Effect of a hydrogel spacer on the intrafractional prostate motion during CyberKnife treatment for prostate cancer

Suzuki, Toshihiro; Saito, Masahide; Oda, Hiroshi; Mochizuki, Zennosuke; Mochizuki, Koji; Satani, Kenichiro; Sano, Nobuyuki; Aoki, Shin; Marino, Kan; Komiyama, Takafumi

doi:10.1002/acm2.13005

Cited by 3 publications

(4 citation statements)

References 27 publications

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“…In our study, there was no significant difference in maximum VL, whereas superior and anterior MIDs were significantly larger in the spacer group in our study, and the difference between the two groups were 0.5 mm in the superior direction and 0.7 mm in the anterior direction. Suzuki et al [32] also reported the effect of the hydrogel spacer on the intrafractional prostate motion during the CyberKnife treatment for prostate cancer. They calculated the mean intrafractional prostate motion in the SI, LR, and AP directions for each patient using two fiducial markers and kV X-ray images and compared the results of the spacer group with the non-spacer group.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, the complications related to the injection of hydrogel spacer have been reported [27,28]. Regarding prostate motion, it was shown that the insertion of hydrogel spacer did not greatly limit interfractional and intrafractional prostate displacements [29][30][31][32][33]. We hypothesized that the hydrogel spacer potentially implicates the prostate variability during RT.…”

Section: Introductionmentioning

confidence: 93%

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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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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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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“…It was also reported that intra-fractional prostate motion was not affected by a hydrogel spacer in the treatment of cyberknife. 27 A similar tumor-tracking system recently became available for tomotherapy systems, potentially allowing the same margin in the treatment of SBRT for localized prostate cancer using tomotherapy.…”

Section: Discussionmentioning

confidence: 99%

Stereotactic body radiotherapy using a hydrogel spacer for localized prostate cancer: A dosimetric comparison between tomotherapy with the newly‐developed tumor‐tracking system and cyberknife

Manabe

Hashimoto

Mukouyama

et al. 2021

J Applied Clin Med Phys

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Purpose With a new tumor‐tracking system (Synchrony®) for tomotherapy (Radixact®), the internal and set‐up margins can be tightened, like cyberknife (CyberKnife®), in the planning of stereotactic body radiotherapy (SBRT) for prostate cancer. Recently, the usefulness of placing a hydrogel spacer between the prostate and rectum has been established in prostate radiotherapy. We evaluated the characteristics of tomotherapy plans with the tumor‐tracking system and compared them with cyberknife SBRT plans for localized prostate cancer using a hydrogel spacer. Methods In 20 patients, two plans were created and compared using tomotherapy and cyberknife. All patients underwent hydrogel spacer injection behind the prostate before simulation CT and MRI for fusion. For all plans, 36.25 Gy in 7.25‐Gy fractions for a minimum coverage dose of 95% of planning target volume (PTV) (D95%) was prescribed. The D99% of PTV and D0.1 ml of the PTV, urethra, bladder, and rectum were intended to be > 90%, 110–130%, 100–110%, <110%, and <100%, respectively, of the prescribed doses. Results All plans using tomotherapy and cyberknife achieved the intended dose constraints. The cyberknife plans yielded better median PTV‐V110% (volume of PTV covered by 110% isodose line, 54.8%), maintaining lower median D0.1 ml of the urethra (37.5 Gy) and V80% of the bladder (11.0 ml) compared to the tomotherapy plans (39.0%; p < 0.0001, 38.2 Gy; p < 0.0001, and 18.3 ml; p < 0.0001, respectively). The tomotherapy plans were superior to the cyberknife plans for the rectum (V80% = 0.4 vs. 1.0 ml, p < 0.001; D1ml = 26.4 vs. 29.0 Gy, p = 0.013). Conclusions Our results suggested that tomotherapy with the tumor‐tracking system has reasonable potential for SBRT for localized prostate cancer using a hydrogel spacer.

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“…Suzuki et al . reported that there was no effect of HS on intrafaction prostate motion in three axes during Cyberknife treatment for Japanese prostate cancer patients [ 17 ]. However, since intrafraction prostate motion may also be affected by irradiation conditions, such as preparation methods and irradiation time, strictly speaking, it is necessary to study each facility, and we are currently continuing to do that.…”

Section: Discussionmentioning

confidence: 99%

Preliminary analysis of prostate positional displacement using hydrogel spacer during the course of proton therapy for prostate cancer

Sato

Katō

Motoyanagi

et al. 2020

Journal of Radiation Research

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In recent years, a novel technique has been employed to maintain a distance between the prostate and the rectum by transperineally injecting a hydrogel spacer (HS). However, the effect of HS on the prostate positional displacement is poorly understood, despite its stability with HS in place. In this study, we investigated the effect of HS insertion on the interfraction prostate motion during the course of proton therapy (PT) for Japanese prostate cancer patients. The study population consisted of 22 cases of intermediate-risk prostate cancer with 11 cases with HS insertion and 11 cases without HS insertion. The irradiation position and preparation were similar for both groups. To test for reproducibility, regular confirmation computed tomography (RCCT) was done four times during the treatment period, and five times overall [including treatment planning CT (TPCT)] in each patient. Considering the prostate position of the TPCT as the reference, the change in the center of gravity of the prostate relative to the bony anatomy in the RCCTs of each patient was determined in the left–right (LR), superior–inferior (SI) and anterior–posterior (AP) directions. As a result, no significant difference was observed across the groups in the LR and SI directions. Conversely, a significant difference was observed in the AP direction (P < 0.05). The proportion of the 3D vector length ≤5 mm was 95% in the inserted group, but 55% in the non-inserted group. Therefore, HS is not only effective in reducing rectal dose, but may also contribute to the positional reproducibility of the prostate.

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Effect of a hydrogel spacer on the intrafractional prostate motion during CyberKnife treatment for prostate cancer

Cited by 3 publications

References 27 publications

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

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

Stereotactic body radiotherapy using a hydrogel spacer for localized prostate cancer: A dosimetric comparison between tomotherapy with the newly‐developed tumor‐tracking system and cyberknife

Preliminary analysis of prostate positional displacement using hydrogel spacer during the course of proton therapy for prostate cancer

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