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Title: Cone Beam Computed Tomography Guidance for Setup of Patients Receiving Accelerated Partial Breast Irradiation

Abstract

Purpose: To evaluate the role of cone-beam CT (CBCT) guidance for setup error reduction and soft tissue visualization in accelerated partial breast irradiation (APBI). Methods and Materials: Twenty patients were recruited for the delivery of radiotherapy to the postoperative cavity (3850 cGy in 10 fractions over 5 days) using an APBI technique. Cone-beam CT data sets were acquired after an initial skin-mark setup and before treatment delivery. These were registered online using the ipsilateral lung and external contours. Corrections were executed for translations exceeding 3 mm. The random and systematic errors associated with setup using skin-marks and setup using CBCT guidance were calculated and compared. Results: A total of 315 CBCT data sets were analyzed. The systematic errors for the skin-mark setup were 2.7, 1.7, and 2.4 mm in the right-left, anterior-posterior, and superior-inferior directions, respectively. These were reduced to 0.8, 0.7, and 0.8 mm when CBCT guidance was used. The random errors were reduced from 2.4, 2.2, and 2.9 mm for skin-marks to 1.5, 1.5, and 1.6 mm for CBCT guidance in the right-left, anterior-posterior, and superior-inferior directions, respectively. Conclusion: A skin-mark setup for APBI patients is sufficient for current planning target volume margins for the population of patientsmore » studied here. Online CBCT guidance minimizes the occurrence of large random deviations, which may have a greater impact for the accelerated fractionation schedule used in APBI. It is also likely to permit a reduction in planning target volume margins and provide skin-line visualization and dosimetric evaluation of cardiac and lung volumes.« less

Authors:
 [1];  [2];  [3];  [2];  [3];  [3];  [2];  [3];  [3];  [2];  [2];  [2];  [2];  [2];  [3];  [3]
  1. Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada). E-mail: Elizabeth.White@rmp.uhn.on.ca
  2. Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada)
  3. (Canada)
Publication Date:
OSTI Identifier:
20951677
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 68; Journal Issue: 2; Other Information: DOI: 10.1016/j.ijrobp.2007.01.048; PII: S0360-3016(07)00230-1; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BEAMS; COMPUTERIZED TOMOGRAPHY; CORRECTIONS; ERRORS; IRRADIATION; LUNGS; MAMMARY GLANDS; PATIENTS; PLANNING; RADIOTHERAPY; SKIN

Citation Formats

White, Elizabeth A., Cho, John, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Vallis, Katherine A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Sharpe, Michael B., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Lee, Grace B.Sc., Blackburn, Helen, Nageeti, Tahani, McGibney, Carol, Jaffray, David A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, and Department of Medical Biophysics, University of Toronto, Toronto, Ontario. Cone Beam Computed Tomography Guidance for Setup of Patients Receiving Accelerated Partial Breast Irradiation. United States: N. p., 2007. Web. doi:10.1016/j.ijrobp.2007.01.048.
White, Elizabeth A., Cho, John, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Vallis, Katherine A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Sharpe, Michael B., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Lee, Grace B.Sc., Blackburn, Helen, Nageeti, Tahani, McGibney, Carol, Jaffray, David A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, & Department of Medical Biophysics, University of Toronto, Toronto, Ontario. Cone Beam Computed Tomography Guidance for Setup of Patients Receiving Accelerated Partial Breast Irradiation. United States. doi:10.1016/j.ijrobp.2007.01.048.
White, Elizabeth A., Cho, John, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Vallis, Katherine A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Sharpe, Michael B., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Lee, Grace B.Sc., Blackburn, Helen, Nageeti, Tahani, McGibney, Carol, Jaffray, David A., Department of Radiation Oncology, University of Toronto, Toronto, Ontario, and Department of Medical Biophysics, University of Toronto, Toronto, Ontario. Fri . "Cone Beam Computed Tomography Guidance for Setup of Patients Receiving Accelerated Partial Breast Irradiation". United States. doi:10.1016/j.ijrobp.2007.01.048.
@article{osti_20951677,
title = {Cone Beam Computed Tomography Guidance for Setup of Patients Receiving Accelerated Partial Breast Irradiation},
author = {White, Elizabeth A. and Cho, John and Department of Radiation Oncology, University of Toronto, Toronto, Ontario and Vallis, Katherine A. and Department of Radiation Oncology, University of Toronto, Toronto, Ontario and Department of Medical Biophysics, University of Toronto, Toronto, Ontario and Sharpe, Michael B. and Department of Radiation Oncology, University of Toronto, Toronto, Ontario and Department of Medical Biophysics, University of Toronto, Toronto, Ontario and Lee, Grace B.Sc. and Blackburn, Helen and Nageeti, Tahani and McGibney, Carol and Jaffray, David A. and Department of Radiation Oncology, University of Toronto, Toronto, Ontario and Department of Medical Biophysics, University of Toronto, Toronto, Ontario},
abstractNote = {Purpose: To evaluate the role of cone-beam CT (CBCT) guidance for setup error reduction and soft tissue visualization in accelerated partial breast irradiation (APBI). Methods and Materials: Twenty patients were recruited for the delivery of radiotherapy to the postoperative cavity (3850 cGy in 10 fractions over 5 days) using an APBI technique. Cone-beam CT data sets were acquired after an initial skin-mark setup and before treatment delivery. These were registered online using the ipsilateral lung and external contours. Corrections were executed for translations exceeding 3 mm. The random and systematic errors associated with setup using skin-marks and setup using CBCT guidance were calculated and compared. Results: A total of 315 CBCT data sets were analyzed. The systematic errors for the skin-mark setup were 2.7, 1.7, and 2.4 mm in the right-left, anterior-posterior, and superior-inferior directions, respectively. These were reduced to 0.8, 0.7, and 0.8 mm when CBCT guidance was used. The random errors were reduced from 2.4, 2.2, and 2.9 mm for skin-marks to 1.5, 1.5, and 1.6 mm for CBCT guidance in the right-left, anterior-posterior, and superior-inferior directions, respectively. Conclusion: A skin-mark setup for APBI patients is sufficient for current planning target volume margins for the population of patients studied here. Online CBCT guidance minimizes the occurrence of large random deviations, which may have a greater impact for the accelerated fractionation schedule used in APBI. It is also likely to permit a reduction in planning target volume margins and provide skin-line visualization and dosimetric evaluation of cardiac and lung volumes.},
doi = {10.1016/j.ijrobp.2007.01.048},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 2,
volume = 68,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2007},
month = {Fri Jun 01 00:00:00 EDT 2007}
}
  • Purpose: On-board cone-beam computed tomography (CBCT) provides soft tissue information that may improve setup accuracy in patients undergoing accelerated partial breast irradiation (APBI). We used CBCT to assess the residual error in soft tissue after two-dimensional kV/MV alignment based on bony anatomy. We also assessed the dosimetric impact of this error. Methods and Materials: Ten patients undergoing APBI were studied as part of an institutional review board-approved prospective trial. Patients were aligned based on skin/cradle marks plus orthogonal kV/MV images registered based on bony landmarks to digitally reconstructed radiographs from the planning CT. A subsequent CBCT was registered to themore » planning CT using soft tissue information. This 'residual error' and its dosimetric impact was measured. Results: The root-mean-square of the residual error was 3, 4, and 4 mm, in the right-left, anterior-posterior, and superior-inferior directions, respectively. The average vector sum was 6 {+-} 2 mm. Average reductions in mean dose to the lumpectomy cavity, clinical target volume (CTV), and planning target volume were 0.1%, 0.4%, and 1%, respectively. The mean difference in the clinical target and planning target volumes that received 95% of the prescribed dose (V95) were 1% and 4%. Conclusions: In this initial study with a modest number of patients, the residual error in soft tissue was typically <5 mm, and with the field margins used, the resultant dosimetric consequences were modest. In patients immobilized in a customized cradle, setup using orthogonal kV images thus appears accurate and reproducible. The CBCT technique may have particular utility in patients with larger breast volumes or breast deformations. Further studies involving larger numbers of patients are needed to further assess the utility of CBCT.« less
  • Purpose: To report setup variations during prone accelerated partial breast irradiation (APBI). Methods: New York University (NYU) 07-582 is an institutional review board-approved protocol of cone-beam computed tomography (CBCT) to deliver image-guided ABPI in the prone position. Eligible are postmenopausal women with pT1 breast cancer excised with negative margins and no nodal involvement. A total dose of 30 Gy in five daily fractions of 6 Gy are delivered to the planning target volume (the tumor cavity with 1.5-cm margin) by image-guided radiotherapy. Patients are set up prone, on a dedicated mattress, used for both simulation and treatment. After positioning withmore » skin marks and lasers, CBCTs are performed and the images are registered to the planning CT. The resulting shifts (setup corrections) are recorded in the three principal directions and applied. Portal images are taken for verification. If they differ from the planning digital reconstructed radiographs, the patient is reset, and a new CBCT is taken. Results: 70 consecutive patients have undergone a total of 343 CBCTs: 7 patients had four of five planned CBCTs performed. Seven CBCTs (2%) required to be repeated because of misalignment in the comparison between portal and digital reconstructed radiograph image after the first CBCT. The mean shifts and standard deviations in the anterior-posterior (AP), superior-inferior (SI), and medial-lateral (ML) directions were -0.19 (0.54), -0.02 (0.33), and -0.02 (0.43) cm, respectively. The average root mean squares of the daily shifts were 0.50 (0.28), 0.29 (0.17), and 0.38 (0.20). A conservative margin formula resulted in a recommended margin of 1.26, 0.73, 0.96 cm in the AP, SI, and ML directions. Conclusion: CBCTs confirmed that the NYU prone APBI setup and treatment technique are reproducible, with interfraction variation comparable to those reported for supine setup. The currently applied margin (1.5 cm) adequately compensates for the setup variation detected.« less
  • Purpose: To quantify the dosimetric effect and margins required to account for prostate intrafractional translation and residual setup error in a cone beam computed tomography (CBCT)-guided hypofractionated radiotherapy protocol. Methods and Materials: Prostate position after online correction was measured during dose delivery using simultaneous kV fluoroscopy and posttreatment CBCT in 572 fractions to 30 patients. We reconstructed the dose distribution to the clinical tumor volume (CTV) using a convolution of the static dose with a probability density function (PDF) based on the kV fluoroscopy, and we calculated the minimum dose received by 99% of the CTV (D{sub 99}). We comparedmore » reconstructed doses when the convolution was performed per beam, per patient, and when the PDF was created using posttreatment CBCT. We determined the minimum axis-specific margins to limit CTV D{sub 99} reduction to 1%. Results: For 3-mm margins, D{sub 99} reduction was {<=}5% for 29/30 patients. Using post-CBCT rather than localizations at treatment delivery exaggerated dosimetric effects by {approx}47%, while there was no such bias between the dose convolved with a beam-specific and patient-specific PDF. After eight fractions, final cumulative D{sub 99} could be predicted with a root mean square error of <1%. For 90% of patients, the required margins were {<=}2, 4, and 3 mm, with 70%, 40%, and 33% of patients requiring no right-left (RL), anteroposterior (AP), and superoinferior margins, respectively. Conclusions: For protocols with CBCT guidance, RL, AP, and SI margins of 2, 4, and 3 mm are sufficient to account for translational errors; however, the large variation in patient-specific margins suggests that adaptive management may be beneficial.« less
  • Purpose: To quantify the differences in setup errors measured with the cone-beam computed tomography (CBCT) and electronic portal image devices (EPID) in breast cancer patients. Methods and Materials: Repeat CBCT scan were acquired for routine offline setup verification in 20 breast cancer patients. During the CBCT imaging fractions, EPID images of the treatment beams were recorded. Registrations of the bony anatomy for CBCT to planning CT and EPID to digitally reconstructed-radiographs (DRRs) were compared. In addition, similar measurements of an anthropomorphic thorax phantom were acquired. Bland-Altman and linear regression analysis were performed for clinical and phantom registrations. Systematic and randommore » setup errors were quantified for CBCT and EPID-driven correction protocols in the EPID coordinate system (U, V), with V parallel to the cranial-caudal axis and U perpendicular to V and the central beam axis. Results: Bland-Altman analysis of clinical EPID and CBCT registrations yielded 4 to 6-mm limits of agreement, indicating that both methods were not compatible. The EPID-based setup errors were smaller than the CBCT-based setup errors. Phantom measurements showed that CBCT accurately measures setup error whereas EPID underestimates setup errors in the cranial-caudal direction. In the clinical measurements, the residual bony anatomy setup errors after offline CBCT-based corrections were {Sigma}{sub U} = 1.4 mm, {Sigma}{sub V} = 1.7 mm, and {sigma}{sub U} = 2.6 mm, {sigma}{sub V} = 3.1 mm. Residual setup errors of EPID driven corrections corrected for underestimation were estimated at {Sigma}{sub U} = 2.2mm, {Sigma}{sub V} = 3.3 mm, and {sigma}{sub U} = 2.9 mm, {sigma}{sub V} = 2.9 mm. Conclusion: EPID registration underestimated the actual bony anatomy setup error in breast cancer patients by 20% to 50%. Using CBCT decreased setup uncertainties significantly.« less
  • Purpose: Kilovoltage cone-beam computed tomography (CBCT) has been developed to provide accurate soft-tissue and bony setup information. We evaluated clinical CBCT setup data and compared CBCT measurements with electronic portal imaging device (EPID) images for lung cancer patients. Methods and Materials: The setup error for CBCT scans at the treatment unit relative to the planning CT was measured for 62 patients (524 scans). For 19 of these patients (172 scans) portal images were also made. The mean, systematic setup error ({sigma}), and random setup error ({sigma}) were calculated for the CBCT and the EPID. The differences between CBCT and EPIDmore » and the rotational setup error derived from the CBCT were also evaluated. An offline shrinking action level correction protocol, based on the CBCT measurements, was used to reduce systematic setup errors and the impact of this protocol was evaluated. Results: The CBCT setup errors were significantly larger than the EPID setup errors for the cranial-caudal and anterior-posterior directions (p < 0.05). The mean overall setup errors after correction measured with the CBCT were 0.2 mm ({sigma} = 1.6 mm, {sigma} 2.9 mm) in the left-right, -0.8 mm ({sigma} = 1.7 mm, {sigma} = 4.0 mm) in cranial-caudal and 0.0 mm ({sigma} = 1.5 mm, {sigma} = 2.0 mm) in the anterior-posterior direction. Using our correction protocol only 2 patients had mean setup errors larger than 5 mm, without this correction protocol 51% of the patients would have had a setup error larger than 5 mm. Conclusion: Use of CBCT scans provided more accurate information concerning the setup of lung cancer patients than did portal imaging.« less