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Sundaramoorthy D, Chandrasekaran A. Patient Dose Analysis Using GafchromicTM EBT3 Film: A Retrospective Study with a Four Dual-Field Technique in Total Skin Electron Therapy. Asian Pac J Cancer Prev 2023; 24:2505-2513. [PMID: 37505785 PMCID: PMC10676495 DOI: 10.31557/apjcp.2023.24.7.2505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/09/2023] [Indexed: 07/29/2023] Open
Abstract
OBJECTIVE The Six dual-field is the most commonly used treatment technique in total skin electron therapy (TSET). Because of the prolonged treatment period, the patient may experience discomfort, and routine radiotherapy treatments may be affected. This reflects the idea of using a modified technique in TSET. The study aims to report our experience with the four dual-field technique and review the in-vivo dosimetry using gafchromic film. MATERIALS AND METHODS The in-vivo dosimetry reports using gafchromic EBT-3 films of 12 patients who received TSET with the four dual-field techniques in our hospital were analysed in this study. The dosimetric parameter including percentage depth dose, dose homogeneity, flatness and symmetry were analysed in this study. RESULTS AND DISCUSSION For all the patients, the mean dose to the skin was close to the prescription dose, and it was within 10% (99.3%-103%) of the prescription dose. The standard deviation was observed between 5.8 and 12.4 cGy. According to international standards, all of the measured dosimetric parameters were within the acceptable limit and thereby validating our technique. The in-vivo dosimetry study using radiochromic film in TSET is relatively uncommon. So, based on our results, gafchromic films are a viable choice. The objective of our four dual-field techniques is to reduce the overall treatment time on the machine, whereas our study shows a time reduction when compared to regular techniques, which aids in the smooth operation of daily routines. CONCLUSION The preliminary results of this novel modified technique in TSET demonstrated favourable effectiveness with minimal skin toxicity. This four dual-field technique is simple and easy to implement. Comparatively, this study shows the dose homogeneity of ±10% and better dose in the underdose areas proving the reliability and homogeneity of four-dual field technique.
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Affiliation(s)
- Dhivya Sundaramoorthy
- Department of Radiation Oncology, Apollo cancer Hospitals, Chennai, India.
- School of Advanced Sciences, Vellore Institute of Technology, Vellore, India.
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Xhaferllari I, Kim JP, Liyanage R, Liu C, Du D, Doemer A, Chetty IJ, Wen N. Clinical utility of Gafchromic film in an MRI-guided linear accelerator. Radiat Oncol 2021; 16:117. [PMID: 34174932 PMCID: PMC8236160 DOI: 10.1186/s13014-021-01844-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/15/2021] [Indexed: 11/18/2022] Open
Abstract
Background The purpose of this study is to comprehensively evaluate the suitability of Gafchromic EBT3 and EBT-XD film for dosimetric quality assurance in 0.35 T MR-guided radiotherapy. Methods A 0.35 T magnetic field strength was utilized to evaluate magnetic field effects on EBT3 and EBT-XD Gafchromic films by studying the effect of film exposure time within the magnetic field using two timing sequences and film not exposed to MR, the effect of magnetic field exposure on the crystalline structure of the film, and the effect of orientation of the film with respect to the bore within the magnetic field. The orientation of the monomer crystal was qualitatively evaluated using scanning electron microscopy (SEM) compared to unirradiated film. Additionally, dosimetric impact was evaluated through measurements of a series of open field irradiations (0.83 × 0.83-cm2 to 19.92 × 19.92-cm2) and patient specific quality assurance measurements. Open fields were compared to planned dose and an independent dosimeter. Film dosimetry was applied to twenty conventional and twenty stereotactic body radiotherapy (SBRT) patient specific quality assurance cases. Results No visual changes in crystal orientation were observed in any evaluated SEM images nor were any optical density differences observed between films irradiated inside or outside the magnetic field for both EBT3 and EBT-XD film. At small field sizes, the average difference along dose profiles measured in film compared to the same points measured using an independent dosimeter and to predicted treatment planning system values was 1.23% and 1.56%, respectively. For large field sizes, the average differences were 1.91% and 1.21%, respectively. In open field tests, the average gamma pass rates were 99.8% and 97.2%, for 3%/3 mm and 3%/1 mm, respectively. The median (interquartile range) 3%/3 mm gamma pass rates in conventional QA cases were 98.4% (96.3 to 99.2%), and 3%/1 mm in SBRT QA cases were 95.8% (95.0 to 97.3%). Conclusions MR exposure at 0.35 T had negligible effects on EBT3 and EBT-XD Gafchromic film. Dosimetric film results were comparable to planned dose, ion chamber and diode measurements.
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Affiliation(s)
- Ilma Xhaferllari
- Department of Radiation Oncology, Beaumont Health, Troy, MI, USA
| | - Joshua P Kim
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Ruchira Liyanage
- Department of Chemical Engineering and Material Science, Wayne State University, Detroit, MI, USA
| | - Chang Liu
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Dongsu Du
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Anthony Doemer
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Indrin J Chetty
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Ning Wen
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA.
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Ansari L, Nasiri N, Aminolroayaei F, Sani KG, Dorri-Giv M, Abedi-Firouzjah R, Sardari D. The Measurement of Thyroid Absorbed dose by Gafchromic™ EBT2 Film and Changes in Thyroid Hormone Levels Following Radiotherapy in Patients with Breast Cancer. J Med Signals Sens 2020; 10:42-47. [PMID: 32166076 PMCID: PMC7038746 DOI: 10.4103/jmss.jmss_10_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 08/03/2019] [Accepted: 08/06/2019] [Indexed: 11/04/2022]
Abstract
Background: Radiotherapy is a main method for the treatment of breast cancer. This study aimed to measure the absorbed dose of thyroid gland using Gafchromic EBT2 film during breast cancer radiotherapy. In addition, the relationship between the absorbed dose and thyroid hormone levels was evaluated. Methods: Forty-six breast cancer patients, with the age ranged between 25 and 35 years, undergoing external radiotherapy were studied. The patients were treated with 6 and 18 MV X-ray beams, and the absorbed thyroid dose was measured by EBT2 film. Thyroid hormone levels, thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxin (T4), were measured before and after the radiotherapy. Pearson's, Spearman's, and Chi-square tests were performed to evaluate the correlation between the thyroid dose and hormone levels. Results: The mean thyroid dose was 26 ± 9.45 cGy with the range of 7.85–48.35 cGy. There were not any significant differences at thyroid hormone levels between preradiotherapy and postradiotherapy (P > 0.05). There was a significant relationship between increased thyroid absorbed dose and changes in TSH and T4 levels (P < 0.05), but it was not significant in T3 level (P = 0.1). Conclusion: Regarding the results, the thyroid absorbed dose can have an effect on its function. Therefore, the thyroid gland should be considered as an organ at risk in breast cancer radiotherapy.
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Affiliation(s)
- Leyla Ansari
- Department of Radiation Sciences, Faculty of Paramedicine, Yasuj University of Medical Science, Yasuj, Iran
| | - Neda Nasiri
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Fahimeh Aminolroayaei
- Department of Medical Physics and Radiology, School of Allied Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Karim Ghazikhanlou Sani
- Department of Radiology, Paramedical School, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Masoumeh Dorri-Giv
- Department of Paramedical, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Razzagh Abedi-Firouzjah
- Department of Medical Physics Radiobiology and Radiation Protection, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Dariush Sardari
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
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Kunimoto H, Miura H, Miyazawa M, Hayata M, Matsuura T, Ozawa S, Yamada K, Nagata Y. [Improvement of Nonuniformity on Flatbed Scanner for Radiochromic Film Dosimetry Using Average Correction Factor with Multi-direction Scan Data]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2020; 76:375-384. [PMID: 32307365 DOI: 10.6009/jjrt.2020_jsrt_76.4.375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In order to correct the lateral effect caused by the light source of the flatbed scanner in the Gafchromic film EBT3, the usefulness of the correction method using the average value of the correction coefficient considering the scan directions were evaluated. EBT3 was scanned from four directions to measure the optical density (OD) of the red, blue, and, red/blue components and the correction coefficient were calculated. For the correction coefficients, average values were calculated for the purpose of use, when the scan directions could not be aligned (average lateral effect correction). Correction accuracy was verified with the pass rate of gamma analysis (3 mm/3%, threshold 30%) of the dose distribution using the EBT3 film irradiated with the step pattern. OD of the red, blue, and, red/blue components in the scanning vertical direction tended to be higher in the center than in the peripheral portion. The pass rate of the step pattern was the red component's before correction, from 26.9 to 45.1% (before correction), from 84.1 to 96.7% (after correction), the red/blue component, from 37.6 to 48.4% (before correction) and from 84.4 to 96.7% (after correction). When using the correction coefficient using the average value, the pass rate was 89.8% for the red component and 94.7% for the red/blue component. The lateral effect correction improves the accuracy of the dose distribution verification, and the correction coefficient using the average value is useful when the scanning direction is different from that at the time of obtaining the dose concentration curve.
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Affiliation(s)
- Haruhide Kunimoto
- Hiroshima High-Precision Radiotherapy Cancer Center(Current address: Department of Diagnostic Radiology /Radiation Oncology, Hiroshima Prefectural Hospital)
| | - Hideharu Miura
- Hiroshima High-Precision Radiotherapy Cancer Center
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University
| | | | | | - Takaaki Matsuura
- Hiroshima High-Precision Radiotherapy Cancer Center
- Division of Integrated Health Sciences, Graduate School of Biomedical & Health Sciences, Hiroshima University
| | - Shuichi Ozawa
- Hiroshima High-Precision Radiotherapy Cancer Center
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University
| | | | - Yasushi Nagata
- Hiroshima High-Precision Radiotherapy Cancer Center
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University
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Ade N, van Eeden D, du Plessis FCP. Characterization of Nylon-12 as a water-equivalent solid phantom material for dosimetric measurements in therapeutic photon and electron beams. Appl Radiat Isot 2019; 155:108919. [PMID: 31622845 DOI: 10.1016/j.apradiso.2019.108919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 08/26/2019] [Accepted: 10/02/2019] [Indexed: 10/25/2022]
Abstract
The tissue- or water-equivalence of dosimetry phantoms used as substitutes for water is essential for absorbed dose measurements in radiotherapy. At our institution, a heterogeneous pelvic phantom that consists of stacked Nylon-12 layers has recently been manufactured for Gafchromic film dosimetry. However, data on the use of Nylon as tissue-mimicking media for dosimetric applications are scarce. This study characterizes the water-equivalence of Nylon-12 for dosimetric measurements in therapeutic photon and electron beams. Employing an Elekta Synergy and SL25 linear accelerator (Linac), photon beam transmission measurements for 6 MV and 15 MV, acquired in narrow beam geometry with a 0.6 cm3 Farmer-type ion chamber showed that the mass attenuation coefficient μm of Nylon-12 agrees with the values of water, water-equivalent RW3 and Perspex phantom materials within 3%. For 6 MV, the μm values were 0.0477 ± 0.002 cm2/g, 0.0490 ± 0.003 cm2/g, 0.0482 ± 0.001 cm2/g and 0.0479 ± 0.002cm2/g for Nylon-12, water, RW3, and Perspex, respectively. Differences within 2% were attained between depth dose data measured in Nylon-12 slabs with Gafchromic EBT3 films and in water with a Roos ion chamber for 10 × 10 cm2 6, 12 and 20 MeV electron beams produced by the Elekta Synergy and SL25 Linacs. Also, a good agreement within 2% was obtained between percent depth doses computed by DOSXYZnrc Monte Carlo simulations in water, Nylon-12 and RW3 materials for photon spectra between 250 kV and 15 MV. The discrepancies between the ratios of average, restricted stopping powers of Nylon to air and water to air for photon spectra ranging from 2 to 45 MV are typically within 1% signifying that Nylon and water have equivalent stopping power characteristics. This study highlights that Nylon-12 can be used as a tissue-mimicking phantom material for dosimetric measurements in clinical megavoltage photon and electron beams as it exhibits good water-equivalence.
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Affiliation(s)
- Nicholas Ade
- Medical Physics Department, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - D van Eeden
- Medical Physics Department, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - F C P du Plessis
- Medical Physics Department, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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Harwood JR, Nelli FE. A model-based algorithm to correct for the loss of backscatter in superficial X-ray radiation therapy. Phys Med 2019; 65:157-166. [PMID: 31494369 DOI: 10.1016/j.ejmp.2019.08.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/29/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022] Open
Abstract
Dosimetry protocols for superficial X-rays prescribe the determination of kerma on the surface of a phantom through the use of a backscatter factor (Bw) that accounts for the effect of phantom scatter. Bw values corresponding to full-scatter phantoms are provided by these protocols. In practice, clinical situations arise wherein there is insufficient scattering material downstream, resulting in published Bw values that overestimate the amount of occurring scatter. To provide an accurate dose calculation the backscatter values need to be corrected for any reduction in scattered radiation. Estimating the change of Bw in situations with incomplete backscatter has previously been achieved by direct measurements or Monte Carlo modelling. For increasing the accuracy of clinical dosimetries, we developed a physical model to deduce an algorithm for calculating backscatter factors in situations with reduced downstream scattering medium. The predictions of the model were validated by comparison with published data, Monte Carlo simulations and film-based measurements for beams with a half-value layer of 0.8, 2 and 4 mm Al. Our algorithm accurately predicts the effect of partial scatter conditions with suitable precision. Its reliability, combined with the simplicity of calculation, makes this methodology suitable to be incorporated into routine clinical dosimetry. The algorithm's underlying physical model provides an intuitive understanding of the effects of field size and beam energy on backscatter reduction, permitting a rational management of this effect.
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Affiliation(s)
- Jeffrey R Harwood
- Andrew Love Cancer Centre, University Hospital Geelong, 70 Swanston St, Geelong, Vic 3220, Australia.
| | - Flavio E Nelli
- Andrew Love Cancer Centre, University Hospital Geelong, 70 Swanston St, Geelong, Vic 3220, Australia
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Ardekani MA, Haghparast M, Nourollahi S, Refahi S. Design of a slab phantom for breast dosimetry applications. J Cancer Res Ther 2018; 14:1126-1129. [PMID: 30197361 DOI: 10.4103/0973-1482.191028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Background Design of phantoms for use in radiotherapy should consider the complex geometry of breast tissue and inhomogeneity. The aim of this study is design of a slab phantom for breast dosimetry applications. Materials and Methods In this study, an anatomical slab phantom was designed with cork lung inhomogeneity and plexi colored heart part, also describes the different size of breast and chest wall phantom that have been designed and constructed for dosimetry. Three size different phantoms have been manufactured that installed in one trunk, as "small," "medium," and "large," two breast size fixed and one size was movable on a chest wall phantom. Two different dosimeters selected to dosimetry in this phantom, film was chosen for this dosimetry since it provides good spatial resolution and suitable for two-dimensional dosimetry also measure dose distribution used a point dosimetry with thermoluminescent dosimeter (TLD). Results The results were shown near date due to either software or phantom calculation. Conclusion Application include assessment dose in the junction region between the tangential fields and the supraclavicular fossa field, as well as assess dose in inhomogeneities, the phantom were formed from a variety of tissue substitute materials.
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Affiliation(s)
- Mahdieh Afkhami Ardekani
- Department of Radiology, Faculty of Para- Medicine, Hormozgan University of Medical Sciences, Bandare-Abbas, Iran
| | - Mohamad Haghparast
- Department of Radiology, Faculty of Para- Medicine, Hormozgan University of Medical Sciences, Bandare-Abbas, Iran
| | - Somaieh Nourollahi
- Department of Radiation and Oncology, Shahid Fayazbakhsh Hospital, Tehran, Iran
| | - Soheila Refahi
- Department of Medical Physics, Faculty of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Jagtap AS, Palani Selvam T, Patil BJ, Chavan ST, Pethe SN, Kulkarni G, Dahiwale SS, Bhoraskar VN, Dhole SD. Monte Carlo based investigations of electron contamination from telecobalt unit head in build up region and its impact on surface dose. Appl Radiat Isot 2016; 118:175-181. [PMID: 27642727 DOI: 10.1016/j.apradiso.2016.09.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 09/10/2016] [Accepted: 09/12/2016] [Indexed: 10/21/2022]
Abstract
A Telecobalt unit has wide range of applications in cancer treatments and is used widely in many countries all around the world. Estimation of surface dose in Cobalt-60 teletherapy machine becomes important since clinically useful photon beam consist of contaminated electrons during the patient treatment. EGSnrc along with the BEAMnrc user code was used to model the Theratron 780E telecobalt unit. Central axis depth dose profiles including surface doses have been estimated for the field sizes of 0×0, 6×6, 10×10, 15×15, 20×20, 25×25, 30×30cm2 and at Source-to-surface distance (SSD) of 60 and 80cm. Surface dose was measured experimentally by the Gafchromic RTQA2 films and are in good agreement with the simulation results. The central axis depth dose data are compared with the data available from the British Journal of Radiology report no. 25. Contribution of contaminated electrons has also been calculated using Monte Carlo simulation by the different parts of the Cobalt-60 head for different field size and SSD's. Moreover, depth dose curve in zero area field size is calculated by extrapolation method and compared with the already published data. They are found in good agreement.
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Affiliation(s)
- A S Jagtap
- School of Basic Medical Sciences, Department of Physics, Savitribai Phule Pune University, Pune 411007, India; Department of Radiotherapy, Cama & Albless Hospital, Mumbai, India
| | - T Palani Selvam
- Radiological Physics and Advisory Division, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, India
| | - B J Patil
- Abasaheb Garware College, Pune, India.
| | - S T Chavan
- SAMEER, IIT Powai Campus, Mumbai 400076, India
| | - S N Pethe
- SAMEER, IIT Powai Campus, Mumbai 400076, India
| | - Gauri Kulkarni
- School of Basic Medical Sciences, Department of Physics, Savitribai Phule Pune University, Pune 411007, India
| | - S S Dahiwale
- School of Basic Medical Sciences, Department of Physics, Savitribai Phule Pune University, Pune 411007, India
| | - V N Bhoraskar
- School of Basic Medical Sciences, Department of Physics, Savitribai Phule Pune University, Pune 411007, India
| | - S D Dhole
- School of Basic Medical Sciences, Department of Physics, Savitribai Phule Pune University, Pune 411007, India.
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Abstract
Background The technologic improvements in Multislice scanners include the increment in the X-ray beam width. Some new CT scanners are equipped with a 320 detector row which allows a longitudinal coverage of 160 mm and a total of 640 slices for a single rotation. When such parameters are used the length of the traditional pencil chamber (10 cm) is no more appropriate to measure the standard weighted computed tomography dose index (CTDIw) value. Materials and methods. Dosimetric measurements were performed on a 640 slices Toshiba Aquilion One CT scanner using common instrumentation available in Medical Physics Departments. Results For the measurements in air, two different ionization chambers were completely exposed to the beam. Dosimeters showed an acceptable agreement in the measurements. To evaluate the actual shape of the dose profile strips of Gafchromic XRQA film were used. Films were previously calibrated on site. From the graphic response of the scanned film it is possible to evaluate the full width at half maximum (FWHM) of the dose profile which represent the actual beam width. Conclusions Computed Tomography Dose Index (CTDI) and Dose Length Product (DLP) need to be changed when the beam width of the CT scanner is over 100 mm. To perform dose evaluation with the conventional instrumentation, two parameters should be considered: the average absorbed dose and the actual beam width. To measure the average absorbed dose, the conventional ionization chamber can be used. For the measurement of the width of the dose profile, Gafchromic XRQA film seemed to be suitable.
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Saidatul A, Azlan C, Megat Amin M, Abdullah B, Ng Kh. A survey of radiation dose to patients and operators during radiofrequency ablation using computed tomography. Biomed Imaging Interv J 2010; 6:e1. [PMID: 21611060 DOI: 10.2349/biij.6.1.e2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Accepted: 10/15/2009] [Indexed: 11/17/2022] Open
Abstract
Computed tomography (CT) fluoroscopy is able to give real time images to a physician undertaking minimally invasive procedures such as biopsies, percutaneous drainage, and radio frequency ablation (RFA). Both operators executing the procedure and patients too, are thus at risk of radiation exposure during a CT fluoroscopy. This study focuses on the radiation exposure present during a series of radio frequency ablation (RFA) procedures, and used Gafchromic film (Type XR-QA; International Specialty Products, USA) and thermoluminescent dosimeters (TLD-100H; Bicron, USA) to measure the radiation received by patients undergoing treatment, and also operators subject to scatter radiation. The voltage was held constant at 120 kVp and the current 70mA, with 5mm thickness. The duration of irradiation was between 150-638 seconds. Ultimately, from a sample of 30 liver that have undergone RFA, the study revealed that the operator received the highest dose at the hands, which was followed by the eyes and thyroid, while secondary staff dosage was moderately uniform across all parts of the body that were measured.
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