1
|
Evaluation of the accuracy of a six-degree-of-freedom robotic couch using optical surface and cone beam CT images of an SRS QA phantom. JOURNAL OF RADIOTHERAPY IN PRACTICE 2023. [DOI: 10.1017/s1460396922000395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abstract
Purpose:
To assess the accuracy of the Varian PerfectPitch six-degree-of-freedom (6DOF) robotic couch by using a Varian SRS QA phantom.
Methods:
The stereotactic radiosurgery (SRS) phantom has five tungsten carbide BBs each with 7·5 mm in diameter arranged with the known geometry. Optical surface images and cone beam CT (CBCT) images of the phantom were taken at different pitch, roll and rotation angles. The pitch, roll, and rotation angles were varied from −3 to 3 degrees by inputs from the linac console. A total of 39 Vision RT images with different rotation angle combinations were collected, and the Vision RT software was used to determine the rotation angles and translational shifts from those images. Eight CBCT images at most allowed rotational angles were analysed by in-house software. The software took the coordinates of the voxel of the maximum CT number inside a 7·5-mm sphere surrounding one BB to be the measured position of this BB. Expected BB positions at different rotation angles were determined by multiplying measured BB positions at zero pitch and roll values by a rotation matrix. Applying the rotation matrix to 5 BB positions yielded 15 equations. A linear least square method was used for regression analysis to approximate the solutions of those equations.
Results:
Of the eight calculations from CBCT images, the maximum rotation angle differences (degree) were 0·10 for pitch, 0·15 for roll and 0·09 for yaw. The maximum translation differences were 0·3 mm in the left–right direction, 0·5 mm in the anterior–posterior direction and 0·4 mm in the superior–inferior direction.
Conclusions:
The uncertainties of the 6-DOF couch were examined with the methods of optical surface imaging and CBCT imaging of the SRS QA phantom. The rotational errors were less than 0·2 degree, and the isocentre shifts were less than 0·8 mm.
Collapse
|
2
|
PTV margin calculation for head and neck patients treated with VMAT: a systematic literature review. JOURNAL OF RADIOTHERAPY IN PRACTICE 2021. [DOI: 10.1017/s1460396921000546] [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
Aim:
The intent of the review was to identify different methodological approaches used to calculate the planning target volume (PTV) margin for head and neck patients treated with volumetric arc therapy (VMAT), and whether the necessary factors to calculate the margin size with the selected formula were used.
Materials and Methods:
A comprehensive, systematic search of related studies was done using the Hydi search engine and different databases: MEDLINE, PubMed, CINAHL, ProQuest (Nursing and Allied Health), Scopus, ScienceDirect and tipsRO. The literature search included studies published between January 2007 and December 2020. Eligibility screening was performed by two reviewers.
Results:
A total of seven studies were found. All the reviewed studies used the Van Herk formula to measure the PTV margin. None of the studies incorporated the systematic errors of target volume delineation in the PTV equation. Inter-fraction translational errors were assessed in all the studies, whilst intra-fraction errors were only included in the margin equation for two studies. The studies showed great heterogeneity in the key characteristics, aims and methods.
Findings:
Since systemic errors from target volume delineation were not considered and not all studies assess intra-fraction errors, PTV margins may be underestimated. The recommendations are that studies need to determine the effect of target volume variance on PTV margins. It is also recommended to compare PTV margin results using various formulas.
Collapse
|
3
|
Real-Time Whole-Brain Radiation Therapy: A Single-Institution Experience. Int J Radiat Oncol Biol Phys 2017; 100:1280-1288. [PMID: 29397212 DOI: 10.1016/j.ijrobp.2017.12.282] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 11/21/2022]
Abstract
PURPOSE To demonstrate the feasibility of a real-time whole-brain radiation therapy (WBRT) workflow, taking advantage of contemporary radiation therapy capabilities and seeking to optimize clinical workflow for WBRT. METHODS AND MATERIALS We developed a method incorporating the linear accelerator's on-board imaging system for patient simulation, used cone-beam computed tomography (CBCT) data for treatment planning, and delivered the first fraction of prescribed therapy, all during the patient's initial appointment. Simulation was performed in the linear accelerator vault. An acquired CBCT data set was used for scripted treatment planning protocol, providing inversely planned, automated treatment plan generation. The osseous boundaries of the brain were auto-contoured to create a target volume. Two parallel-opposed beams using field-in-field intensity modulate radiation therapy covered this target to the user-defined inferior level (C1 or C2). The method was commissioned using an anthropomorphic head phantom and verified using 100 clinically treated patients. RESULTS Whole-brain target heterogeneity was within 95%-107% of the prescription dose, and target coverage compared favorably to standard, manually created 3-dimensional plans. For the commissioning CBCT datasets, the secondary monitor unit verification and independent 3-dimensional dose distribution comparison for computed and delivered doses were within 2% agreement relative to the scripted auto-plans. On average, time needed to complete the entire process was 35.1 ± 10.3 minutes from CBCT start to last beam delivered. CONCLUSIONS The real-time WBRT workflow using integrated on-site imaging, planning, quality assurance, and delivery was tested and deemed clinically feasible. The design necessitates a synchronized team consisting of physician, physicist, dosimetrist, and therapists. This work serves as a proof of concept of real-time planning and delivery for other treatment sites.
Collapse
|
5
|
Zhang Q, Driewer J, Wang S, Li S, Zhu X, Zheng D, Cao Y, Zhang J, Jamshidi A, Cox BW, Knisely JPS, Potters L, Klein EE. Accuracy evaluation of a six-degree-of-freedom couch using cone beam CT and IsoCal phantom with an in-house algorithm. Med Phys 2017; 44:3888-3898. [PMID: 28500790 DOI: 10.1002/mp.12342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 04/24/2017] [Accepted: 05/03/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE The accuracy of a six degree of freedom (6DoF) couch was evaluated using a novel method. METHODS Cone beam CT (CBCT) images of a 3D phantom (IsoCal) were acquired with different, known combinations of couch pitch and roll angles. Pitch and roll angles between the maximum allowable values of 357 and 3 degrees were tested in one degree increments. A total of 49 combinations were tested at 0 degrees of yaw (couch rotation angle). The 3D positions of 16 tungsten carbide ball bearings (BBs), each 4 mm in diameter and arranged in a known geometry within the IsoCal phantom, were determined in the 49 image sets with in-house software. The BB positions at different rotation angles were determined using a rotation matrix from the original BB positions at zero pitch and roll angles. A linear least squares fit method estimated the rotation angles and differences between detected and nominal rotation angles were calculated. This study was conducted for the case with and without extra weight on the couch. Couch walk shifts for the system were investigated using eight combinations of rotation, roll and pitch. RESULTS A total of 49 CBCT images with voxel sizes 0.5 × 0.5 × 1.0 mm3 were taken for the case without extra weight on the couch. The 16 BBs were determined to evaluate the isocenter translation and rotation differences between the calculated and nominal couch values. Among all 49 calculations, the maximum rotation angle differences were 0.10 degrees for pitch, 0.15 degrees for roll and 0.09 degrees for yaw. The corresponding mean and standard deviation values were 0.028 ± 0.032, -0.043 ± 0.058, and -0.009 ± 0.033 degrees. The maximum translation differences were 0.3 mm in the left-right direction, 0.5 mm in the anterior-posterior direction and 0.4 mm in the superior-inferior direction. The mean values and corresponding standard deviations were 0.07 ± 0.12, -0.05 ± 0.25, and -0.12±0.14 mm for the planes described above. With an 80 kg phantom on the couch, the maximum translation shift was 0.69 mm. The couch walk translation shifts were less than 0.1 mm and rotation shifts were less than 0.1 degree. CONCLUSIONS Errors of a new 6DoF couch were tested using CBCT images of a 3D phantom. The rotation errors were less than 0.3 degree and the translation errors were less than or equal to 0.8 mm in each direction. This level of accuracy is warranted for clinical radiotherapy utilization including stereotactic radiosurgery.
Collapse
Affiliation(s)
- Qinghui Zhang
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Joseph Driewer
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Shuo Wang
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Sicong Li
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Xiaofeng Zhu
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Dandan Zheng
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yijian Cao
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Jiaju Zhang
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Abolghassem Jamshidi
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Brett W Cox
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Jonathan P S Knisely
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Louis Potters
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| | - Eric E Klein
- Department of Radiation Medicine, Northwell Health and Hofstra Northwell School of Medicine, New York, NY, 11042, USA
| |
Collapse
|
7
|
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
|
9
|
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.
Collapse
Affiliation(s)
- Q Zhang
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|