Assessment of Internal and External Surrogates for Lung Stereotactic Body Radiation Therapy (original) (raw)
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Journal of radiosurgery and SBRT, 2015
Narrow PTV margins and steep dose gradients underscore the importance of evaluating breathing-associated tumor motion for lung SBRT. The specific aim of this study was to determine the impact of anatomic tumor location on inter-fraction tumor motion. Forty-one patients underwent standard free-breathing 4DCT simulation and daily image-guidance 4DCTs during lung SBRT. Absolute tumor motion amplitude in the mediolateral (ML), anterior-posterior (AP), and superior-inferior (SI) directions was analyzed from 159 total 4DCT scans (simulation and daily pre-treatment). Overall, the inter-fraction tumor motion amplitude in the ML, AP, and SI directions was small (mean ≤2.5 mm). Similarly, while both upper lobe (UL) and lower lobe (LL) tumors exhibited limited inter-fraction motion in both the ML and AP directions (mean ≤2.2 mm), tumors in the LL had increased inter-fraction motion in the SI direction compared to UL tumors (mean 4.3±4.0 mm vs. 1.7±1.7 mm, p=0.008). Moreover, 28.6% (n=4) of LL ...
Practical Radiation Oncology, 2014
To evaluate how well tumor motion measured prior to treatment based on 4-dimensional computer tomography (4DCT) reflects actual tumor motion during beam-on throughout the course of treatment. Methods and Materials: Twenty-three patients who had lung stereotactic body radiation therapy (SBRT) treatments were retrospectively selected. All patients had 4DCT simulation for treatment planning, from which tumor motion ranges were measured (R 4DCT). Tumor motion was monitored during treatment using megavoltage (MV) imaging. Tumor motion trajectories were extracted from cine MV images and were used to determine mean and maximum tumor motion range (Mean R MV , Max R MV) throughout entire course of treatment. Comparison and correlations between mean and max R MV and R 4DCT were calculated. Results: On average, an insignificant difference was found between mean R MV and R 4DCT
Lung tumor motion change during stereotactic body radiotherapy (SBRT): an evaluation using MRI
Journal of applied clinical medical physics / American College of Medical Physics, 2014
The purpose of this study is to investigate changes in lung tumor internal target volume during stereotactic body radiotherapy treatment (SBRT) using magnetic resonance imaging (MRI). Ten lung cancer patients (13 tumors) undergoing SBRT (48 Gy over four consecutive days) were evaluated. Each patient underwent three lung MRI evaluations: before SBRT (MRI-1), after fraction 3 of SBRT (MRI-3), and three months after completion of SBRT (MRI-3m). Each MRI consisted of T1-weighted images in axial plane through the entire lung. A cone-beam CT (CBCT) was taken before each fraction. On MRI and CBCT taken before fractions 1 and 3, gross tumor volume (GTV) was contoured and differences between the two volumes were compared. Median tumor size on CBCT before fractions1 (CBCT-1) and 3 (CBCT-3) was 8.68 and 11.10 cm3, respectively. In 12 tumors, the GTV was larger on CBCT-3 compared to CBCT-1 (median enlargement, 1.56 cm3). Median tumor size on MRI-1, MRI-3, and MRI-3m was 7.91, 11.60, and 3.33 cm...
Journal of Radiation Oncology, 2020
Purpose To evaluate the amplitude of lung tumor motion and impact of tumor motion on dose delivered to the organs at risk (OARs) during lung stereotactic body radiation therapy (SBRT). Materials and methods This study included 55 patients (30 males and 25 females) with lung cancer who had a small gross tumor volume (GTV). SBRT lung cancer patients were treated with a prescribed dose of 60 Gy in 4 to 8 fractions. Radiotherapy plans were planned in Pinnacle 9.10 with two partial dynamic conformal arcs (DCAs) for the peripheral region (PR) and three to four partial DCAs for the central region (CR). The amplitude of tumor motion and their impact on the maximum dose delivered (D max) to the OARs were evaluated in the upper lobe (UL) and lower lobe (LL) in cases of CR and PR tumor's localizations. Results The median tumor motions between CR and PR were 4.5 vs 2.2 mm in the UL and 12.5 vs 7.0 mm in the LL. Max dose delivered to the OARs between CR and PR in the UL and LL were as follows: 6.7 vs 8.9 Gy and 9.1 vs 11.7 Gy for the spinal cord; 15.2 vs 0.6 Gy and 22.4 vs 7.6 Gy for the heart; and 11.7 vs 10.8 Gy and 14.8 vs 9.8 Gy for the esophagus, respectively. Conclusion The dose received by the OARs depends on the amplitude of tumor motion and is relative to the OAR's location and motion, due to patient respiration and heart contribution.
Polish Journal of Medical Physics and Engineering, 2020
Purpose: To evaluate the breathing amplitude, tumor motion, patient positioning, and treatment volumes among consecutive four-dimensional computed tomography (4D-CT) scans, during the simulation for lung stereotactic body radiation therapy (SBRT). Material and methods: The variation and shape of the breathing amplitude, patient positioning, and treatment volumes were evaluated for 55 lung cancer patients after consecutive 4D-CT acquisitions, scanned at one-week intervals. The impact of variation in the breathing amplitude on lung tumor motion was determined for 20 patients. The gross tumor volume (GTV) was contoured from a free-breathing CT scan and at ten phases of the respiratory cycle, for both 4D-CTs (440 phases in total). Results: Breathing amplitude decreased by 3.6 (3.4-4.9) mm, tumor motion by 3.2 (0.4-5.0) mm while breathing period increased by 4 (2-6) s, inter-scan for 20 patients. Intra-scan variation was 4 times greater for the breathing amplitude, 5 times for the breath...
Radiation Oncology, 2022
Objectives To characterise the motion of pulmonary tumours during stereotactic body radiation therapy (SBRT) and to evaluate different margins when creating the planning target volume (PTV) on a single 4D CT scan (4DCT). Methods We conducted a retrospective single-site analysis on 30 patients undergoing lung SBRT. Two 4DCTs (4DCT1 and 4DCT2) were performed on all patients. First, motion was recorded for each 4DCT in anterior–posterior (AP), superior-inferior (SI) and rightleft (RL) directions. Then, we used 3 different margins (3,4 and 5 mm) to create the PTV, from the internal target volume (ITV) of 4DCT1 only (PTV D1 + 3, PTV D1 + 4, PTV D1 + 5). We compared, using the Dice coefficient, the volumes of these 3 PTVs, to the PTV actually used for the treatment (PTVttt). Finally, new treatment plans were calculated using only these 3 PTVs. We studied the ratio of the D2%, D50% and D98% between each new plan and the plan actually used for the treatment (D2% PTVttt, D50% PTVttt, D50% IT...
Clinical Oncology, 2014
Aims: The delivery of radical radiotherapy in lung cancer is complicated by respiratory-induced tumour motion. The aim of the study was to correlate tumour motion characteristics with tumour and patient factors, particularly the anatomical lobe and pulmonary zone. Materials and methods: Lung tumour volumes on four-dimensional computed tomography were delineated by a single observer at maximal expiration and propagated through all 10 phases of the breathing cycle. Movements were tracked in the superioreinferior (SI), anterioreposterior (AP) and medio-lateral (ML) directions by changes in the tumour centroid coordinates. Tumour motion characteristics were correlated with anatomical lobe, pulmonary zone, tumour volume, T-stage, smoking status and spirometry. Results: In 101 consecutive patients, the median magnitude of tumour motion in the SI direction was significantly larger in tumours located in lower lobes compared with upper lobes and middle/lingular lobes (0.70 cm versus 0.09 cm versus 0.26 cm, P < 0.01). No significant difference was found in median tumour motion between lower, upper and middle/lingular lobes in the AP (0.16 cm versus 0.13 cm versus 0.16 cm, P ¼ 0.45) and ML (0.08 cm versus 0.08 cm versus 0.13 cm, P ¼ 0.32) directions, respectively. When assessed by zone, the median tumour displacement in the SI direction was significantly larger in the lower zones (0.81 cm) as compared with the middle zones (0.30 cm) and upper zones (0.11 cm), P < 0.01. No difference was observed in the AP (P ¼ 0.45) and ML (P ¼ 0.73) directions. Tumour volume, T-stage and forced expiratory ratio were not statistically significant predictors of respiratory-induced tumour motion. Conclusion: Respiratory-induced tumour motion in the SI direction was significantly greater in lower lobe and lower pulmonary zone tumours compared with apical tumours. Tumour volume, T-stage and spirometry did not correlate with the magnitude or direction of respiratory-induced tumour motion. During curative radiotherapy in lung cancer, attention should be paid to motion management, especially for lower lobe tumours.
Acta Oncologica, 2013
Purpose . To investigate the stability of target motion amplitude and motion directionality throughout full stereotactic body radiotherapy (SBRT) treatments of tumors in the liver. Material and methods. Ten patients with gold markers implanted in the liver received 11 courses of 3-fraction SBRT on a conventional linear accelerator. A four-dimensional computed tomography (4DCT) scan was obtained for treatment planning. The time-resolved marker motion was determined throughout full treatment fi eld delivery using the kV and MV imagers of the accelerator. The motion amplitude and motion directionality of all individual respiratory cycles were determined using principal component analysis (PCA). The variations in motion amplitude and directionality within the treatment courses and the difference from the motion in the 4DCT scan were determined. Results. The patient mean ( Ϯ 1 standard deviation) peak-to-peak 3D motion amplitude of individual respiratory cycles during a treatment course was 7.9 Ϯ 4.1 mm and its difference from the 4DCT scan was Ϫ 0.8 Ϯ 2.5 mm (max, 6.6 mm). The mean standard deviation of 3D respiratory cycle amplitude within a treatment course was 2.0 Ϯ 1.6 mm. The motion directionality of individual respiratory cycles on average deviated 4.6 Ϯ 1.6 ° from the treatment course mean directionality. The treatment course mean motion directionality on average deviated 7.6 Ϯ 6.5 ° from the directionality in the 4DCT scan. A single patient-specifi c oblique direction in space explained 97.7 Ϯ 1.7% and 88.3 Ϯ 10.1% of all positional variance (motion) throughout the treatment courses, excluding and including baseline shifts between treatment fi elds, respectively. Conclusion. Due to variable breathing amplitudes a single 4DCT scan was not always representative of the mean motion amplitude during treatment. However, the motion was highly directional with a fairly stable direction throughout treatment, indicating a potential for more optimal individualized motion margins aligned to the preferred direction of motion.
Acta Oncologica, 2008
Introduction. With the purpose of implementing gated radiotherapy for lung cancer patients, this study investigated the interfraction variations in tumour size and internal displacement over entire treatment courses. To explore the potential of image guided radiotherapy (IGRT) the variations were measured using a set-up strategy based on imaging of bony landmarks and compared to a strategy using in room lasers, skin tattoos and cupper landmarks. Materials and methods. During their six week treatment course of 60 Gy in 2 Gy fractions, ten patients underwent 3 respiratory gated CT scans. The tumours were contoured on each CT scan to evaluate the variations in volumes and position. The lung tumours and the mediastinal tumours were contoured separately. The positional variations were measured as 3D mobility vectors and correlated to matching of the scans using the two different strategies. Results. The tumour size was significantly reduced from the first to the last CT scan. For the lung tumours the reduction was 19%, p 00.03, and for the mediastinal tumours the reduction was 34%, p 00.0007. The mean 3D mobility vector and the SD for the lung tumours was 0.51 cm (90.21) for matching using bony landmarks and 0.85 cm (90.54) for matching using skin tattoos. For the mediastinal tumours the corresponding vectors and SD's were 0.55 cm (90.19) and 0.72 cm (90.43). The differences between the vectors were significant for the lung tumours p00.004. The interfractional overlap of lung tumours was 80Á87% when matched using bony landmarks and 70Á76% when matched using skin tattoos. The overlap of the mediastinal tumours were 60Á65% and 41Á47%, respectively. Conclusions. Despite the use of gating the tumours varied considerably, regarding both position and volume. The variations in position were dependent on the set-up strategy. Set-up using IGRT was superior to set-up using skin tattoos.