Potential radiotherapy improvements with respiratory gating

Keall, P.; Kini, V. R.; Vedam, Sastry; Mohan, Radhe

doi:10.1007/bf03178368

Cited by 148 publications

(104 citation statements)

References 31 publications

(29 reference statements)

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“…Reproducibility of free‐breathing extrema positions while the patient is freely breathing, is crucial for passively‐gated respiratory‐correlated therapy. The data in Table 2 show that the average

{FB}_{insp}

SD is greater than the average

{FB}_{exp}

SD, suggesting that end‐expiration is the best phase for passive respiratory‐gated treatment where the patient is freely breathing, which is in agreement with previous observations 12 , 18 …”

Section: Discussionsupporting

confidence: 90%

Comparison of breath‐hold and free‐breathing positions of an external fiducial by analysis of respiratory traces

Hunjan

Starkschall

Rosen

et al. 2008

J Applied Clin Med Phys

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An internal target volume (ITV) accounting for respiratory‐induced tumor motion is best obtained using 4DCT. However, when 4DCT is not available, inspiratory/expiratory breath‐hold false(BHinsp, BHexpfalse) CT images have been suggested as an alternative. In such cases, an external fiducial on the abdomen can be used as a substitute for tumor motion and CT images are acquired when the marker position matches – as judged by the therapist/physicist ‐ its positions at previously determined free‐breathing (FB) respiratory extrema false(FBinsp, FBexpfalse). In this study we retrospectively determined the accuracy of these matches. Free breathing 4DCT images were acquired, followed by BHinsp and BHexp CT images for 25 patients with non‐small‐cell lung cancer. Respiration was monitored using a commercial external fiducial system, which generates positional information while CT studies are conducted. Software was written for statistically analyzing the displacement of the external fiducial during BHinsp and BHexp CT acquisition and comparing these displacements with corresponding mean FB extrema positions false(FBinsp and FBexp, respectivelyfalse) using a Student's t‐test. In 72% of patients, mean positions at BHinsp differed significantly from mean positions at FBinsp false(normalp<0.05: 0.13–1.40 cmfalse). In 92% of patients, mean positions at BHexp differed significantly from mean positions at FBexp false(normalp<0.05: 0.03–0.70 cmfalse), although this difference was smaller than 0.5 cm in many cases false(median=0.34 cmfalse). Our findings indicate that relying solely on abdominal external markers for accurate BH CT imaging in order to accurately estimate FB extrema positions may be subject to significant error.PACS numbers 87.53.bd, 87.57.C‐, 87.59.Fm, 87.55.Gh

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{FB}_{insp}

SD is greater than the average

{FB}_{exp}

SD, suggesting that end‐expiration is the best phase for passive respiratory‐gated treatment where the patient is freely breathing, which is in agreement with previous observations 12 , 18 …”

Section: Discussionsupporting

confidence: 90%

Comparison of breath‐hold and free‐breathing positions of an external fiducial by analysis of respiratory traces

Hunjan

Starkschall

Rosen

et al. 2008

J Applied Clin Med Phys

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show abstract

“…Infrared cameras, sensor belts and spirometers are examples of noninvasive and radiation‐free devices commonly used in motion monitoring systems to obtain the tracking signal 6. However, the correlation between external surrogate motion and internal tumor motion is not always reproducible and may vary inter and intrafractionally 7.…”

Section: Introductionmentioning

confidence: 99%

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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“…The safety margins are based on probability calculations and added to the tumor volume in the MidV position, resulting in smaller treatment volumes than the ITV concept. Using a gating approach [4,5], the tumor is only irradiated in a predefined respiratory window with a smaller range of motion. This technique leads to a reduction of irradiated volumes but increases overall treatment time.…”

Section: Introductionmentioning

confidence: 99%

Respiratory motion-management in stereotactic body radiation therapy for lung cancer – A dosimetric comparison in an anthropomorphic lung phantom (LuCa)

Ehrbar

Perrin

Peroni

et al. 2016

Radiotherapy and Oncology

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BACKGROUND AND PURPOSE The objective of this study was to compare the latest respiratory motion-management strategies, namely the internal-target-volume (ITV) concept, the midventilation (MidV) principle, respiratory gating and dynamic couch tracking. MATERIALS AND METH-ODS An anthropomorphic, deformable and dynamic lung phantom was used for the dosimetric validation of these techniques. Stereotactic treatments were adapted to match the techniques and five distinct respiration patterns, and delivered to the phantom while radiographic film measurements were taken inside the tumor. To report on tumor coverage, these dose distributions were used to calculate mean doses (Dmean), changes in homogeneity indices (ΔH2-98), gamma agreement, and areas covered by the planned minimum dose (A>Dmin). RESULTS All techniques achieved good tumor coverage (A>Dmin>99.0%) and minor changes in Dmean (±3.2%). Gating and tracking strategies showed superior results in gamma agreement and ΔH2-98 compared to ITV and MidV concepts, which seem to be more influenced by the interplay and the gradient effect. For lung, heart and spinal cord, significant dose differences between the four techniques were found (p<0.05), with lowest doses for gating and tracking strategies. CONCLUSION Active motion-management techniques, such as gating or tracking, showed superior tumor dose coverage and better organ dose sparing than the passive techniques based on tumor margins. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1016/j.radonc.2016.10.011 This article is protected by copyright. All rights reserved. AbstractBackground and Purpose: The objective of this study was to compare the latest respiratory motion-management strategies, namely the internal-target-volume (ITV) concept, the mid-ventilation (MidV) principle, respiratory gating and dynamic couch tracking. Materials and Methods: An anthropomorphic, deformable and dynamic lung phantom was used for the dosimetric validation of these techniques. Stereotactic treatments were adapted to match the techniques and five distinct respiration patterns, and delivered to the phantom while radiographic film measurements were taken inside the tumor. To report on tumor coverage, these dose distributions were used to calculate mean doses (Dmean), changes in homogeneity indices (ΔH 2-98 ), gamma agreement, and areas covered by the planned minimum dose (A >Dmin ).Results: All techniques achieved good tumor coverage (A >Dmin >99.0%) and minor changes in D mean (±3.2%). Gating and tracking strategies showed superior results in gamma agreement and ΔH 2-98 compared to ITV and MidV concepts, which seem to be more influenced by the interplay and the gradient effect. For lung, heart and spinal cord, significant dose differences between the four techniques were found (p<0.05), with l...

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Potential radiotherapy improvements with respiratory gating

Cited by 148 publications

References 31 publications

Comparison of breath‐hold and free‐breathing positions of an external fiducial by analysis of respiratory traces

Comparison of breath‐hold and free‐breathing positions of an external fiducial by analysis of respiratory traces

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

Respiratory motion-management in stereotactic body radiation therapy for lung cancer – A dosimetric comparison in an anthropomorphic lung phantom (LuCa)

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