Extracranial stereotactic radiation therapy: set-up accuracy of patients treated for liver metastases

Herfarth, Klaus; Debus, Jürgen; Lohr, Frank; Bahner, M. L.; Fritz, Péter; Höss, Angelika; Schlegel, Wolfgang; Wannenmacher, M.

doi:10.1016/s0360-3016(99)00413-7

Cited by 191 publications

(92 citation statements)

References 25 publications

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“…They reported mean patient movements of

1.6 mm \pm 1.2 mm

in the LAT direction,

1.4 mm \pm 1.0 mm

in the AP direction, and

2.3 mm \pm - 1.3 mm

in the SI direction. Another study by Herfarth et al (12) presented similar results. The study by Wulf et al (11) on the treatment accuracy using another stereotactic body frame showed SDs of 3.5 mm in the longitudinal (SI), 2.2 mm in the AP, and 3.9 mm in the LAT directions.…”

Section: Resultssupporting

confidence: 53%

Stereotactic IMRT for prostate cancer: Setup accuracy of a new stereotactic body localization system

Wang

Jacob

Chen

et al. 2004

J Applied Clin Med Phys

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The purpose of this work is to prospectively assess the setup accuracy that can be achieved with a stereotactic body localizer (SBL) in immobilizing patients for stereotactic intensity‐modulated radiotherapy (IMRT) for prostate cancer. By quantifying this important factor and target mobility in the SBL, we expect to provide a guideline for selecting planning target volume margins for stereotactic treatment planning. We analyzed data from 40 computed tomography (CT) studies (with slice thickness of 3 mm) involving 10 patients with prostate cancer. Each patient had four sets of CT scans during the course of radiotherapy. For the purpose of this study, all four sets of CT scans were obtained with the patients immobilized in a customized body pillow formed by vacuum suction. Unlike other immobilization devices, this system consists not only of a customized body pillow, but also of a fixation sheet used to suppress patient respiratory motion, a stereotactic body frame to provide stereotaxy, and a carbon fiber base board to which both the body cushion and the frame are affixed. We identified four bony landmarks and measured their coordinates in the stereotactic body frame on each set of CT scans. The displacements of the bony landmarks from their corresponding positions on the simulation scan (first CT scan) were analyzed in three dimensions in terms of overall, systematic, and random categories. The initial planned isocenter was also marked on the patients' skin with fiducials for each CT study. The distance from each bony landmark to the fiducial‐based isocenter was measured and compared among the four sets of CT scans. The deviations in distances were also compared to those measured from the landmarks to the stereotactic frame center, in order to determine the effectiveness of the rigid body frame in positioning patients with prostate cancer. Target inter‐fraction motion in this system was also studied for five patients by measuring the deviations in distances from the target geometric center to the bony landmarks. Our results showed that the overall setup accuracy had standard deviations (SDs) of 2.58 mm, 2.41 mm, and 3.51 mm in lateral (LAT), anterior‐posterior (AP), and superior‐inferior (SI) directions, respectively. The random component had SDs of 1.72 mm, 2.06 mm, and 2.79 mm, and the systematic component showed SDs of 0.92 mm, –0.27 mm, and 0.90 mm in these three directions. In terms of three‐dimensional vector, the mean displacement over 116 measurements was 3.0 mm with an SD of 1.29 mm. Compared to the rigid reference, the skin‐mark‐based reference was less reliable for patient repositioning in terms of reproducing known bony landmark positions. The mean target mobility relative to the bony landmarks was 2.22±3.45 mm,0.17±1.11 mm, and 0.11±2.69 mm in the AP, LAT, and SI directions, respectively. In conclusion, the body immobilization system has the ability to immobilize prostate cancer patients with satisfactory setup accuracy for fractionated extracranial stereotactic radiotherapy. A rigid frame system ser...

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“…They reported mean patient movements of

1.6 mm \pm 1.2 mm

in the LAT direction,

1.4 mm \pm 1.0 mm

in the AP direction, and

2.3 mm \pm - 1.3 mm

Section: Resultssupporting

confidence: 53%

Stereotactic IMRT for prostate cancer: Setup accuracy of a new stereotactic body localization system

Wang

Jacob

Chen

et al. 2004

J Applied Clin Med Phys

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“…This results in an ablative dose of radiation at the target with a steep dose gradient to minimize damage to tissues outside of the target 9 , 10 , 11 , 12 . SRS treatments are generally associated with small intracranial targets, and recently the term stereotactic body radiosurgery (SBRT) was developed to describe stereotactic‐guided radiotherapy to extracranial sites 13 , 14 , 15 , 16 , 17 …”

Section: Introductionmentioning

confidence: 99%

Quantifying isocenter measurements to establish clinically meaningful thresholds

Denton

Shields

Howe

et al. 2015

J Applied Clin Med Phys

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A dataset range of isocenter congruency verification tests have been examined from a statistical perspective for the purpose of establishing tolerance levels that are meaningful, based on the fundamental limitation of linear accelerator isocentricity and the demands of a high‐precision stereotactic radiosurgery program. Using a laser‐defined isocenter, a total of 149 individual isocenter congruency tests were examined with recorded values for ideal spatial corrections to the isocenter test tool. These spatial corrections were determined from radiation exposures recorded on an electronic portal imaging device (EPID) at various gantry, collimator, and treatment couch combinations. The limitations of establishing an ideal isocenter were quantified from each variable which contributed to uncertainty in isocenter definition. Individual contributors to uncertainty, specifically, daily positioning setup errors, gantry sag, multileaf collimator (MLC) offset, and couch walkout, were isolated from isocenter congruency measurements to determine a clinically meaningful isocenter measurement. Variations in positioning of the test tool constituted, on average, 0.38 mm magnitude of correction. Gantry sag and MLC offset contributed 0.4 and 0.16 mm, respectively. Couch walkout had an average degrading effect to isocenter of 0.72 mm. Considering the magnitude of uncertainty contributed by each uncertainty variable and the nature of their combination, an appropriate schedule action and immediate action level were determined for use in analyzing daily isocenter congruency test results in a stereotactic radiosurgery (SRS) program. The recommendations of this study for this linear accelerator include a schedule action level of 1.25 mm and an immediate action level of 1.50 mm, requiring prompt correction response from clinical medical physicists before SRS or stereotactic body radiosurgery (SBRT) is administered. These absolute values were derived from considering relative data from a specific linear accelerator and, therefore, represent a means by which a numerical quantity can be used as a test threshold with relative specificity to a particular linear accelerator.PACS number: 87.53Ly, 29.20.Ej, 87.56.Fc

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“…[32][33][34][35][36] This was confirmed by Guckenberger M. et al who conducted a 4D-IGRT study in liver SBRT with acquisition of a CBCT study immediately before and after treatment delivery. Despite successful immobilization of the patient with a SBF, they observed considerable drifts in the target position independently from the bony anatomy in an order of 3.7 ± 2.2 mm on average.…”

Section: Discussionmentioning

confidence: 64%

Imaged-guided liver stereotactic body radiotherapy using VMAT and real-time adaptive tumor gating. Concerns about technique and preliminary clinical results

Llacer-Moscardo

Riou

Azria

et al. 2017

Reports of Practical Oncology & Radiotherapy

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Extracranial stereotactic radiation therapy: set-up accuracy of patients treated for liver metastases

Cited by 191 publications

References 25 publications

Stereotactic IMRT for prostate cancer: Setup accuracy of a new stereotactic body localization system

Stereotactic IMRT for prostate cancer: Setup accuracy of a new stereotactic body localization system

Quantifying isocenter measurements to establish clinically meaningful thresholds

Imaged-guided liver stereotactic body radiotherapy using VMAT and real-time adaptive tumor gating. Concerns about technique and preliminary clinical results

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