1
|
Radici L, Petrucci E, Casanova Borca V, Cante D, Piva C, Pasquino M. Impact of beam complexity on plan delivery accuracy verification of a transmission detector in volumetric modulated arc therapy. Phys Med 2024; 122:103387. [PMID: 38797025 DOI: 10.1016/j.ejmp.2024.103387] [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: 06/22/2023] [Revised: 04/22/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024] Open
Abstract
OBJECTIVE To study the effect of beam complexity on VMAT delivery accuracy evaluated by means of a transmission detector, together with the possibility of scoring plan complexity. METHODS 43 clinical VMAT plans delivered by a TrueBeam linear accelerator to both Delta4 Discover and Delta4 Phantom+ for patient-specific quality assurance were evaluated. Global Dose-γ analysis, MLC-γ analysis, percentage of leaves with a deviation between planned and measured leaf tip position lower than 1 mm (LD) were computed. Modulation complexity score (MCSv), average leaf travel (LT), a multiplicative combination of LT and MCSv (LTMCS), percentage of leaves with speed lower than 5 mm/s (LS), from 5 to 20 mm/s (MS), higher than 20 mm/s (HS) and the average value of leaf speed (MLCSav) were evaluated by means of an home-made Matlab script. RESULTS Dose-γ passing rate showed a moderate correlation with MCSv, LT, MLCSav, LS and HS, while a stronger positive correlation was found with LTMCS. A strong correlation was observed between LD and both LT and leaves speed, while a weak correlation was observed with MCSv. A correlation between MLC-γ pass rate and plan complexity parameters was found except for MCSv; a moderate correlation with LS was observed, while all other parameters showed weak correlations. CONCLUSIONS The study confirmed the possibility to establish correlations between plan complexity indices versus dose distribution and MLC parameters measured by a transmissive detector. Further investigation is necessary to define specific values of the complexity indices to evaluate whether a VMAT plan is deliverable as intended.
Collapse
|
2
|
Seo J, Lee H, Hwan Ahn S, Yoon M. Feasibility study of a scintillation sheet-based detector for fluence monitoring during external photon beam radiotherapy. Phys Med 2023; 112:102628. [PMID: 37354806 DOI: 10.1016/j.ejmp.2023.102628] [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: 11/20/2022] [Revised: 03/24/2023] [Accepted: 06/13/2023] [Indexed: 06/26/2023] Open
Abstract
PURPOSE This study evaluated the properties of a scintillation sheet-based dosimetry system for beam monitoring with high spatial resolution, including the effects of this system on the treatment beam. The dosimetric characteristics and feasibility of this system for clinical use were also evaluated. METHODS The effects of the dosimetry system on the beam were evaluated by measuring the percentage depth doses, dose profiles, and transmission factors. Fifteen treatment plans were created, and the influence of the dosimetry system on these clinical treatment plans was evaluated. The performance of the system was assessed by determining signal linearity, dose rate dependence, and reproducibility. The feasibility of the system for clinical use was evaluated by comparing intensity distributions with reference intensity distributions verified by quality assurance. RESULTS The spatial resolution of the dosimetry system was found to be 0.43 mm/pixel when projected to the isocenter plane. The dosimetry system attenuated the intensity of 6 MV beams by about 1.1%, without affecting the percentage depth doses and dose profiles. The response of the dosimetry system was linear, independent of the dose rate used in the clinic, and reproducible. Comparison of intensity distributions of evaluation treatment fields with reference intensity distributions showed that the 1%/1 mm average gamma passing rate was 99.6%. CONCLUSIONS The dosimetry system did not significantly alter the beam characteristics, indicating that the system could be implemented by using only a transmission factor. The dosimetry system is clinically suitable for monitoring treatment beam delivery with higher spatial resolution than other transmission detectors.
Collapse
Affiliation(s)
- Jaehyeon Seo
- Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea; Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon, Republic of Korea
| | - Hyunho Lee
- Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea; Department of Radiation Oncology, Samsung Medical Center, Seoul, Republic of Korea
| | - Sung Hwan Ahn
- Department of Radiation Oncology, Samsung Medical Center, Seoul, Republic of Korea.
| | - Myonggeun Yoon
- Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea; FieldCure Ltd, Seoul, Republic of Korea.
| |
Collapse
|
3
|
Guo Y, Li B, Li Y, Du W, Feng W, Feng S, Miao G. Application of a linear interpolation algorithm in radiation therapy dosimetry for 3D dose point acquisition. Sci Rep 2023; 13:4539. [PMID: 36941321 PMCID: PMC10027884 DOI: 10.1038/s41598-023-31562-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 03/14/2023] [Indexed: 03/23/2023] Open
Abstract
Air-vented ion chambers are generally used in radiation therapy dosimetry to determine the absorbed radiation dose with superior precision. However, in ion chamber detector arrays, the number of array elements and their spacing do not provide sufficient spatial sampling, which can be overcome by interpolating measured data. Herein, we investigated the potential principle of the linear interpolation algorithm in volumetric dose reconstruction based on computed tomography images in the volumetric modulated arc therapy (VMAT) technique and evaluated how the ion chamber spacing and anatomical mass density affect the accuracy of interpolating new data points. Plane measurement doses on 83 VMAT treatment plans at different anatomical sites were acquired using Octavius 729, Octavius1500, and MatriXX ion chamber detector arrays, followed by the linear interpolation to reconstruct volumetric doses. Dosimetric differences in planning target volumes (PTVs) and organs at risk (OARs) between treatment planning system and reconstruction were evaluated by dose volume histogram metrics. The average percentage dose deviations in the mean dose (Dmean) of PTVs reconstructed by 729 and 1500 arrays ranged from 4.7 to 7.3% and from 1.5 to 2.3%, while the maximum dose (Dmax) counterparts ranged from 2.3 to 5.5% and from 1.6 to 7.6%, respectively. The average percentage dose/volume deviations of mixed PTVs and OARs in the abdomen/gastric and pelvic sites were 7.6%, 3.5%, and 7.2%, while mediastinum and lung plans showed slightly larger values of 8.7%, 5.1%, and 8.9% for 729, 1500, and MatriXX detector arrays, respectively. Our findings indicated that the smaller the spacing between neighbouring detectors and the more ion chambers present, the smaller the error in interpolating new data points. Anatomical regions with small local mass density inhomogeneity were associated with superior dose reconstruction. Given a large mass density difference in the various human anatomical structures and the characteristics of the linear interpolation algorithm, we suggest that an alternative data interpolation method should be used in radiotherapy dosimetry.
Collapse
Affiliation(s)
- Yixiao Guo
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Bo Li
- Department of Bone and Soft-Tissue Carcinoma, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Yazhou Li
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Wen Du
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Weigui Feng
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Shifang Feng
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China
| | - Guoying Miao
- Department of Radiation Oncology, Gansu Provincial Hospital, Lanzhou, 730000, People's Republic of China.
| |
Collapse
|
4
|
Velthuis J, Li Y, Pritchard J, De Sio C, Beck L, Hugtenburg R. Performance of a Full-Scale Upstream MAPS-Based Verification Device for Radiotherapy. SENSORS (BASEL, SWITZERLAND) 2023; 23:1799. [PMID: 36850398 PMCID: PMC9960806 DOI: 10.3390/s23041799] [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: 11/29/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
Intensity-modulated radiotherapy is a widely used technique for accurately targeting cancerous tumours in difficult locations using dynamically shaped beams. This is ideally accompanied by real-time independent verification. Monolithic active pixel sensors are a viable candidate for providing upstream beam monitoring during treatment. We have already demonstrated that a Monolithic Active Pixel Sensor (MAPS)-based system can fulfill all clinical requirements except for the minimum required size. Here, we report the performance of a large-scale demonstrator system consisting of a matrix of 2 × 2 sensors, which is large enough to cover almost all radiotherapy treatment fields when affixed to the shadow tray of the LINAC head. When building a matrix structure, a small dead area is inevitable. Here, we report that with a newly developed position algorithm, leaf positions can be reconstructed over the entire range with a position resolution of below ∼200 μm in the centre of the sensor, which worsens to just below 300 μm in the middle of the gap between two sensors. A leaf position resolution below 300 μm results in a dose error below 2%, which is good enough for clinical deployment.
Collapse
Affiliation(s)
- Jaap Velthuis
- School of Physics, University of Bristol, Bristol BS7 1TL, UK
- Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea University, Swansea SA2 8PP, UK
- School of Nuclear Science and Technology, University of South China, Hengyang 421001, China
| | - Yutong Li
- School of Physics, University of Bristol, Bristol BS7 1TL, UK
| | | | - Chiara De Sio
- School of Physics, University of Bristol, Bristol BS7 1TL, UK
| | - Lana Beck
- School of Physics, University of Bristol, Bristol BS7 1TL, UK
| | - Richard Hugtenburg
- School of Physics, University of Bristol, Bristol BS7 1TL, UK
- Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea University, Swansea SA2 8PP, UK
- Department of Medical Physics and Clinical Engineering, Swansea Bay University Health Board, Swansea SA2 4QA, UK
| |
Collapse
|
5
|
Casanova Borca V, Radici L, Petrucci E, Piva C, Cante D, Pasquino M. Preliminary evaluation of a novel secondary check tool for intensity modulated radiotherapy treatment planning. Phys Med 2023; 106:102528. [PMID: 36610176 DOI: 10.1016/j.ejmp.2023.102528] [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: 08/29/2022] [Revised: 01/02/2023] [Accepted: 01/02/2023] [Indexed: 01/07/2023] Open
Abstract
PURPOSE To evaluate the dosimetric accuracy of the Delta4 Insight (DI) secondary-check dosimetry system. METHODS Absolute dosimetry in reference conditions, output factors, percent depth doses normalized and off-axis dose profiles for different field sizes calculated by DI were compared with measurements. Dose calculations for 20 clinical IMRT/VMAT plans generated in the TPS using both AAA or AcurosXB algorithms were compared with measurements. The average difference between calculated and measured point dose in high-dose region was calculated for all cases. 3D dose measurements were performed in Delta4 Phantom+ and a comparison between calculated and measured dose distributions was performed by means of the gamma analysis with 3 %/2 mm criteria. The dose distributions calculated by DI for 20 IMRT/VMAT plans were compared with those calculated by the TPS. RESULTS The absolute dosimetry computed by DI showed dose value in agreement with the measured one within 0.3 %. The average differences between measured and calculated output factors were less than 2.5 %. The average PDD differences were less than 0.6 %. An excellent agreement between calculations and off-axis measurements is found. The point doses calculated for the 20 recalculated plan showed good agreement with measurements with average differences less than 0.5 %. The average gamma pass rate values for the Delta4 Phantom + 3D dose analysis was greater than 97.%. The comparison of DI with theTPS showed good agreement for the used metrics. CONCLUSIONS Delta4 Insight may provide a useful independent secondary dose verification system for IMRT/VMAT plans, complementing the traditional global QA protocols.
Collapse
Affiliation(s)
| | - Lorenzo Radici
- Medical Physics Department, A.S.L. TO4, 10015 Ivrea (TO), Italy
| | | | - Cristina Piva
- Radiotherapy Department, A.S.L. TO4, 10015 Ivrea (TO), Italy
| | - Domenico Cante
- Radiotherapy Department, A.S.L. TO4, 10015 Ivrea (TO), Italy
| | - Massimo Pasquino
- Medical Physics Department, A.S.L. TO4, 10015 Ivrea (TO), Italy.
| |
Collapse
|
6
|
Hoegele W, Zygmanski P. Strip detector array (SDA) for beam monitoring in radiotherapy: reconstruction of MLC parameters from multiple projections of flux. Biomed Phys Eng Express 2022; 8. [PMID: 35803210 DOI: 10.1088/2057-1976/ac7fbc] [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: 05/26/2022] [Accepted: 07/08/2022] [Indexed: 11/11/2022]
Abstract
Objective:In this paper we propose and investigate a new detector with multiple strip detector arrays (SDA) for monitoring MLC shaped x-ray beams for radiotherapy treatment.Approach:Each SDA measures 1D dose profiles equivalent to dose projections. The goal of such a detector is to determine individual MLC leaf positions as well as the Monitor Units (MU) per MLC segment during radiotherapy. In the present work we investigate an optimal SDA detector configuration and reconstruction algorithm. We determine the accuracy of SDA for different treatment sites (spine, pelvis, retroperitoneum, prostate, brain SRT, SRS, lung and head and neck). We perform a simulation study accounting for different type of MLC leaf positional errors: random MLC leaf, systematic for the whole leaf bank and systematic for an individual leaf. In a similar fashion, we also account for errors in Monitor Units per segment.Main results:We demonstrate that for a broad range of IMRT treatment plans a robust reconstruction of errors is achievable with only 3 projections (3 sets of SDA oriented at at 0◦, 45◦ and 135◦). The SDA is capable of capturing both systematic errors in leaf banks and individual leaves as well as random errors sufficient for practical clinical purposes.Significance:These features of the SDA detector makes it suitable for real-time Quality Control of MLC collimated linac output.
Collapse
Affiliation(s)
- Wolfgang Hoegele
- Computer Science and Mathematics, Munich University of Applied Sciences, Lothstraße 64, Munich, Bavaria, 80335, GERMANY
| | - Piotr Zygmanski
- Radiation Oncology, Brigham and Women's Hospital & Harvard Medical School, 75 Francis Street, Boston, Massachusetts, 02115, UNITED STATES
| |
Collapse
|