Evaluation of intrafraction prostate motion tracking using the Clarity Autoscan system for safety margin validation

Richter, Anne; Exner, Florian; Weick, Stefan; Lawrenz, Ingulf; Polat, Bülent; Flentje, Michael; Mantel, Frederick

doi:10.1016/j.zemedi.2019.12.004

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…In contrast, margins were never exceeded in the left-right axis. Intrafraction motion amplitude was highest in the antero-posterior axis and lowest in the left-right axis, in accordance with the motions that could be expected from rectum and bladder filling and with previous findings [8,11,[23][24][25]. The Calypso Ò data showed that the median offset of prostate during SBRT was close to 0, with a maximum of 2.3 mm (Table 2).…”

Section: Discussionsupporting

confidence: 90%

Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking

Jaccard

Ehrbar

Miralbell

et al. 2021

Radiotherapy and Oncology

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To reconstruct the dose delivered during single-fraction urethra-sparing prostate stereotactic body radiotherapy (SBRT) accounting for intrafraction motion monitored by intraprostatic electromagnetic transponders (EMT). Methods: We analyzed data of 15 patients included in the phase I/II ''ONE SHOT" trial and treated with a single fraction of 19 Gy to the planning target volume (PTV) and 17 Gy to the urethra planning risk volume. During delivery, prostate motion was tracked with implanted EMT. SBRT was interrupted when a 3mm threshold was trespassed and corrected unless the offset was transient. Motion-encoded reconstructed (MER) plans were obtained by splitting the original plans into multiple sub-beams with isocenter shifts based on recorded EMT positions, mimicking prostate motion during treatment. We analyzed intrafraction motion and compared MER to planned doses. Results: The median EMT motion range (±SD) during delivery was 0.26 ± 0.09, 0.22 ± 0.14 and 0.18 ± 0. 10 cm in the antero-posterior, supero-inferior, and left-right axes, respectively. Treatment interruptions were needed for 8 patients because of target motion beyond limits in the antero-posterior (n = 6) and/or supero-inferior directions (n = 4). Comparing MER vs. original plan there was a median relative dose difference of À1.9% (range, À7.9 to À1.0%) and of +0.5% (À0.3-1.7%) for PTV D 98% and D 2% , respectively. The clinical target volume remained sufficiently covered with a median D 98% difference of À0.3% (À1.6-0.5%). Bladder and rectum dosimetric parameters showed significant differences between original and MER plans, but mostly remained within acceptable limits. Conclusions: The dosimetric impact of intrafraction prostate motion was minimal for target coverage for single-fraction prostate SBRT with real-time electromagnetic tracking combined with beam gating.

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Section: Discussionsupporting

confidence: 90%

Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking

Jaccard

Ehrbar

Miralbell

et al. 2021

Radiotherapy and Oncology

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“…Similar to other studies, some of which using other monitoring devices, the detected intrafraction displacements were generally small (> 3 mm in 16% of treatment time and > 5 mm in 5% of treatment time) but larger displacements (≥ 8 mm) occurred with a frequency less than 1%, as also reported elsewhere (9,11,12,20). The smallest displacements were observed in LR directions and the largest ones in inferior and posterior directions (7,9,11,17,25,26).…”

Section: Discussionsupporting

confidence: 87%

“…Then, to evaluate the effectiveness of NI-AS margins, treatment plans were re-computed using an autoplanning algorithm (19). Several studies dealing with intrafraction prostate monitoring during treatment can be found in the literature (9)(10)(11)20) as well as many margins recipes that consider interfractional motion (16,17,21). However, to our knowledge, this is one of the first that uses monitoring device to investigate non homogeneous and time-dependent margins for intrafractional prostate motion during moderate HF radiation therapy.…”

Section: Introductionmentioning

confidence: 99%

Minimum non-isotropic and asymmetric margins for taking into account intrafraction prostate motion during moderately hypofractionated radiotherapy

et al. 2022

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“…The difference is probably ascribed to the fact that Sihono et al may have used mean intrafractional motion for margin calculation, whereas we used maximum intrafractional motion. The mean intrafractional prostate displacement by Richter et al [16], who also used the Clarity system, was remarkably little: − 0.06 ± 0.49 mm, − 0.09 ± 0.61 mm, and − 0.01 ± 0.78 mm in the SI, LR and AP directions, respectively. Levin-Epstein et al [17] reported that the margins calculated with the intra-fractional motion were 2.7 mm, 1.9 mm, and 3.1 mm in the SI, LR, and AP directions, respectively.…”

Section: Discussionmentioning

confidence: 92%

“…Recently, the trial of the single-fraction SBRT for localized prostate cancer under the intrafractional tracking was reported [7]. While higher quality of positioning is required in SBRT to optimize treatments, it is known that organs in pelvis including prostate are shifting under the influence of rectal volume, bladder volume, and change of muscle tension among other things [8][9][10][11][12][13][14][15][16][17]. These intrafractional uncertainties possibly affect the dose distributions [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Injection of hydrogel spacer increased maximal intrafractional prostate motion in anterior and superior directions during volumetric modulated arc therapy-stereotactic body radiation therapy for prostate cancer

et al. 2022

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Background The aim of this study was to clarify the association between intrafractional prostate shift and hydrogel spacer. Methods Thirty-eight patients who received definitive volumetric modulated arc therapy (VMAT)-stereotactic body radiation therapy (SBRT) for prostate cancer with prostate motion monitoring in our institution in 2018–2019 were retrospectively evaluated. In order to move the rectum away from the prostate, hydrogel spacer (SpaceOAR system, Boston Scientific, Marlborough, the United States) injection was proposed to the patients as an option in case of meeting the indication of use. We monitored intrafractional prostate motion by using a 4-dimensional (4D) transperineal ultrasound device: the Clarity 4D ultrasound system (Elekta AB). The deviation of the prostate was monitored in each direction: superior-inferior, left–right, and anterior–posterior. We also calculated the vector length. The maximum intrafractional displacement (MID) per fraction for each direction was detected and mean of MIDs was calculated per patient. The MIDs in the non-spacer group and the spacer group were compared using the unpaired t-test. Results We reviewed 33 fractions in eight patients as the spacer group and 148 fractions in 30 patients as the non-spacer group. The superior MID was 0.47 ± 0.07 (mean ± SE) mm versus 0.97 ± 0.24 mm (P = 0.014), the inferior MID was 1.07 ± 0.11 mm versus 1.03 ± 0.25 mm (P = 0.88), the left MID was 0.74 ± 0.08 mm versus 0.87 ± 0.27 mm (P = 0.55), the right MID was 0.67 ± 0.08 mm versus 0.92 ± 0.21 mm (P = 0.17), the anterior MID was 0.45 ± 0.06 mm versus 1.16 ± 0.35 mm (P = 0.0023), and the posterior MID was 1.57 ± 0.17 mm versus 1.37 ± 0.22 mm (P = 0.56) in the non-spacer group and the spacer group, respectively. The max of VL was 2.24 ± 0.19 mm versus 2.89 ± 0.62 mm (P = 0.19), respectively. Conclusions Our findings suggest that maximum intrafractional prostate motion during VMAT-SBRT was larger in patients with hydrogel spacer injection in the superior and anterior directions. Since this difference seemed not to disturb the dosimetric advantage of the hydrogel spacer, we do not recommend routine avoidance of the hydrogel spacer use.

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Evaluation of intrafraction prostate motion tracking using the Clarity Autoscan system for safety margin validation

Cited by 9 publications

References 31 publications

Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking

Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking

Minimum non-isotropic and asymmetric margins for taking into account intrafraction prostate motion during moderately hypofractionated radiotherapy

Injection of hydrogel spacer increased maximal intrafractional prostate motion in anterior and superior directions during volumetric modulated arc therapy-stereotactic body radiation therapy for prostate cancer

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