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Scott H, Alvarez PE, Howell RM, Riegel A, Sun R, Liu K, Kry SF. Chromatic bleaching and fractionation effects on optically stimulated luminescent dosimeter reuse. Med Phys 2024. [PMID: 38852196 DOI: 10.1002/mp.17231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 04/14/2024] [Accepted: 05/02/2024] [Indexed: 06/11/2024] Open
Abstract
BACKGROUND Optically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance. PURPOSE The aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs. METHODS OSLDs (N = 240) were irradiated on a cobalt-60 beam in different step sizes until they reached an accumulated dose of 50 Gy. Between irradiations they were bleached using light sources of different wavelengths: the Imaging and Radiation Oncology Core (IROC) bleaching system (our control); monochromatic red, green, yellow, and blue lights; and a polychromatic white light. Sensitivity and linearity-based correction factors were determined as a function of dose step-size. The rate of signal removal from different light sources was characterized by sampling these OSLDs at various time points during their bleaching process. Relative doses were calculated according to the American Association of Physicists in Medicine Task Group-191. Signal repopulation was investigated by irradiating OSLDs (N = 300) to various delivered doses of 2, 10, 20, 30, 40, and 50 Gy in a single fraction, bleached with one of the colors, and read over time. Fractionation effects were evaluated by irradiating OSLDs up to 30 Gy in different size steps. After reading, the OSLDs were bleached following IROC protocol. OSLDs (N = 40) received irradiations in 5, 10, 15, 30 Gy fractions until they had an accumulated dose of 30 Gy; The sensitivity response of these OSLDs was compared with reference OSLDs that had no accumulated dose. RESULTS Light sources with polychromatic spectrums (IROC and white) bleached OSLDs faster than did sources with monochromatic spectra. Polychromatic light sources (white light and IROC system) provided the greatest dose stability for OSLDs that had larger amounts of accumulated dose. Signal repopulation was related to the choice of bleaching light source, timing of bleaching, and amount of accumulated dose. Changes to relative dosimetry were more pronounced in OSLDs that received larger fractions. At 5-Gy fractions and above, all OSLDs had heightened sensitivity, with OSLDs exposed to 30-Gy fractions being 6.4% more sensitive than reference dosimeters. CONCLUSIONS The choice of bleaching light plays a role in how fast an OSLD is bleached and how much accumulated dose an OSLD can be exposed to while maintaining stable signal sensitivity. We have expanded upon investigations into signal repopulation to show that bleaching light plays a role in the migration of deep traps to dosimetric traps after bleaching. Our research concludes that the bleaching light source and fractionation need to be considered when reusing OSLD.
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Affiliation(s)
- Hayden Scott
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Paola E Alvarez
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Rebecca M Howell
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Adam Riegel
- Department of Radiation Oncology, Columbia University Irving Medical Center, New York City, New York, USA
| | - Ryan Sun
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Kevin Liu
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Stephen F Kry
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
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Wong JHD, Ismail WH. Addressing challenges in diagnostic X-ray dosimetry: uncertainties and corrections for Al 2O 3:C-based optically stimulated luminescent dosimeters. Phys Eng Sci Med 2024:10.1007/s13246-024-01407-y. [PMID: 38526646 DOI: 10.1007/s13246-024-01407-y] [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: 07/19/2023] [Accepted: 02/14/2024] [Indexed: 03/27/2024]
Abstract
The use of Al2O3:C-based optically stimulated luminescent dosimeters (OSLDs) in diagnostic X-ray is a challenge because of their energy dependence (ED) and variability of element sensitivity factors (ESFs). This study aims to develop a method to determine ED and ESFs of Landauer nanoDot™ OSLDs for clinical X-ray and investigate the uncertainties associated with ESF and ED correction factors. An area of 2 × 2 cm2 at the central axis of the X-ray field was used to establish the ESFs. A total of 80 OSLDs were categorized into "controlled" (n = 40) and "less-controlled" groups (n = 40). The ESFs of the OSLDs were determined using an 80 kVp X-ray beam quality in free-air geometry. The OSLDs were cross-calibrated with an ion chamber to establish the average calibration coefficient and ESFs. The OSLDs were then irradiated at tube potentials ranging from 50 to 150 kVp to determine their ED. The uniformity of the X-ray field was ± 1.5% at 100 cm source-to-surface distance. The batch homogeneities of user-defined ESFs were 2.4% and 8.7% for controlled and less-controlled OSLDs, respectively. The ED of OSLDs ranged from 1.125 to 0.812 as tube potential increased from 50 kVp to 150 kVp. The total uncertainty of OSLDs, without ED correction, could be as high as 16%. After applying ESF and ED correction, the total uncertainties were reduced to 6.3% in controlled OLSDs and 11.6% in less-controlled ones. OSLDs corrected with user-defined ESF and ED can reduce the uncertainty of dose measurements in diagnostic X-rays, particularly in managing less-controlled OSLDs.
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Affiliation(s)
- Jeannie Hsiu Ding Wong
- Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
- Medical Physics Laboratory, Radiation Safety and Health Division, Malaysian Nuclear Agency, 43000, Bangi, Kajang, Selangor, Malaysia.
- Universiti Malaya Research Imaging Centre (UMRIC), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
| | - Wan Hazlinda Ismail
- Medical Physics Laboratory, Radiation Safety and Health Division, Malaysian Nuclear Agency, 43000, Bangi, Kajang, Selangor, Malaysia
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Goto S, Hayashi H, Yamaguchi H, Sekiguchi H, Akino R, Shimizu M. Signal-stabilized Al2O3:C-OSL dosimeter “checking chip” for correcting OSL reader sensitivity variation. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Romano F, Bailat C, Jorge PG, Lerch MLF, Darafsheh A. Ultra‐high dose rate dosimetry: challenges and opportunities for FLASH radiation therapy. Med Phys 2022; 49:4912-4932. [PMID: 35404484 PMCID: PMC9544810 DOI: 10.1002/mp.15649] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/03/2022] [Accepted: 02/20/2022] [Indexed: 11/11/2022] Open
Affiliation(s)
- Francesco Romano
- Istituto Nazionale di Fisica Nucleare Sezione di Catania Catania Italy
| | - Claude Bailat
- Institute of Radiation Physics Lausanne University Hospital Lausanne University Switzerland
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics Lausanne University Hospital Lausanne University Switzerland
- Department of Radiation Oncology Lausanne University Hospital Lausanne Switzerland
- Radio‐Oncology Laboratory DO/CHUV Lausanne University Hospital Lausanne Switzerland
| | | | - Arash Darafsheh
- Department of Radiation Oncology Washington University School of Medicine St. Louis MO 63110 USA
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Yoon SW, Lin H, Mihailidis D, Kennedy C, Li T. Technical Note: Sources of systemic error in TBI and TSET in-vivo measurements using NanoDot OSLDs within high-efficiency clinics. Med Phys 2022; 49:3489-3496. [PMID: 35213731 DOI: 10.1002/mp.15571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/09/2022] [Accepted: 02/13/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To identify sources of systemic errors and estimate their effects, especially the vendor-provided sensitivity Ss,i,vendor , on total body irradiation (TBI) and total skin electron therapy (TSET) in-vivo OSLD measurements. MATERIALS Calibration nanoDot OSLDs were irradiated 50∼300cGy under reference conditions. Raw OSLD readings Mraw were corrected by Ss,i,vendor to obtain corrected readings Mcorr . A quadratic calibration curve relating Mcorr to delivered dose Dw was established and commissioned for clinical use. For clinical measurements, directly adjacent pairs of nanoDot OSLDs were placed on TBI and TSET patients with a medical tape with or without 1.5cm of bolus respectively before treatment. Used OSLDs were bleached between each use until cumulative dose of 15Gy. Relative difference in corrected counts (∆Mcorr,rel =pair-difference/mean) was fitted multi-linearly versus possible sources of systemic errors (Ss,i,vendor , bleaching history, cumulative dose, and age differences). Total of 101 TBI and 110 TSET measurement pairs from calibrated batches were analyzed. RESULTS Ss,i,vendor introduced a residual systemic error to corrected readings Mcorr (-0.98% per +0.01, p = 4e-12). Given Ss,i,vendor distribution is σ = ±0.025, measured dose 1-σ error is ±2.5%, compared to ±2.8% uncertainty reported in the literature which may include this systemic error. Bleaching or cumulative dose did not affect Mcorr significantly after adjusting for Ss,i,vendor . Adjusting for the systemic error in Ss,i,vendor decreased two-sample mean Dw median absolute error from ±2.6% to ±1.9% and 95-percentile absolute error from ±7.1% to ±5.5%. Variability between paired clinical OSLDs was larger for TBI versus TSET at σpd = ±4.7% and ±6.3% respectively, despite similar predictor distributions. CONCLUSION Our findings suggest Mraw correction via vendor-provided sensitivity results in a small but significant systemic error. Dosimeters with outlier sensitivities should be excluded during batch calibration to minimize error. Bleaching and cumulative dose likely minimally affect measurements if cumulative dose is controlled below 15Gy. Random errors were higher for TSET than TBI. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Suk Whan Yoon
- Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania, 19104, USA
| | - Hui Lin
- Department of Radiation Oncology, University of California San Francisco, 505 Parnassus Ave, San Francisco, California, 94143, USA
| | - Dimitris Mihailidis
- Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania, 19104, USA
| | - Christopher Kennedy
- Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania, 19104, USA
| | - Taoran Li
- Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania, 19104, USA
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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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Liu K. Preliminary Investigation into the regeneration of luminescent signal in nanoDot OSLDs. J Appl Clin Med Phys 2020; 21:256-262. [PMID: 33001568 PMCID: PMC7700939 DOI: 10.1002/acm2.13035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/07/2020] [Accepted: 08/12/2020] [Indexed: 01/12/2023] Open
Abstract
Purpose Methods Results Conclusion
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