Retrospective Cohort Study of Bronchial Doses and Radiation-Induced Atelectasis After Stereotactic Body Radiation Therapy of Lung Tumors Located Close to the Bronchial Tree

Karlsson, Kristin; Nyman, Jan; Baumann, Pia; Wersäll, Peter; Drugge, Ninni; Gagliardi, Giovanna; Johansson, Karl-Axel; Persson, Jan–Olov; Rutkowska, Eva; Tullgren, Owe; Lax, Ingmar

doi:10.1016/j.ijrobp.2013.06.2055

Cited by 35 publications

(34 citation statements)

References 87 publications

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“…Pathoanatomic conditions such as atelectasis (AT) can occur in up to 25% of patients with locally advanced lung cancer and may increase tumor position variability 10, 11, 12, 13, 14. There is a paucity of data that explore interfractional tumor position and shape changes that might be associated with AT.…”

Section: Introductionmentioning

confidence: 99%

Effect of variations in atelectasis on tumor displacement during radiation therapy for locally advanced lung cancer

Tennyson

Weiss

Sleeman

et al. 2017

Advances in Radiation Oncology

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PurposeAtelectasis (AT), or collapsed lung, is frequently associated with central lung tumors. We investigated the variation of atelectasis volumes during radiation therapy and analyzed the effect of AT volume changes on the reproducibility of the primary tumor (PT) position.Methods and materialsTwelve patients with lung cancer who had AT and 10 patients without AT underwent repeated 4-dimensional fan beam computed tomography (CT) scans during radiation therapy per protocols that were approved by the institutional review board. Interfraction volume changes of AT and PT were correlated with PT displacements relative to bony anatomy using both a bounding box (BB) method and change in center of mass (COM). Linear regression modeling was used to determine whether PT and AT volume changes were independently associated with PT displacement. PT displacement was compared between patients with and without AT.ResultsThe mean initial AT volume on the planning CT was 189 cm3 (37-513 cm3), and the mean PT volume was 93 cm3 (12-176 cm3). During radiation therapy, AT and PT volumes decreased on average 136.7 cm3 (20-369 cm3) for AT and 40 cm3 (−7 to 131 cm3) for PT. Eighty-three percent of patients with AT had at least one unidirectional PT shift that was greater than 0.5 cm outside of the initial BB during treatment. In patients with AT, the maximum PT COM shift was ≥0.5 cm in all patients and >1 cm in 58% of patients (0.5-2.4 cm). Changes in PT and AT volumes were independently associated with PT displacement (P < .01), and the correlation was smaller with COM (R2 = 0.58) compared with the BB method (R2 = 0.80). The median root mean squared PT displacement with the BB method was significantly less for patients without AT (0.45 cm) compared with those with AT (0.8cm, P = .002).ConclusionsChanges in AT and PT volumes during radiation treatment were significantly associated with PT displacements that often exceeded standard setup margins. Repeated 3-dimensional imaging is recommended in patients with AT to evaluate for PT displacements during treatment.

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Section: Introductionmentioning

confidence: 99%

Effect of variations in atelectasis on tumor displacement during radiation therapy for locally advanced lung cancer

Tennyson

Weiss

Sleeman

et al. 2017

Advances in Radiation Oncology

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“…In a retrospective study by Son et al complete or partial bronchial stricture was reported in 89% of patients treated with SBRT for central tumors [19]. Karlsson et al demonstrated some grade of atelectasis in 24.3% of patients treated for tumors close to the bronchial tree [20].…”

Section: Literature Overview On Toxicities and Dosimetric Parametersmentioning

confidence: 99%

Organs at risk in lung SBRT

et al. 2017

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“…Initial atelectasis presentation rates for patients undergoing external beam radiotherapy have been reported to range between 10% and 40% 2–5 . During the course of radiotherapy, tumor regression or progression can cause changes in atelectasis, either resolution or expansion.…”

Section: Introductionmentioning

confidence: 99%

“…The aforementioned studies relied on followup CTs taken months or years after treatment 2,4 or cone-beam CT scans which have relatively poor contrast resolution and electron density inaccuracies 3,5,6 which make clear identification of the atelectatic regions challenging. The purpose of this study is to quantitatively characterize mass and density changes of obstructive lobar atelectasis during treatment in NSCLC patients using weekly helical CTs and to investigate the dosimetric impact of such changes on normal tissue structures in lieu of adaptive replanning.…”

Section: Introductionmentioning

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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Retrospective Cohort Study of Bronchial Doses and Radiation-Induced Atelectasis After Stereotactic Body Radiation Therapy of Lung Tumors Located Close to the Bronchial Tree

Cited by 35 publications

References 87 publications

Effect of variations in atelectasis on tumor displacement during radiation therapy for locally advanced lung cancer

Effect of variations in atelectasis on tumor displacement during radiation therapy for locally advanced lung cancer

Organs at risk in lung SBRT

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

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