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Varasteh M, Ali A, Esteve S, Jeevanandam P, Göpfert F, Irvine DM, Hounsell AR, McGarry CK. Patient specific evaluation of breathing motion induced interplay effects. Phys Med 2023; 105:102501. [PMID: 36529007 DOI: 10.1016/j.ejmp.2022.11.005] [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: 01/13/2022] [Revised: 09/18/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022] Open
Abstract
PURPOSE In lung SABR, interplay between target motion and dynamically changing beam parameters can affect the target coverage. To identify the potential need for motion-management techniques, a comprehensive methodology for pre-treatment estimation of interplay effects has been implemented. METHODS In conjunction with an alpha-version of VeriSoft and OCTAVIUS 4D (PTW-Freiburg, Germany), a method is presented to calculate a virtual, motion-simulated 3D dose distribution based on measurement data acquired in a stationary phantom and a subsequent correction with time-dependent target-motion patterns. In-house software has been developed to create user-defined motion patterns based on either simplistic or real patient-breathing patterns including the definition of the exact beam starting phase. The approach was validated by programmed couch and phantom motion during beam delivery. Five different breathing traces with extremely altered beam-on phases (0 % and 50 % respiratory phase) and a superior-inferior motion altitude of 25 mm were used to probe the influence of interplay effects for 14 lung SABR plans. Gamma analysis (2 %/2mm) was used for quantification. RESULTS Validation measurements resulted in >98 % pass rates. Regarding the interplay effect evaluation, gamma pass rates of <92 % were observed for sinusoidal breathing patterns with <25 number of breaths per delivery time (NBs) and realistic patterns with <18 NBs. CONCLUSION The potential influence of interplay effects on the target coverage is highly dependent on the patient's breathing behaviour. The presented moving-platform-free approach can be used for verification of ITV-based treatment plans to identify whether the clinical goals are achievable without explicit use of a respiratory management technique.
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Affiliation(s)
- Mohammad Varasteh
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK
| | - Asmaa Ali
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK
| | - Sergio Esteve
- Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | | | | | - Denise M Irvine
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK; Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Alan R Hounsell
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK; Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Conor K McGarry
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK; Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
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Torres Valderrama A, Olaciregui-Ruiz I, González P, Perik T, Mijnheer B, Mans A. Portal dosimetry of small unflattened beams. Phys Med Biol 2021; 66. [PMID: 32217828 DOI: 10.1088/1361-6560/ab843d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 03/27/2020] [Indexed: 11/12/2022]
Abstract
We developed and validated a dedicated small field back-projection portal dosimetry model for pretreatment andin vivoverification of stereotactic plans entailing small unflattened photon beams. For this purpose an aSi-EPID was commissioned as a small field dosimeter. Small field output factors for 6 MV FFF beams were measured using the PTW microDiamond detector and the Agility 160-leaf MLC from Elekta. The back-projection algorithm developed in our department was modified to better model the small field physics. The feasibility of small field portal dosimetry was validated via absolute point dose differences w.r.t. small static beams, and 5 hypofractionated stereotactic VMAT clinical plans measured with the OCTAVIUS 1000 SRS array dosimeter and computed with the treatment planning system Pinnacle v16.2. Dose reconstructions using the currently clinically applied back-projection model were also computed for comparison. We found that the latter yields underdosage of about -8% for square beams with cross section near 10 mm x 10 mm and about -6% for VMAT treatments with PTV volumes smaller than about 2cm3. With the methods described in this work such errors can be reduced to less than the ±3.0% recommendations for clinical use. Our results indicate that aSi-EPIDs can be used as accurate small field radiation dosimeters, offering advantages over point dose detectors, the correct positioning and orientation of which is challenging for routine clinical QA.
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Affiliation(s)
- Aldemar Torres Valderrama
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Igor Olaciregui-Ruiz
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Patrick González
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Thijs Perik
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Ben Mijnheer
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
| | - Anton Mans
- Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan, 121 1066 CX Amsterdam, The Netherlands
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Olaciregui‐Ruiz I, Vivas‐Maiques B, Kaas J, Perik T, Wittkamper F, Mijnheer B, Mans A. Transit and non-transit 3D EPID dosimetry versus detector arrays for patient specific QA. J Appl Clin Med Phys 2019; 20:79-90. [PMID: 31083776 PMCID: PMC6560233 DOI: 10.1002/acm2.12610] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/10/2019] [Accepted: 04/23/2019] [Indexed: 01/09/2023] Open
Abstract
PURPOSE Despite their availability and simplicity of use, Electronic Portal Imaging Devices (EPIDs) have not yet replaced detector arrays for patient specific QA in 3D. The purpose of this study is to perform a large scale dosimetric evaluation of transit and non-transit EPID dosimetry against absolute dose measurements in 3D. METHODS After evaluating basic dosimetric characteristics of the EPID and two detector arrays (Octavius 1500 and Octavius 1000SRS ), 3D dose distributions for 68 VMAT arcs, and 10 IMRT plans were reconstructed within the same phantom geometry using transit EPID dosimetry, non-transit EPID dosimetry, and the Octavius 4D system. The reconstructed 3D dose distributions were directly compared by γ-analysis (2L2 = 2% local/2 mm and 3G2 = 3% global/2 mm, 50% isodose) and by the percentage difference in median dose to the high dose volume (%∆HDVD 50 ). RESULTS Regarding dose rate dependency, dose linearity, and field size dependence, the agreement between EPID dosimetry and the two detector arrays was found to be within 1.0%. In the 2L2 γ-comparison with Octavius 4D dose distributions, the average γ-pass rate value was 92.2 ± 5.2%(1SD) and 94.1 ± 4.3%(1SD) for transit and non-transit EPID dosimetry, respectively. 3G2 γ-pass rate values were higher than 95% in 150/156 cases. %∆HDVD 50 values were within 2% in 134/156 cases and within 3% in 155/156 cases. With regard to the clinical classification of alerts, 97.5% of the treatments were equally classified by EPID dosimetry and Octavius 4D. CONCLUSION Transit and non-transit EPID dosimetry are equivalent in dosimetric terms to conventional detector arrays for patient specific QA. Non-transit 3D EPID dosimetry can be readily used for pre-treatment patient specific QA of IMRT and VMAT, eliminating the need of phantom positioning.
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Affiliation(s)
- Igor Olaciregui‐Ruiz
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Begoña Vivas‐Maiques
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Jochem Kaas
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Thijs Perik
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Frits Wittkamper
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Ben Mijnheer
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
| | - Anton Mans
- Department of Radiation OncologyThe Netherlands Cancer Institute – Antoni van LeeuwenhoekAmsterdamThe Netherlands
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Jeevanandam P, Agnew CE, Irvine DM, McGarry CK. Improvement of off-axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system. Med Phys 2018; 45:1738-1747. [PMID: 29431850 DOI: 10.1002/mp.12805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 12/11/2017] [Accepted: 01/26/2018] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Stereotactic ablative body radiotherapy (SABR) for lung patients can be performed with volumetric-modulated arc therapy (VMAT) plans using off-axis target geometry to allow treatment in their CBCT verified position. For patient-specific quality assurance measurements using the PTW Octavius 4D phantom (PTW, Freiburg, Germany) (OCT4D) in conjunction with an Octavius 1000SRS array (OCT1000) (PTW, Freiburg, Germany), repositioning the phantom off-axis is required to ensure the measurement area coincides with the tumor. The aim of this work is to quantify delivery errors using an array repositioned off-axis and evaluate new software which incorporates corrections for off-axis phantom measurements. METHODS Dynamic conformal arcs and 25 lung SABR plans were created with the isocenter at the patient midline and the target volume off-axis. Measurements were acquired with an OCT4D phantom in conjunction with a 729 array (PTW, Freiburg, Germany) (OCT729) placed at isocenter. These plans were recalculated and delivered to both the OCT729 and OCT1000 arrays repositioned so that the high-dose region was at the center of the phantom. Comparisons were made using VeriSoft v7.0 (PTW, Freiburg, Germany) and the newly implemented version 7.1 with 2%/2 mm gamma criterion (10% threshold) and results correlated with off-axis distance to the tumor. RESULTS Average pass rates for VeriSoft v7.0 significantly reduced from 92.7 ± 2.4% to 84.9 ± 4.1% when the phantom was repositioned compared to the isocenter setup for the OCT729. The gamma pass rates significantly decreased the further the phantom was moved off-axis. Significantly higher pass rates were observed for the OCT1000 of 95.7 ± 3.6% and a significant decrease in gamma pass rate with off-axis phantom distance was again observed. In contrast, even with phantom repositioning, the pass rates for analysis with VeriSoft v7.1 were 93.7 ± 2.1% and 99.4 ± 1.1% for OCT729 and OCT1000, respectively. No significant difference in gamma pass rate was observed with off-axis phantom position irrespective of array type with the new software. CONCLUSION The errors in QA phantom measurements due to dose reconstruction at off-axis target geometry have been demonstrated for conformal arcs and clinical VMAT SABR plans. A novel software solution implemented by the vendor to allow accurate pass rates has been tested. This solution enables high-resolution arrays with small active detection areas to be used for quality assurance of SABR treatment plans in the off-axis treatment position.
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Affiliation(s)
- Prakash Jeevanandam
- Northern Ireland Cancer Center, Belfast City Hospital, 51 Lisburn Road, Belfast, BT9 7AB, UK
| | - Christina E Agnew
- Northern Ireland Cancer Center, Belfast City Hospital, 51 Lisburn Road, Belfast, BT9 7AB, UK
| | - Denise M Irvine
- Northern Ireland Cancer Center, Belfast City Hospital, 51 Lisburn Road, Belfast, BT9 7AB, UK
| | - Conor K McGarry
- Northern Ireland Cancer Center, Belfast City Hospital, 51 Lisburn Road, Belfast, BT9 7AB, UK.,Centre for Cancer Research and Cell Biology, Queen's University, 79 Lisburn Road, Belfast, BT9 7AE, UK
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Brualla-González L, Vázquez-Luque A, Zapata M, González-Castaño DM, Luna-Vega V, Guiu-Souto J, Prieto-Pena J, García T, Granero D, Vicedo A, Rosellò J, Pombar M, Gómez F, Pardo-Montero J. Development and clinical characterization of a novel 2041 liquid-filled ionization chambers array for high-resolution verification of radiotherapy treatments. Med Phys 2018; 45:1771-1781. [PMID: 29446083 DOI: 10.1002/mp.12816] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/10/2017] [Accepted: 02/03/2018] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The aim of this study was to present a novel 2041 liquid-filled ionization chamber array for high-resolution verification of radiotherapy treatments. MATERIALS AND METHODS The prototype has 2041 ionization chambers of 2.5 × 2.5 mm2 area filled with isooctane. The detection elements are arranged in a central square grid of 43 × 43, totally covering an area of 107.5 × 107.5 mm2 . The central inline and cross-line are extended to 227 mm and the diagonals to 321 mm to be able to perform profile measurements of large fields. We have studied stability, pixel response uniformity, dose rate dependence, depth and field size dependence and anisotropy. We present results for output factors, tongue-and-groove, garden fence, small field profiles, irregular fields, and verification of dose planes of patient treatments. RESULTS Comparison with other detectors used for small field dosimetry (SFD, CC13, microDiamond) has shown good agreement. Output factors measured with the device for square fields ranging from 10 × 10 to 100 × 100 mm2 showed relative differences within 1%. The response of the detector shows a strong dependence on the angle of incident radiation that needs to be corrected for. On the other hand, inter-pixel relative response variations in the 0.95-1.08 range have been found and corrected for. The application of the device for the verification of dose planes of several treatments has shown gamma passing rates above 97% for tolerances of 2% and 2 mm. The verification of other clinical fields, like small fields and irregular fields used in the commissioning of the TPS, also showed large passing rates. The verification of garden fence and tongue-and-groove fields was affected by volume-averaging effects. CONCLUSIONS The results show that the liquid filled ionization chamber prototype here presented is appropriate for the verification of radiotherapy treatments with high spatial resolution. Recombination effects do not affect very much the verification of relative dose distributions. However, verification of absolute dose distributions may require normalization to a radiation field which is representative of the dose rate of the treatment delivered.
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Affiliation(s)
- Luis Brualla-González
- Servicio de Radiofísica, ERESA, Hospital General Universitario de Valencia, Avd. Tres Cruces 2, 46014, Valencia, Spain
| | - Aurelio Vázquez-Luque
- Detection and Radiation Technologies (DART), Edificio Emprendia, 15782, Santiago de Compostela, Spain.,Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Sur s/n, 15782, Santiago de Compostela, Spain
| | - Martín Zapata
- Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Diego Miguel González-Castaño
- Laboratorio de Radiofísica, RIAIDT, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain.,Grupo de Imaxe Molecular, Instituto de Investigación Sanitaria (IDIS), Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Víctor Luna-Vega
- Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Jacobo Guiu-Souto
- Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Juan Prieto-Pena
- Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Sur s/n, 15782, Santiago de Compostela, Spain
| | - Trinitat García
- Servicio de Radiofísica, ERESA, Hospital General Universitario de Valencia, Avd. Tres Cruces 2, 46014, Valencia, Spain
| | - Domingo Granero
- Servicio de Radiofísica, ERESA, Hospital General Universitario de Valencia, Avd. Tres Cruces 2, 46014, Valencia, Spain
| | - Aurora Vicedo
- Servicio de Radiofísica, ERESA, Hospital General Universitario de Valencia, Avd. Tres Cruces 2, 46014, Valencia, Spain
| | - Joan Rosellò
- Servicio de Radiofísica, ERESA, Hospital General Universitario de Valencia, Avd. Tres Cruces 2, 46014, Valencia, Spain
| | - Miguel Pombar
- Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain.,Grupo de Imaxe Molecular, Instituto de Investigación Sanitaria (IDIS), Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Faustino Gómez
- Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Sur s/n, 15782, Santiago de Compostela, Spain.,Grupo de Imaxe Molecular, Instituto de Investigación Sanitaria (IDIS), Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
| | - Juan Pardo-Montero
- Servizo de Radiofísica e Protección Radiolóxica, Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain.,Grupo de Imaxe Molecular, Instituto de Investigación Sanitaria (IDIS), Complexo Hospitalario Universitario de Santiago, Travesía da Choupana s/n, 15706, Santiago de Compostela, Spain
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