Flattening filter free VMAT for a stereotactic, single‐dose of 30 Gy to lung lesion in a 15‐min treatment slot

Pokhrel, Damodar; Sanford, Lana; Dhanireddy, Bhaswanth; Molloy, J; Randall, Marcus E.; McGarry, Ronald C.

doi:10.1002/acm2.12829

Cited by 13 publications

(16 citation statements)

References 31 publications

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“…Upgrading Halcyon's maximum achievable dose rates to a practical 1000 MU/min may potentially match or improve BOT relative to Truebeam. This may aid in improved treatment delivery efficiency for a 50-55 Gy in five fractions treatment scheme.However, delivering an ultrahigh single dose of 30 Gy or 34 Gy46,47 or more drastic hypofractionated 54-60 Gy in three fractions treatment schemata48 on Halcyon Linac for lung SBRT may take longer treatment times for the patient on the table. Therefore, we currently only recommend treating selective lung SBRT patients with 50-55 Gy in five fractions on the Halcyon.…”

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confidence: 99%

Clinical validation of ring‐mounted halcyon linac for lung SBRT: comparison to SBRT‐dedicated C‐arm linac treatments

Pokhrel

Visak

Critchfield

et al. 2020

J Applied Clin Med Phys

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Stereotactic body radiotherapy (SBRT) of lung tumors via the ring‐mounted Halcyon Linac, a fast kilovoltage cone beam CT‐guided treatment with coplanar geometry, a single energy 6MV flattening filter free (FFF) beam and volumetric modulated arc therapy (VMAT) is a fast, safe, and feasible treatment modality for selected lung cancer patients. Four‐dimensional (4D) CT‐based treatment plans were generated using advanced AcurosXB algorithm with heterogeneity corrections using an SBRT board and Halcyon couch insert. Halcyon VMAT‐SBRT plans with stacked and staggered multileaf collimators produced highly conformal radiosurgical dose distribution to the target, lower intermediate dose spillage, and similar dose to adjacent organs at risks (OARs) compared to SBRT‐dedicated highly conformal clinical noncoplanar Truebeam VMAT plans following the RTOG‐0813 requirements. Due to low monitor units per fraction and less multileaf collimator (MLC) modulation, the Halcyon VMAT plan can deliver lung SBRT fractions with an overall treatment time of less than 15 min (for 50 Gy in five fractions), significantly improving patient comfort and clinic workflow. Higher pass rates of quality assurance results demonstrate a more accurate treatment delivery on Halcyon. We have implemented Halcyon for lung SBRT treatment in our clinic. We suggest others use Halcyon for lung SBRT treatments using abdominal compression or 4D CT‐based treatment planning, thus expanding the access of curative ultra‐hypofractionated treatments to other centers with only a Halcyon Linac. Clinical follow‐up results for patients treated on Halcyon Linac with lung SBRT is ongoing.

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confidence: 99%

Clinical validation of ring‐mounted halcyon linac for lung SBRT: comparison to SBRT‐dedicated C‐arm linac treatments

Pokhrel

Visak

Critchfield

et al. 2020

J Applied Clin Med Phys

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“…We had initial concerns about the feasibility of single-fraction breath-hold lung SABR on the MR-linac due to the long delivery times, as well as technical challenges such as the stability of patient positioning, and the ability to treat small tumors eligible for single-fraction SABR. Our MR-guided approach is generally more complex, requiring longer delivery times than with FFF-VMAT [15] , [19] , [30] . Single-fraction SMART also involved additional mid-treatment simulation and plan assessment.…”

Section: Discussionmentioning

confidence: 99%

“…Approaches for tracking lung tumors without using fiducials have also been developed, but their reliability depends on tumor size and density [13] , [14] . Fast delivery of single-fraction lung SABR can be performed using flattening-filter-free (FFF) volumetric modulated arc therapy (VMAT), using an internal target volume (ITV) approach [15] . However, active motion monitoring is desirable as both 4-dimensional (4D) computed tomography (CT) and cone-beam CT (CBCT) may underestimate tumor motion during lung SABR [16] .…”

Section: Introductionmentioning

confidence: 99%

Delivery of magnetic resonance-guided single-fraction stereotactic lung radiotherapy

Finazzi¹,

Koste²,

Palacios

et al. 2020

Physics and Imaging in Radiation Oncology

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Background and purpose: Single-fraction stereotactic ablative radiotherapy (SABR) is an effective treatment for early-stage lung cancer, but concerns remain about the accurate delivery of SABR in a single session. We evaluated the delivery of single-fraction lung SABR using magnetic resonance (MR)-guidance. Materials and methods: An MR-simulation was performed in 17 patients, seven of whom were found to be unsuitable, largely due to unreliable tracking of small tumors. Ten patients underwent single-fraction SABR to 34 Gy on a 0.35 T MR-linac system, with online plan adaptation. Gated breath-hold SABR was delivered using a planning target volume (PTV) margin of 5 mm, and a 3 mm gating window. Continuous MR-tracking of the gross tumor volume (GTV t) was performed in sagittal plane, with visual patient feedback provided using an in-room monitor. The real-time MR images were analyzed to determine precision and efficiency of gated delivery. Results: All but one patient completed treatment in a single session. The median total in-room procedure was 120 min, with a median SABR delivery session of 39 min. Review of 7.4 h of cine-MR imaging revealed a mean GTV t coverage by the PTV during beam-on of 99.6%. Breath-hold patterns were variable, resulting in a mean duty cycle efficiency of 51%, but GTV t coverage was not influenced due to real-time MR-guidance. On-table adaptation improved PTV coverage, but had limited impact on GTV doses. Conclusions: Single-fraction gated SABR of lung tumors can be performed with high precision using MR-guidance. However, improvements are needed to ensure MR-tracking of small tumors, and to reduce treatment times.

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“…It has previously been shown that 30 Gy in a single fraction can be delivered to the lung lesion in a 15-min time slot. 32 Delivering a single fraction treatment subjects the plan to delivery potential errors that could greatly enhanced the interplay effect, so our k-DCA routine could potentially limit this effect by providing less MLC modulation across the target and improve small-field dosimetry. 33 Further validation and clinical implementation of this KBP model and automated k-DCA routine for SBRT patient treatment is underway.…”

Section: Discussionmentioning

confidence: 99%

“…The use of the MC code opens the possibility of using this routinely in the clinic for either online adaptive re‐planning or same/next day offline adaptive re‐planning of lung SBRT treatment. It has previously been shown that 30 Gy in a single fraction can be delivered to the lung lesion in a 15‐min time slot 32 . Delivering a single fraction treatment subjects the plan to delivery potential errors that could greatly enhanced the interplay effect, so our k ‐DCA routine could potentially limit this effect by providing less MLC modulation across the target and improve small‐field dosimetry 33 .…”

Section: Discussionmentioning

confidence: 99%

An Automated knowledge‐based planning routine for stereotactic body radiotherapy of peripheral lung tumors via DCA‐based volumetric modulated arc therapy

Visak

McGarry

et al. 2020

J Applied Clin Med Phys

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PurposeTo develop a knowledge‐based planning (KBP) routine for stereotactic body radiotherapy (SBRT) of peripherally located early‐stage non‐small‐cell lung cancer (NSCLC) tumors via dynamic conformal arc (DCA)‐based volumetric modulated arc therapy (VMAT) using the commercially available RapidPlanTM software. This proposed technique potentially improves plan quality, reduces complexity, and minimizes interplay effect and small‐field dosimetry errors associated with treatment delivery.MethodsKBP model was developed and validated using 70 clinically treated high quality non‐coplanar VMAT lung SBRT plans for training and 20 independent plans for validation. All patients were treated with 54 Gy in three treatments. Additionally, a novel k‐DCA planning routine was deployed to create plans incorporating historical three‐dimensional‐conformal SBRT planning practices via DCA‐based approach prior to VMAT optimization in an automated planning engine. Conventional KBPs and k‐DCA plans were compared with clinically treated plans per RTOG‐0618 requirements for target conformity, tumor dose heterogeneity, intermediate dose fall‐off and organs‐at‐risk (OAR) sparing. Treatment planning time, treatment delivery efficiency, and accuracy were recorded.ResultsKBPs and k‐DCA plans were similar or better than clinical plans. Average planning target volume for validation was 22.4 ± 14.1 cc (7.1–62.3 cc). KBPs and k‐DCA plans provided similar conformity to clinical plans with average absolute differences of 0.01 and 0.01, respectively. Maximal doses to OAR were lowered in both KBPs and k‐DCA plans. KBPs increased monitor units (MU) on average 1316 (P < 0.001) while k‐DCA reduced total MU on average by 1114 (P < 0.001). This routine can create k‐DCA plan in less than 30 min. Independent Monte Carlo calculation demonstrated that k‐DCA plans showed better agreement with planned dose distribution.ConclusionA k‐DCA planning routine was developed in concurrence with a knowledge‐based approach for the treatment of peripherally located lung tumors. This method minimizes plan complexity associated with model‐based KBP techniques and improve plan quality and treatment planning efficiency.

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Flattening filter free VMAT for a stereotactic, single‐dose of 30 Gy to lung lesion in a 15‐min treatment slot

Cited by 13 publications

References 31 publications

Clinical validation of ring‐mounted halcyon linac for lung SBRT: comparison to SBRT‐dedicated C‐arm linac treatments

Clinical validation of ring‐mounted halcyon linac for lung SBRT: comparison to SBRT‐dedicated C‐arm linac treatments

Delivery of magnetic resonance-guided single-fraction stereotactic lung radiotherapy

An Automated knowledge‐based planning routine for stereotactic body radiotherapy of peripheral lung tumors via DCA‐based volumetric modulated arc therapy

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