Dosimetric validation for an automatic brain metastases planning software using single‐isocenter dynamic conformal arcs

Liu, Haisong; Li, Jun; Pappas, E.; Andrews, David W.; Evans, James J.; Werner‐Wasik, Maria; Yan, Yu; Dicker, Adam P.; Shi, Wenyin

doi:10.1120/jacmp.v17i5.6320

Cited by 12 publications

(8 citation statements)

References 19 publications

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“…With the recent introduction of commercial single‐isocenter planning algorithms for simultaneously treating multiple brain metastases, either using automated dynamic conformal arcs or automated VMAT, more dosimetric comparison to GK is required. These studies have already demonstrated a reduction in monitor units compared with conventional VMAT.…”

Section: Discussionmentioning

confidence: 99%

GammaKnife versus VMAT radiosurgery plan quality for many brain metastases

Potrebko

Keller

All

et al. 2018

J Applied Clin Med Phys

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The purpose of this work was to compare dose distributions between two radiosurgery modalities, single‐isocenter volumetric modulated arc therapy (VMAT), and GammaKnife Perfexion (GK), in the treatment of a large number (≥7) of brain metastases. Twelve patients with 103 brain metastases were analyzed. The median number of targets per patient was 8 (range: 7–14). GK plans were compared to noncoplanar VMAT plans using both 6‐MV flattening filter‐free (FFF) and 10‐MV FFF modes. Parameters analyzed included radiation therapy oncology group conformity index (CI), 12, 6, and 3 Gy isodose volumes (V12 Gy, V6 Gy, V3 Gy), mean and maximum hippocampal dose, and maximum skin dose. There were statistically significant differences in CI (2.5 ± 1.6 vs 1.6 ± 0.8 and 1.7 ± 0.9, P < 0.001, P < 0.001), V12 Gy (2.8 ± 6.1 cc vs 3.0 ± 5.2 cc and 3.1 ± 5.4 cc, P = 0.003, P < 0.001), and V3 Gy (323.0 ± 294.8 cc vs, 880.1 ± 369.1 cc and 937.9 ± vs 361.9 cc, P = 0.005, P = 0.001) between GK versus both 6‐MV FFF and 10‐MV FFF. No significant differences existed for maximum hippocampal or skin doses. In conclusion, highly optimized VMAT produced improved conformity at the expense of a higher V12 Gy and V3 Gy volume when compared with highly optimized GK.

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Section: Discussionmentioning

confidence: 99%

GammaKnife versus VMAT radiosurgery plan quality for many brain metastases

Potrebko

Keller

All

et al. 2018

J Applied Clin Med Phys

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“…This hollow phantom can be printed with bone‐mimicking materials based on anatomical structures of a past patient, based on CT data or scans, and it is filled with water and a 3D polymer gel dosimeter insert to simulate soft tissue equivalence 30 . Irradiation of this gel phantom provides the ability to evaluate 3D dose distributions for SRS 18,31,32 . The custom phantom is designed with a glossy white exterior, which is incompatible with the SGRT cameras.…”

Section: Methodsmentioning

confidence: 99%

“…30 Irradiation of this gel phantom provides the ability to evaluate 3D dose distributions for SRS. 18,31,32 The custom phantom is designed with a glossy white exterior, which is incompatible with the SGRT cameras. A nude makeup foundation (Stay Matte, Rimmel, London) was applied to the phantom's surface to simulate a skin tone visualizable by the scanner units.…”

Section: Rtsafe Prime Phantommentioning

confidence: 99%

“…35,36 More specifically, studies have evaluated the suitability of using 3Dprinted head phantoms with bone mimicking materials for patient-specific plan verification procedures, and they demonstrate excellent agreement with the actual patient. 18,37 Gel dosimetry permits evaluation of 3D dose distributions for SRS 18,31,32 and has been recommended for initial validation of a stereotactic program. However, it is important to note that the equipment…”

Section: Gel Dosimetersmentioning

confidence: 99%

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End to end comparison of surface‐guided imaging versus stereoscopic X‐rays for the SRS treatment of multiple metastases with a single isocenter using 3D anthropomorphic gel phantoms

Bry

Saenz

Pappas

et al. 2022

J Applied Clin Med Phys

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Introduction Two end‐to‐end tests evaluate the accuracy of a surface‐guided radiation therapy (SGRT) system (CRAD Catalyst HD) for position verification in comparison to a stereoscopic x‐ray imaging system (Brainlab Exactrac ) for single‐isocenter, multiple metastases stereotactic radiosurgery (SRS) using 3D polymer gel inserts. Materials and methods A 3D‐printed phantom (Prime phantom, RTsafe PC, Athens, Greece) with two separate cylindrical polymer gel inserts were immobilized in open‐face masks and treated with a single isocentric, multitarget SRS plan. Planning was done in Brainlab (Elements) to treat five metastatic lesions in one fraction, and initial setup was done using cone beam computed tomography. Positional verification was done using orthogonal X‐ray imaging (Brainlab Exactrac) and/or a surface imaging system (CRAD Catalyst HD, Uppsala, Sweden), and shift discrepancies were recorded for each couch angle. Forty‐two hours after irradiation, the gel phantom was scanned in a 1.5 Tesla MRI, and images were fused with the patient computed tomography data/structure set for further analysis of spatial dose distribution. Results Discrepancies between the CRAD Catalyst HD system and Brainlab Exactrac were <1 mm in the translational direction and <0.5° in the angular direction at noncoplanar couch angles. Dose parameters (DMean%, D95%) and 3D gamma index passing rates were evaluated for both setup modalities for each planned target volume (PTV) at a variety of thresholds: 3%/2 mm (Exactrac≥93.1% and CRAD ≥87.2%), 5%/2 mm (Exactrac≥95.6% and CRAD ≥94.6%), and 5%/1 mm (Exactrac≥81.8% and CRAD ≥83.7%). Conclusion Dose metrics for a setup with surface imaging was found to be consistent with setup using x‐ray imaging, demonstrating high accuracy and reproducibility for treatment delivery. Results indicate the feasibility of using surface imaging for position verification at noncoplanar couch angles for single‐isocenter, multiple‐target SRS using end‐to‐end quality assurance (QA) testing with 3D polymer gel dosimetry.

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“…3D printing is being increasingly employed in radiotherapy for applications ranging from construction of treatment accessories (Canters et al 2016, Lindegaard et al 2016, Ricotti et al 2016, Jones et al 2017, Zhao et al 2017 to patient geometry and/or material reproduction (Ehler et al 2014, Liu et al 2016, Madamesila et al 2016, Kamomae et al 2017, Yea et al 2017. Regarding the latter, introducing material inhomogeneities in the phantoms has recently drawn considerable attention.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a novel 3D printed patient specific phantom for quality assurance in cranial stereotactic radiosurgery applications

et al. 2019

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In single-isocenter stereotactic radiosurgery/radiotherapy (SRS/SRT) intracranial applications, multiple targets are being treated concurrently, often involving non-coplanar arcs, small photon beams and steep dose gradients. In search for more rigorous quality assurance protocols, this work presents and evaluates a novel methodology for patient-specific pre-treatment plan verification, utilizing 3D printing technology. In a patient’s planning CT scan, the external contour and bone structures were segmented and 3D-printed using high-density bone-mimicking material. The resulting head phantom was filled with water while a film dosimetry insert was incorporated. Patient and phantom CT image series were fused and inspected for anatomical coherence. HUs and corresponding densities were compared in several anatomical regions within the head. Furthermore, the level of patient-to-phantom dosimetric equivalence was evaluated both computationally and experimentally. A single-isocenter multi-focal SRS treatment plan was prepared, while dose distributions were calculated on both CT image series, using identical calculation parameters. Phantom- and patient-derived dose distributions were compared in terms of isolines, DVHs, dose-volume metrics and 3D gamma index (GI) analysis. The phantom was treated as if the real patient and film measurements were compared against the patient-derived calculated dose distribution. Visual inspection of the fused CT images suggests excellent geometric similarity between phantom and patient, also confirmed using similarity indices. HUs and densities agreed within one standard deviation except for the skin (modeled as ‘bone’) and sinuses (water-filled). GI comparison between the calculated distributions resulted in passing rates better than 97% (1%/1 mm). DVHs and dose-volume metrics were also in satisfying agreement. In addition to serving as a feasibility proof-of-concept, experimental absolute film dosimetry verified the computational study results. GI passing rates were above 90%. Results of this work suggest that employing the presented methodology, patient-equivalent phantoms (except for the skin and sinuses areas) can be produced, enabling literally patient-specific pre-treatment plan verification in intracranial applications.

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Dosimetric validation for an automatic brain metastases planning software using single‐isocenter dynamic conformal arcs

Cited by 12 publications

References 19 publications

GammaKnife versus VMAT radiosurgery plan quality for many brain metastases

GammaKnife versus VMAT radiosurgery plan quality for many brain metastases

End to end comparison of surface‐guided imaging versus stereoscopic X‐rays for the SRS treatment of multiple metastases with a single isocenter using 3D anthropomorphic gel phantoms

Characterization of a novel 3D printed patient specific phantom for quality assurance in cranial stereotactic radiosurgery applications

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