthermore, the scintillator emission spectra and impact of dosimeter thickness on surface dose were also quantified. Since the scintillators were custom-machined, dosimeter-to-dosimeter variation was tested. Scintillator surface dose measurements were compared to those obtained by optically stimulated luminescence dosimeters (OSLD). Light output from scintillator dosimeters evaluated in this study was insensitive to radiation damage, temperature, and dose rate. Maximum wavelength of emission was found to be 422 nm. Dose reported by scintillators was linearly related to that from OSLDs. Build-up from placement of scintillators and OSLDs had a similar effect on surface dose (4.9% increase). Variation among scintillator dosimeters was found to be 0.3 ± 0.2%. Scintillator light output increased linearly with dosimeter thickness (~1.9 × /mm). All dosimeter diameters tested were able to accurately measure surface dose. Scintillator dosimeters can potentially improve surface dosimetry-associated workflow for TSET in the radiation oncology clinic. Since scintillator data output can be automatically recorded to a patient medical record, the chances of human error in reading out and recording surface dose are minimized.
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Affiliation(s)
- Irwin I Tendler
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
| | - Mike Jermyn
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
- DoseOptics LLC, Lebanon, NH, United States of America
| | - Xu Cao
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
| | - Benjamin B Williams
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH, United States of America
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States of America
| | - Lesley A Jarvis
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH, United States of America
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States of America
| | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
- DoseOptics LLC, Lebanon, NH, United States of America
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States of America
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH, United States of America
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States of America
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