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Neupane T, Shang C, Kassel M, Muhammad W, Leventouri T, Williams TR. Viability of the virtual cone technique using a fixed small multi-leaf collimator field for stereotactic radiosurgery of trigeminal neuralgia. J Appl Clin Med Phys 2023; 24:e14148. [PMID: 37722766 PMCID: PMC10691631 DOI: 10.1002/acm2.14148] [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: 11/09/2022] [Revised: 08/04/2023] [Accepted: 08/20/2023] [Indexed: 09/20/2023] Open
Abstract
Dosimetric uncertainties in very small (≤1.5 × 1.5 cm2 ) photon fields are remarkably higher, which undermines the validity of the virtual cone (VC) technique with a diminutive and variable MLC fields. We evaluate the accuracy and reproducibility of the VC method with a very small, fixed MLC field setting, called a fixed virtual cone (fVC), for small target radiosurgery such as trigeminal neuralgia (TGN). The fVC is characterized by 0.5 cm x 0.5 cm high-definition (HD) MLC field of 10MV FFF beam defined at 100 cm SAD, while backup jaws are positioned at 1.5 cm x 1.5 cm. A spherical dose distribution equivalent to 5 mm (diameter) physical cone was generated using 10-14 non-coplanar, partial arcs. Dosimetric accuracy was validated using SRS diode (PTW 60018), SRS MapCHECK (SNC) measurements. As a quality assurance measure, 10 treatment plans (SRS) for TGN, consisting of various arc ranges at different collimator angles were analyzed using 6 MV FFF and 10 MV FFF beams, including a field-by-field study (n = 130 fields). Dose outputs were compared between the Eclipse TPS and measurements (SRS MapCHECK). Moreover, dosimetric changes in the field defining fVC, prompted by a minute (± 0.5-1.0 mm) leaf shift, was examined among TPS, diode measurements, and Monte Carlo (MC) simulations. The beam model for fVC was validated (≤3% difference) using SRS MapCHECK based absolute dose measurements. The equivalent diameters of the 50% isodose distribution were found comparable to that of a 5 mm cone. Additionally, the comparison of field output factors, dose per MU between the TPS and SRS diode measurements using the fVC field, including ± 1 mm leaf shift, yielded average discrepancies within 5.5% and 3.5% for 6 MV FFF and 10 MV FFF beams, respectively. Overall, the fVC method is a credible alternative to the physical cone (5 mm) that can be applied in routine radiosurgical treatment of TGN.
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Affiliation(s)
- Taindra Neupane
- Department of PhysicsFlorida Atlantic UniversityBoca RatonFloridaUSA
| | - Charles Shang
- RSOSouth Florida Proton Therapy InstituteDelray BeachFloridaUSA
| | - Maxwell Kassel
- Department of PhysicsFlorida Atlantic UniversityBoca RatonFloridaUSA
| | - Wazir Muhammad
- Department of PhysicsFlorida Atlantic UniversityBoca RatonFloridaUSA
| | - Theodora Leventouri
- Center for Biological and Materials Physics (CBAMP)Department of PhysicsFlorida Atlantic UniversityBoca RatonFloridaUSA
| | - Timothy R. Williams
- Medical DirectorSouth Florida Proton Therapy InstituteDelray BeachFloridaUSA
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Kawata K, Hirashima H, Tsuruta Y, Sasaki M, Matsushita N, Fujimoto T, Nakamura M, Nakata M. Applicability evaluation of the TRS-483 protocol for the determination of small-field output factors using different multi-leaf collimator and field-shaping types. Phys Med 2023; 113:102664. [PMID: 37573811 DOI: 10.1016/j.ejmp.2023.102664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/15/2023] Open
Abstract
PURPOSE To evaluate the applicability of TRS-483 output correction factors (CFs) for small-field output factors (OFs) using different multi-leaf collimators (MLC) and field-shaping types. METHODS All measurements were performed on TrueBeam, TrueBeam STx, and Halcyon using 6 MV flattening filter-free energy. Four detectors, including CC01, CC04, microDiamond, and EDGE, were used. Nominal field sizes ranging from 1 × 1 to 4 × 4, and 10 × 10 cm2 were used to measure small-field OFs at source-to-axis distance of 100 cm with a 0° gantry angle in a 3D water phantom. Further, the field-shaping types were defined using jaw collimator or MLC (five different configurations). A field size of 10 × 10 cm2 was used as the reference for calculation of OFs obtained as ratio of detector readings (OFdet). The percentage difference and coefficient of variation of OFdet and OFdet corrected by applying CF were compared for each field size and configuration. RESULTS For OFdet corrected by applying CF, the ranges of percentage difference and coefficient of variation in all configurations for ≥ 2 × 2 cm2 fields were reduced from 1.2-2.2 to 0.8-1.3 percentage points (%pt) and from 0.5-1.0 to 0.4-0.7%, respectively. For 1 × 1 cm2 field, the ranges of percentage difference and coefficient of variation were reduced from 3.3-5.7 to 1.2-2.2 %pt and from 2.2-3.7 to 0.8-1.1%, respectively. CONCLUSIONS The CFs described in TRS-483 dosimetry protocol have broad applicability in reducing OF variations between detectors under different MLC and field-shaping types.
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Affiliation(s)
- Kohei Kawata
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Hideaki Hirashima
- Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan.
| | - Yusuke Tsuruta
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan; Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Makoto Sasaki
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Norimasa Matsushita
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Takahiro Fujimoto
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
| | - Mitsuhiro Nakamura
- Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan; Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Manabu Nakata
- Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan
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Huang YY, Yang J, Liu YB. Planning issues on linac-based stereotactic radiotherapy. World J Clin Cases 2022; 10:12822-12836. [PMID: 36568990 PMCID: PMC9782937 DOI: 10.12998/wjcc.v10.i35.12822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/20/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022] Open
Abstract
This work aims to summarize and evaluate the current planning progress based on the linear accelerator in stereotactic radiotherapy (SRT). The specific techniques include 3-dimensional conformal radiotherapy, dynamic conformal arc therapy, intensity-modulated radiotherapy, and volumetric-modulated arc therapy (VMAT). They are all designed to deliver higher doses to the target volume while reducing damage to normal tissues; among them, VMAT shows better prospects for application. This paper reviews and summarizes several issues on the planning of SRT to provide a reference for clinical application.
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Affiliation(s)
- Yang-Yang Huang
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, Jiangxi Province, China
- Department of Radiotherapy, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, Henan Province, China
| | - Jun Yang
- Department of Radiotherapy, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan Province, China
| | - Yi-Bao Liu
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, Jiangxi Province, China
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Lechner W, Alfonso R, Arib M, Huq MS, Ismail A, Kinhikar R, Lárraga-Gutiérrez JM, Mani KR, Maphumulo N, Sauer OA, Shoeir S, Suriyapee S, Christaki K. A multi-institutional evaluation of small field output factor determination following the recommendations of IAEA/AAPM TRS-483. Med Phys 2022; 49:5537-5550. [PMID: 35717637 PMCID: PMC9541513 DOI: 10.1002/mp.15797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 03/31/2022] [Accepted: 05/25/2022] [Indexed: 11/15/2022] Open
Abstract
Purpose The aim of this work was to test the implementation of small field dosimetry following TRS‐483 and to develop quality assurance procedures for the experimental determination of small field output factors (SFOFs). Materials and methods Twelve different centers provided SFOFs determined with various detectors. Various linac models using the beam qualities 6 MV and 10 MV with flattening filter and without flattening filter were utilized to generate square fields down to a nominal field size of 0.5 cm × 0.5 cm. The detectors were positioned at 10 cm depth in water. Depending on the local situation, the source‐to‐surface distance was either set to 90 cm or 100 cm. The SFOFs were normalized to the output of the 10 cm × 10 cm field. The spread of SFOFs measured with different detectors was investigated for each individual linac beam quality and field size. Additionally, linac‐type specific SFOF curves were determined for each beam quality and the SFOFs determined using individual detectors were compared to these curves. Example uncertainty budgets were established for a solid state detector and a micro ionization chamber. Results The spread of SFOFs for each linac and field was below 5% for all field sizes. With the exception of one linac‐type, the SFOFs of all investigated detectors agreed within 10% with the respective linac‐type SFOF curve, indicating a potential inter‐detector and inter‐linac variability. Conclusion Quality assurance on the SFOF measurements can be done by investigation of the spread of SFOFs measured with multiple detectors and by comparison to linac‐type specific SFOFs. A follow‐up of a measurement session should be conducted if the spread of SFOFs is larger than 5%, 3%, and 2% for field sizes of 0.5 cm × 0.5 cm, 1 cm × 1 cm, and field sizes larger than 2 cm × 2 cm, respectively. Additionally, deviations of measured SFOFs to the linac‐type‐curves of more than 7%, 3%, and 2% for field sizes 0.5 cm × 0.5 cm, 1 cm × 1 cm, and field sizes larger than 1 cm × 1 cm, respectively, should be followed up.
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Affiliation(s)
- Wolfgang Lechner
- Department of Radiation Oncology, Division of Medical Physics, Medical University Vienna, Vienna, 1090, Austria
| | - Rodolfo Alfonso
- Department of Nuclear Engineering, Higher Institute of Technology and Applied Sciences, University of Havana, Havana, 10400, Cuba
| | - Mehenna Arib
- King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania, USA
| | - Anas Ismail
- Protection and Safety Department, Atomic Energy Commission of Syria, Damascus, PO Box 6091, Syria
| | - Rajesh Kinhikar
- Department of Medical Physics, Tata Memorial Centre, Mumbai, India 400012 & Homi Bhabha National Institute, Mumbai, 400094, India
| | - José M Lárraga-Gutiérrez
- Laboratorio de Física-Médica, Instituto Nacional de Neurología y Neurocirugía, Insurgentes sur 3877, La Fama, Tlalpan 14269, CDMX, México
| | - Karthick Raj Mani
- Department of Radiation Oncology, United Hospital Ltd., Dhaka, 1212, Bangladesh
| | - Nkosingiphile Maphumulo
- Radiation Dosimetry Section, National Metrology Institute of South Africa, Pretoria, South Africa
| | - Otto A Sauer
- Department of Radiation Oncology, University of Würzburg, 97080, Würzburg, Germany
| | | | - Sivalee Suriyapee
- Division of Radiation Oncology, Department of Radiology, Chulalongkorn University, Bangkok, Thailand
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McGrath AN, Golmakani S, Williams TJ. Determination of correction factors in small MLC-defined fields for the Razor and microSilicon diode detectors and evaluation of the suitability of the IAEA TRS-483 protocol for multiple detectors. J Appl Clin Med Phys 2022; 23:e13657. [PMID: 35652320 PMCID: PMC9278669 DOI: 10.1002/acm2.13657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/31/2022] [Accepted: 05/03/2022] [Indexed: 11/11/2022] Open
Abstract
Small field output factors for Multileaf collimator (MLC)‐defined field sizes between 0.5 × 0.5 cm2 and 3 × 3 cm2 were measured with six different detectors for a Varian TrueBeam in 6‐MV, 6‐FFF, 10‐MV, and 10‐FFF photon beams. Correction factors kQclin,Qreffclin,fref from the IAEA publication TRS‐483 were used to correct the measured output factors. The corrected output factors from the six detectors were used to calculate correction factors for the PTW microSilicon T60023 (PTW, Freiburg, Germany) and IBA Razor (IBA Dosimetry, Schwarzenbruck, Germany) detectors. The uncertainty of the output and correction factors in this study was calculated and the calculations presented in detail. The application of the TRS‐483 correction factors significantly reduced the variation in output factors between the various detectors, with the exception of the PTW 60016 diode in 6‐MV and 6‐FFF beams, and the IBA PFD in 10‐MV and 10‐FFF beams. Correction factors calculated for the Razor agreed within 2.9% of existing literature for all energies, while the microSilicon correction factors agreed within 1.6% to the literature for 6‐MV beams. The uncertainty in the microSilicon and Razor correction factors was calculated to be less than 0.9% (k = 1). This study shows that TRS‐483 correction factors reduce the variation in output factors between the detectors used in this study and presents a suitable method for determining correction factors for detectors with unpublished values.
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Affiliation(s)
- Andrew N McGrath
- W.P. Holman Clinic, Royal Hobart Hospital, Hobart, Tasmania, Australia
| | - Samane Golmakani
- W.P. Holman Clinic, Royal Hobart Hospital, Hobart, Tasmania, Australia
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Dose area product primary standards established by graphite calorimetry at the LNE-LNHB for small radiation fields in radiotherapy. Phys Med 2022; 98:18-27. [PMID: 35489128 DOI: 10.1016/j.ejmp.2022.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 03/10/2022] [Accepted: 03/19/2022] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To present primary standards establishment in terms of Dose Area Product (DAP) for small field sizes. METHODS A large section graphite calorimeter and two plane-parallel ionization chambers were designed and built in-house. These chambers were calibrated in a 6MV FFF beam at the maximum dose rate of 1400 UM/min for fields defined by specifically designed circular collimators of 5, 7.5, 10, 13 and 15 mm diameter and jaws of 5, 7, 10, 13 and 15 mm side length on a Varian TrueBeam linac. RESULTS The two chambers show the same behaviour regardless of field shape and size. From 5 to 15 mm, calibration coefficients slightly increase with the field size with a magnitude of 1.8% and 1.1% respectively for the two chambers, and are independent of the field shape. This tendency was confirmed by Monte Carlo calculations. The average associated uncertainty of the calibration coefficients is around 0.6% at k=1. CONCLUSIONS For the first time, primary standards in terms of DAP were established by graphite calorimetry for an extended range of small field sizes. These promising results open the door for an alternative approach in small fields dosimetry.
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Quantitative evaluation of dosimetric uncertainties associated with small electron fields. J Med Imaging Radiat Sci 2022; 53:273-282. [PMID: 35304080 DOI: 10.1016/j.jmir.2022.02.007] [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: 08/26/2021] [Revised: 11/24/2021] [Accepted: 02/14/2022] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Although many studies have investigated small electron fields, there are several dosimetric issues that are not well understood. This includes lack of charged particle equilibrium, lateral scatter, source occlusion and volume averaging of the detectors used in the measurement of the commissioning data. High energy electron beams are also associated with bremsstrahlung production that contributes to dose deposition, which is not well investigated, particularly for small electron fields. The goal of this work has been to investigate dosimetric uncertainties associated with small electron fields using dose measurements with different detectors as well as calculations with eMC dose calculation algorithm. METHODS Different dosimetric parameters including output factors, depth dose curves and dose profiles from small electron field cutouts were investigated quantitatively. These dosimetric parameters were measured using different detectors that included small ion chambers and diodes for small electron cutouts with diameters ranging from 15-50mm mounted on a 6 × 6cm2 cone with beam energies from 6-20MeV. RESULTS Large deviations existed between the output factors calculated with the eMC algorithm and measured with small detectors for small electron fields up to 55% for 6MeV. The discrepancy between the calculated and measured doses increased 10%-55% with decreasing electron beam energy from 20 MeV to 6 MeV for 15mm circular field. For electron fields with cutouts 20mm and larger, the measured and calculated doses agreed within 5% for all electron energies from 6-20MeV. For small electron fields, the maximal depth dose shifted upstream and becomes more superficial as the electron beam energy increases from 6-20MeV as measured with small detectors. DISCUSSION Large dose discrepancies were found between the measured and calculated doses for small electron fields where the eMC underestimated output factors by 55% for small circular electron fields with a diameter of 15 mm, particularly for low energy electron beams. The measured entrance doses and dmax of the depth dose curves did not agree with the corresponding values calculated by eMC. Furthermore, the measured dose profiles showed enhanced dose deposition in the umbra region and outside the small fields, which mostly resulted from dose deposition from the bremsstrahlung produced by high energy electrons that was not accounted for by the eMC algorithm due to inaccurate modeling of the lateral dose deposition from bremsstrahlung. CONCLUSION Electron small field dosimetry require more consideration of variations in beam quality, lack of charged particle equilibrium, lateral scatter loss and dose deposition from bremsstrahlung produced by energetic electron beams in a comprehensive approach similar to photon small field dosimetry. Furthermore, most of the commercially available electron dose calculation algorithms are commissioned with large electron fields; therefore, vendors should provide tools for the modeling of electron dose calculation algorithms for small electron fields.
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Investigation of field output factors using IAEA-AAPM TRS-483 code of practice recommendations and Monte Carlo simulation for 6 MV photon beams. JOURNAL OF RADIOTHERAPY IN PRACTICE 2021. [DOI: 10.1017/s1460396921000662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
Introduction:
This study aims to experimentally determine field output factors using the methodologies suggested by the IAEA-AAPM TRS-483 for small field dosimetry and compare with the calculation from Monte Carlo (MC) simulation.
Methods:
The IBA-CC01, Sun Nuclear EDGE and IBA-SFD detectors were employed to determine the uncorrected and the corrected field output factors for 6 MV photon beams. Measurements were performed at 100 cm source to axis distance, 10 cm depth in water, and the field sizes ranged from 1 × 1 to 10 × 10 cm2. The use of field output correction factors proposed by the TRS-483 was utilised to determine field output factors. The measured field output factors were compared to that calculated using the egs_chamber user code.
Results:
The decrease in the percentage standard deviation of the measured three detectors was observed after applying the field output correction factors. Measured field output factors using CC01 and EDGE detectors agreed with MC values within 3% for field sizes down to 1 × 1 cm2, except the SFD detector.
Conclusions:
The corrected field output factors agree with the calculation from MC, except the SFD detector. CC01 and EDGE are suitable for determining field output factors, while the SFD may need more implementation of the intermediate field method.
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Lárraga-Gutiérrez JM, García-Garduño OA, Herrera-González JA, Galván de la Cruz OO. Evaluation of Acuros® XB accuracy for static small fields dose calculations based on the IAEA/AAPM TRS-483 recommendation. Phys Med 2021; 89:140-146. [PMID: 34365118 DOI: 10.1016/j.ejmp.2021.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 06/14/2021] [Accepted: 06/27/2021] [Indexed: 12/01/2022] Open
Abstract
PURPOSE Evaluate Acuros® XB dose calculation accuracy following TRS-483 recommendations in small static fields for flattened and un-flattened 6 MV X-ray beams. METHODS Field output factors were measured following TRS-483 recommendations using four radiation detectors. Two sets of field output factors were measured. One set was used to configure the beam model into Acuros® XB down to a jaw-defined field size of 1.0 cm × 1.0 cm. The second set was used to evaluate the differences between calculated and measured field output factors for MLC-fields down to a field size of 0.5 cm × 0.5 cm. RESULTS Acuros® XB showed an accuracy within 1.5% down to an MLC-field of 1.0 cm × 1.0 cm, for a focal spot size of 1.0 and 0.0 mm in the cross and in-plane directions. For an MLC-field of 0.5 cm × 0.5 cm, an agreement was found within 3% between calculated and measured field output factors. These results were addressed by optimizing the focal spot size to minimize the differences between calculated and measured dose profiles. CONCLUSIONS By optimizing the focal spot size, Acuros® XB showed an acceptable agreement within 3% down to an MLC-field of 0.5 cm × 0.5 cm. The results of this work suggest that if static and modulated delivery of very small targets is planned, then a field output factor table down to a field size of 1.0 cm is required in the beam configuration model.
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Affiliation(s)
- José M Lárraga-Gutiérrez
- Lab. de Física Médica, Instituto Nacional de Neurología y Neurocirugía, Insurgentes sur 3877, La Fama, Tlalpan 14269, CMDX, Mexico.
| | - Olivia A García-Garduño
- Lab. de Física Médica, Instituto Nacional de Neurología y Neurocirugía, Insurgentes sur 3877, La Fama, Tlalpan 14269, CMDX, Mexico
| | - José A Herrera-González
- Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, Insurgentes sur 3877, La Fama, Tlalpan 14269, CMDX, Mexico; Depto. de Biofísica, Instituto Nacional de Cancerología, San Fernando 22, Belisario Domínguez Secc 16, Tlalpan 14080, CDMX, Mexico
| | - Olga O Galván de la Cruz
- Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, Insurgentes sur 3877, La Fama, Tlalpan 14269, CMDX, Mexico
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Yi B, Becker SJ. Simplified method for determining dose to a non-water phantom through the use of N D,w and IAEA TRS 483 for the GammaPod. Phys Med 2021; 88:138-141. [PMID: 34242885 DOI: 10.1016/j.ejmp.2021.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/12/2021] [Accepted: 05/16/2021] [Indexed: 11/26/2022] Open
Abstract
PURPOSE GammaPod, a breast stereotactic radiosurgery device, utilizes 25 rotating Co-60 sources to deliver highly conformal dose distributions. The GammaPod system requires that reference dosimetry be performed in a specific vendor-supplied poly-methylmethacrylate (PMMA) phantom. The nonstandard nature of GammaPod dosimetry, in both the phantom material and machine-specific reference (msr), prohibits use of the American Association of Physicists in Medicine Task Group 51 (TG-51) protocol. This study proposes a practical method using TRS 483 to make the reference dosimetry procedure simpler and to reduce overall uncertainties. METHODS The dose to PMMA (DPMMA) is determined under msr conditions using TRS 483 with an Exradin A1SL chamber placed in a PMMA phantom. The conversion factor, which converts from the dose-to-water (Dw) in broad-beam Co-60 reference geometry to DPMMA in the msr small field Co-60 (Qmsr) geometry, is derived using the Monte Carlo simulations and procedure described in TRS 483. RESULTS The new conversion factor value for an Exradin A1SL chamber is 0.974. When combined with ND,w, DPMMA differs by 0.5% from the TG-21/Nx method and 0.2% from the IROC values. Uncertainty decreased from 2.2% to 1.6%. CONCLUSION We successfully implemented TRS 483 reference dosimetry protocols utilizing ND,w for the GammaPod in the PMMA phantom. These results show not only agreement between measurements performed with the previously published method and independent thermoluminescent dosimetry measurements but also reductions in uncertainty. This also provides readers with a pathway to develop their own IAEA TRS 483 factor for any new small field machine that may be developed.
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Affiliation(s)
- ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Stewart J Becker
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Ghemiş DM, Marcu LG. Progress and prospects of flattening filter free beam technology in radiosurgery and stereotactic body radiotherapy. Crit Rev Oncol Hematol 2021; 163:103396. [PMID: 34146680 DOI: 10.1016/j.critrevonc.2021.103396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/31/2021] [Accepted: 06/03/2021] [Indexed: 12/25/2022] Open
Abstract
The aim of this work is to summarize and evaluate the current status of knowledge on flattening filter free (FFF) beams and their applications in stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). A PubMed search was undertaken in order to identify relevant publications using FFF and stereotactic radiotherapy as keywords. On a clinical aspect, lung tumors treated with FFF SBRT show promising results in terms of local control and overall survival with acute toxicities consistent with those that occur with standard radiotherapy. Beside lung, SBRT is suitable for different anatomical sites such as liver, prostate, cervix, etc. offering similar results: reduced treatment time, good tumor control and mild acute toxicities. Regarding brain tumors, the employment of SRS with FFF beams significantly reduces treatment time and provides notable normal tissue sparing due to the sharp dose fall-off outside the tumor.
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Affiliation(s)
- Diana M Ghemiş
- West University of Timisoara, Faculty of Physics, Timisoara, Romania; MedEuropa, Oradea, Romania
| | - Loredana G Marcu
- West University of Timisoara, Faculty of Physics, Timisoara, Romania; Faculty of Informatics & Science, University of Oradea, Oradea, 410087, Romania; Cancer Research Institute, University of South Australia, Adelaide, SA, 5001, Australia.
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Dwivedi S, Kansal S, Dangwal VK, Bharati A, Shukla J. Dosimetry of a 6 MV flattening filter-free small photon beam using various detectors. Biomed Phys Eng Express 2021; 7. [PMID: 33930875 DOI: 10.1088/2057-1976/abfd80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/30/2021] [Indexed: 11/12/2022]
Abstract
The present study aimed to dosimetrically evaluate the small-fields of a 6 MV flattening filter-free (FFF) photon beam using different detectors.The 6 MV FFF photon beam was used for measurement of output factor, depth dose, and beam profile of small-fields of sizes 0.6 cm × 0.6 cm to 6.0 cm × 6.0 cm. The five detectors used were SNC125c, PinPoint, EDGE, EBT3, and TLD-100. All measurements were performed as per the International Atomic Energy Agency TRS 483 protocol. Output factors measured using different detectors as direct reading ratios showed significant variation for the smallest fields, whereas after correcting them according to TRS 483, all sets of output factors were nearly compatible with each other when measurement uncertainty was also considered. The beam profile measured using SNC125c showed the largest penumbra for all field sizes, whereas the smallest was recorded with EDGE. Compared with that of EBT3, the surface dose was found to be much higher for all the other detectors. PinPoint, EBT3, TLD-100, and EDGE were found to be the detector of choice for small-field output factor measurements; however, PinPoint needs special attention when used for the smallest field size (0.6 cm × 0.6 cm). EDGE and EBT3 are optimal for measuring beam profiles. EBT3, PinPoint, and EDGE can be selected for depth dose measurements, and EBT3 is suitable for surface dose estimation.
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Affiliation(s)
- Shekhar Dwivedi
- Department of Medical Physics, Tata Memorial Centre, Homi Bhabha Cancer Hospital and Research Centre, Mullanpur, Mohali, Punjab, 140901, India.,Department of Physics, Maharaja Ranjit Singh Punjab Technical University, Bathinda, Punjab, 151001, India
| | - Sandeep Kansal
- Department of Physics, Maharaja Ranjit Singh Punjab Technical University, Bathinda, Punjab, 151001, India
| | - Vinod Kumar Dangwal
- Department of Radiotherapy, Government Medical College, Patiala, Punjab, 147001, India
| | - Avinav Bharati
- Department of Radiation Oncology, Dr Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, 226010, India
| | - Jooli Shukla
- Department of Physics, Dr Bhimrao Ambedkar University, Agra, Uttar Pradesh, 282004, India
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13
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Bouchard H. Reference dosimetry of modulated and dynamic photon beams. Phys Med Biol 2021; 65:24TR05. [PMID: 33438582 DOI: 10.1088/1361-6560/abc3fb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the late 1980s, a new technique was proposed that would revolutionize radiotherapy. Now referred to as intensity-modulated radiotherapy, it is at the core of state-of-the-art photon beam delivery techniques, such as helical tomotherapy and volumetric modulated arc therapy. Despite over two decades of clinical application, there are still no established guidelines on the calibration of dynamic modulated photon beams. In 2008, the IAEA-AAPM work group on nonstandard photon beam dosimetry published a formalism to support the development of a new generation of protocols applicable to nonstandard beam reference dosimetry (Alfonso et al 2008 Med. Phys. 35 5179-86). The recent IAEA Code of Practice TRS-483 was published as a result of this initiative and addresses exclusively small static beams. But the plan-class specific reference calibration route proposed by Alfonso et al (2008 Med. Phys. 35 5179-86) is a change of paradigm that is yet to be implemented in radiotherapy clinics. The main goals of this paper are to provide a literature review on the dosimetry of nonstandard photon beams, including dynamic deliveries, and to discuss anticipated benefits and challenges in a future implementation of the IAEA-AAPM formalism on dynamic photon beams.
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Affiliation(s)
- Hugo Bouchard
- Département de physique, Université de Montréal, Complexe des sciences, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec H2V 0B3, Canada. Centre de recherche du Centre hospitalier de l'Université de Montréal, 900 Rue Saint-Denis, Montréal, Québec H2X 0A9, Canada. Département de radio-oncologie, Centre hospitalier de l'Université de Montréal (CHUM), 1051 Rue Sanguinet, Montréal, Québec H2X 3E4, Canada
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Mirzakhanian L, Bassalow R, Huntzinger C, Seuntjens J. Extending the IAEA‐AAPM TRS‐483 methodology for radiation therapy machines with field sizes down to 10 × 2 cm
2. Med Phys 2020; 47:5209-5221. [DOI: 10.1002/mp.14325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 04/17/2020] [Accepted: 05/21/2020] [Indexed: 11/10/2022] Open
Affiliation(s)
| | | | | | - Jan Seuntjens
- Medical Physics Unit McGill University Montreal QCH4A 3J1Canada
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Buchegger N, Grogan G, Hug B, Oliver C, Ebert M. CyberKnife reference dosimetry: An assessment of the impact of evolving recommendations on correction factors and measured dose. Med Phys 2020; 47:3573-3585. [DOI: 10.1002/mp.14190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/29/2020] [Accepted: 03/30/2020] [Indexed: 11/06/2022] Open
Affiliation(s)
- Nicole Buchegger
- Department of Radiation Oncology Sir Charles Gairdner Hospital Nedlands WA 6009 Australia
| | - Garry Grogan
- Department of Radiation Oncology Sir Charles Gairdner Hospital Nedlands WA 6009 Australia
| | - Ben Hug
- 5D Clinics Claremont WA 6010 Australia
| | - Chris Oliver
- Australian Radiation Protection and Nuclear Safety Agency Yallambie Vic. 3085 Australia
| | - Martin Ebert
- Department of Radiation Oncology Sir Charles Gairdner Hospital Nedlands WA 6009 Australia
- 5D Clinics Claremont WA 6010 Australia
- Department of Physics University of Western Australia Crawley WA 6009 Australia
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Mamesa S, Oonsiri S, Sanghangthum T, Yabsantia S, Suriyapee S. The impact of corrected field output factors based on IAEA/AAPM code of practice on small-field dosimetry to the calculated monitor unit in eclipse™ treatment planning system. J Appl Clin Med Phys 2020; 21:65-75. [PMID: 32237215 PMCID: PMC7286014 DOI: 10.1002/acm2.12855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 12/13/2020] [Accepted: 02/08/2020] [Indexed: 12/14/2022] Open
Abstract
The objective of this study was to investigate the effect of field output factors (FOFs) according to the current protocol for small-field dosimetry in conjunction to treatment planning system (TPS) commissioning. The calculated monitor unit (MU) for intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans in Eclipse™ TPS were observed. Micro ion chamber (0.01 CC) (CC01), photon field diode (shielded diode) (PFD), and electron field diode (unshielded diode) (EFD) were used to measure percentage depth doses, beam profiles, and FOFs from 1 × 1 cm2 to 10 × 10 cm2 field sizes of 6 MV photon beams. CC01 illustrated the highest percentage depth doses at 10 cm depth while EFD exhibited the lowest with the difference of 1.6% at 1 × 1 cm2 . CC01 also produced slightly broader penumbra, the difference with other detectors was within 1 mm. For uncorrected FOF of three detectors, the maximum percent standard deviation (%SD) was 5.4% at 1 × 1 cm2 field size. When the correction factors were applied, this value dropped to 2.7%. For the calculated MU in symmetric field sizes, beam commissioning group from uncorrected FOF demonstrated maximum %SD of 6.0% at 1 × 1 cm2 field size. This value decreased to 2.2% when the corrected FOF was integrated. For the calculated MU in IMRT-SRS plans, the impact of corrected FOF reduced the maximum %SD from 6.0% to 2.5% in planning target volume (PTV) less than 0.5 cm3 . Beam commissioning using corrected FOF also decreased %SD for VMAT-SRS plans, although it was less pronounced in comparison to other treatment planning techniques, since the %SD remained less than 2%. The use of FOFs based on IAEA/AAPM TRS 483 has been proven in this research to reduce the discrepancy of calculated MU among three beam commissioning datasets in Eclipse™ TPS. The dose measurement of both symmetric field and clinical cases comparing to the calculation illustrated the dependence of the types of detector commissioning and the algorithm of the treatment planning for small field size.
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Affiliation(s)
- Sammuel Mamesa
- Medical Physics Program, Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Sornjarod Oonsiri
- Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Taweap Sanghangthum
- Medical Physics Program, Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Sumalee Yabsantia
- Medical Physics Program, Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Sivalee Suriyapee
- Medical Physics Program, Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
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Casar B, Gershkevitsh E, Mendez I, Jurković S, Saiful Huq M. Output correction factors for small static fields in megavoltage photon beams for seven ionization chambers in two orientations - perpendicular and parallel. Med Phys 2020; 47:242-259. [PMID: 31677278 PMCID: PMC7003763 DOI: 10.1002/mp.13894] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/22/2019] [Accepted: 10/28/2019] [Indexed: 12/03/2022] Open
Abstract
PURPOSE The goal of the present work was to provide a large set of detector-specific output correction factors for seven small volume ionization chambers on two linear accelerators in four megavoltage photon beams utilizing perpendicular and parallel orientation of ionization chambers in the beam for nominal field sizes ranging from 0.5 cm2 × 0.5 cm2 to 10 cm2 × 10 cm2 . The present study is the second part of an extensive research conducted by our group. METHODS Output correction factors k Q clin , Q ref f clin , f ref were experimentally determined on two linacs, Elekta Versa HD and Varian TrueBeam for 6 and 10 MV beams with and without flattening filter for nine square fields ranging from 0.5 cm2 × 0.5 cm2 to 10 cm2 × 10 cm2 , for seven mini and micro ionization chambers, IBA CC04, IBA Razor, PTW 31016 3D PinPoint, PTW 31021 3D Semiflex, PTW 31022 3D PinPoint, PTW 31023 PinPoint, and SI Exradin A16. An Exradin W1 plastic scintillator and EBT3 radiochromic films were used as the reference detectors. RESULTS For all ionization chambers, values of output correction factors k Q clin , Q ref f clin , f ref were lower for parallel orientation compared to those obtained in the perpendicular orientation. Five ionization chambers from our study set, IBA Razor, PTW 31016 3D PinPoint, PTW 31022 3D PinPoint, PTW 31023 PinPoint, and SI Exradin A16, fulfill the requirement recommended in the TRS-483 Code of Practice, that is, 0.95 < k Q clin , Q ref f clin , f ref < 1.05 , down to the field size 0.8 cm2 × 0.8 cm2 , when they are positioned in parallel orientation; two of the ionization chambers, IBA Razor and PTW 31023 PinPoint, satisfy this condition down to the field size of 0.5 cm2 × 0.5 cm2 . CONCLUSIONS The present paper provides experimental results of detector-specific output correction factors for seven small volume ionization chambers. Output correction factors were determined in 6 and 10 MV photon beams with and without flattening filter down to the square field size of 0.5 cm2 × 0.5 cm2 for two orientations of ionization chambers - perpendicular and parallel. Our main finding is that output correction factors are smaller if they are determined in a parallel orientation compared to those obtained in a perpendicular orientation for all ionization chambers regardless of the photon beam energy, filtration, or linear accelerator being used. Based on our findings, we recommend using ionization chambers in parallel orientation, to minimize corrections in the experimental determination of field output factors. Latter holds even for field sizes below 1.0 cm2 × 1.0 cm2 , whenever necessary corrections remain within 5%, which was the case for several ionization chambers from our set. TRS-483 recommended perpendicular orientation of ionization chambers for the determination of field output factors. The present study presents results for both perpendicular and parallel orientation of ionization chambers. When validated by other researchers, the present results for parallel orientation can be considered as a complementary dataset to those given in TRS-483.
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Affiliation(s)
- Božidar Casar
- Department for Dosimetry and Quality of Radiological ProceduresInstitute of Oncology LjubljanaLjubljanaSlovenia
| | | | - Ignasi Mendez
- Department for Dosimetry and Quality of Radiological ProceduresInstitute of Oncology LjubljanaLjubljanaSlovenia
| | - Slaven Jurković
- Medical Physics DepartmentUniversity Hospital RijekaRijekaCroatia
- Department of Physics and BiophysicsFaculty of MedicineUniversity of RijekaRijekaCroatia
| | - M. Saiful Huq
- Department of Radiation OncologyUniversity of Pittsburgh School of Medicine and UPMC Hillman Cancer CenterPittsburghPAUSA
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