On-Line Target Position Localization in the Presence of Respiration: A Comparison of two Methods

Hugo, Geoffrey D.; Liang, Jian; Campbell, Jonathan A.; Yan, Di

doi:10.1016/j.ijrobp.2007.08.023

Cited by 51 publications

(59 citation statements)

References 19 publications

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“…We note that although in this study, the respiration-averaged CBCT is produced from the RC-CBCT using all projections, a standard one-minute CBCT spans typically spans 15 or more respiration cycles, thus would be sufficient for this purpose. Our findings are comparable to those of Hugo et al, 26 who have found that mean discrepancy in tumor position between the respiration-averaged and respiration-correlated methods is within 1.0-1.4 mm in each of the three principal directions.…”

Section: Discussionsupporting

confidence: 91%

A study of respiration‐correlated cone‐beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

et al. 2012

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Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D imagebased correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II-IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction, seven required a single correction, one required two corrections, and one required three corrections. Mean residual GTV deviation (3D distance) following GTV-based systematic correction (mean ± 1 standard deviation 4.8 ± 1.5 mm) is significantly lower than for systematic skeletal-based (6.5 ± 2.9 mm, p = 0.015), and weekly skeletal-based correction (7.2 ± 3.0 mm, p = 0.001), but is not significantly lower than daily skeletal-based correction (5.4 ± 2.6 mm, p = 0.34). In two cases, first-day CBCT images reveal tumor changes-one showing tumor growth, the other showing large tumor displacement-that are not readily observed in radiographs. Differences in computed GTV deviations between respiration-correlated and respiration-averaged images are 0.2 ± 1.8 mm in the superior-inferior direction and are of similar magnitude in the other directions. Conclusions: An off-line protocol to correct GTV-based systematic error in locally advanced lung tumor cases can be effective at reducing tumor deviations, although the findings need confirmation with larger patient s...

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Section: Discussionsupporting

confidence: 91%

A study of respiration‐correlated cone‐beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

et al. 2012

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“…MIP images, average intensity projection (AIP) images (also named average CT images) were reconstructed with the images of 10 phases. Average CT images were used as reference images during image registration in our study according to previous research 16 , 17 , 18 . Average CT images were more like slow CT images, so were free‐breathing cone‐beam CT (CBCT) images, which makes the registration feasible and accurate.…”

Section: Discussionmentioning

confidence: 99%

Inter‐ and intrafractional setup errors and baseline shifts of fiducial markers in patients with liver tumors receiving free‐breathing postoperative radiation analyzed by cone‐beam computed tomography

Zhang

Wang

et al. 2014

J Applied Clin Med Phys

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This study was to evaluate the interfractional and intrafractional setup errors and baseline shifts of golden fiducial markers in patients receiving postoperative radiotherapy (RT) using cone‐beam computed tomography (CBCT) in order to calculate PTV margins for patients with liver cancer. Twelve patients with liver tumors underwent postoperative RT. CBCT images were acquired before and after the treatment. Off‐line vertebral body match and fiducial marker match were used, respectively. The results of vertebral body match represented the setup errors of the patients, while the results of fiducial marker match represented the absolute position errors of the target volume. Baseline shifts of the target volume were calculated as the absolute target position errors minus setup errors. A total of 12 patients with 214 acquisitions of CBCTs were analyzed. Both Σ and σ of setup errors and baseline shifts in left–right (L/R), superior–inferior (S/I), and anterior–posterior(A/P) directions were calculated, including interfractional and intrafractional uncertainties. Planning target volume (PTV) margins were calculated according to margin=2.5Σ+0.7σ. Margins of 1.8 mm, 3.8 mm, and 1.4 mm in L/R, S/I, and A/P directions are needed to compensate intrafractional errors when daily online CBCT correction is used. When CBCT correction with no action level (NAL) protocol is used, PTV margin should be 2.6 mm, 5.9 mm, and 2.6 mm in L/R, S/I, and A/P directions. Margins of 5.5 mm, 14.6 mm, and 7.2 mm were needed to compensate the baseline shifts when electronic portal imaging devices (EPID) or CBCT with bone match is used for online correction of setup error.PACS number: 87.55.‐x

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“…In that regard, setup correction protocols based on the tumor itself, instead of the bony anatomy, may significantly minimize the systematic and random components of the tumor BS [5,[12][13][14]. However, these tumorbased setup correction protocols implicitly require images acquired during the successive IGRT sessions to be accurately registered in the tumor vicinity with the planning CT images.…”

Section: Introductionmentioning

confidence: 99%

Impact of motion induced artifacts on automatic registration of lung tumors in Tomotherapy

et al. 2015

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On-Line Target Position Localization in the Presence of Respiration: A Comparison of two Methods

Cited by 51 publications

References 19 publications

A study of respiration‐correlated cone‐beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

A study of respiration‐correlated cone‐beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

Inter‐ and intrafractional setup errors and baseline shifts of fiducial markers in patients with liver tumors receiving free‐breathing postoperative radiation analyzed by cone‐beam computed tomography

Impact of motion induced artifacts on automatic registration of lung tumors in Tomotherapy

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