1
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Antunes PCG, Siqueira PDTD, Shorto JMB, Yoriyaz H. Heterogeneous physical phantom for I-125 dose measurements and dose-to-medium determination. Brachytherapy 2024; 23:73-84. [PMID: 38016863 DOI: 10.1016/j.brachy.2023.08.007] [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: 04/17/2023] [Revised: 07/30/2023] [Accepted: 08/30/2023] [Indexed: 11/30/2023]
Abstract
PURPOSE In this paper we present a further step in the implementation of a physical phantom designed to generate sets of "true" independent reference data as requested by TG-186, intending to address and mitigate the scarcity of experimental studies on brachytherapy (BT) validation in heterogeneous media. To achieve this, we incorporated well-known heterogeneous materials into the phantom in order to perform measurements of 125I dose distribution. The work aims to experimentally validate Monte Carlo (MC) calculations based on MBDCA and determine the conversion factors from LiF response to absorbed dose in different media, using cavity theory. METHODS AND MATERIALS The physical phantom was adjusted to incorporate tissue equivalent materials, such as: adipose tissue, bone, breast and lung with varying thickness. MC calculations were performed using MCNP6.2 code to calculate the absorbed dose in the LiF and the dose conversion factors (DCF). RESULTS The proposed heterogeneous phantom associated with the experimental procedure carried out in this work yielded accurate dose data that enabled the conversion of the LiF responses into absorbed dose to medium. The results showed a maximum uncertainty of 6.92 % (k = 1), which may be considered excellent for dosimetry with low-energy BT sources. CONCLUSIONS The presented heterogeneous phantom achieves the required precision in dose evaluations due to its easy reproducibility in the experimental setup. The obtained results support the dose conversion methodology for all evaluated media. The experimental validation of the DCF in different media holds great significance for clinical procedures, as it can be applied to other tissues, including water, which remains a widely utilized reference medium in clinical practice.
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Affiliation(s)
- Paula Cristina Guimarães Antunes
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, Sao Paulo, Brazil; Institute of Physics, University of Sao Paulo, Sao Paulo, Brazil.
| | | | | | - Hélio Yoriyaz
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, Sao Paulo, Brazil
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2
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Cederhag J, Kadesjö N, Nilsson M, Alstergren P, Shi XQ, Hellén-Halme K. Comparison of absorbed doses and organ doses measured with thermoluminescent dosimeters and Gafchromic film for cone beam computed tomography examination of the posterior mandibular region in a head phantom. Oral Surg Oral Med Oral Pathol Oral Radiol 2023; 136:769-776. [PMID: 37625926 DOI: 10.1016/j.oooo.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 06/26/2023] [Accepted: 07/02/2023] [Indexed: 08/27/2023]
Abstract
OBJECTIVES We aimed to map the correlation between thermoluminescent dosimeters (TLDs) and Gafchromic film for measuring absorbed doses and to compare minimum, maximum, and mean absorbed doses over larger regions of interest and at various craniofacial organs and tissues during cone beam computed tomography (CBCT) exposure of the mandibular third molar region. STUDY DESIGN We positioned TLDs at 75 measurement points in a head phantom. Gafchromic film was cut to the same shape as the 5 levels of the phantom and was placed on top of the TLDs. Both dosimetry methods thus included the surface of each level simultaneously. CBCT scans were made using a 5 × 5 cm field of view and a rotation angle of 200°. Measurements included absorbed dose distributions, doses at all 75 points, and minimum, maximum, and mean doses within organs and tissues. RESULTS The correlation of point-dose measurements at all TLD sites with doses measured on film was strong (R2 = 0.9687), with greatest correlation at lower doses (<2 mGy). Large deviations between TLD and film measurements of minimum and maximum doses and absorbed doses to the organs occurred at all 5 levels. TLD positioning failed to cover several organ sites; for these, only absorbed dose measurements from the film were available. CONCLUSIONS TLDs were unable to sample dose distributions and gradients accurately. The characteristics of Gafchromic LD-V1 film make it a favorable alternative in dental CBCT dosimetry.
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Affiliation(s)
- Josefine Cederhag
- Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden.
| | - Nils Kadesjö
- Medical Radiation Physics, Karolinska University Hospital, Stockholm, Sweden
| | - Mats Nilsson
- Department of Medical Radiation Physics, Lund University, Malmö, Sweden
| | - Per Alstergren
- Department of Orofacial Pain and Jaw Function, Faculty of Odontology, Malmö University, Malmö, Sweden; Specialized Pain Rehabilitation, Skåne University Hospital, Lund, Sweden; Scandinavian Center for orofacial Neurosciences, Malmö University, Malmö, Sweden
| | - Xie-Qi Shi
- Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden; Section of Oral and Maxillofacial Radiology, Department of Clinical Dentistry, University of Bergen, Bergen, Norway
| | - Kristina Hellén-Halme
- Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden
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3
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Manna F, Pugliese M, Buonanno F, Gherardi F, Iannacone E, La Verde G, Muto P, Arrichiello C. Use of Thermoluminescence Dosimetry for QA in High-Dose-Rate Skin Surface Brachytherapy with Custom-Flap Applicator. SENSORS (BASEL, SWITZERLAND) 2023; 23:3592. [PMID: 37050652 PMCID: PMC10098582 DOI: 10.3390/s23073592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 06/19/2023]
Abstract
Surface brachytherapy (BT) lacks standard quality assurance (QA) protocols. Commercially available treatment planning systems (TPSs) are based on a dose calculation formalism that assumes the patient is made of water, resulting in potential deviations between planned and delivered doses. Here, a method for treatment plan verification for skin surface BT is reported. Chips of thermoluminescent dosimeters (TLDs) were used for dose point measurements. High-dose-rate treatments were simulated and delivered through a custom-flap applicator provided with four fixed catheters to guide the Iridium-192 (Ir-192) source by way of a remote afterloading system. A flat water-equivalent phantom was used to simulate patient skin. Elekta TPS Oncentra Brachy was used for planning. TLDs were calibrated to Ir-192 through an indirect method of linear interpolation between calibration factors (CFs) measured for 250 kV X-rays, Cesium-137, and Cobalt-60. Subsequently, plans were designed and delivered to test the reproducibility of the irradiation set-up and to make comparisons between planned and delivered dose. The obtained CF for Ir-192 was (4.96 ± 0.25) μC/Gy. Deviations between measured and TPS calculated doses for multi-catheter treatment configuration ranged from -8.4% to 13.3% with an average of 0.6%. TLDs could be included in clinical practice for QA in skin BT with a customized flap applicator.
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Affiliation(s)
- Francesco Manna
- Department of Physics “E. Pancini”, Federico II University, 80126 Naples, Italy
- Centro Servizi Metrologici e Tecnologici Avanzati, Federico II University, 80146 Naples, Italy
| | - Mariagabriella Pugliese
- Department of Physics “E. Pancini”, Federico II University, 80126 Naples, Italy
- National Institute of Nuclear Physics, Section of Naples, 80126 Naples, Italy
| | - Francesca Buonanno
- Radiotherapy Unit, Istituto Nazionale Tumori, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Fondazione G. Pascale, 80131 Naples, Italy
| | - Federica Gherardi
- Radiotherapy Unit, Istituto Nazionale Tumori, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Fondazione G. Pascale, 80131 Naples, Italy
| | - Eva Iannacone
- Radiotherapy Unit, Istituto Nazionale Tumori, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Fondazione G. Pascale, 80131 Naples, Italy
| | - Giuseppe La Verde
- Department of Physics “E. Pancini”, Federico II University, 80126 Naples, Italy
- National Institute of Nuclear Physics, Section of Naples, 80126 Naples, Italy
| | - Paolo Muto
- Radiotherapy Unit, Istituto Nazionale Tumori, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Fondazione G. Pascale, 80131 Naples, Italy
| | - Cecilia Arrichiello
- Radiotherapy Unit, Istituto Nazionale Tumori, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Fondazione G. Pascale, 80131 Naples, Italy
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Rezazadeh F, Negarestani A, Sina S, Farajzadeh E, Karari B. MEASUREMENT OF ENTRANCE SKIN DOSE AND ABSORBED DOSE TO DIFFERENT ORGANS IN DUAL-ENERGY X-RAY ABSORPTIOMETRY SCANS USING THERMOLUMINESCENCE DOSIMETRY. RADIATION PROTECTION DOSIMETRY 2023; 199:116-123. [PMID: 36448827 DOI: 10.1093/rpd/ncac233] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 09/05/2022] [Accepted: 09/27/2022] [Indexed: 06/17/2023]
Abstract
Thermoluminescence dosimetry is considered as an effective method in estimating the absorbed doses to organs in different imaging modalities. The present study focuses on dosimetry in dual-energy X-ray absorptiometry scans, for patients, and phantoms in various imaging centres. The cubical LiF (Mg, Ti) thermoluminescence dosemeters were inserted inside the holes of the Rando phantom slabs, to measure the absorbed dose to different organs in the whole body and lumbar scans. According to the results the maximum entrance skin dose was found to be 202.06 μGy for Hologic discovery W, which uses the fan beam scanning mode. The Norland XR-800 device took the scans with a much lower dose, as it uses the pencil beam for scanning the patients. The results of the study show that the radiation beam type, patient thickness, imaging technique and scan time may affect the radiation dose received by patient.
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Affiliation(s)
- Fatemeh Rezazadeh
- Faculty of science, and modern technology, Kerman Graduate University of Advanced Technology, end of Haft Bagh Alavi expressway, Kerman, Iran
| | - Ali Negarestani
- Faculty of science, and modern technology, Kerman Graduate University of Advanced Technology, end of Haft Bagh Alavi expressway, Kerman, Iran
| | - Sedigheh Sina
- Nuclear Engineering Department, Shiraz University, Mollasadra street, Shiraz, Iran
- Radiation Research Center, Shiraz University, Mollasadra street, Shiraz, Iran
| | - Ebrahim Farajzadeh
- Radiation Research Center, Shiraz University, Mollasadra street, Shiraz, Iran
| | - Behnaz Karari
- Nuclear Engineering Department, Shiraz University, Mollasadra street, Shiraz, Iran
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Antunes PCG, Siqueira PDTD, Shorto JBM, Yoriyaz H. A versatile physical phantom design and construction for I-125 dose measurements and dose-to-medium determination. Brachytherapy 2023; 22:80-92. [PMID: 36396567 DOI: 10.1016/j.brachy.2022.10.005] [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: 06/29/2022] [Revised: 09/15/2022] [Accepted: 10/09/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE In this paper we present a phantom designed to provide conditions to generate set of "true" independent reference data as requested by TG-186, and mitigating the scarcity of experimental studies on brachytherapy validation. It was used to perform accurate experimental measurements of dose of 125I brachytherapy seeds using LiF dosimeters, with the objective of experimentally validating Monte Carlo (MC) calculations with model-based dose calculation algorithm (MBDCA). In addition, this work intends to evaluate a methodology to convert the experimental values from LiF into dose in the medium. METHODS AND MATERIALS The proposed PMMA physical phantom features cavities to insert a LiF dosimeter and a 125I seed, adjusted in different configurations with variable thickness. Monte Carlo calculations performed with MCNP6.2 code were used to score the absorbed dose in the LiF and the dose conversion parameters. A sensitivity analysis was done to verify the source of possible uncertainties and quantify their impact on the results. RESULTS The proposed phantom and experimental procedure developed in this work provided precise dose data within 5.68% uncertainty (k = 1). The achieved precision made it possible to convert the LiF responses into absorbed dose to medium and to validate the dose conversion factor methodology. CONCLUSIONS The proposed phantom is simple both in design and as in its composition, thus achieving the demanded precision in dose evaluations due to its easy reproducibility of experimental setup. The results derived from the phantom measurements support the dose conversion methodology. The phantom and the experimental procedure developed here can be applied for other materials and radiation sources.
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Affiliation(s)
| | | | | | - Hélio Yoriyaz
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, São Paulo, Brazil
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6
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Kaveckyte V, Jørgensen EB, Kertzscher G, Johansen JG, Tedgren ÅC. Monte Carlo characterization of high atomic number inorganic scintillators for in vivo dosimetry in 192 Ir brachytherapy. Med Phys 2022; 49:4715-4730. [PMID: 35443079 DOI: 10.1002/mp.15674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/01/2022] [Accepted: 04/06/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND There is increased interest in vivo dosimetry for 192 Ir brachytherapy (BT) treatments using high atomic number (Z) inorganic scintillators. Their high light output enables construction of small detectors with negligible stem effect and simple readout electronics. Experimental determination of absorbed-dose energy dependence of detectors relative to water is prevalent, but it can be prone to high detector positioning uncertainties and does not allow for decoupling of absorbed-dose energy dependence from other factors affecting detector response. PURPOSE To investigate which measurement conditions and detector properties could affect their absorbed-dose energy dependence in BT in vivo dosimetry. METHODS We used a general-purpose MC code penelope for the characterization of high-Z inorganic scintillators with the focus on ZnSe (Z¯=32). Two other promising media CsI (Z¯=54) and Al2 O3 (Z¯=11) were included for comparison in selected scenarios. We determined absorbed-dose energy dependence of crystals relative to water under different scatter conditions (calibration phantom 12 × 12 × 30 cm3 , characterization phantoms 20 × 20 × 20 cm3 , 30 × 30 × 30 cm3 , 40 × 40 × 40 cm3 , and patient-like elliptic phantom 40 × 30 × 25 cm3 ). To mimic irradiation conditions during prostate treatments, we evaluated whether the presence of pelvic bones and calcifications affect ZnSe response. ZnSe detector design influence was also investigated. RESULTS In contrast to low-Z organic and medium-Z inorganic scintillators, ZnSe and CsI media have substantially greater absorbed-dose energy dependence relative to water. The response was phantom-size dependent and changed by 11 % between limited- and full-scatter conditions for ZnSe, but not for Al2 O3 . For a given phantom size, a part of the absorbed-dose energy dependence of ZnSe is caused not due to in-phantom scatter but due to source anisotropy. Thus, the absorbed-dose energy dependence of high-Z scintillators is a function of not only the radial distance but also the polar angle. Pelvic bones did not affect ZnSe response, whereas large and intermediate size calcifications reduced it by 9 % and 5 %, respectively, when placed midway between the source and the detector. CONCLUSIONS Unlike currently prevalent low- and medium-Z scintillators, high-Z crystals are sensitive to characterization and in vivo measurement conditions. However, good agreement between MC data for ZnSe in the present study and experimental data for ZnSe:O by Jørgensen et al (2021) suggest that detector signal is proportional to the average absorbed dose to the detector cavity. This enables an easy correction for non-TG43-like scenarios (e.g., patient sizes and calcifications) through MC simulations. Information that should be provided to the clinic by the detector vendors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Vaiva Kaveckyte
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, SE-581 85, Sweden
| | - Erik B Jørgensen
- Department of Clinical Medicine, Aarhus University, Aarhus, DK-8000, Denmark.,Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Gustavo Kertzscher
- Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Jacob G Johansen
- Department of Clinical Medicine, Aarhus University, Aarhus, DK-8000, Denmark.,Department of Oncology, Aarhus University Hospital, Aarhus, DK-8000, Denmark
| | - Åsa Carlsson Tedgren
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, SE-581 85, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, SE-171 76, Sweden.,Department of Oncology-Pathology, Karolinska Institute, Stockholm, SE-171 76, Sweden
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7
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Zhang S, Tang K, Fan H, Li Z, Huang G, Wu K, Fu L. A RADIOLUMINESCENCE STUDY OF DOSE CHARACTERISTICS OF LIF:MG,TI. RADIATION PROTECTION DOSIMETRY 2021; 195:69-74. [PMID: 34341830 DOI: 10.1093/rpd/ncab113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/29/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
A radioluminescence (RL) study of dose characteristics of tissue-equivalent LiF:Mg,Ti was carried out to determine the possible application as a real-time dosemeter. An RL measurements system based on LiF:Mg,Ti coupled with optical fiber was developed, and a blank fiber was set to remove the stem effect generated by the optical fiber due to direct radiation. A slight increase of RL sensitivity with accumulated dose and the afterglow effect due to shallow traps in LiF:Mg,Ti were observed, thus a set of algorithms was adopted to correct measured dose rate. A good linearity of dose-rate response using RL in LiF:Mg,Ti over more than four orders of magnitude (from 0.76 mGy/h to 8.02 Gy/h) was shown, and the deviation of calibrated dose rate is within 20%. Moreover, a satisfactory reproducibility (1.45%) of the measured dose rate after correction was represented. The results indicated that LiF:Mg,Ti might be promising for real-time dose monitoring.
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Affiliation(s)
- Siyuan Zhang
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
| | - Kaiyong Tang
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
- Solid Dosimetric Detector and Method Laboratory, P.O. Box 1044 Ext. 204, Beijing 102205, PR China
| | - Haijun Fan
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
| | - Zhiyuan Li
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
| | - Guangwei Huang
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
| | - Kun Wu
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
| | - Li Fu
- State Key Laboratory of NBC Protection for Civilian, P.O. Box 1044 Ext. 201, Beijing 102205, PR China
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Arzaga-Barajas E, Massillon-JL G. Thermoluminescent relative efficiency of TLD-100 glow peaks after exposure to X-rays of 20 kV–300 kV, 137Cs and 60Co gamma. RADIAT MEAS 2021. [DOI: 10.1016/j.radmeas.2021.106635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Das IJ, Francescon P, Moran JM, Ahnesjö A, Aspradakis MM, Cheng CW, Ding GX, Fenwick JD, Saiful Huq M, Oldham M, Reft CS, Sauer OA. Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non-equilibrium conditions. Med Phys 2021; 48:e886-e921. [PMID: 34101836 DOI: 10.1002/mp.15030] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/06/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022] Open
Abstract
Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion of the primary photon source, and the limited choice of suitable radiation detectors. These challenges greatly influence dosimetric accuracy. Many high-profile radiation incidents have demonstrated a poor understanding of appropriate methodology for small-field dosimetry. These incidents are a cause for concern because the use of small fields in various specialized radiation treatment techniques continues to grow rapidly. Reference and relative dosimetry in small and composite fields are the subject of the International Atomic Energy Agency (IAEA) dosimetry code of practice that has been published as TRS-483 and an AAPM summary publication (IAEA TRS 483; Dosimetry of small static fields used in external beam radiotherapy: An IAEA/AAPM International Code of Practice for reference and relative dose determination, Technical Report Series No. 483; Palmans et al., Med Phys 45(11):e1123, 2018). The charge of AAPM task group 155 (TG-155) is to summarize current knowledge on small-field dosimetry and to provide recommendations of best practices for relative dose determination in small megavoltage photon beams. An overview of the issue of LCPE and the changes in photon beam perturbations with decreasing field size is provided. Recommendations are included on appropriate detector systems and measurement methodologies. Existing published data on dosimetric parameters in small photon fields (e.g., percentage depth dose, tissue phantom ratio/tissue maximum ratio, off-axis ratios, and field output factors) together with the necessary perturbation corrections for various detectors are reviewed. A discussion on errors and an uncertainty analysis in measurements is provided. The design of beam models in treatment planning systems to simulate small fields necessitates special attention on the influence of the primary beam source and collimating devices in the computation of energy fluence and dose. The general requirements for fluence and dose calculation engines suitable for modeling dose in small fields are reviewed. Implementations in commercial treatment planning systems vary widely, and the aims of this report are to provide insight for the medical physicist and guidance to developers of beams models for radiotherapy treatment planning systems.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Paolo Francescon
- Department of Radiation Oncology, Ospedale Di Vicenza, Vicenza, Italy
| | - Jean M Moran
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Anders Ahnesjö
- Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Maria M Aspradakis
- Institute of Radiation Oncology, Cantonal Hospital of Graubünden, Chur, Switzerland
| | - Chee-Wai Cheng
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D Fenwick
- Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh, School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Mark Oldham
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Chester S Reft
- Department of Radiation Oncology, University of Chicago, Chicago, IL, USA
| | - Otto A Sauer
- Department of Radiation Oncology, Klinik fur Strahlentherapie, University of Würzburg, Würzburg, Germany
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Kržanović N, Blideanu V, Ciraj-Bjelac O, Plagnard J, Schoonjans W, Živanović M, Dabin J. Performance testing of dosimeters used in interventional radiology: Results from the VERIDIC project. RADIAT MEAS 2021. [DOI: 10.1016/j.radmeas.2021.106515] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Rosado PH, Salata C, David MG, Mantuano A, Pickler A, Mota CL, de Almeida CE. Determination of the absorbed dose to water for medium-energy x-ray beams using Fricke dosimetry. Med Phys 2020; 47:5802-5809. [PMID: 32964481 DOI: 10.1002/mp.14473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/22/2020] [Accepted: 08/30/2020] [Indexed: 12/25/2022] Open
Abstract
PURPOSE For x-ray beams in the low and medium energy range, reference dosimetry is established in terms of air kerma. Fricke dosimetry has shown great potential in the absolute measurements of the absorbed dose to water for high-energy ranges. Therefore, the main purpose of this work was to compare the absorbed dose to water for medium-energy x-ray beams obtained through Fricke dosimetry with that obtained from the air kerma rate. METHODS To determine the absorbed dose to water using Fricke dosimetry, the polyethylene bags methodology was chosen. Fricke solution was irradiated at four different beam qualities. The absorbed dose to water values obtained using Fricke dosimetry were compared to those obtained using the standard protocol, using the Z-score. RESULTS Values of the Z-score were <2 for all measurements of absorbed dose to water, which means that the values obtained using Fricke dosimetry are equivalent to those obtained using the reference protocol. The combined standard uncertainty for the absorbed dose to water obtained by Fricke dosimetry was lower than that obtained with the ionization chamber. CONCLUSIONS Chemical dosimetry using a standard FeSO4 solution has been demonstrated to be a potential option as a standard for the quantity absorbed dose to water for medium kV x-ray qualities.
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Affiliation(s)
- Paulo Henrique Rosado
- Brazilian National Ionizing Radiation Metrology Laboratory, Radioprotection and Dosimetry Institute (IRD), Rio de Janeiro, Brazil.,Department of Medical and Research Facilities, National Nuclear Energy Authority (CNEN), Rio de Janeiro, Brazil
| | - Camila Salata
- Department of Medical and Research Facilities, National Nuclear Energy Authority (CNEN), Rio de Janeiro, Brazil.,Radiological Sciences Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil
| | - Mariano Gazineu David
- Polytechnic Institute of the Rio de Janeiro State University (IPRJ/UERJ), Rio de Janeiro, Brazil
| | - Andrea Mantuano
- Radiological Sciences Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil
| | - Arissa Pickler
- Radiological Sciences Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil
| | - Carla Lemos Mota
- Radiological Sciences Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil.,Physics Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil
| | - Carlos E de Almeida
- Radiological Sciences Department, Rio de Janeiro State University (UERJ), Rio de Janeiro, Brazil
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12
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Does dose optimisation in digital panoramic radiography affect diagnostic performance? Clin Oral Investig 2020; 25:637-643. [PMID: 32845471 DOI: 10.1007/s00784-020-03535-7] [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: 04/20/2020] [Accepted: 08/17/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To compare the overall diagnostic performance of digital panoramic radiographs obtained with low-dose protocols and to estimate the absorbed dose in the head and neck. MATERIALS AND METHODS Forty-eight panoramic radiographs were obtained from eight imaging phantoms using six exposure protocols of progressively lower tube voltages (kVp) and currents (mA), as follows: (1) 70 kVp and 12.5 mA, (2) 66 kVp and 10 mA, (3) 66 kVp and 8 mA, (4) 66 kVp and 5 mA, (5) 66 kVp and 4 mA and (6) 66 kVp and 3.2 mA. Five oral radiologists independently evaluated the images and reported all detectable radiographic findings. Intra-examiner reproducibility was assessed by re-evaluation of 25% of the images. The data were analysed using the McNemar and weighted Kappa tests. Absorbed doses of the six protocols were obtained from thermoluminescent dosimeters placed inside a Rando phantom and compared using one-way ANOVA with post hoc Tukey (α = 0.05). RESULTS The overall diagnostic performance of panoramic radiographs obtained with low-dose protocols did not differ from that of panoramic radiographs obtained with the highest dose (p > 0.05). Moreover, substantial agreement was observed between all protocols. Protocol 1 resulted in the highest absorbed dose and protocols 4, 5 and 6 in the lowest absorbed doses, with the difference being significant (p ≤ 0.05). CONCLUSION Although digital panoramic radiography is considered a relatively low-dose examination, the radiation dose can be further reduced without negatively affecting its overall diagnostic performance. CLINICAL RELEVANCE Considering the risks associated with X-rays, digital panoramic radiographs can be obtained at even lower exposure levels.
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EGSnrc-based depth-dependent photon energy response and phantom scatter corrections for low-energy brachytherapy sources. Radiol Phys Technol 2020; 13:256-267. [PMID: 32816228 DOI: 10.1007/s12194-020-00578-z] [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: 01/20/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 10/23/2022]
Abstract
In the present study, beam quality correction, [Formula: see text], and phantom scatter correction, kphan(r), for low-energy brachytherapy sources, 131Cs, 125I, and 103Pd, are calculated using the Monte Carlo-based EGSnrc code system as a function of the distance along the transverse axis of the source. The solid-state detectors investigated are diamond, LiF, Li2B4O7, Al2O3, and radiochromic films, such as HS, EBT, EBT2, EBT3, RTQA, XRT, and XRQA. The solid phantoms investigated are polystyrene, PMMA, virtual water, solid water, plastic water (LR), A150, RW1, RW3, and WE210. For a given detector and brachytherapy source, [Formula: see text] is independent of distance in the water phantom. Meanwhile, for a given detector, kphan(r) depends on the distance from the source for the investigated solid phantoms. Moreover, the kphan(r) values do not change with the detector type for sources 131Cs, 125I, and 103Pd at all distances. The LR and A150 phantoms are water equivalent for the investigated distances of 1-5 cm. The phantoms including solid water, virtual water, and WE210 are not water-equivalent for distances beyond 1 cm. Furthermore, PMMA, polystyrene, RW1, and RW3 are not water equivalent.
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14
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Shang D, Gu W, Landers A, Woods K, Yu V, Neph R, Tenn S, Sheng K. Technical Note: Robust individual thermoluminescence dosimeter tracking using optical fingerprinting. Med Phys 2020; 47:267-271. [PMID: 31677160 PMCID: PMC9829522 DOI: 10.1002/mp.13895] [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: 04/03/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 01/12/2023] Open
Abstract
PURPOSE The thermoluminescence dosimeter (TLD) has desirable features including low cost, reusability, small size, and relatively low energy dependence. However, the commonly available poly-crystal TLDs (e.g., TLD-100) exhibit high interdetector variability that requires individual calibration for high detection accuracy. To improve individual TLD tracking robustness, we developed an optical fingerprinting method to identify the TLD-100 chips. METHODS Seven hundred and fifty-two images were initially captured using a digital microscope camera to build a feature library for both facets of 376 TLD-100 chips. A median intensity thresholding method was used to segment images into foreground and background. The affine transformation was used to register the segmented images to the same position. The fingerprint of each image was calculated from its registered image. All fingerprints were then recorded in an Elasticsearch® search database. The TLD fingerprint match was tested three times when the library was established and repeated once 20 months later. All chips were irradiated at 0, 1, 4, and 8 Gy on a calibrated clinical MV linac to establish the individual calibration curve. RESULTS The true positive rate of identifying TLDs based on their optical fingerprints was 100% at initialization of the inventory. After 20 months and multiple deployments for characterization, calibration, and dose measurement, the true positive match rate dropped to 99% with zero false-positive matches. The TLDs exhibited high self-consistency in the dose-response test with R2 between 0.988 and 1 with linear regression. CONCLUSIONS The TLD-100 chips surface textures are unique and sufficient to support accurate identification based on the optical fingerprinting. This method provides inexpensive and robust management of the TLDs for individual calibration and dosimetry.
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Affiliation(s)
- Daili Shang
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Wenbo Gu
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Angelia Landers
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Kaley Woods
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Victoria Yu
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Ryan Neph
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Stephen Tenn
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - Ke Sheng
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
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15
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Kaveckyte V, Persson L, Malusek A, Benmakhlouf H, Alm Carlsson G, Carlsson Tedgren Å. Investigation of a synthetic diamond detector response in kilovoltage photon beams. Med Phys 2019; 47:1268-1279. [PMID: 31880809 DOI: 10.1002/mp.13988] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/04/2019] [Accepted: 12/01/2019] [Indexed: 12/28/2022] Open
Abstract
PURPOSE An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed-dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low-energy brachytherapy (BT) beams, we determined their intrinsic and absorbed-dose energy responses in 25-250 kV beams relative to a 60 Co beam, which is usually the reference beam quality for detector calibration in radiotherapy. MATERIAL AND METHODS Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air-kerma free in air in six x-ray beam qualities (from 25 to 250 kV) and in terms of absorbed dose to water in a 60 Co beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed-dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 125 I BT seed (effective photon energy of 28 keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra-cameral components on the absorbed-dose energy response of a microDiamond detector was studied using MC simulations. RESULTS The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50 kV beams compared to the 60 Co beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG-43 formalism-based calculations for the 125 I seed. MC study of microDiamond detector design features provided a possible explanation for inter-detector response variation at low-energy photon beams by differences in the effective thickness of the active volume. CONCLUSIONS MicroDiamond detectors had a non-negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed-dose energy response relative to water at low-energy photon beams. Silicon diodes, in contrast, had an absorbed-dose energy dependence on photon energy that varied by a factor of 6, whereas the intrinsic energy dependence on beam quality was within 10%. It is important to decouple these two responses for a full characterization of detector energy response especially when the user and reference beam qualities differ significantly, and MC alone is not enough.
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Affiliation(s)
- Vaiva Kaveckyte
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Linda Persson
- Swedish Radiation Safety Authority, SE-171 16, Stockholm, Sweden
| | - Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
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Kry SF, Alvarez P, Cygler JE, DeWerd LA, Howell RM, Meeks S, O'Daniel J, Reft C, Sawakuchi G, Yukihara EG, Mihailidis D. AAPM TG 191: Clinical use of luminescent dosimeters: TLDs and OSLDs. Med Phys 2019; 47:e19-e51. [DOI: 10.1002/mp.13839] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Stephen F. Kry
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | - Paola Alvarez
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | | | | | | | - Sanford Meeks
- University of Florida Health Cancer Center Orlando FL USA
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17
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Parisi A, Dabin J, Schoonjans W, Van Hoey O, Mégret P, Vanhavere F. Photon energy response of LiF:Mg,Ti (MTS) and LiF:Mg,Cu,P (MCP) thermoluminescent detectors: Experimental measurements and microdosimetric modeling. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.05.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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End-to-end test and MOSFET in vivo skin dosimetry for 192Ir high-dose-rate brachytherapy of chronic psoriasis. J Contemp Brachytherapy 2019; 11:384-391. [PMID: 31523241 PMCID: PMC6737575 DOI: 10.5114/jcb.2019.86973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/19/2019] [Indexed: 01/17/2023] Open
Abstract
Purpose This study was performed using end-to-end testing and real-time in vivo skin dose measurements, using metal oxide semiconductor field effect transistor (MOSFET) dosimeters on our first chronic psoriasis patient treated with iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy (BT). Material and methods Treatment delivery was planned with the prescription dose of 1.8 Gy to a 3 mm depth for 12 fractions, using our custom-fabricated surface mold and Varian soft catheters. The optimal technique to provide an adequate and acceptable skin dose as well as its feasibility were evaluated by an end-to-end exercise using a perspex finger phantom. The accuracy and reliability of MOSFET dose measurement was explored with a thermoluminescence dosimetry (TLD) before being used in vivo to monitor skin doses during treatment delivery for each BT fraction. Results Using custom-made surface mold (2.4 mm Med-Tec thermoplastic mask for hand fixation and 5 applicators attached to each finger for dose delivery), the optimal skin dose on the phantom was obtained without the need for additional bolus to increase thickness of applicator. We acquired mean skin doses at different skin depths from various dose-volume parameters of no-bolus and 3 mm-added bolus plans. They were 125% and 110% (1 mm), 120% and 108% (2 mm), and 114% and 106% (3 mm), respectively. There was excellent agreement between MOSFET and TLD for 192Ir HDR-BT within ±3% (mean 2.65%, SD = 2.05%). With no energy correction, MOSFET overestimated the Acuros BV surface doses by up to 7% in the phantom study and in the clinical case. Conclusions We demonstrated achievable HDR-BT for our first case of nail bed psoriasis. The end-to-end exercise was an efficient methodology to evaluate new feasibility for this technique. Real-time dose monitoring using MOSFET was an effective and reliable tool to ensure treatment quality and patient safety.
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Pagulayan C, Heng SM, Corde S. Dosimetric validation of the Theragenics AgX-100® I-125 seed for ROPES eye plaque brachytherapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:599-609. [PMID: 31087233 DOI: 10.1007/s13246-019-00761-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 05/04/2019] [Indexed: 10/26/2022]
Abstract
With the discontinued distribution of the I-125 Oncura Onco seed (model 6711), the Theragenics AgX100® I-125 seeds were considered as a suitable alternative for eye plaque brachytherapy as their physical properties matched the requirements for use with the ROPES eye plaques. The purpose of this study aims at validating the dosimetry of the AgX-100 loaded ROPES plaques (11 mm diameter, 15 mm diameter with flange, 15 mm diameter with notch, 18 mm diameter) and assess the differences with the discontinued I-125 6711 model. To independently verify the plaque dosimetry, the brachytherapy module of RADCALC® version 6.2.3.6 was commissioned for the new AgX-100 I-125 seed using the published AAPM TG43 data from the literature. Experimental dosimetry verification was performed using EBT3 Gafchromic™ film and TLD-100 micro-cubes in a specially designed Solid Water® phantom. Both RADCALC® and film confirmed the dosimetry calculated by Plaque Simulator (PS) version 6.4.6 The dose calculated by PS agrees with RADCALC® to within 2% for depths of 1-15 mm for the 4 available ROPES plaques. The dosimetric measurements agreed with the calculations of PS for clinically relevant depths (4 mm to 6 mm) within the evaluated uncertainties of 4.7% and 7.2% for EBT3 film and TLDs respectively. The AgX-100 I-125 seed was a suitable replacement for the 6711 I-125 seed. Due to the introduction of the stainless-steel backscatter factor in PS v6.4.6, the department has decided to report both the homogenous dose and heterogeneity corrected dose for each eye plaque patient.
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Affiliation(s)
- Claire Pagulayan
- Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, Sydney, Australia.
| | - Soo Min Heng
- Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, Sydney, Australia
| | - Stephanie Corde
- Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, Sydney, Australia
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20
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Chen LY, Hsu CH, Hsu FY. Development and efficacy testing of a new optically stimulated luminescence ring dosimeter and algorithm. RADIAT MEAS 2019. [DOI: 10.1016/j.radmeas.2019.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Hauri P, Schneider U. Whole-body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy. J Appl Clin Med Phys 2019; 20:56-70. [PMID: 30791198 PMCID: PMC6414138 DOI: 10.1002/acm2.12543] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/08/2018] [Accepted: 12/31/2018] [Indexed: 12/24/2022] Open
Abstract
PURPOSE This study investigates the difference in whole-body dose equivalent between 6 and 15 MV image-guided radiotherapy (IGRT) for the treatment of a rhabdomyosarcoma in the prostate. METHODS A previously developed model for stray radiation of the primary beam was improved and used to calculate the photon dose and photon energy in the out-of-field region for a radiotherapy patient. The dose calculated by the treatment planning system was fused with the model-calculated out-of-field dose, resulting in a whole-body photon dose distribution. The peripheral neutron dose equivalent was calculated using an analytical model from the literature. A daily cone beam CT dose was added to the neutron and photon dose equivalents. The calculated 3D dose distributions were compared to independent measurements conducted with thermoluminescence dosimeters and an anthropomorphic phantom. The dose contributions from the IGRT treatments of three different techniques applied with two nominal X-ray energies were compared using dose equivalent volume histograms (DEVHs). RESULTS The calculated and measured out-of-field whole-body dose equivalents for the IGRT treatments agreed within (9 ± 10) % (mean and type A SD). The neutron dose equivalent was a minor contribution to the total out-of-field dose up to 50 cm from the isocenter. Further from the isocenter, head leakage was dominating inside the patient body, whereas the neutron dose equivalent contribution was important close to the surface. There were small differences between the whole-body DEVHs of the 6 and 15 MV treatments applied with the same technique, although the single scatter contributions showed large differences. Independent of the beam energy, the out-of-field dose of the volumetric-modulated arc therapy (VMAT) treatment was significantly lower than the dynamic intensity-modulated radiation therapy (IMRT) treatment. CONCLUSION The calculated whole-body dose helped to understand the importance of the dose contributions in different areas of the patient. Regarding radiation protection of the patient for IGRT treatments, the choice of beam energy is not important, whereas the treatment technique has a large influence on the out-of-field dose. If the patient is treated with intensity-modulated beams, VMAT should be used instead of dynamic IMRT in terms of radiation protection of the patient. In general, the developed models for photon and neutron dose equivalent calculation can be used for any patient geometry, tumor location, and linear accelerator.
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Affiliation(s)
- Pascal Hauri
- Department of PhysicsUniversity of ZurichZurichSwitzerland
- Radiotherapy HirslandenHirslanden Medical CenterAarauSwitzerland
| | - Uwe Schneider
- Department of PhysicsUniversity of ZurichZurichSwitzerland
- Radiotherapy HirslandenHirslanden Medical CenterAarauSwitzerland
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22
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Hashimoto S, Nakajima Y, Kadoya N, Abe K, Karasawa K. Energy dependence of a radiophotoluminescent glass dosimeter for HDR 192 Ir brachytherapy source. Med Phys 2018; 46:964-972. [PMID: 30506576 DOI: 10.1002/mp.13319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 11/06/2018] [Accepted: 11/22/2018] [Indexed: 12/12/2022] Open
Abstract
PURPOSE We determined correction factors for absorbed dose energy dependence and intrinsic energy dependence for measurements of absorbed dose to water around an 192 Ir source using a radiophotoluminescent glass dosimeter (RPLD) calibrated with a 4-MV photon beam. METHODS The ratio of the absorbed dose to the water and the average absorbed dose to RPLD for the 192 Ir beam relative to the same ratio in a 4 MV photon beam defines the absorbed dose energy dependence and was determined at distances of 2-10 cm (at intervals of 1 cm) from the 192 Ir source in a water phantom using the egs_chamber user code. The RPLD was calibrated to measure absorbed dose to water, Dw , in a 4 MV photon beam using an ionization chamber, which was also used to measure absorbed dose to water, Dw , in a water phantom using the 192 Ir source. The detector response radiophotoluminescence (RPL signal per average absorbed dose in the detector) in the 192 Ir beam relative to that in the 4 MV photon beam (the relative intrinsic efficiency) was determined experimentally. Finally, the beam quality correction factor was obtained as the quotient between the absorbed dose energy dependence and the relative intrinsic efficiency and corrects for the difference between the beam quality Q0 used at calibration and the beam quality Q used in the measurements. RESULTS The relative dose ratio of the average absorbed dose to water relative to RPLD ranged from 0.930 to 0.746, and the beam quality correction factor ranged from 0.999 to 0.794 for distances of 2-10 cm from the 192 Ir source. The relative detector response to an 192 Ir source and a 4-MV photon beam was 0.930, and it did not vary significantly with distance. CONCLUSIONS These results demonstrate that corrections for absorbed dose energy dependence and intrinsic energy dependence are required when using an RPLD to measure with sources different from the reference source providing the primary calibration.
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Affiliation(s)
- Shimpei Hashimoto
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo, 113-8677, Japan
| | - Yujiro Nakajima
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo, 113-8677, Japan.,Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Noriyuki Kadoya
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Kota Abe
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Katsuyuki Karasawa
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo, 113-8677, Japan
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23
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Silva EH, Struelens L, Covens P, Ueno S, Koguchi Y, Vanhavere F, Buls N. OPTIMIZATION OF A RADIOPHOTOLUMINESCENT GLASS DOSEMETER FOR OCCUPATIONAL EYE LENS DOSIMETRY IN INTERVENTIONAL RADIOLOGY/CARDIOLOGY. RADIATION PROTECTION DOSIMETRY 2018; 182:177-183. [PMID: 29584902 DOI: 10.1093/rpd/ncy046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/02/2018] [Indexed: 06/08/2023]
Abstract
Hospital based workers that perform interventional radiology are at risk of reaching the eye lens dose limit of 20 mSv/y. These workers are exposed to the radiation scattered by the patient, which creates a complex field, with low radiation energy reaching the eyes of the medical staff from wide angles. Therefore, the dosemeter used in the assessment of the eye lens dose of interventional radiologists needs to respond accurately in such conditions. In this study, the angular response of a commercially available radiophotoluminescent glass dosemeter, GD-352M, was optimized via Monte Carlo simulations, aiming at its use as eye lens dosemeter in interventional radiology. The improved dosemeter was manufactured and then characterized in terms of Hp(3), the quantity recommended for eye lens dosimetry. Its response was compared to the IEC 62387:2012 requirements for Hp(3) and to requirements proposed specifically for eye lens dosemeters used in interventional radiology. The improved dosemeter meets the IEC 62387:2012 requirements for energy and angular response for Hp(3) and also shows good agreement with the more strict requisites proposed for eye lens dosemeters to be used in interventional radiology.
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Affiliation(s)
- Edilaine H Silva
- Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol, Belgium
- Universitair Ziekenhuis, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
- CAPES Foundation, Ministry of Education of Brazil, Brasília, Brazil
| | - Lara Struelens
- Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol, Belgium
| | - Peter Covens
- Department of Radiation Protection, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Satoshi Ueno
- Oarai Reseach Center, Chiyoda Technol Corporation, 3681 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki, Japan
| | - Yasuhiro Koguchi
- Oarai Reseach Center, Chiyoda Technol Corporation, 3681 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki, Japan
| | - Filip Vanhavere
- Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol, Belgium
| | - Nico Buls
- Universitair Ziekenhuis, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
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Hammer CG, Rosen BS, Fagerstrom JM, Culberson WS, DeWerd LA. Experimental investigation of GafChromic®
EBT3 intrinsic energy dependence with kilovoltage x rays, 137
Cs, and 60
Co. Med Phys 2017; 45:448-459. [DOI: 10.1002/mp.12682] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/13/2017] [Accepted: 11/07/2017] [Indexed: 11/10/2022] Open
Affiliation(s)
- Cliff G. Hammer
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Benjamin Saul Rosen
- Department of Radiation Oncology; University of Michigan; Ann Arbor MI 48109 USA
| | | | - Wesley S. Culberson
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Larry A. DeWerd
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
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Poirier Y, Kuznetsova S, Villarreal-Barajas JE. Characterization of nanoDot optically stimulated luminescence detectors and high-sensitivity MCP-N thermoluminescent detectors in the 40-300 kVp energy range. Med Phys 2017; 45:402-413. [DOI: 10.1002/mp.12691] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 10/10/2017] [Accepted: 10/27/2017] [Indexed: 01/04/2023] Open
Affiliation(s)
- Yannick Poirier
- Department of Radiation Oncology; University of Maryland School of Medicine; Baltimore MD 21201 USA
| | - Svetlana Kuznetsova
- Department of Physics and Astronomy; University of Calgary; Calgary AB T2N 1N4 Canada
- Department of Oncology; University of Calgary; Calgary AB T2N 1N4 Canada
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Kaveckyte V, Malusek A, Benmakhlouf H, Alm Carlsson G, Carlsson Tedgren Å. Suitability of microDiamond detectors for the determination of absorbed dose to water around high-dose-rate 192 Ir brachytherapy sources. Med Phys 2017; 45:429-437. [PMID: 29171060 DOI: 10.1002/mp.12694] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 10/26/2017] [Accepted: 10/29/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Experimental dosimetry of high-dose-rate (HDR) 192 Ir brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high sensitivity, direct readout, and nearly water-equivalent active volume. The purpose of this study was to evaluate the suitability of microDiamond detectors for the determination of absorbed dose to water around HDR 192 Ir BT sources. Three microDiamond detectors were used, allowing for the comparison of their properties. METHODS In-phantom measurements were performed using microSelectron and VariSource iX HDR 192 Ir BT treatment units. Their treatment planning systems (TPSs), Oncentra (v. 4.3) and BrachyVision (v. 13.6), respectively, were used to create irradiation plans for a cubic PMMA phantom with the microDiamond positioned at one of three source-to-detector distances (SDDs) (1.5, 2.5, and 5.5 cm) at a time. The source was stepped in increments of 0.5 cm over a total length of 6 cm to yield absorbed dose of 2 Gy at the nominal reference-point of the detector. Detectors were calibrated in 60 Co beam in terms of absorbed dose to water, and Monte Carlo (MC) calculated beam quality correction factors were applied to account for absorbed-dose energy dependence. Phantom correction factors were applied to account for differences in dimensions between the measurement phantom and a water phantom used for absorbed dose calculations made with a TPS. The same measurements were made with all three of the detectors. Additionally, dose-rate dependence and stability of the detectors were evaluated in 60 Co beam. RESULTS The percentage differences between experimentally determined and TPS-calculated absorbed doses to water were from -1.3% to +2.9%. The values agreed to within experimental uncertainties, which were from 1.9% to 4.3% (k = 2) depending on the detector, SDD and treatment delivery unit. No dose-rate or intrinsic energy dependence corrections were applied. All microDiamonds were comparable in terms of preirradiation dose, stability of the readings and energy response, and showed a good agreement. CONCLUSIONS The results indicate that the microDiamond is potentially suitable for the determination of absorbed dose to water around HDR 192 Ir BT sources and may be used for independent verification of TPS's calculations, as well as for QA measurements of HDR 192 Ir BT treatment delivery units at clinical sites.
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Affiliation(s)
- Vaiva Kaveckyte
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
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Hauri P, Schneider U. Whole-body dose and energy measurements in radiotherapy by a combination of LiF:Mg,Cu,P and LiF:Mg,Ti. Z Med Phys 2017; 28:96-109. [PMID: 28807441 DOI: 10.1016/j.zemedi.2017.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/07/2017] [Accepted: 07/09/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs. We present a dosimeter which automatically corrects for the energy variation of the measured photons by combining LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) chips. METHODS The response with radiation energy of TLD100 and TLD100H compared to 60Co was taken from the literature. For the measurement, a TLD100H was placed on top of a TLD100 chip. The dose ratio between the TLD100 and TLD100H, combined with the ratio of the response curves was used to determine the mean energy. With the energy, the individual correction factors for TLD100 and TLD100H could be found. The accuracy in determining the in- and out-of-field dose for a nominal beam energy of 6MV using the double-TLD unit was evaluated by an end-to-end measurement. Furthermore, published Monte Carlo (M.C.) simulations of the mean photon energy for brachytherapy sources, stray radiation of a treatment machine and cone beam CT (CBCT) were compared to the measured mean energies. Finally, the photon energy distribution in an Alderson phantom was measured for different treatment techniques applied with a linear accelerator. Additionally, a treatment plan was measured with a cobalt machine combined with an MRI. RESULTS For external radiotherapy, the presented double-TLD unit showed a relative type A uncertainty in doses of -1%±2% at the two standard deviation level compared to an ionization chamber. The type A uncertainty in dose was in agreement with the theoretically calculated type B uncertainty. The measured energies for brachytherapy sources, stray radiation of a treatment machine and CBCT imaging were in agreement with M.C. simulations. A shift in energy with increasing distance to the isocenter was noticed for the various treatment plans measured with the Alderson phantom. The calculated type B uncertainties in energy were in line with the experimentally evaluated type A uncertainties. CONCLUSION The double-TLD unit is able to predict the photon energy of scatter radiation in external radiotherapy, X-ray imagine and brachytherapy sources. For external radiotherapy, the individual energy correction factors enabled a more accurate dose determination compared to conventional TLD measurements.
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Affiliation(s)
- Pascal Hauri
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland.
| | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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Rivard MJ, Ballester F, Butler WM, DeWerd LA, Ibbott GS, Meigooni AS, Melhus CS, Mitch MG, Nath R, Papagiannis P. Supplement 2 for the 2004 update of the AAPM Task Group No. 43 Report: Joint recommendations by the AAPM and GEC-ESTRO. Med Phys 2017. [DOI: 10.1002/mp.12430] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Mark J. Rivard
- Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
| | - Facundo Ballester
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valéncia; Bujassot 46100 Spain
| | - Wayne M. Butler
- Schiffler Cancer Center; Wheeling Hospital; Wheeling WV 26003 USA
| | - Larry A. DeWerd
- Accredited Dosimetry and Calibration Laboratory; University of Wisconsin; Madison WI 53706 USA
| | - Geoffrey S. Ibbott
- Department of Radiation Physics; M.D. Anderson Cancer Center; Houston TX 77030 USA
| | - Ali S. Meigooni
- Comprehensive Cancer Centers of Nevada; Las Vegas NV 89169 USA
| | - Christopher S. Melhus
- Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
| | - Michael G. Mitch
- Radiation Physics Division; National Institute of Standards and Technology; Gaithersburg MD 20899 USA
| | - Ravinder Nath
- Department of Therapeutic Radiology; Yale University School of Medicine; New Haven CT 06510 USA
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Hauri P, Hälg RA, Schneider U. Technical note: No increase in effective dose from half compared to full rotation pelvis cone beam CT. J Appl Clin Med Phys 2017; 18:364-368. [PMID: 28766828 PMCID: PMC5875828 DOI: 10.1002/acm2.12150] [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] [Received: 05/03/2017] [Revised: 06/13/2017] [Accepted: 06/28/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To image the abdomen of a patient with a gantry mounted imaging system of a linear accelerator, different cone beam computed tomography (CBCT) protocols are available. The whole-body dose of a full rotation abdomen CBCT and a half rotation CBCT was compared. In our clinic, both CBCT protocols are used in daily routine work. METHODS With an adult anthropomorphic Alderson phantom, the whole-body dose per CBCT scan was measured with thermoluminescence dosimeters. The half rotation CBCT was applied such that the gantry mounted X-ray source rotated around the right side of the phantom. The 183 measurement locations covered all ICRP recommended critical organs (except the gonads). The effective dose was calculated with the mean organ dose and the corresponding tissue weighting factors. A point-by-point dose comparison of both protocols was conducted. RESULTS The effective dose was 5.4 mSv ±5% and 5.0 mSv ±5% (estimated type B 1σ) for the full and the half rotation CBCT respectively. There was no significant difference (α = 0.05) in the effective dose within the precision of the measurement (1σ = 5%). The half rotation CBCT displayed an inhomogeneous dose distribution in a transversal phantom slice in contrast with the full rotation CBCT. In the imaging region, the mean dose was (20.5 ± 3.4) mGy and (19.2 ± 7.4) mGy (measured type A 1σ) for the full and the half rotation CBCT respectively. CONCLUSION The half compared to the full rotation CBCT displays a smaller field-of-view in a transversal slice and no significant difference in the effective dose. Hence, the full rotation CBCT is favorable compared to the half rotation CBCT. However, by using the half rotation protocol, critical volumes in the patient can be spared compared to the full rotation protocol.
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Affiliation(s)
- Pascal Hauri
- Department of Physics, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Roger A Hälg
- Department of Physics, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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Pappas EP, Zoros E, Moutsatsos A, Peppa V, Zourari K, Karaiskos P, Papagiannis P. On the experimental validation of model-based dose calculation algorithms for192Ir HDR brachytherapy treatment planning. Phys Med Biol 2017; 62:4160-4182. [DOI: 10.1088/1361-6560/aa6a01] [Citation(s) in RCA: 14] [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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Hauri P, Hälg RA, Schneider U. Technical Note: Comparison of peripheral patient dose from MR-guided 60 Co therapy and 6 MV linear accelerator IGRT. Med Phys 2017; 44:3788-3793. [PMID: 28437010 DOI: 10.1002/mp.12293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose of this study was to quantify the difference in out-of-field dose to the patient between the image guided radiation therapy (IGRT) treatment applied with a linear accelerator with cone beam CT (CBCT) equipment and a Cobalt machine combined with an MRI. METHODS The treatment of a rhabdomyosarcoma in the prostate was planned and irradiated using different modalities and radiation therapy machines. The whole-body dose was measured for a 3D-conformal radiation therapy (3DCRT), an intensity-modulated radiation therapy (IMRT), and a volumetric-modulated arc therapy plan applied with a conventional linear accelerator operated at 6 MV beam energy. Additionally, the dose of an IMRT plan applied with a 60 Co machine combined with an MRI was measured. Furthermore, the dose of one CBCT scan using the linear accelerator's on-board imaging system was determined. The 3D dose measurements were performed in an anthropomorphic phantom containing 168 slots for thermoluminescence dosimeters (TLDs). A combination of LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) was used to accurately determine the in- and out-of-field dose. The plans were rescaled to different fractionation schemes (2 Gy, 3 Gy, and 5 Gy fraction dose) and the dose of one CBCT scan was additionally added to the treatment dose per fraction applied with the linear accelerator. The resulting absorbed doses per fraction of the two machines were compared. RESULTS In the target region, all measured treatment plans presented the same magnitude of dose, while the CBCT dose was a factor of 100 smaller. Close to the planned target volume (PTV), the dose from the 60 Co machine was a factor of two higher compared with the 3DCRT + CBCT dose. Up to 45 cm from the PTV, the treatment applied with the 60 Co-sources showed an increased out-of-field dose compared to the linear accelerator + CBCT IGRT treatments. Further away from the PTV in the region where leakage from the gantry head is dominating, the out-of-field dose of the Cobalt machine was smaller compared to the linear accelerator + CBCT. CONCLUSION The peripheral dose of the 60 Co machine combined with an MRI is larger up to 45 cm from the PTV and further away, it is lower than the dose from a linear accelerator + CBCT treatment. The presented fractionation schemes had a marginal impact on the results.
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Affiliation(s)
- Pascal Hauri
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Roger A Hälg
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Uwe Schneider
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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De Saint-Hubert M, Verellen D, Poels K, Crijns W, Magliona F, Depuydt T, Vanhavere F, Struelens L. Out-of-field doses from pediatric craniospinal irradiations using 3D-CRT, IMRT, helical tomotherapy and electron-based therapy. Phys Med Biol 2017; 62:5293-5311. [PMID: 28398210 DOI: 10.1088/1361-6560/aa6c9e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Medulloblastoma treatment involves irradiation of the entire central nervous system, i.e. craniospinal irradiation (CSI). This is associated with the significant exposure of large volumes of healthy tissue and there is growing concern regarding treatment-associated side effects. The current study compares out-of-field organ doses in children receiving CSI through 3D-conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), helical tomotherapy (HT) and an electron-based technique, and includes radiation doses resulting from imaging performed during treatment. An extensive phantom study is performed, using an anthropomorphic phantom corresponding to a five year old child, in which organ absorbed doses are measured using thermoluminescent detectors. Additionally, the study evaluates and explores tools for calculating out-of-field patient doses using the treatment planning system (TPS) and analytical models. In our study, 3D-CRT resulted in very high doses to a limited number of organs, while it was able to spare organs such as the lungs and breast when compared to IMRT and HT. Both IMRT and HT spread the dose over more organs and were able to spare the heart, thyroid, bladder, uterus and testes when compared to 3D-CRT. The electron-based technique considerably decreased the out-of-field doses in deep-seated organs but could not avoid nearby out-of-field organs such as the lungs, ribs, adrenals, kidneys and uterus. The daily imaging dose is small compared to the treatment dose burden. The TPS error for out-of-field doses was most pronounced for organs further away from the target; nevertheless, no systematic underestimation was observed for any of the studied TPS systems. Finally, analytical modeling was most optimal for 3D-CRT although the number of organs that could be modeled was limited. To conclude, none of the techniques studied was capable of sparing all organs from out-of-field doses. Nevertheless, the electron-based technique showed the most promise for out-of-field organ dose reduction during CSI when compared to photon techniques.
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Vũ Bezin J, Allodji RS, Mège JP, Beldjoudi G, Saunier F, Chavaudra J, Deutsch E, de Vathaire F, Bernier V, Carrie C, Lefkopoulos D, Diallo I. A review of uncertainties in radiotherapy dose reconstruction and their impacts on dose-response relationships. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2017; 37:R1-R18. [PMID: 28118156 DOI: 10.1088/1361-6498/aa575d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Proper understanding of the risk of radiation-induced late effects for patients receiving external photon beam radiotherapy requires the determination of reliable dose-response relationships. Although significant efforts have been devoted to improving dose estimates for the study of late effects, the most often questioned explanatory variable is still the dose. In this work, based on a literature review, we provide an in-depth description of the radiotherapy dose reconstruction process for the study of late effects. In particular, we focus on the identification of the main sources of dose uncertainty involved in this process and summarise their impacts on the dose-response relationship for radiotherapy late effects. We provide a number of recommendations for making progress in estimating the uncertainties in current studies of radiotherapy late effects and reducing these uncertainties in future studies.
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Affiliation(s)
- Jérémi Vũ Bezin
- Inserm, Radiation Epidemiology Team, CESP-U1018, F-94807, Villejuif, France. Gustave Roussy, Villejuif, F-94805, France. Paris-Sud University, Orsay, F-91400, France
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Experimental determination of the photon-energy dependent dose-to-water response of TLD600 and TLD700 (LiF:Mg,Ti) thermoluminescence detectors. Z Med Phys 2017; 27:13-20. [DOI: 10.1016/j.zemedi.2016.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 02/15/2016] [Accepted: 02/16/2016] [Indexed: 11/20/2022]
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35
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Branco ISL, Antunes PCG, Fonseca GP, Yoriyaz H. Monte Carlo studies on water and LiF cavity properties for dose-reporting quantities when using x-ray and brachytherapy sources. Phys Med Biol 2016; 61:8890-8907. [DOI: 10.1088/1361-6560/61/24/8890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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36
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Cabrera-Santiago A, Massillon-Jl G. Track-average LET of secondary electrons generated in LiF:Mg,Ti and liquid water by 20-300 kV x-ray, 137Cs and 60Co beams. Phys Med Biol 2016; 61:7919-7933. [PMID: 27779122 DOI: 10.1088/0031-9155/61/22/7919] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrons generated in matter by photons could be a fundamental basis for an adequate analysis of radiation effects and damage. We have studied separately the 'primary electrons' generated directly by photons from the 'secondary electrons' (SE) produced by electron-electron interactions. In this work, track-average linear energy transfer, [Formula: see text], of SE in LiF:Mg,Ti and liquid water produced by twelve photon energy beams from 20 kV x-ray to 60Co gamma rays have been investigated using the EGSnrc Monte Carlo Code. The exposure of LiF:Mg,Ti in different phantom materials has been considered. Depending on the photon energy, SE represent 40%-90% of the total electron fluence (TEF) between 1 keV and 10 keV, being higher when the photon energy increases. Independent of the medium, [Formula: see text] versus mean photon energy displays a local minimum at around 40 keV, followed by a local maximum at ~80 keV-100 keV. The [Formula: see text] of SE generated by the x-ray beams are of order of 11 keV µm-1 to 19 keV µm-1 in LiF:Mg,Ti and 5 keV µm-1 to 9 keV µm-1 in liquid water which represent 3-5 times those produced by 60Co gamma rays in both media. These values were considerably greater than those of TEF, by factors of 3-8. Furthermore, [Formula: see text] of SE generated in liquid water by 20 kV-200 kV x-rays are similar to those of 76 MeV-120 MeV 3He ions. Contrary to the TEF, where [Formula: see text] were independent of the phantom material, at low photon energies [Formula: see text] of SE was found to be sensitive to the surrounding medium showing higher values within the phantom than in air. This result, which agrees with published experimental results, implies the importance of the SE ionization density for an understanding of dosimeter response induced by photon beams.
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Affiliation(s)
- A Cabrera-Santiago
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan, Mexico City, Mexico
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37
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Del Sol Fernández S, García-Salcedo R, Mendoza JG, Sánchez-Guzmán D, Rodríguez GR, Gaona E, Montalvo TR. Thermoluminescent characteristics of LiF:Mg, Cu, P and CaSO4:Dy for low dose measurement. Appl Radiat Isot 2016; 111:50-5. [DOI: 10.1016/j.apradiso.2016.02.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 02/18/2016] [Accepted: 02/19/2016] [Indexed: 11/24/2022]
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Freesmeyer M, Winkens T, Opfermann T, Kühnel C. Radiation exposure of the investigator's hand during fusion imaging of the thyroid with 99mTcO4-free-hand SPECT and ultrasound. RADIATION PROTECTION DOSIMETRY 2016; 168:531-536. [PMID: 26231559 DOI: 10.1093/rpd/ncv375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/08/2015] [Indexed: 06/04/2023]
Abstract
The objective of this study was to assess the radiation exposure of the investigators' hand during free-hand single photon emission tomography/ultrasound ((99m)TcO4-fhSPECT/US) of the thyroid. Conventional dosimetry by rings with thermoluminescent detectors (TLDs) was performed in 32 patients (Group A), followed by TLD-chipstrate dosimetry in further 20 patients (Group B). In both the groups, the ambient dose rate was measured by dose rate meter (DRM). The applied activity was in the range of 60-80 MBq (99m)TcO4. In Group A, the exposure per investigation was 7.53 µSv (calculated average) by ring dosimetry and 9.02±5.64 µSv by DRM; in Group B, 10.93 and 9.51 ± 1.76 µSv, respectively. Based on estimated 1224 yearly thyroid investigations per nuclear medicine specialist in Germany, the estimated cumulative yearly exposure of the hand was 11.32 mSv. The hand exposure during a thyroid (99m)TcO4-fhSPECT/US of 20-min duration proved modest and comparable with different methods. Yearly examinations in excess of 1000 per investigator are not expected to add a relevant cumulative risk.
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Affiliation(s)
| | - Thomas Winkens
- Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany
| | - Thomas Opfermann
- Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany
| | - Christian Kühnel
- Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany Medical Engineering and Biotechnology, Jena University of Applied Sciences (EAH Jena), Jena, Germany
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Thermoluminescent dosimeters for low dose X-ray measurements. Appl Radiat Isot 2016; 107:340-345. [DOI: 10.1016/j.apradiso.2015.11.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 10/30/2015] [Accepted: 11/10/2015] [Indexed: 11/17/2022]
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40
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Robinson RC, Nelson CL, Bloom ES, Kisling KD, Mason BE, Fisher GD, Kirsner SM. Contralateral breast dose from partial breast brachytherapy. J Appl Clin Med Phys 2015; 16:17–22. [PMID: 26699549 PMCID: PMC5690998 DOI: 10.1120/jacmp.v16i6.5296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 08/21/2015] [Accepted: 05/19/2015] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to determine the dose to the contralateral breast during accelerated partial breast irradiation (APBI) and to compare it to external beam-published values. Thermoluminescent dosimeter (TLD) packets were used to measure the dose to the most medial aspect of the contralateral breast during APBI simulation, daily quality assurance (QA), and treatment. All patients in this study were treated with a single-entry, multicatheter device for 10 fractions to a total dose of 34 Gy. A mark was placed on the patient's skin on the medial aspect of the opposite breast. Three TLD packets were taped to this mark during the pretreatment simulation. Simulations consisted of an AP and Lateral scout and a limited axial scan encompassing the lumpectomy cavity (miniscan), if rotation was a concern. After the simulation the TLD packets were removed and the patients were moved to the high-dose-rate (HDR) vault where three new TLD packets were taped onto the patients at the skin mark. Treatment was administered with a Nucletron HDR afterloader using Iridium-192 as the treatment source. Post-treatment, TLDs were read (along with the simulation and QA TLD and a set of standards exposed to a known dose of 6 MV photons). Measurements indicate an average total dose to the contralateral breast of 70 cGy for outer quadrant implants and 181 cGy for inner quadrant implants. Compared to external beam breast tangents, these results point to less dose being delivered to the contralateral breast when using APBI.
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Chofor N, Harder D, Selbach HJ, Poppe B. The mean photon energy ĒF at the point of measurement determines the detector-specific radiation quality correction factor kQ,M in (192)Ir brachytherapy dosimetry. Z Med Phys 2015; 26:238-50. [PMID: 26387927 DOI: 10.1016/j.zemedi.2015.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 06/19/2015] [Accepted: 08/03/2015] [Indexed: 11/17/2022]
Abstract
The application of various radiation detectors for brachytherapy dosimetry has motivated this study of the energy dependence of radiation quality correction factor kQ,M, the quotient of the detector responses under calibration conditions at a (60)Co unit and under the given non-reference conditions at the point of measurement, M, occurring in photon brachytherapy. The investigated detectors comprise TLD, radiochromic film, ESR, Si diode, plastic scintillator and diamond crystal detectors as well as ionization chambers of various sizes, whose measured response-energy relationships, taken from the literature, served as input data. Brachytherapy photon fields were Monte-Carlo simulated for an ideal isotropic (192)Ir point source, a model spherical (192)Ir source with steel encapsulation and a commercial HDR GammaMed Plus source. The radial source distance was varied within cylindrical water phantoms with outer radii ranging from 10 to 30cm and heights from 20 to 60cm. By application of this semiempirical method - originally developed for teletherapy dosimetry - it has been shown that factor kQ,M is closely correlated with a single variable, the fluence-weighted mean photon energy ĒF at the point of measurement. The radial profiles of ĒF obtained with either the commercial (192)Ir source or the two simplified source variants show little variation. The observed correlations between parameters kQ,M and ĒF are represented by fitting formulae for all investigated detectors, and further variation of the detector type is foreseen. The herewith established close correlation of radiation quality correction factor kQ,M with local mean photon energy ĒF can be regarded as a simple regularity, facilitating the practical application of correction factor kQ,M for in-phantom dosimetry around (192)Ir brachytherapy sources. ĒF values can be assessed by Monte Carlo simulation or measurement. A technique describing the local measurement of ĒF will be published separately.
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Affiliation(s)
- Ndimofor Chofor
- Medical Radiation Physics Group, University of Oldenburg and Pius-Hospital Oldenburg, Germany.
| | - Dietrich Harder
- Medical Radiation Physics Group, University of Oldenburg and Pius-Hospital Oldenburg, Germany
| | - Hans-Joachim Selbach
- Medical Radiation Physics Group, University of Oldenburg and Pius-Hospital Oldenburg, Germany
| | - Björn Poppe
- Medical Radiation Physics Group, University of Oldenburg and Pius-Hospital Oldenburg, Germany
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Rodriguez M, Rogers DWO. Effect of improved TLD dosimetry on the determination of dose rate constants for (125)I and (103)Pd brachytherapy seeds. Med Phys 2015; 41:114301. [PMID: 25370677 DOI: 10.1118/1.4895003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE To more accurately account for the relative intrinsic energy dependence and relative absorbed-dose energy dependence of TLDs when used to measure dose rate constants (DRCs) for (125)I and (103)Pd brachytherapy seeds, to thereby establish revised "measured values" for all seeds and compare the revised values with Monte Carlo and consensus values. METHODS The relative absorbed-dose energy dependence, f(rel), for TLDs and the phantom correction, Pphant, are calculated for (125)I and (103)Pd seeds using the EGSnrc BrachyDose and DOSXYZnrc codes. The original energy dependence and phantom corrections applied to DRC measurements are replaced by calculated (f(rel))(-1) and Pphant values for 24 different seed models. By comparing the modified measured DRCs to the MC values, an appropriate relative intrinsic energy dependence, kbq (rel), is determined. The new Pphant values and relative absorbed-dose sensitivities, SAD (rel), calculated as the product of (f(rel))(-1) and (kbq (rel))(-1), are used to individually revise the measured DRCs for comparison with Monte Carlo calculated values and TG-43U1 or TG-43U1S1 consensus values. RESULTS In general, f(rel) is sensitive to the energy spectra and models of the brachytherapy seeds. Values may vary up to 8.4% among (125)I and (103)Pd seed models and common TLD shapes. Pphant values depend primarily on the isotope used. Deduced (kbq (rel))(-1) values are 1.074 ± 0.015 and 1.084 ± 0.026 for (125)I and (103)Pd seeds, respectively. For (1 mm)(3) chips, this implies an overall absorbed-dose sensitivity relative to (60)Co or 6 MV calibrations of 1.51 ± 1% and 1.47 ± 2% for (125)I and (103)Pd seeds, respectively, as opposed to the widely used value of 1.41. Values of Pphant calculated here have much lower statistical uncertainties than literature values, but systematic uncertainties from density and composition uncertainties are significant. Using these revised values with the literature's DRC measurements, the average discrepancies between revised measured values and Monte Carlo values are 1.2% and 0.2% for (125)I and (103)Pd seeds, respectively, compared to average discrepancies for the original measured values of 4.8%. On average, the revised measured values are 4.3% and 5.9% lower than the original measured values for (103)Pd and (125)I seeds, respectively. The average of revised DRCs and Monte Carlo values is 3.8% and 2.8% lower for (125)I and (103)Pd seeds, respectively, than the consensus values in TG-43U1 or TG-43U1S1. CONCLUSIONS This work shows that f(rel) is TLD shape and seed model dependent suggesting a need to update the generalized energy response dependence, i.e., relative absorbed-dose sensitivity, measured 25 years ago and applied often to DRC measurements of (125)I and (103)Pd brachytherapy seeds. The intrinsic energy dependence for LiF TLDs deduced here is consistent with previous dosimetry studies and emphasizes the need to revise the DRC consensus values reported by TG-43U1 or TG-43U1S1.
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Affiliation(s)
- M Rodriguez
- Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada and Princess Margaret Hospital, Toronto, Ontario M5G 2M9, Canada
| | - D W O Rogers
- Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada
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Adolfsson E, White S, Landry G, Lund E, Gustafsson H, Verhaegen F, Reniers B, Carlsson Tedgren Å, Carlsson GA. Measurement of absorbed dose to water around an electronic brachytherapy source. Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film. Phys Med Biol 2015; 60:3869-82. [PMID: 25906141 DOI: 10.1088/0031-9155/60/9/3869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film. Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water. Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison. This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies ((192)Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.
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Affiliation(s)
- Emelie Adolfsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
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Rijken JD, Harris-Phillips W, Lawson JM. Calculation of the TLD700:LiF energy response from Ir-192 using novel Monte Carlo and empirical methods. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 38:129-38. [PMID: 25663432 DOI: 10.1007/s13246-015-0332-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 01/26/2015] [Indexed: 11/28/2022]
Abstract
Lithium fluoride thermoluminescent dosimeters (TLDs) exhibit a dependence on the energy of the radiation beam of interest so need to be carefully calibrated for different energy spectra if used for clinical radiation oncology beam dosimetry and quality assurance. TLD energy response was investigated for a specific set of TLD700:LiF(Mg,Ti) chips for a high dose rate (192)Ir brachytherapy source. A novel method of energy response calculation for (192)Ir was developed where dose was determined through Monte Carlo modelling in Geant4. The TLD response was then measured experimentally. Results showed that TLD700 has a depth dependent response in water ranging from 1.170 ± 0.125 at 20 mm to 0.976 ± 0.043 at 50 mm (normalised to a nominal 6 MV beam response). The method of calibration and Monte Carlo data developed through this study could be easily applied by other Medical Physics departments seeking to use TLDs for (192)Ir patient dosimetry or treatment planning system experimental verification.
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Affiliation(s)
- J D Rijken
- Medical Physics Department, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia,
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45
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Ávila O, Ramírez-Barbosa E, Gamboa-deBuen I. Energy dependence of TLD-900 dosimeters exposed to low energy X-rays. RADIAT MEAS 2014. [DOI: 10.1016/j.radmeas.2014.07.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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46
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47
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Reed JL, Rasmussen BE, Davis SD, Micka JA, Culberson WS, DeWerd LA. Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for125I and103Pd brachytherapy sources relative to60Co. Med Phys 2014; 41:122103. [DOI: 10.1118/1.4901300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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48
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Experimental determination of the Task Group-43 dosimetric parameters of the new I25.S17plus 125I brachytherapy source. Brachytherapy 2014; 13:618-26. [DOI: 10.1016/j.brachy.2014.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/02/2014] [Accepted: 07/02/2014] [Indexed: 11/24/2022]
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49
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Koivisto J, Schulze D, Wolff J, Rottke D. Effective dose assessment in the maxillofacial region using thermoluminescent (TLD) and metal oxide semiconductor field-effect transistor (MOSFET) dosemeters: a comparative study. Dentomaxillofac Radiol 2014; 43:20140202. [PMID: 25143020 PMCID: PMC4240264 DOI: 10.1259/dmfr.20140202] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/11/2014] [Accepted: 08/19/2014] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The objective of this study was to compare the performance of metal oxide semiconductor field-effect transistor (MOSFET) technology dosemeters with thermoluminescent dosemeters (TLDs) (TLD 100; Thermo Fisher Scientific, Waltham, MA) in the maxillofacial area. METHODS Organ and effective dose measurements were performed using 40 TLD and 20 MOSFET dosemeters that were alternately placed in 20 different locations in 1 anthropomorphic RANDO(®) head phantom (the Phantom Laboratory, Salem, NY). The phantom was exposed to four different CBCT default maxillofacial protocols using small (4 × 5 cm) to full face (20 × 17 cm) fields of view (FOVs). RESULTS The TLD effective doses ranged between 7.0 and 158.0 µSv and the MOSFET doses between 6.1 and 175.0 µSv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20 × 17 cm) (MOSFET, 83.4 µSv; TLD, 87.6 µSv; -5%); teeth, upper jaw (FOV, 8.5 × 5.0 cm) (MOSFET, 6.1 µSv; TLD, 7.0 µSv; -14%); tooth, mandible and left molar (FOV, 4 × 5 cm) (MOSFET, 10.3 µSv; TLD, 12.3 µSv; -16%) and teeth, both jaws (FOV, 10 × 10 cm) (MOSFET, 175 µSv; TLD, 158 µSv; +11%). The largest variation in organ and effective dose was recorded in the small FOV protocols. CONCLUSIONS Taking into account the uncertainties of both measurement methods and the results of the statistical analysis, the effective doses acquired using MOSFET dosemeters were found to be in good agreement with those obtained using TLD dosemeters. The MOSFET dosemeters constitute a feasible alternative for TLDs for the effective dose assessment of CBCT devices in the maxillofacial region.
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Affiliation(s)
- J Koivisto
- 1 Department of Physics, University of Helsinki, Helsinki, Finland
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50
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Lucas PA, Aubineau-Lanièce I, Lourenço V, Vermesse D, Cutarella D. Using LiF:Mg,Cu,P TLDs to estimate the absorbed dose to water in liquid water around an 192Ir brachytherapy source. Med Phys 2014; 41:011711. [PMID: 24387503 DOI: 10.1118/1.4851636] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
PURPOSE The absorbed dose to water is the fundamental reference quantity for brachytherapy treatment planning systems and thermoluminescence dosimeters (TLDs) have been recognized as the most validated detectors for measurement of such a dosimetric descriptor. The detector response in a wide energy spectrum as that of an (192)Ir brachytherapy source as well as the specific measurement medium which surrounds the TLD need to be accounted for when estimating the absorbed dose. This paper develops a methodology based on highly sensitive LiF:Mg,Cu,P TLDs to directly estimate the absorbed dose to water in liquid water around a high dose rate (192)Ir brachytherapy source. METHODS Different experimental designs in liquid water and air were constructed to study the response of LiF:Mg,Cu,P TLDs when irradiated in several standard photon beams of the LNE-LNHB (French national metrology laboratory for ionizing radiation). Measurement strategies and Monte Carlo techniques were developed to calibrate the LiF:Mg,Cu,P detectors in the energy interval characteristic of that found when TLDs are immersed in water around an (192)Ir source. Finally, an experimental system was designed to irradiate TLDs at different angles between 1 and 11 cm away from an (192)Ir source in liquid water. Monte Carlo simulations were performed to correct measured results to provide estimates of the absorbed dose to water in water around the (192)Ir source. RESULTS The dose response dependence of LiF:Mg,Cu,P TLDs with the linear energy transfer of secondary electrons followed the same variations as those of published results. The calibration strategy which used TLDs in air exposed to a standard N-250 ISO x-ray beam and TLDs in water irradiated with a standard (137)Cs beam provided an estimated mean uncertainty of 2.8% (k = 1) in the TLD calibration coefficient for irradiations by the (192)Ir source in water. The 3D TLD measurements performed in liquid water were obtained with a maximum uncertainty of 11% (k = 1) found at 1 cm from the source. Radial dose values in water were compared against published results of the American Association of Physicists in Medicine and the European Society for Radiotherapy and Oncology and no significant differences (maximum value of 3.1%) were found within uncertainties except for one position at 9 cm (5.8%). At this location the background contribution relative to the TLD signal is relatively small and an unexpected experimental fluctuation in the background estimate may have caused such a large discrepancy. CONCLUSIONS This paper shows that reliable measurements with TLDs in complex energy spectra require a study of the detector dose response with the radiation quality and specific calibration methodologies which model accurately the experimental conditions where the detectors will be used. The authors have developed and studied a method with highly sensitive TLDs and contributed to its validation by comparison with results from the literature. This methodology can be used to provide direct estimates of the absorbed dose rate in water for irradiations with HDR (192)Ir brachytherapy sources.
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Affiliation(s)
- P Avilés Lucas
- CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France
| | - I Aubineau-Lanièce
- CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France
| | - V Lourenço
- CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France
| | - D Vermesse
- CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France
| | - D Cutarella
- CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette, France
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