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Duggar WN, Morris B, He R, Yang C. Total workflow uncertainty of frameless radiosurgery with the Gamma Knife Icon cone-beam computed tomography. J Appl Clin Med Phys 2022; 23:e13564. [PMID: 35157361 PMCID: PMC9121051 DOI: 10.1002/acm2.13564] [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: 10/29/2021] [Revised: 12/29/2021] [Accepted: 02/01/2022] [Indexed: 11/21/2022] Open
Abstract
Objective Frameless treatment with the Gamma Knife Icon is still relatively new as a treatment option. As a result, additional confidence/knowledge about the uncertainty that exists within each portion of the treatment workflow could be gained especially regarding steps that have not been previously studied in the literature. Methods The Icon base delivery device (Perfexion) uncertainty is quantified and validated. The novel portions of the Icon such as mask immobilization, cone‐beam computed tomography image guidance, and the intrafraction motion management methods are studied specifically and to a greater extent to determine a total workflow uncertainty of frameless treatment with the Icon. Results The uncertainty of each treatment workflow step has been identified with the total workflow uncertainty being identified in this work as 1.3 mm with a standard deviation of 0.51 mm. Conclusion The total uncertainty of frameless treatment with the Icon has been evaluated and this data may indicate the need for setup margin in this setting with data that could be used by other institutions to calculate needed setup margin per their preferred recipe after validation of this data in their context.
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Affiliation(s)
- William N Duggar
- Department of Radiation Oncology, University of MS Medical Center, Jackson, Mississippi, USA
| | - Bart Morris
- Department of Radiation Oncology, University of MS Medical Center, Jackson, Mississippi, USA
| | - Rui He
- Department of Radiation Oncology, University of MS Medical Center, Jackson, Mississippi, USA
| | - Claus Yang
- Department of Radiation Oncology, University of MS Medical Center, Jackson, Mississippi, USA
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2
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Duggar WN, Morris B, He R, Yang CC. Ramifications of Setup Margin Use During Frameless Stereotactic Radiosurgery/Therapy With Gamma Knife Icon Cone-Beam Computed Tomography (CBCT): A Dosimetric Study. Cureus 2022; 14:e21996. [PMID: 35282559 PMCID: PMC8906882 DOI: 10.7759/cureus.21996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2022] [Indexed: 11/05/2022] Open
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Zhang M, Fan Q, Lei Y, Thapa B, Padula G. Assessment of an Elekta Versa HD linear accelerator for stereotactic radiosurgery with circular cone collimators. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2020; 28:71-82. [PMID: 31904001 DOI: 10.3233/xst-190580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
BACKGROUND Versa HD linear accelerators (linacs) are used for stereotactic radiosurgery treatment. However, the mechanical accuracy of such systems remains a concern. OBJECTIVE The purpose of this study was to evaluate the accuracy of an Elekta Versa HD linac. METHODS We performed measurements with a ball bearing phantom to calculate the rotational isocenter radii of the linac's gantry, collimator, and table, and determine the relative locations of those isocenters. We evaluated the accuracy of the cone-beam computed tomography (CBCT) guidance with a film-embedding head phantom and circular cone-collimated radiation beams. We also performed dosimetric simulations to study the effects of the linac mechanical uncertainties on non-coplanar cone arc delivery. RESULTS The mechanical uncertainty of the linac gantry rotation was 0.78 mm in radius, whereas that of the collimator and the table was <0.1 mm and 0.33 mm, respectively. The axes of rotation of the collimator and the table were coinciding with and 0.13 mm away from the gantry isocenter, respectively. Experiments with test plans demonstrated the limited dosimetric consequences on the circular arc delivery given the aforementioned mechanical uncertainties. End-to-end measurements determined that the uncertainty of the CBCT guidance was≤1 mm in each direction with respect to the reference CT image. CONCLUSIONS In arc delivery, the mechanical uncertainties associated with the gantry and the table do not require remarkable increases in geometric margins. If large enough, the residual setup errors following CBCT guidance will dominate the overall dosimetric consequence. Therefore, the Versa HD linac is a valid system for stereotactic radiosurgery using non-coplanar arc delivery.
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Affiliation(s)
- Mutian Zhang
- Radiation Therapy, Summa Health Cancer Institute, Akron, Ohio, USA
| | - Qiyong Fan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yu Lei
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Bishnu Thapa
- Radiation Therapy, Summa Health Cancer Institute, Akron, Ohio, USA
| | - Gilbert Padula
- Radiation Therapy, Summa Health Cancer Institute, Akron, Ohio, USA
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Calvo-Ortega JF, Moragues-Femenía S, Laosa-Bello C, San José-Maderuelo S, Casals-Farran J. A closer look at the conventional Winston-Lutz test: Analysis in terms of dose. Rep Pract Oncol Radiother 2019; 24:421-427. [PMID: 31367194 DOI: 10.1016/j.rpor.2019.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 04/27/2019] [Accepted: 07/06/2019] [Indexed: 10/26/2022] Open
Abstract
Aim To investigate whether the target-isocenter deviations reported by a conventional Winston-Lutz (WL) test actually reflect the shifts of the measured prescription isodose line with respect to the target. Background A conventional WL test uses a metallic ball as a target that aims at several fields. But this test does not report information on the accuracy of the delivery in terms of dose. Materials and methods A conventional WL test using a metallic pointer as a target (Pointer-WL test) has been recreated in the Eclipse treatment planning system over an acrylic phantom containing a radiochromic film (Dose-WL test). After Dose-WL test delivery, the shift of the 80% prescription isodose line with respect to the target center (d80%-center) was measured using film dosimetry. The Pointer-WL and Dose-WL tests were performed in 10 different sessions. The isocenter deviation reported by the Pointer-WL test was compared to the d80%-center vector, according to the three patient's directions (Left-Right or LR; Anterior-Posterior or AP; and Superior-Inferior or SI). Results The deviations (mean ± SD) found for the Dose-WL tests (LR: 0.5 ± 0.4 mm; AP: 0.5 ± 0.4 mm; SI: 0.6 ± 0.2 mm) were in most cases less than 1 mm, and they were significantly smaller (all p < 0.05) than the maximum deviations reported by the Pointer-WL tests (LR: 1.3 ± 0.3 mm; AP: 1.2 ± 0.4 mm; SI: 1.1 ± 0.3 mm). Conclusions The Dose-WL test described in this study allows estimating the spatial accuracy of the prescription isodose line.
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Affiliation(s)
- Juan-Francisco Calvo-Ortega
- Servicio de Oncología Radioterápica, Hospital Quirónsalud, Barcelona, Spain.,Servicio de Oncología Radioterápica, Hospital Universitari Dexeus, Barcelona, Spain
| | - Sandra Moragues-Femenía
- Servicio de Oncología Radioterápica, Hospital Quirónsalud, Barcelona, Spain.,Servicio de Oncología Radioterápica, Hospital Universitari Dexeus, Barcelona, Spain
| | - Coral Laosa-Bello
- Servicio de Oncología Radioterápica, Hospital Quirónsalud, Barcelona, Spain.,Servicio de Oncología Radioterápica, Hospital Universitari Dexeus, Barcelona, Spain
| | - Sol San José-Maderuelo
- Servicio de Oncología Radioterápica, Hospital Quirónsalud, Barcelona, Spain.,Servicio de Oncología Radioterápica, Hospital Universitari Dexeus, Barcelona, Spain
| | - Joan Casals-Farran
- Servicio de Oncología Radioterápica, Hospital Quirónsalud, Barcelona, Spain.,Servicio de Oncología Radioterápica, Hospital Universitari Dexeus, Barcelona, Spain
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Fatemi A, Kanakamedala MR, Yang CC, Morris B, Duggar WN, Vijayakumar S. Evaluation of the Geometric and Dosimetric Accuracy of Synthetic Computed Tomography Images for Magnetic Resonance Imaging-only Stereotactic Radiosurgery. Cureus 2019; 11:e4404. [PMID: 31245194 PMCID: PMC6559689 DOI: 10.7759/cureus.4404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Introduction Stereotactic radiosurgery (SRS) plans created using synthetic computed tomography (CT) images derived from magnetic resonance imaging (MRI) data may offer the advantage of inhomogeneity correction by convolution algorithms, as is done for CT-based plans. We sought to determine and validate the clinical significance and accuracy of synthetic CT images for inhomogeneity correction in MRI-only stereotactic radiosurgery plans for treatment of brain tumors. Methods In this retrospective study, data from two patients with brain metastases and one with meningioma who underwent imaging with multiple modalities and received frameless SRS treatment were analyzed. The SRS plans were generated using a convolution algorithm to account for brain inhomogeneity using CT and synthetic CT images and compared with the original clinical TMR10 plans created using MRI images. Results Synthetic CT-derived SRS plans are comparable with CT-based plans using convolution algorithm, and for some targets, based on location, they provided better coverage and a lower maximum dose. Conclusions The results suggest similar dose delivery results for CT and synthetic CT-based treatment plans. Synthetic CT plans offered a noticeable improvement in target dose coverage and a more gradual dose fall-off relative to TMR10 MRI-based plans. The major disadvantage is a slightly increased dose (by 0.37%) to nearby healthy tissue (brainstem) for synthetic CT-based plans relative to those created using clinical MRI images, which may be a problem for patients undergoing high-dose treatment.
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Affiliation(s)
- Ali Fatemi
- Radiation Oncology, University of Mississippi Medical Center, Jackson, USA
| | | | - Claus Chunli Yang
- Radiation Oncology, University of Mississippi Medical Center, Jackson, USA
| | - Bart Morris
- Radiation Oncology, University of Mississippi Medical Center, Jackson, USA
| | - William N Duggar
- Radiation Oncology, University of Mississippi Medical Center, Jackson, USA
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Duan X, Giles W, Kirkpatrick JP, Yin FF. The effect of setup uncertainty on optimal dosimetric margin in LINAC-based stereotactic radiosurgery with dynamic conformal arc technique. JOURNAL OF RADIOSURGERY AND SBRT 2019; 6:55-65. [PMID: 30775075 PMCID: PMC6355454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/19/2018] [Indexed: 06/09/2023]
Abstract
PURPOSE To estimate the combined effect of setup uncertainty on optimal dosimetric margin by analyzing the dose distribution and biological effect in LINAC-based stereotactic radiosurgery (SRS) with dynamic conformal arc (DCA) technique. METHODS SRS treatment plans were generated from CT scans of the Rando head phantom using four non-coplanar DCA's with total 480-degrees of arc. A single spherical planning target volume (PTV) of 4 different diameters was placed at the center of the phantom to simulate brain lesions. For each PTV, 5 treatment plans were created using identical dose calculation parameters, each with 5 different dosimetric margins. To simulate the effect of setup uncertainty, the isocenter for each plan was shifted to 13 different positions. A marginal dose of 20Gy in a single fraction with 6MV photon beam was prescribed to 49 different percentage isodose surfaces (%IDS). The plan quality was evaluated using Conformity Index (CI), Gradient Index (GI), EUD-based Tumor Control Probability (TCP), Normal Tissue Complication Probability (NTCP), and uncomplicated biological objective function (TCP x (1-NTCP) =p+). RESULTS A +1mm dosimetric margin could result in a much higher p+ compared to 0mm and 1mm dosimetric margins and a smaller GI while achieving an equivalent p+ in a certain range of %IDS compared to +2mm and +3mm dosimetric margins. With 2mm setup error and +1mm dosimetric margin, the %IDS range optimized for each PTV is: around 80%IDS (10mm diameter); 63~70%IDS (20mm diameter); 66~79%IDS (30mm diameter). CONCLUSION This simulation study identified the preferred prescription %IDS for a given setup error and dosimetric margin to achieve an optimal dose distribution and favorable biological effect.
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Affiliation(s)
- Xiaoyu Duan
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
| | - William Giles
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
| | - John P. Kirkpatrick
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
- Department of Neurosurgery, Duke University Medical Center, Durham, NC 27710, USA
| | - Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
- Medical Physics Graduate Program, Duke Kunshan University, Kunshan, Jiangsu, 215316, China
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A comparison of clinical and radiologic outcomes between frame-based and frameless stereotactic radiosurgery for brain metastases. Pract Radiat Oncol 2016; 6:e283-e290. [DOI: 10.1016/j.prro.2016.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 04/26/2016] [Accepted: 05/05/2016] [Indexed: 11/18/2022]
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Fractionated stereotactic radiation therapy for vestibular schwannomas: Dosimetric factors predictive of hearing outcomes. Pract Radiat Oncol 2016; 6:e155-e162. [DOI: 10.1016/j.prro.2015.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/31/2015] [Accepted: 11/27/2015] [Indexed: 11/21/2022]
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Calvo Ortega JF, Wunderink W, Delgado D, Moragues S, Pozo M, Casals J. Evaluation of the setup margins for cone beam computed tomography-guided cranial radiosurgery: A phantom study. Med Dosim 2016; 41:199-204. [PMID: 26994824 DOI: 10.1016/j.meddos.2015.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 12/01/2015] [Accepted: 12/29/2015] [Indexed: 12/31/2022]
Abstract
The aim of this study is to evaluate the setup margins from the clinical target volume (CTV) to planning target volume (PTV) for cranial stereotactic radiosurgery (SRS) treatments guided by cone beam computed tomography (CBCT). We designed an end-to-end (E2E) test using a skull phantom with an embedded 6mm tungsten ball (target). A noncoplanar plan was computed (E2E plan) to irradiate the target. The CBCT-guided positioning of the skull phantom on the linac was performed. Megavoltage portal images were acquired after 15 independent deliveries of the E2E plan. The displacement 2-dimensional (2D) vector between the centers of the square field and the ball target on each portal image was used to quantify the isocenter accuracy. Geometrical margins on each patient׳s direction (left-right or LR, anterior-posterior or AP, superior-inferior or SI) were calculated. Dosimetric validation of the margins was performed in 5 real SRS cases: 3-dimesional (3D) isocenter deviations were mimicked, and changes in CTV dose coverage and organs-at-risk (OARs) dosage were analyzed. The CTV-PTV margins of 1.1mm in LR direction, and 0.7mm in AP and SI directions were derived from the E2E tests. The dosimetric analysis revealed that a 1-mm uniform margin was sufficient to ensure the CTV dose coverage, without compromising the OAR dose tolerances. The effect of isocenter uncertainty has been estimated to be 1mm in our CBCT-guided SRS approach.
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Affiliation(s)
| | - Wouter Wunderink
- Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - David Delgado
- Department of Radiation Oncology, Hospital Quirón, Barcelona, Spain
| | - Sandra Moragues
- Department of Radiation Oncology, Hospital Quirón, Barcelona, Spain
| | - Miquel Pozo
- Department of Radiation Oncology, Hospital Quirón, Barcelona, Spain
| | - Joan Casals
- Department of Radiation Oncology, Hospital Quirón, Barcelona, Spain
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Sun Y, Ge H, Cheng S, Yang C, Zhu Q, Li D, Tian Y. Evaluation of interfractional variation of the centroid position and volume of internal target volume during stereotactic body radiotherapy of lung cancer using cone-beam computed tomography. J Appl Clin Med Phys 2016; 17:461-472. [PMID: 27074466 PMCID: PMC5874940 DOI: 10.1120/jacmp.v17i2.5835] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 02/14/2016] [Accepted: 11/04/2015] [Indexed: 12/25/2022] Open
Abstract
The purpose of this study was to determine interfractional variation of the centroid position and volume of internal target volume (ITV) during stereotactic body radiation therapy (SBRT) of lung cancer. From January 2014 to August 2014, a total of 32 patients with 37 primary or metastatic lung tumors were enrolled in our study. All patients received SBRT treatment in 4-5 fractions to a median dose of 48 Gy. Both 3D CT and 4D CT scans were used for radiotherapy treatment planning. 3D CBCT was acquired prior to treatment delivery to verify patient positioning. A total of 163 3D CBCT images were available for evaluation. 3D CBCT scans acquired for verification were registered with simulation CT scans. The ITVs were contoured on all verification 3D CBCT scans and compared to the initial gross target volume (GTV) or ITV in treatment planning system. GTV was based on 3D CT while ITV was based on both 3D CT and 4D CT. To assess the interfractional variation of ITV centroid position, we used vertebrae body adja-cent to the tumor as reference point when performing the registration procedure. To eliminate the effect of time on tumor volume between simulation CT scan and the first fraction, the interfractional variation of ITV was evaluated from the first fraction to the last fraction. The overall 3D vector shift was 4.4 ± 2.5 mm (range: 0.4-13.8 mm). The interfractional variation of ITV centroid position in superior-inferior, anterior-posterior, and left-right directions were -0.7 ± 2.7 mm, -1.4 ± 3.4 mm, and -0.5 ± 2.2 mm, respectively. No significant difference was observed between three directions (p = 0.147). Large interfractional variations (≥ 5 mm) were observed in 12 fractions (9.3%) in superior-inferior direction, 24 fractions (18.6%) in anterior-posterior direction, and 5 fractions (3.9%) in left-right direction. No time trend of tumor volume change measured in 3D CBCT was detected during four fractions (p = 0.074). A significant (p = 0.010) time trend was detected when evaluating the time trend of ITV change during 5 fractions and diameter was found to be significantly correlated with the ITV change (p = 0.000). ITV did not show significant regression during SBRT treatment, but interfractional variation in the ITV centroid position was observed, especially in anterior-posterior direc-tion. An isotropic margin of 7 mm around ITV might be necessary for adequate coverage of interfractional variation of ITV centroid position, but only in case no soft tissue-based setup is performed during SBRT treatment.
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Affiliation(s)
- Yanan Sun
- The Affiliated Cancer Hospital of Zhengzhou University.
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11
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Zhang M, Zhang Q, Gan H, Li S, Zhou SM. Setup uncertainties in linear accelerator based stereotactic radiosurgery and a derivation of the corresponding setup margin for treatment planning. Phys Med 2016; 32:379-85. [DOI: 10.1016/j.ejmp.2016.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/12/2016] [Accepted: 02/02/2016] [Indexed: 11/28/2022] Open
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Zhang Q, Tian S, Borasi G. A new definition of biological effective dose: The dose distribution effects. Phys Med 2015; 31:1060-1064. [DOI: 10.1016/j.ejmp.2015.07.145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/05/2015] [Accepted: 07/06/2015] [Indexed: 12/30/2022] Open
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Wang CW, Lin YC, Tseng HM, Xiao F, Chen CM, Cheng WL, Lu SH, Lan KH, Chen WY, Liang HK, Kuo SH. Prolonged treatment time deteriorates positioning accuracy for stereotactic radiosurgery. PLoS One 2015; 10:e0123359. [PMID: 25894841 PMCID: PMC4404334 DOI: 10.1371/journal.pone.0123359] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Accepted: 03/02/2015] [Indexed: 12/25/2022] Open
Abstract
Introduction The accuracy of radiation delivery is increasingly important as radiotherapy technology continues to develop. The goal of this study was to evaluate intrafractional motion during intracranial radiosurgery and the relationship between motion change and treatment time. Methods and Materials A total of 50 treatment records with 5988 images, all acquired during treatments with the CyberKnife Radiosurgery System, were retrospectively analyzed in this study. We measured translation and rotation motion including superior-inferior (SI), right-left (RL), anterior-posterior (AP), roll, tilt and yaw. All of the data was obtained during the first 45 minutes of treatment. The records were divided into 3 groups based on 15-min time intervals following the beginning of treatment: group A (0-15 min), group B (16-30 min) and group C (31-45 min). The mean deviations, systematic errors, random errors and margin for planning target volume (PTV) were calculated for each group. Results The mean deviations were less than 0.1 mm in all three translation directions in the first 15 minutes. Greater motion occurred with longer treatment times, especially in the SI direction. For the 3D vector, a time-dependent change was observed, from 0.34 mm to 0.77 mm (p=0.01). There was no significant correlation between the treatment time and deviations in the AP, LR and rotation axes. Longer treatment times were associated with increases in systematic error, but not in random error. The estimated PTV margin for groups A, B and C were 0.86 / 1.14 / 1.31 mm, 0.75 / 1.12 / 1.20 mm, and 0.43 / 0.54 / 0.81 mm in the SI, RL, and AP directions, respectively. Conclusions During intracranial radiosurgery, a consistent increase in the positioning deviation over time was observed, especially in the SI direction. If treatment time is greater than 15 minutes, we recommend increasing the PTV margins to ensure treatment precision.
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Affiliation(s)
- Chun-Wei Wang
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Radiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yin-Chun Lin
- CyberKnife Center, National Taiwan University Hospital, Taipei, Taiwan
| | - Ham-Min Tseng
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Furen Xiao
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Chang-Mu Chen
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Wei-Li Cheng
- CyberKnife Center, National Taiwan University Hospital, Taipei, Taiwan
| | - Szu-Huai Lu
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
| | - Keng-Hsueh Lan
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
| | - Wan-Yu Chen
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
| | - Hsiang-Kuang Liang
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
| | - Sung-Hsin Kuo
- Division of Radiation Oncology, Departments of Oncology, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Oncology, National Taiwan University, Taipei, Taiwan
- * E-mail:
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Calvo-Ortega JF, Moragues S, Pozo M, Delgado D, Casals J. Dosimetric feasibility of an "off-target isocenter" technique for cranial intensity-modulated radiosurgery. Med Dosim 2015; 40:279-84. [PMID: 25824421 DOI: 10.1016/j.meddos.2015.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 10/03/2014] [Accepted: 02/23/2015] [Indexed: 12/31/2022]
Abstract
To evaluate the dosimetric effect of placing the isocenter away from the planning target volume (PTV) on intensity-modulated radiosurgery (IMRS) plans to treat brain lesions. A total of 15 patients who received cranial IMRS at our institution were randomly selected. Each patient was treated with an IMRS plan designed with the isocenter located at the target center (plan A). A second off-target isocenter plan (plan B) was generated for each case. In all the plans,100% of the prescription dose covered 99% of the target volume. The plans A and B were compared for the target dosage (conformity index [CI] and homogeneity index) and organs-at-risk (OAR) dose sparing. Peripheral dose falloff was compared by using the metrics volume of normal brain receiving more than 12-Gy dose (V12) and CI at the level of the 50% of the prescription dose (CI 50%). The values found for each metric (plan B vs plan A) were (mean ± standard deviation [SD]) as follows-CI: 1.28 ± 0.15 vs 1.28 ± 0.15, p = 0.978; homogeneity index (HI): 1.29 ± 0.14 vs 1.34 ± 0.17, p = 0.079; maximum dose to the brainstem: 2.95 ± 2.11 vs 2.89 ± 1.88Gy, p = 0.813; maximum dose to the optical pathway: 2.65 ± 4.18 vs 2.44 ± 4.03Gy, p = 0.195; and maximum dose to the eye lens: 0.33 ± 0.73 vs 0.33 ± 0.53Gy, p = 0.970. The values of the peripheral dose falloff were (plan B vs plan A) as follows-V12: 5.98 ± 4.95 vs 6.06 ± 4.92cm(3), p = 0.622, and CI 50%: 6.08 ± 2.77 vs 6.28 ± 3.01, p = 0.119. The off-target isocenter solution resulted in dosimetrically comparable plans as the center-target isocenter technique, by avoiding the risk of gantry-couch collision during the cone beam computed tomography (CBCT) acquisition.
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Affiliation(s)
| | - Sandra Moragues
- Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona, Spain
| | - Miquel Pozo
- Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona, Spain
| | - David Delgado
- Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona, Spain
| | - Joan Casals
- Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona, Spain
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Serna A, Escolar PP, Puchades V, Mata F, Ramos D, Gómez MA, Iglesias A, Salinas J, Alcaraz M. Single fraction volumetric modulated arc radiosurgery of brain metastases. Clin Transl Oncol 2015; 17:596-603. [PMID: 25775918 DOI: 10.1007/s12094-015-1282-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 02/28/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE To show the clinical results of the treatment of brain metastases via radiosurgery using Volumetric Modulated Arc Therapy (VMAT). MATERIALS AND METHODS 52 patients having lung (62 %), breast (17 %), colorectal (8 %) and other cancers (13 %) with one to three brain metastases were treated with 5 non-coplanar VMAT arcs. The treatment dose varied from 12 to 20 Gy, administered in one single session. The volume of metastases ranged from 0.04 to 24.92 cc. Radiosurgery alone was used for 54 % of cases, while 19 % received whole brain radiotherapy due to relapse. Patients were classified according to the Disease-specific graded prognostic assessment (DS-GPA) index and survival was assessed via the Kaplan-Meier model. RESULTS The median survival time was 7.2 months from the date of radiosurgery. The Karnofsky and DS-GPA indices were the most significant with regard to survival. Patients with a Karnofsky performance status (KPS) over 70 had a longer survival time of 9.2 months, as opposed to those with a KPS below 70 of 3.5 months. No significant differences were found with regard to the type of cancer or the number of lesions. Local tumour control was achieved for 42 metastases (82 %), of which a complete response was achieved for 7 lesions, a partial response for 21; 15 lesions were stabilized. Local progression was observed in 8 lesions (15 %). The median treatment time per patient was 29 min. CONCLUSIONS The VMAT technique proves to be safe and effective for treating brain metastases via radiosurgery.
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Affiliation(s)
- A Serna
- Department of Medical Physics and Radiation Protection, Santa Lucia University Hospital, 30202, Cartagena, Murcia, Spain,
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Zhang Q, Xiong W, Chan MF, Song Y, Burman C. Rotation effects on the target-volume margin determination. Phys Med 2015; 31:80-4. [DOI: 10.1016/j.ejmp.2014.10.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/04/2014] [Accepted: 10/12/2014] [Indexed: 10/24/2022] Open
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Interfractional variations of tumor centroid position and tumor regression during stereotactic body radiotherapy for lung tumor. BIOMED RESEARCH INTERNATIONAL 2014; 2014:372738. [PMID: 25548770 PMCID: PMC4274869 DOI: 10.1155/2014/372738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/11/2014] [Accepted: 10/02/2014] [Indexed: 12/25/2022]
Abstract
Purpose. To determine interfractional changes of lung tumor centroid position and tumor regression during stereotactic body radiation therapy (SBRT). Methods and Materials. 34 patients were treated by SBRT in 4-5 fractions to a median dose of 50 Gy. The CT scans acquired for verification were registered with simulation CT scans. The gross target volume (GTV) was contoured on all verification CT scans and compared to the initial GTV in treatment plan system. Results. The mean (±standard deviation, SD) three-dimension vector shift was 5.2 ± 3.1 mm. The mean (±SD) interfractional variations of tumor centroid position were −0.7 ± 4.5 mm in anterior-posterior (AP) direction, 0.2 ± 3.1 mm in superior-inferior (SI) direction, and 0.4 ± 2.4 mm in right-left (RL) direction. Large interfractional variations (≥5 mm) were observed in 5 fractions (3.3%) in RL direction, 16 fractions (10.5%) in SI direction, and 36 fractions (23.5%) in AP direction. Tumor volume did not decrease significantly during lung SBRT. Conclusions. Small but insignificant tumor volume regression was observed during lung SBRT. While the mean interfractional variations of tumor centroid position were minimal in three directions, variations more than 5 mm account for approximately a third of all, indicating additional margin for PTV, especially in AP direction.
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Zheng B, Huang Z, Li J. The effects of the shape and size of the clinical target volume on the planning target volume margin. PLoS One 2014; 9:e109244. [PMID: 25275442 PMCID: PMC4183560 DOI: 10.1371/journal.pone.0109244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 09/09/2014] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To investigate the impact of clinical target volume (CTV) shape and size on CTV to planning target volume (PTV) margin expansion. METHODS AND MATERIALS Using numerical integration methods, margins accounting for random errors and systematic errors were calculated for CTVs of different shapes and sizes. We use k(r-95) and k(s-95) to represent the coefficients, for random errors and systematic errors, respectively, that ensure that every point of the CTV receives ≥95% of the prescribed dose. RESULTS The part of the margin accounting for random errors depends on CTV shape and size; generally, a convex part of a CTV would have a larger margin than a concave part. However, the part of the margin accounting for systematic errors is independent of CTV shape and size. CONCLUSIONS CTV shape and size should be considered when generating a PTV. For a complex CTV, the margins of the various parts of the CTV are different and related to local forms.
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Affiliation(s)
- Buhong Zheng
- Department of Radiation Oncology, Teaching Hospital of Fujian Medical University, Fujian Provincial Cancer Hospital, Fuzhou, Fujian, P. R. China
| | - Zhiyu Huang
- Department of Radiation Oncology, Teaching Hospital of Fujian Medical University, Fujian Provincial Cancer Hospital, Fuzhou, Fujian, P. R. China
| | - Jinluan Li
- Department of Radiation Oncology, Teaching Hospital of Fujian Medical University, Fujian Provincial Cancer Hospital, Fuzhou, Fujian, P. R. China
- * E-mail:
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Zhang Q, Zheng D, Lei Y, Morgan B, Driewer J, Zhang M, Li S, Zhou S, Zhen W, Thompson R, Wahl A, Lin C, Enke C. A new variable for SRS plan quality evaluation based on normal tissue sparing: the effect of prescription isodose levels. Br J Radiol 2014; 87:20140362. [PMID: 25226047 DOI: 10.1259/bjr.20140362] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines. METHODS 40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing. RESULTS Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings. CONCLUSION A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing. ADVANCES IN KNOWLEDGE A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.
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Affiliation(s)
- Q Zhang
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
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