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Gotanda T, Kawaji Y, Yatake H, Imai S, Akagawa T, Gotanda R, Katsuda T. Comparison of sensitivity characteristics between GAFCHROMIC LD-V1 and GAFCHROMIC XR-QA2 in mammographic dosimetry. RADIATION PROTECTION DOSIMETRY 2023; 199:2391-2395. [PMID: 37609988 DOI: 10.1093/rpd/ncad237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 07/07/2023] [Accepted: 08/08/2023] [Indexed: 08/24/2023]
Abstract
In recent years, radiochromic films have begun to be used for dosimetry in mammography; however, the most sensitive GAFCHROMIC XR-QA2 (XR-QA2) film is no longer available owing to its discontinuation. In this study, we evaluated the sensitivity characteristics of GAFCHROMIC LD-V1 (LD-V1) as an alternative to XR-QA2 in the field of mammography, at a low dose and low energy. Our results show that the average ratio of the concentration change of LD-V1 divided by the concentration change of XR-QA2 at each absorbed dose was 53.7%, indicating the sensitivity of LD-V1 to be approximately half of XR-QA2. In addition, the linearity of the concentration change is sufficient even within a dose range of 0.59-14.52 mGy, which is lower than the manufacturer's recommended dose range. Therefore, the LD-V1 is capable of accurate dose assessment even with a low dose and the low level of energy used in mammography.
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Affiliation(s)
- Tatsuhiro Gotanda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Okayama 701-0193, Japan
| | - Yasuyuki Kawaji
- Department of Radiological Science, Faculty of Health Science, Junshin Gakuen University, Fukuoka 815-8510, Japan
| | - Hidetoshi Yatake
- Department of Breast Cancer Center, Kaizuka City Hospital, Osaka 597-0015, Japan
| | - Shinya Imai
- Department of Radiological Science, Faculty of Health Science, Morinomiya University of Medical Sciences, Osaka 559-8611, Japan
| | - Takuya Akagawa
- Department of Radiological Technology, Tokushima Red Cross Hospital, Tokushima 773-0001, Japan
| | - Rumi Gotanda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Okayama 701-0193, Japan
| | - Toshizo Katsuda
- Medical Radiation Technology, Shizuoka College of Medical Care Science, Hamamatsu 434-0041, Japan
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2
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Tanki N, Katsuda T, Gotanda R, Gotanda T, Imai S, Kawaji Y, Noguchi A, Kuwano T, Fujita H, Takeda Y. THE CONCEPT OF X-RAY CT DOSE EVALUATION METHOD USING RADIOCHROMIC FILM AND FILM-FOLDING PHANTOM. RADIATION PROTECTION DOSIMETRY 2021; 193:96-104. [PMID: 33786601 DOI: 10.1093/rpd/ncab033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/22/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
In this paper, we propose a novel radiochromic film (RCF)-based computed tomography (CT) dosimetry method, which is different from the method based on CT dose index. RCF dosimetry using Gafchromic QA2 films was performed using two lengths of film-folding phantoms. The phantom was exposed to X-ray CT through a single scan, while the RCF was sandwiched between the phantoms. We analysed the dose profile curve in two directions to investigate the dose distribution. We observed a difference in the dose distribution as the phantom size changed. Our results contradict with the results of previous studies such as Monte Carlo simulation or direct measurement. The ability to visually evaluate 2D dose distributions is an advantage of RCF dosimetry over other methods. This research investigated the ability of 2D X-ray CT dose evaluation using RCF and film-folding phantom.
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Affiliation(s)
- Nobuyoshi Tanki
- Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
- Brain Activity Imaging Center, ATR-Promotions Inc., 2-2-2 Hikaridai, Sorakugun Seika-cho, Kyoto 619-0288, Japan
| | - Toshizo Katsuda
- Department of Medical Radiation Sciences, Shizuoka College of Medicalcare Science, 2000 Hiraguchi, Hamakita-ku, Hamamatsu, 434-0041 Shizuoka, Japan
| | - Rumi Gotanda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, 701-0193 Okayama, Japan
| | - Tatsuhiro Gotanda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, 701-0193 Okayama, Japan
| | - Shinya Imai
- Department of Radiological Science, Faculty of Health Science, Morinomiya University of Medical Sciences, 1-26-16 Nankou-kita, Suminoe-ku, 559-8611 Osaka, Japan
| | - Yasuyuki Kawaji
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, 1-1-1 Chikushioka, Minami-ku, 815-8510 Fukuoka, Japan
| | - Atsushi Noguchi
- Aoi Hospital, Medical Incorporated Association Seishokai, 6-14-2 Aramaki, Itami, 664-0001 Hyogo, Japan
| | - Tadao Kuwano
- Osaka Center for Cancer and Cardiovasucular Disease Prevention, 1-6-107 Morinomiya, Joutou-ku, 536-8588 Osaka, Japan
| | - Hideki Fujita
- Department of Radiation Oncology, Osaka Saiseikai Nakatsu Hospital, 2-10-39 Shibata, Kita-ku 530-0012 Osaka, Japan
| | - Yoshihiro Takeda
- Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
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Ultraviolet ray irradiation duration for the pre-exposure of Gafchromic EBT2. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2018. [DOI: 10.2478/pjmpe-2018-0026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract
The strength and density change of the ultraviolet (UV) ray of Gafchromic EBT2 were investigated. Previous studies suggested that UV-A rays can be substituted for the x-ray double-exposure technique to correct Gafchromic EBT2’s non-uniformity error. In this study, we aimed to determine the appropriate strength of UV-A rays for irradiating an active layer that would correct the non-uniformity error of Gafchromic EBT2.
UV-A rays with a wavelength of 375 nm were used to irradiate Gafchromic EBT2 in various durations, and the resulting density change was investigated. To correct Gafchromic EBT2’s non-uniformity error, a pre-irradiation with a UV-A lamp was conducted at a distance of 72 cm for 30 min. To determine the most appropriate irradiation duration, a UV light-emitting diode generating UV-A of 375 nm was used to irradiate the Gafchromic EBT2 film with varying durations of 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 min at a distance of 5.3 cm. A 12.7 diameter region of interest was set by the irradiation area, and a histogram of pixel values was created. The condition options were decided based on two important requirements: 1) no zero values of the mode and seconds exist, and 2) the 1/10 value of the mode intersects both histogram sleeves.
In the case of Gafchromic EBT2, the irradiation strength was 85.43 mJ/cm2 for one minute in which the pixel value of mean ± SD was 255.34 ± 213.29. The irradiation duration of 4 min was the border duration of the above two conditions. When a UV ray of 375 nm wavelength is used to irradiate Gafchromic EBT2 as a substitute for x-ray exposure, the 4-min pre-irradiation duration (341.74 mJ/cm2) is demonstrably sufficient.
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Determining optimum wavelength of ultraviolet rays to pre-exposure of non-uniformity error correction in Gafchromic EBT2 films. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2018. [DOI: 10.2478/pjmpe-2018-0002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Gafchromic films have been used to measure X-ray doses in diagnostic radiology such as computed tomography. The double-exposure technique is used to correct non-uniformity error of Gafchromic EBT2 films. Because of the heel effect of diagnostic x-rays, ultraviolet A (UV-A) is intended to be used as a substitute for x-rays. When using a UV-A light-emitting diode (LED), it is necessary to determine the effective optimal UV wavelength for the active layer of Gafchromic EBT2 films. This study evaluated the relation between the increase in color density of Gafchromic EBT2 films and the UV wavelengths. First, to correct non-uniformity, a Gafchromic EBT2 film was pre-irradiated using uniform UV-A radiation for 60 min from a 72-cm distance. Second, the film was irradiated using a UV-LED with a wavelength of 353-410 nm for 60 min from a 5.3-cm distance. The maximum, minimum, and mean ± standard deviation (SD) of pixel values of the subtraction images were evaluated using 0.5 inches of a circular region of interest (ROI). The highest mean ± SD (8915.25 ± 608.86) of the pixel value was obtained at a wavelength of 375 nm. The results indicated that 375 nm is the most effective and sensitive wavelength of UV-A for Gafchromic EBT2 films and that UV-A can be used as a substitute for x-rays in the double-exposure technique.
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Katsuda T, Gotanda R, Gotanda T, Akagawa T, Tanki N, Kuwano T, Noguchi A, Yabunaka K. Intensities of Incident and Transmitted Ultraviolet-A Rays through Gafchromic Films. J Med Phys 2017; 42:86-89. [PMID: 28706354 PMCID: PMC5496275 DOI: 10.4103/jmp.jmp_136_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Gafchromic films have been applied to X-ray dosimetry in diagnostic radiology. To correct nonuniformity errors in Gafchromic films, X-rays in the double-exposure technique can be replaced with ultraviolet (UV)-A rays. Intensities of the incident and transmitted UV-A rays were measured. However, it is unclear whether the chemical color change of Gafchromic films affects the UV-A transmission intensity. Gafchromic EBT3 films were suitable to be used in this study because non-UV protection layers are present on both sides of the film. The film is placed between UV-A ray light-emitting diodes and a probe of a UV meter. Gafchromic EBT3 films were irradiated by UV-A rays for up to 60 min. Data for analysis were obtained in the subsequent 60 min. Images from before and after UV-A irradiation were subtracted. When using 375 nm UV-A, the mean ± standard deviation (SD) of the pixel values in the subtracted image was remarkably high (11,194.15 ± 586.63). However, the UV-A transmissivity remained constant throughout the 60 min irradiation period. The mean ± SD UV-A transmission intensity was 184.48 ± 0.50 μm/cm2. Our findings demonstrate that color density changes in Gafchromic EBT3 films do not affect their UV-A transmission. Therefore, Gafchromic films were irradiated by UV-A rays as a preexposure.
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Affiliation(s)
- Toshizo Katsuda
- Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Rumi Gotanda
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan
| | - Tatsuhiro Gotanda
- Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Takuya Akagawa
- Department of Radiological Technology, Tokushima Red Cross Hospital, Komatsushima, Japan
| | - Nobuyoshi Tanki
- Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Tadao Kuwano
- Graduate School of Health Sciences, Okayama University, Okayama, Japan
| | - Atsushi Noguchi
- Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Kouichi Yabunaka
- Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Gotanda T, Katsuda T, Gotanda R, Kuwano T, Akagawa T, Tanki N, Tabuchi A, Shimono T, Kawaji Y, Takeda Y. Effective energy measurement using radiochromic film: application of a mobile scanner. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2016. [DOI: 10.1515/pjmpe-2016-0015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The effective energy calculated using the half-value layer (HVL) is an important parameter for quality assurance (QA) and quality control (QC). However constant monitoring has not been performed because measurements using an ionization chamber (IC) are time-consuming and complicated. To solve these problems, a method using radiochromic film (GAFCHROMIC EBT2 dosimetry film (GAF-EBT2) with slight energy dependency errors), a mobile scanner and step-shaped aluminum (SSAl) filter is developed. The results of the method using a mobile scanner were compared with those of the recommended method using an IC in order to evaluate its applicability. The difference ratios of the effective energies by each method using a mobile scanner with GAF-EBT2 were less than 5% compared with results of an IC. It is considered that this method offers a simple means of determining HVL for QA and QC consistently and quickly without the need for an IC dosimeter.
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Affiliation(s)
- Tatsuhiro Gotanda
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Toshizo Katsuda
- Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Rumi Gotanda
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan
| | - Tadao Kuwano
- Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, Okayama, Japan
| | - Takuya Akagawa
- Department of Radiological Technology, Tokushima Red Cross Hospital, Tokushima, Japan
| | - Nobuyoshi Tanki
- Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Akihiko Tabuchi
- Department of Radiology, Kawasaki Medical School Kawasaki Hospital, Okayama, Japan
| | - Tetsunori Shimono
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Yasuyuki Kawaji
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Yoshihiro Takeda
- Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, Okayama, Japan
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Gotanda T, Katsuda T, Gotanda R, Kuwano T, Akagawa T, Tanki N, Tabuchi A, Shimono T, Kawaji Y. Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film. J Med Phys 2016; 41:266-270. [PMID: 28144120 PMCID: PMC5228051 DOI: 10.4103/0971-6203.195192] [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] [Indexed: 11/21/2022] Open
Abstract
Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.
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Affiliation(s)
- Tatsuhiro Gotanda
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Toshizo Katsuda
- Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Rumi Gotanda
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan
| | - Tadao Kuwano
- Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, Okayama, Japan
| | - Takuya Akagawa
- Department of Radiological Technology, Tokushima Red Cross Hospital, Tokushima, Japan
| | - Nobuyoshi Tanki
- Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, Osaka, Japan
| | - Akihiko Tabuchi
- Department of Radiology, Kawasaki Medical School Kawasaki Hospital, Okayama, Japan
| | - Tetsunori Shimono
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Yasuyuki Kawaji
- Department of Radiological Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
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Katsuda T, Gotanda R, Gotanda T, Akagawa T, Tanki N, Kuwano T, Yabunaka K. Correction of nonuniformity error of Gafchromic EBT2 and EBT3. J Appl Clin Med Phys 2016; 17:41-51. [PMID: 27167258 PMCID: PMC5690916 DOI: 10.1120/jacmp.v17i3.5862] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 01/12/2016] [Accepted: 11/15/2015] [Indexed: 11/23/2022] Open
Abstract
This study investigates an X‐ray dose measurement method for computed tomography using Gafchromic films. Nonuniformity of the active layer is a major problem in Gafchromic films. In radiotherapy, nonuniformity error is reduced by applying the double‐exposure technique, but this is impractical in diagnostic radiology because of the heel effect. Therefore, we propose replacing the X‐rays in the double‐exposure technique with ultraviolet (UV)‐A irradiation of Gafchromic EBT2 and EBT3. To improve the reproducibility of the scan position, Gafchromic EBT2 and EBT3 films were attached to a 3‐mm‐thick acrylic plate. The samples were then irradiated with a 10 W UV‐A fluorescent lamp placed at a distance of 72 cm for 30, 60, and 90 minutes. The profile curves were evaluated along the long and short axes of the film center, and the standard deviations of the pixel values were calculated over large areas of the films. Paired t‐test was performed. UV‐A irradiation exerted a significant effect on Gafchromic EBT2 (paired t‐test; p=0.0275) but not on EBT3 (paired t‐test; p=0.2785). Similarly, the homogeneity was improved in Gafchromic EBT2 but not in EBT3. Therefore, the double‐exposure technique under UV‐A irradiation is suitable only for EBT2 films. PACS number(s): 87.53 Bn
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Katsuda T, Gotanda R, Gotanda T, Akagawa T, Tanki N, Kuwano T, Yabunaka K. Comparing three UV wavelengths for pre-exposing Gafchromic EBT2 and EBT3 films. J Appl Clin Med Phys 2015; 16:449–457. [PMID: 26699578 PMCID: PMC5691032 DOI: 10.1120/jacmp.v16i6.5663] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/17/2015] [Accepted: 05/26/2015] [Indexed: 11/23/2022] Open
Abstract
Gafchromic films are used for X‐ray dose measurements during diagnostic examinations and have begun to be used for three‐dimensional X‐ray dose measurements using the high‐resolution characteristics of Gafchromic films for computed tomography. However, the problem of unevenness in Gafchromic film active layers needs to be resolved. Double exposures using X‐rays are performed during therapeutic radiology, although this is difficult for a diagnostic examination because of a heel effect. Thus, it has been suggested that ultraviolet (UV) radiation be used as a substitute for X‐rays. However, the appropriate UV wavelength has not been determined. Thus, we conducted this study to decide an appropriate UV wavelength. UV peak wavelengths of 245 nm (UV‐A), 310 nm (UV‐B), and 365 nm (UV‐C) were used to irradiate EBT2 and EBT3 films. Each UV wavelength was irradiated for 5, 15, 30, and 60 min, and irradiation was then repeated every 60 min up to 360 min. Gafchromic films were scanned after every irradiation using a flatbed scanner. Images were split into RGB images, and red images were analyzed using ImageJ, version 1.44, image analysis software. A region of interest (ROI) one‐half inch in diameter was placed in the center of subtracted Gafchromic film images, and UV irradiation times were plotted against mean pixel values. There were reactions in the front and back of Gafchromic EBT3 and the back of Gafchromic EBT2 with UV‐A and UV‐B. However, UV‐C resulted in some reactions in both sides of Gafchromic EBT2 and EBT3. The UV‐A and UV‐B wavelengths should be used. PACS number(s): 87.53 Bn
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Katsuda T, Gotanda R, Gotanda T, Akagawa T, Tanki N, Kuwano T, Yabunaka K. Ultraviolet exposure of Gafchromic XR-RV3 and XR-SP2 films. J Appl Clin Med Phys 2015; 16:427–434. [PMID: 26699326 PMCID: PMC5690151 DOI: 10.1120/jacmp.v16i5.5664] [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: 02/23/2015] [Revised: 04/29/2015] [Accepted: 04/20/2015] [Indexed: 11/23/2022] Open
Abstract
Gafchromic film has been used for X-ray dose measurement in diagnostic examinations. Their use has been initiated for three-dimensional X-ray dose measurement by using the high-resolution characteristics of Gafchromic films in computed tomography. However, it is necessary to solve the problem of nonuniform thickness in the active layers of Gafchromic films. A double exposure technique using X-rays is performed in therapeutic radiology; it is difficult to use in a diagnostic examination because of the heel effect. Therefore, it is suggested that ultraviolet (UV) rays be substituted for X-rays. However, the appropriate UV wavelength is unknown. In this study, we aimed to determine which UV wavelengths are effective to expose Gafchromic XR-RV3 and XR-SP2. UV lamps with peak wavelengths of 245 nm, 310 nm, and 365 nm were used. The three UV wavelengths were used to irradiate Gafchromic XR-RV3 and XR-SP2 films for 60 min, and irradiation was repeated every 60 min for 600 min thereafter. Films were scanned after each irradiation period on a flatbed scanner. The images were split into their red-green-blue components, and red images were stored using ImageJ version 1.44o image analysis software. Regions of interest (ROI), 0.5 inches in diameter, were placed at the centers of the subtracted Gafchromic film images, and graphs of UV irradiation duration and mean pixel values were plotted. There were reactions to UV-A on both Gafchromic XR-RV3 and XR-SP2; those to UV-B were moderate. However, UV-C demonstrated few reactions with Gafchromic XR-RV3 and XR-SP2. From these results, irradiation with UV-A may be able to correct nonuniformity errors. Uniform UV-A irradiation of Gafchromic films with large areas is possible, and UV rays can be used as a substitute for X-rays in the double exposure technique.
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11
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Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C. Advances in kilovoltage x-ray beam dosimetry. Phys Med Biol 2014; 59:R183-231. [DOI: 10.1088/0031-9155/59/6/r183] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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12
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Gotanda T, Katsuda T, Akagawa T, Gotanda R, Tabuchi A, Yamamoto K, Kuwano T, Yatake H, Yabunaka K, Takeda Y. Evaluation of GAFCHROMIC EBT2 dosimetry for the low dose range using a flat-bed scanner with the reflection mode. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2013; 36:59-63. [PMID: 23479183 DOI: 10.1007/s13246-013-0187-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 02/18/2013] [Indexed: 11/27/2022]
Abstract
Recently developed radiochromic films can easily be used to measure absorbed doses because they do not need development processing and indicate a density change that depends on the absorbed dose. However, in GAFCHROMIC EBT2 dosimetry (GAF-EBT2) as a radiochromic film, the precision of the measurement was compromised, because of non-uniformity problems caused by image acquisition using a flat-bed scanner with a transmission mode. The purpose of this study was to improve the precision of the measurement using a flat-bed scanner with a reflection mode at the low absorbed dose dynamic range of GAF-EBT2. The calibration curves of the absorbed dose versus the film density for GAF-EBT2 were provided. X-rays were exposed in the range between ~0 and 120 mGy in increments of about 12 mGy. The results of the method using a flat-bed scanner with the transmission mode were compared with those of the method using the same scanner with the reflection mode. The results should that the determination coefficients (r (2) ) for the straight-line approximation of the calibration curve using the reflection mode were higher than 0.99, and the gradient using the reflection mode was about twice that of the one using the transmission mode. The non-uniformity error that is produced by a flat-bed scanner with the transmission mode setting could be almost eliminated by converting from the transmission mode to the reflection mode. In light of these findings, the method using a flat-bed scanner with the reflection mode (only using uniform white paper) improved the precision of the measurement for the low absorbed dose range.
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Affiliation(s)
- Tatsuhiro Gotanda
- Department of Radiology, Oishi Hospital, 1-7-15 Kawaguchi Cho, Fukuyama, Hiroshima, 720-0822, Japan.
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