Localization Accuracy of the Clinical Target Volume During Image-Guided Radiotherapy of Lung Cancer

Hugo, Geoffrey D.; Weiss, Elisabeth; Badawi, Ahmed M.; Orton, Matthew

doi:10.1016/j.ijrobp.2010.11.032

Cited by 25 publications

(25 citation statements)

References 28 publications

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“…Under conventional fraction treatment, the inter-fraction variability of the tumor position was substantial due to tumor regression and pathological changes over the course of the treatment [5,14-16]. In our study cohort, the tumor was not likely to undergo substantial regression due to the brief treatment duration (maximum two weeks).…”

Section: Discussionmentioning

confidence: 98%

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

et al. 2014

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BackgroundTo analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy.MethodsSingle-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations.ResultsPre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P < 0.05), except in the CC direction post-treatment. However, no significant correlation was detected between the relative tumor position, the total treatment time and the tumor reproducibility (P > 0.05).ConclusionsUsing ABC for single-breath-hold CBCT guidance is an effective method to reduce the PTV margin of hypofraction radiotherapy for lung cancer. Using ABC, the tumor position was significantly altered relative to the vertebral position. The reproducibility of the tumor position was affected by the vertebral bone but not by the relative tumor position or the total treatment time.

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Section: Discussionmentioning

confidence: 98%

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

et al. 2014

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“…This showed potentially significant reduction in lung dose. Hugo et al 17 described a deformable registration technique with repeat CT scans on 13 patients. This provided a method of adding doses throughout a course of treatment to changing volumes.…”

Section: Introductionmentioning

confidence: 99%

An assessment of cone beam CT in the adaptive radiotherapy planning process for non-small-cell lung cancer patients

Duffton

Harrow

McJury

2016

BJR

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Objective: To investigate the potential use of cone beam CT (CBCT) in adaptive radiotherapy (ART) planning process for non-small-cell lung cancer (NSCLC). Methods: 17 retrospective patients with NSCLC Stage T1-T4, who had completed a course of radiotherapy with weekly CBCT imaging were selected for the study. The patients had been delineated and planned for threedimensional (3D) conformal treatment (prescription: 55 Gy in 20 fractions) based on free-breathing fourdimensional CT data. Of these initial 17 patients, 12 had full quantitative data on gross tumour volume (GTV) position and volume throughout treatment. GTV delineation was carried out on weekly CBCT by a clinical oncologist. For each patient, mean percentage change in GTV and centre of mass (COM) displacement (based on 3D vectors) were calculated throughout treatment. Volume overlap between GTVs was calculated. Correlation of the COM displacement and planning GTV (pGTV) was assessed. A linear mixed model with patients as random effects was fitted to the data to assess potential benefit from using ART for these patients. Results: Comparison of CBCT-based GTV acquired prior to Fraction 1 (cbctGTV1) to pGTV showed mean 20 6 19%

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“…Dose variation to GTV was analyzed rather than CTV, as it is not clear if the midtreatment CTV should be constructed by re-expansion of the GTV or by tracking the movement of tissue within the CTV region 9,10 . Means (stdev) of changes in volume of GTV receiving at least the prescription dose, V Rx , were −5.5% (13.5%) and −5.3% (15.5%) for bone and carina alignments, respectively, and are reported in units of % GTV volume.…”

Section: Resultsmentioning

confidence: 99%

Effect of atelectasis changes on tissue mass and dose during lung radiotherapy

et al. 2016

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Purpose:To characterize mass and density changes of lung parenchyma in non-small cell lung cancer (NSCLC) patients following midtreatment resolution of atelectasis and to quantify the impact this large geometric change has on normal tissue dose.Methods:Baseline and midtreatment CT images and contours were obtained for 18 NSCLC patients with atelectasis. Patients were classified based on atelectasis volume reduction between the two scans as having either full, partial, or no resolution. Relative mass and density changes from baseline to midtreatment were calculated based on voxel intensity and volume for each lung lobe. Patients also had clinical treatment plans available which were used to assess changes in normal tissue dose constraints from baseline to midtreatment. The midtreatment image was rigidly aligned with the baseline scan in two ways: (1) bony anatomy and (2) carina. Treatment parameters (beam apertures, weights, angles, monitor units, etc.) were transferred to each image. Then, dose was recalculated. Typical IMRT dose constraints were evaluated on all images, and the changes from baseline to each midtreatment image were investigated.Results:Atelectatic lobes experienced mean (stdev) mass changes of −2.8% (36.6%), −24.4% (33.0%), and −9.2% (17.5%) and density changes of −66.0% (6.4%), −25.6% (13.6%), and −17.0% (21.1%) for full, partial, and no resolution, respectively. Means (stdev) of dose changes to spinal cord Dmax, esophagus Dmean, and lungs Dmean were 0.67 (2.99), 0.99 (2.69), and 0.50 Gy (2.05 Gy), respectively, for bone alignment and 0.14 (1.80), 0.77 (2.95), and 0.06 Gy (1.71 Gy) for carina alignment. Dose increases with bone alignment up to 10.93, 7.92, and 5.69 Gy were found for maximum spinal cord, mean esophagus, and mean lung doses, respectively, with carina alignment yielding similar values. 44% and 22% of patients had at least one metric change by at least 5 Gy (dose metrics) or 5% (volume metrics) for bone and carina alignments, respectively. Investigation of GTV coverage showed mean (stdev) changes in VRx, Dmax, and Dmin of −5.5% (13.5%), 2.5% (4.2%), and 0.8% (8.9%), respectively, for bone alignment with similar results for carina alignment.Conclusions:Resolution of atelectasis caused mass and density decreases, on average, and introduced substantial changes in normal tissue dose metrics in a subset of the patient cohort.

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Localization Accuracy of the Clinical Target Volume During Image-Guided Radiotherapy of Lung Cancer

Cited by 25 publications

References 28 publications

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

An assessment of cone beam CT in the adaptive radiotherapy planning process for non-small-cell lung cancer patients

Effect of atelectasis changes on tissue mass and dose during lung radiotherapy

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