Progress and prospects of flattening filter free beam technology in radiosurgery and stereotactic body radiotherapy

Ghemiş, Diana M.; Marcu, Loredana G.

doi:10.1016/j.critrevonc.2021.103396

Cited by 8 publications

(2 citation statements)

References 58 publications

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“…As Pokhrel et al previously emphasized, flattening filter free (FFF) VMAT for SBRT of lung lesions would improve dose coverage at tumor-lung interface compared to flattened beams, 46 and additionally, there is growing evidence for FFF VMAT of various other tumor sites including the liver, brain, prostate, cervix cancers. 47 Therefore, FFF VMAT could logically be compared, however, as we do not use FFF but 6 MV FF VMAT in our clinic, we hypothesized and tried to obtain a more efficient WO-DCA technique based on DCA treatment without MLC modulation in target to potentially minimize small-field dosimetry errors and MLC interplay effects. If we had used FFF for 6MV photon energy in our clinic and followed the identical plans for both treatment techniques in this investigation, the impact would most likely be the same on both arms, and the proportionate difference between the two planning techniques would most probably not have been altered.…”

Section: Discussionmentioning

confidence: 99%

Novel Clinically Weight-Optimized Dynamic Conformal Arcs (WO-DCA) for Liver SBRT: A Comparison with Volumetric Modulated Arc Therapy (VMAT)

Saglam¹,

Bölükbaşı²,

Atasoy³

et al. 2021

TCRM

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Purpose To evaluate the feasibility of shortening the duration of liver stereotactic radiotherapy (SBRT) without jeopardizing dosimetry or conformity by utilizing weight-optimized dynamic conformal arcs (WO-DCA) as opposed to volumetric modulated arc therapy (VMAT) for tumors away from critical structures. Methods Nineteen patients with liver metastasis were included, previously treated with 50 Gy in 4 fractions with VMAT technique using two partial coplanar arcs of 6 MV beams delivered in high-definition multi-leaf collimator (HD-MLC). Two coplanar partial WO-DCA were generated on Pinnacle treatment planning system (TPS) for each patient; and MLC aperture around the planning target volume (PTV) was automatically generated at different margins for both arcs and maintained dynamically around the target during arc rotation. Weight of the two arcs using optimization method was adjusted between the arcs to maximize tumor coverage and protect organs at risk (OAR) based on the RTOG‐0438 protocol. Results The WO-DCA plans successfully “agreed” with the standard VMAT for OAR (liver, spinal cord, stomach, duodenum, small bowel, and heart) and PTV (D mean , D 98% , D 2% , CI, and GI), with superior mean quality assurance (QA) pass rate (97.06 vs 93.00 for VMAT; P < 0.001 and t = 8.87). Similarly, the WO-DCA technique additionally reduced the beam‐on time (3.26 vs 4.43; P < 0.001) and monitor unit (1860 vs 2705 for VMAT; P < 0.001) values significantly. Conclusion The WO‐DCA plans might minimize small‐field dosimetry errors and defeat patient‐specific VMAT QA requirements due to the omission of MLC beam modulation through the target volume. The WO‐DCA plans may additionally enable faster treatment delivery times and lower OAR without sacrificing target doses in SBRT of liver tumors away from critical structures.

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Section: Discussionmentioning

confidence: 99%

Novel Clinically Weight-Optimized Dynamic Conformal Arcs (WO-DCA) for Liver SBRT: A Comparison with Volumetric Modulated Arc Therapy (VMAT)

Saglam¹,

Bölükbaşı²,

Atasoy³

et al. 2021

TCRM

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“…To facilitate the delivery of high dose gradients in stereotactic treatments, modern linear accelerators have the ability to administer the photon dose without the flattening filter. While small radiation fields flattening filter-free beams (FFF) have a number of advantages, such as higher dose rate, reduced peripheral dose and scatter, and reduced treatment time [9], the question still arises as to what overall benefits can FFF beams bring in SRT compared to the standard flattened beams (FF). This is an important issue for clinics lacking FFF linear accelerators while employing SRT techniques.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric Parameters in Hypofractionated Stereotactic Radiotherapy for Brain Metastases: Do Flattening Filter-Free Beams Bring Benefits? A Preliminary Study

Ghemiş

Marcu

2023

Cancers

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Purpose: This study aimed to compare the dosimetric results of flattening filter-free (FFF) vs. flattened (FF) treatment plans for fractionated stereotactic radiotherapy (fSRT), with the goal to highlight potential advantages of FFF beams. Methods: A group of 18 patients with brain metastases treated with fSRT (30 Gy delivered in 5 fractions) were included. The dosimetric parameters evaluated were: (1) physical dosimetric parameters (number of monitor units (MUs), conformity index (CI), dose gradient index (DGI), beam on time (BOT)); (2) clinical dosimetric parameters pertaining to target volume (PTV) and organs at risk (OARs). Two treatment plans were performed for all patients: one used 6 MV FFF beams and the other used 6 MV flattened beams. Results: A slight increase in MUs was observed for the FFF mode (+23.3 MUs). The CI showed a difference of −2.7% for the FF plans (p = 0.28), correlated with a poorer coverage of the PTV. DGI values reported in terms of PTV are in line with international recommendations and showed a +1.9% difference for FFF plans. An average BOT of 90.3 s was reported for FFF plans, which was 2.3 times shorter than that required for FF plans delivery (p ≤ 0.001). A slight decrease of PTV coverage (−1.26%, p = 0.036) for FF plans can be considered relevant, but no other significant differences were observed between the two optimizations. No statistically significant benefit of using FFF beams to reduce V20 for normal brain could be demonstrated. Conclusion: These dosimetric results encourage the implementation of fSRT with standard flattened beams in centers where FFF linacs are not available.

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Artificial intelligence‐based motion tracking in cancer radiotherapy: A review

Salari,

Wang,

Wynne

et al. 2024

J Applied Clin Med Phys

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Radiotherapy aims to deliver a prescribed dose to the tumor while sparing neighboring organs at risk (OARs). Increasingly complex treatment techniques such as volumetric modulated arc therapy (VMAT), stereotactic radiosurgery (SRS), stereotactic body radiotherapy (SBRT), and proton therapy have been developed to deliver doses more precisely to the target. While such technologies have improved dose delivery, the implementation of intra‐fraction motion management to verify tumor position at the time of treatment has become increasingly relevant. Artificial intelligence (AI) has recently demonstrated great potential for real‐time tracking of tumors during treatment. However, AI‐based motion management faces several challenges, including bias in training data, poor transparency, difficult data collection, complex workflows and quality assurance, and limited sample sizes. This review presents the AI algorithms used for chest, abdomen, and pelvic tumor motion management/tracking for radiotherapy and provides a literature summary on the topic. We will also discuss the limitations of these AI‐based studies and propose potential improvements.

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Progress and prospects of flattening filter free beam technology in radiosurgery and stereotactic body radiotherapy

Cited by 8 publications

References 58 publications

Novel Clinically Weight-Optimized Dynamic Conformal Arcs (WO-DCA) for Liver SBRT: A Comparison with Volumetric Modulated Arc Therapy (VMAT)

Novel Clinically Weight-Optimized Dynamic Conformal Arcs (WO-DCA) for Liver SBRT: A Comparison with Volumetric Modulated Arc Therapy (VMAT)

Dosimetric Parameters in Hypofractionated Stereotactic Radiotherapy for Brain Metastases: Do Flattening Filter-Free Beams Bring Benefits? A Preliminary Study

Artificial intelligence‐based motion tracking in cancer radiotherapy: A review

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