Intrafraction Variation of Mean Tumor Position During Image-Guided Hypofractionated Stereotactic Body Radiotherapy for Lung Cancer

Shah, Chirag; Grills, I.S.; Kestin, Larry L.; McGrath, Samuel; Ye, Hong; Martin, Shannon; Yan, Di

doi:10.1016/j.ijrobp.2011.02.011

Cited by 62 publications

(63 citation statements)

References 20 publications

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“…The largest standard deviation was in craniocaudal direction as expected given this is the axis of greatest respiratory amplitude. Our reported inter/ intrafraction tumor displacements are comparable to previous studies that used stereotactic patient positioning equipment [11,12] and frameless equipment [11,16,17]. Guckenberger et al [12] used stereotactic frame immobilization and demonstrated intrafraction tumor position variation of 0.4 mm ML (SD 1.0), -0.8 mm AP (SD 1.7), and 0.7 mm CC (SD 1.7).…”

Section: Positional Variability With Frameless Patient Setupsupporting

confidence: 85%

“…Guckenberger et al [12] used stereotactic frame immobilization and demonstrated intrafraction tumor position variation of 0.4 mm ML (SD 1.0), -0.8 mm AP (SD 1.7), and 0.7 mm CC (SD 1.7). Comparing soft-tissue post-correction, pre-treatment CBCTs and post-treatment CBCTs, Shah et al [11] observed 0.01 mm ML (SD 1.5), 0.1 mm AP (SD 1.9), and 0.2 mm CC (SD 1.8) intrafraction displacements with different types of immobilization: stereotactic frame, BodyFIX, or hybrid (alpha cradle+BodyFIX). Utilizing a frameless free-breathing set-up, but 4D CBCT, Sonke et al [17] investigated set up accuracy and validated use of small PTV margins during SBRT.…”

Section: Positional Variability With Frameless Patient Setupmentioning

confidence: 99%

“…Previously noted predictors of larger interfraction and intrafraction positional variability included type of immobilization device [9,11], motion amplitude, [11] and increased treatment time [18], but these have not previously been evaluated in relation to frameless, freebreathing patient set-up. A statistically significant increase in tumor displacement on treatment CBCT was observed when tumor motion amplitude was >9 mm on planning 4DCT.…”

Section: Factors Influencing Positional Accuracymentioning

confidence: 99%

“…In order to achieve the required geometrical precision, SBRT is often performed with complex immobilization systems, such as stereotactic frames, evacuated cushions with or without abdominal compression, and/or cone-beam CT (CBCT) for soft tissue-based patient set up [5][6][7][8]. CBCT has been used to measure inter-/intrafractional positional variations [9][10], to qualitatively and quantitatively identify potential sources of positional variability [11,12], and to determine dosimetric impact of positional variability [5,13]. A known source of positional variation for conventional radiotherapy results from tumor regression as demonstrated by several studies showing average tumor regression of about 40% using 4D-FBCT and CBCT [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Schuster¹

2013

J Nucl Med Radiat Ther

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Purpose: To quantify inter-and intrafractional variations of tumor position and analyze the relationship between these changes and respiratory motion amplitude, volume changes and tumor location, in frameless stereotactic body radiotherapy (SBRT) of lung tumors. Materials and methods:Tumor volumes and bony landmarks were contoured manually by a single physician on 174 pre-and under treatment cone-beam computed tomographies (CBCTs) of 17 patients. The interfraction variation of the tumor position was measured by comparing the centroid position of the tumor relative to bony anatomy of each fraction to the pretreatment CBCT scans. The intrafraction variation was measured by comparing the pretreatment tumor location to under treatment CBCTs for every fraction. Respiratory motion was analyzed on planning 4D fan beam CTs for all patients. The change in tumor volume was determined by comparing the contoured tumor volumes on sequential pretreatment CBCTs. Results:The average interfraction/intrafraction tumor displacementrelative to bony landmark in mm was 0.6 (SD 2.3) /-0.3 (SD 0.7) in mediolateral, -0.7 (SD 3.8) /0.0 (SD 2.1) in anteroposterior, and -0.6 (SD 5.9) /-0.2 (SD 2.3) in craniocaudal direction. Inter-/intrafraction tumor-to-bone variations >3 mm were observed in 60%/14% of scans respectively. On the initial CBCT, the average tumor volume was 9 cm 3 (range 1-37 cm 3 ) with a mean volume reduction over the treatment course of 12% (range, +14% to -54%). Patients with a pretreatment motion amplitude > 9 mm (p=0.002), peripheral tumor location (p=0.04), and volume change >12% (p=0.009) had larger interfraction displacement in lateral direction. Conclusions:Frameless set up is comparable to patient positioning with more elaborate fixation devices. Tumor position variations relative to bony anatomy are an important source of geometric uncertainty providing a rationale for repeated soft tissue-based image guidance, particularly in patients identified in this study to be at higher risk for variations. Central tumor location was defined as within 3 cm of heart, aorta, spinal cord, esophagus and main airways. A total dose of 48-60 Gy was delivered in 4-6 fractions prescribed to PTV covering isodose. The approximate treatment time per fraction was 30 minutes; the duration of the treatment course averaged 10 days (range 8-14 days). All patients completed informed consent which had been approved by the local institutional review board. 4D CT and CBCT acquisitionPatients were immobilized in the supine position with both arms above the head using an AccuFix ArmShuttle (Qfix Systems, Avondale, PA, USA). A free breathing four-dimensional computed tomography (4DCT, Brilliance Big Bore, Philips Medical Systems, Andover, MA) simulation procedure was used for all patients (120 kV, 400 mAs, slice thickness 3 mm). The isocenter was marked with three skin tattoos. The scan range covered the complete thoracic region. For each 4DCT, respiration motion was monitored by tracking the vertical displacement of the upper abdominal wa...

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Section: Positional Variability With Frameless Patient Setupsupporting

confidence: 85%

Section: Positional Variability With Frameless Patient Setupmentioning

confidence: 99%

Section: Factors Influencing Positional Accuracymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Schuster¹

2013

J Nucl Med Radiat Ther

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“…When a baseline shift occurs, the tumor may move away from the gating window, resulting in a longer treatment time or an underdose at the target. Shah et al23 observed the mean target position using the pre–post‐treatment CBCT of 126 patients. They reported that the incidences of mean target position shifts > 2 mm and 5 mm were 40.8% and 4.2%, respectively.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the intra‐ and interfractional tumor motion and variability by fiducial‐based real‐time tracking in liver stereotactic body radiation therapy

Liang

Liu

Xue

et al. 2018

J Applied Clin Med Phys

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PurposeTumor motion amplitude varies during treatment. The purpose of the study was to evaluate the intra‐ and interfraction tumor motion and variability in patients with liver cancer treated with fiducial‐based real‐time tracking stereotactic body radiotherapy (SBRT).MethodsFourteen liver patients were treated with SBRT using a CyberKnife. Two to four fiducial markers implanted near the tumor were used for real‐time monitoring using the Synchrony system. The tumor motion information during treatment was extracted from the log files recorded by the Synchrony system. Logfile‐based amplitudes in the superior–posterior (SI), left–right (LR) and anterior–posterior (AP) directions were compared to the 4DCT‐based amplitudes. The intra‐ and interfraction amplitude variations and the incidence of baseline shifts were analyzed for 66 fractions administered to 14 patients.ResultsThe median (range) logfile‐based liver motion amplitudes for all patients were 11.9 (5.1–17.3) mm, 1.3 (0.4–4) mm and 3.8 (0.9–7.7) mm in the SI, LR and AP directions, respectively. Compared with the logfile‐based amplitude, the 4DCT‐based amplitude was underestimated (P < 0.05). The median (range) intra‐ and interfraction liver motion amplitude variations were 4.3 (1.6–6.0) mm (SI), 0.5 (0.2–2.2) mm(LR) and 1.5 (0.3–3.3) mm (AP) and 1.7 (0.5–4.6) mm (SI), 0.3 (0.1–3.0) mm (LR) and 0.7 (0.3–2.7) mm (AP), respectively. Baseline shifts exceeding 2 mm, 3 mm and 5 mm were observed in 27.3%, 7.6% and 3% of the measurements, respectively, within 10 min, and in 66.7%, 38.1% and 19%, respectively, within 30 min for the square root of the sum of the squares of the distances in the SI, LR and AP directions (3D). The tumor motion amplitude was found to be correlated with the baseline shift.ConclusionsMost patients showed significant intra‐ and interfraction liver motion amplitude variations over the entire course of radiation. More caution is needed for patients with large tumor motion amplitudes.

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A feasibility study of intrafractional tumor motion estimation based on 4D‐CBCT using diaphragm as surrogate

Zhou

Hong

Yan

et al. 2018

J Applied Clin Med Phys

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PurposeTo investigate the intrafractional stability of the motion relationship between the diaphragm and tumor, as well as the feasibility of using diaphragm motion to estimate lung tumor motion.MethodsEighty‐five paired (pre and posttreatment) daily 4D‐CBCT images were obtained from 20 lung cancer patients who underwent SBRT. Bony registration was performed between the pre‐ and post‐CBCT images to exclude patient body movement. The end‐exhalation phase image of the pre‐CBCT image was selected as the reference image. Tumor positions were obtained for each phase image using contour‐based translational alignments. Diaphragm positions were obtained by translational alignment of its apex position. A linear intrafraction model was constructed using regression analysis performed between the diaphragm and tumor positions manifested on the pretreatment 4D‐CBCT images. By applying this model to posttreatment 4D‐CBCT images, the tumor positions were estimated from posttreatment 4D‐CBCT diaphragm positions and compared with measured values. A receiver operating characteristic (ROC) test was performed to determine a suitable indicator for predicting the estimate accuracy of the linear model.ResultsUsing the linear model, per‐phase position, mean position, and excursion estimation errors were 1.12 ± 0.99 mm, 0.97 ± 0.88 mm, and 0.79 ± 0.67 mm, respectively. Intrafractional per‐phase tumor position estimation error, mean position error, and excursion error were within 3 mm 95%, 96%, and 99% of the time, respectively. The residual sum of squares (RSS) determined from pretreatment images achieved the largest prediction power for the tumor position estimation error (discrepancy < 3 mm) with an Area Under ROC Curve (AUC) of 0.92 (P < 0.05).ConclusionUtilizing the relationship between diaphragm and tumor positions on the pretreatment 4D‐CBCT image, intrafractional tumor positions were estimated from intrafractional diaphragm positions. The estimation accuracy can be predicted using the RSS obtained from the pretreatment 4D‐CBCT image.

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Intrafraction Variation of Mean Tumor Position During Image-Guided Hypofractionated Stereotactic Body Radiotherapy for Lung Cancer

Cited by 62 publications

References 20 publications

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Evaluation of the intra‐ and interfractional tumor motion and variability by fiducial‐based real‐time tracking in liver stereotactic body radiation therapy

A feasibility study of intrafractional tumor motion estimation based on 4D‐CBCT using diaphragm as surrogate

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