Risk of target coverage loss for stereotactic body radiotherapy treatment of synchronous lung lesions via single‐isocenter volumetric modulated arc therapy

Critchfield, Lana C.; Bernard, Mark; Randall, Marcus E.; McGarry, Ronald C.; Pokhrel, Damodar

doi:10.1002/acm2.13145

Cited by 6 publications

(5 citation statements)

References 28 publications

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“…Generally, the errors are in the order of several millimeters when pretreatment setup verifications have been routinely performed [14][15][16]. Considering the high modulations and steep dose fall-off in VMAT, a tiny setup error of several millimeters is capable to induce significant dose loss in the target [17][18][19][20]. Liao et al found that a 3 mm setup error appeared to deteriorate plan quality of VMAT for locally advanced breast cancer [19].…”

Section: Introductionmentioning

confidence: 99%

Robustness of VMAT to setup errors in postmastectomy radiotherapy of left-sided breast cancer: Impact of bolus thickness

Chen

Gao

et al. 2023

PLoS ONE

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Background Volumetric modulated arc therapy (VMAT) with varied bolus thicknesses has been employed in postmastectomy radiotherapy (PMRT) of breast cancer to improve superficial target coverage. However, impact of bolus thickness on plan robustness remains unclear. Methods The study enrolled ten patients with left-sided breast cancer who received radiotherapy using VMAT with 5 mm and 10 mm bolus (VMAT-5B and VMAT-10B). Inter-fractional setup errors were simulated by introducing a 3 mm shift to isocenter of the original plans in the anterior-posterior, left-right, and inferior-superior directions. The plans (perturbed plans) were recalculated without changing other parameters. Dose volume histograms (DVH) were collected for plan evaluation. Absolute dose differences in DVH endpoints for the clinical target volume (CTV), heart, and left lung between the perturbed plans and the original ones were used for robustness analysis. Results VMAT-10B showed better target coverage, while VMAT-5B was superior in organs-at-risk (OARs) sparing. As expected, small setup errors of 3 mm could induce dose fluctuations in CTV and OARs. The differences in CTV were small in VMAT-5B, with a maximum difference of -1.05 Gy for the posterior shifts. For VMAT-10B, isocenter shifts in the posterior and right directions significantly decreased CTV coverage. The differences were -1.69 Gy, -1.48 Gy and -1.99 Gy, -1.69 Gy for ΔD95% and ΔD98%, respectively. Regarding the OARs, only isocenter shifts in the posterior, right, and inferior directions increased dose to the left lung and the heart. Differences in VMAT-10B were milder than those in VMAT-5B. Specifically, mean heart dose were increased by 0.42 Gy (range 0.10 ~ 0.95 Gy) and 0.20 Gy (range -0.11 ~ 0.72 Gy), and mean dose for the left lung were increased by 1.02 Gy (range 0.79 ~ 1.18 Gy) and 0.68 Gy (range 0.47 ~ 0.84 Gy) in VMAT-5B and VMAT-10B, respectively. High-dose volumes in the organs were increased by approximate 0 ~ 2 and 1 ~ 3 percentage points, respectively. Nevertheless, most of the dosimetric parameters in the perturbed plans were still clinically acceptable. Conclusions VMAT-5B appears to be more robust to 3 mm setup errors than VMAT-10B. VMAT-5B also resulted in better OARs sparing with acceptable target coverage and dose homogeneity. Therefore 5 mm bolus is recommended for PMRT of left-sided breast cancer using VMAT.

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Section: Introductionmentioning

confidence: 99%

Robustness of VMAT to setup errors in postmastectomy radiotherapy of left-sided breast cancer: Impact of bolus thickness

Chen

Gao

et al. 2023

PLoS ONE

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“…While the latter method can provide substantially shorter treatments, the effectiveness relies primarily on the accuracy of patient set up and the precision of treatment delivery accentuates errors based on various geometric factors. 17 Recently, Varian RapidArc® planning with volume-modulated arc therapy (VMAT) (Varian Medical Systems, Palo Alto, CA, USA) has emerged as an effective treatment planning and delivery technique in lung SBRT. This advanced treatment offers higher precision treatments with steep dose gradients, increased sparing of organs at risk (OAR) and faster delivery times when compared to previous techniques.…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, a single‐isocenter technique can be utilized to treat multiple lung lesions synchronously. While the latter method can provide substantially shorter treatments, the effectiveness relies primarily on the accuracy of patient set up and the precision of treatment delivery accentuates errors based on various geometric factors 17 . Recently, Varian RapidArc® planning with volume‐modulated arc therapy (VMAT) (Varian Medical Systems, Palo Alto, CA, USA) has emerged as an effective treatment planning and delivery technique in lung SBRT.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of using ring‐mounted Halcyon Linac for single‐isocenter/two‐lesion lung stereotactic body radiation therapy

Pokhrel

Webster

Mallory

et al. 2022

J Applied Clin Med Phys

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To demonstrate the plan quality and delivery efficiency of volumetricmodulated arc therapy (VMAT) with the Halcyon Linac ring delivery system (RDS) in the treatment of single-isocenter/two-lesion lung stereotactic body radiation therapy (SBRT). Materials/methods: Sixteen previously treated non-coplanar VMAT singleisocenter/two-lesion lung SBRT plans delivered with SBRT-dedicated C-arm TrueBeam Linac were selected. Prescribed dose was 50 Gy to each lesion over five fractions with treatment delivery every other day and AcurosXB algorithm as the final dose calculation algorithm.TrueBeam single-isocenter plans were reoptimized for Halcyon Linac with coplanar geometry. Both TrueBeam and Halcyon plans were normalized for identical combined target coverage and evaluated. Conformity indices (CIs), heterogeneity index (HI), gradient index (GI), gradient distance (GD), and D 2cm were compared. The normal lung V5Gy, V10Gy, V20Gy, mean lung dose (MLD), and dose to organs at risk (OAR) were evaluated. Treatment delivery parameters, including beam-on time, were recorded. Results: Halcyon plans were statistically similar to clinically delivered True-Beam plans. No statistical differences in target conformity, dose heterogeneity, or intermediate-dose spillage were observed (all, p > 0.05). Halcyon plans, on average,demonstrated statistically insignificant reduced maximum dose to most adjacent OAR and normal lung. However, Halcyon yielded statistically significant lower maximal dose to the ribs (p = 0.041) and heart (p = 0.026), dose to 1 cc of ribs (p = 0.035) and dose to 5 cc of esophagus (p = 0.043). Plan complexity slightly increased as seen in the average increase of total monitor units, modulation factor, and beam-on time by 480, 0.48, and 2.78 min, respectively. However, the estimated overall treatment time was reduced by 2.22 min,on average.Mean dose delivery accuracy of clinical TrueBeam plans and the corresponding Halcyon plans was 98.9 ± 0.85% (range: 98.1%-100%) and 98.45 ± 0.99% (range: 97.9%-100%), respectively, demonstrating similar treatment delivery accuracy. Conclusion: SBRT treatment of synchronous lung lesions via single-isocenter VMAT on Halcyon RDS is feasible and dosimetrically equivalent to clinically delivered TrueBeam plans. Halcyon provides excellent plan quality and shorter overall treatment time that may improve patient compliance, reduce intrafraction movement, improve clinic efficiency, and potentially offering lung SBRT treatments for underserved patients on a Halcyon only clinic.

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“…However, small patient setup errors may occur due to the difficulties of multiple lung lesions alignment on a single cone beam CT (CBCT) scan. These small setup errors may lead to unacceptable loss in target(s) coverage due to lung heterogeneities and the steep dose gradients obtained in the SBRT plan 6 . Thus, a Restricted Single‐Isocenter Stereotactic Body Radiotherapy (RESIST) method was developed to minimize the problems associated with a single‐isocenter VMAT lung SBRT plan (e.g., setup errors, collision issues) 7 .…”

Section: Introductionmentioning

confidence: 99%

“…These small setup errors may lead to unacceptable loss in target(s) coverage due to lung heterogeneities and the steep dose gradients obtained in the SBRT plan. 6 Thus, a Restricted Single-Isocenter Stereotactic Body Radiotherapy (RESIST) method was developed to minimize the problems associated with a singleisocenter VMAT lung SBRT plan (e.g., setup errors, collision issues). 7 It has been reported on a multi-institutional database of 700 patients treated with SBRT that patient outcome is related to a clinic's experience in delivery of SBRT.…”

Section: Introductionmentioning

confidence: 99%

Automation and integration of a novel restricted single‐isocenter stereotactic body radiotherapy (a‐RESIST) method for synchronous two lung lesions

Critchfield

Visak

Bernard

et al. 2021

J Applied Clin Med Phys

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Synchronous treatment of two lung lesions using a single-isocenter volumetric modulated arc therapy (VMAT) stereotactic body radiation therapy (SBRT) plan can decrease treatment time and reduce the impact of intrafraction motion. However, alignment of both lesions on a single cone beam CT (CBCT) can prove difficult and may lead to setup errors and unacceptable target coverage loss. A Restricted Single-Isocenter Stereotactic Body Radiotherapy (RESIST) method was created to minimize setup uncertainties and provide treatment delivery flexibility. RESIST utilizes a single-isocenter placed at patient's midline and allows both lesions to be planned separately but treated in the same session. Herein is described a process of automation of this novel RESIST method. Automation of RESIST significantly reduced treatment planning time while maintaining the benefits of RESIST. To demonstrate feasibility, ten patients with two lung lesions previously treated with a singleisocenter clinical VMAT plan were replanned manually with RESIST (m-RESIST) and with automated RESIST (a-RESIST). a-RESIST method automatically sets isocenter, creates beam geometry, chooses appropriate dose calculation algorithms, and performs VMAT optimization using an in-house trained knowledge-based planning model for lung SBRT. Both m-RESIST and a-RESIST showed lower dose to normal tissues compared to manually planned clinical VMAT although a-RESIST provided slightly inferior, but still clinically acceptable, dose conformity and gradient indices.However, a-RESIST significantly reduced the treatment planning time to less than 20 min and provided a higher dose to the lung tumors. The a-RESIST method provides guidance for inexperienced planners by standardizing beam geometry and plan optimization using DVH estimates. It produces clinically acceptable two lesions VMAT lung SBRT plans efficiently. We have further validated a-RESIST on phantom measurement and independent pretreatment dose verification of another four selected 2-lesions lung SBRT patients and implemented clinically. Further development of a-RESIST for more than two lung lesions and refining this approach for extracranial oligometastastic abdominal/pelvic SBRT, including development of automated simulated collision detection algorithm, merits future investigation.

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Risk of target coverage loss for stereotactic body radiotherapy treatment of synchronous lung lesions via single‐isocenter volumetric modulated arc therapy

Cited by 6 publications

References 28 publications

Robustness of VMAT to setup errors in postmastectomy radiotherapy of left-sided breast cancer: Impact of bolus thickness

Robustness of VMAT to setup errors in postmastectomy radiotherapy of left-sided breast cancer: Impact of bolus thickness

Feasibility of using ring‐mounted Halcyon Linac for single‐isocenter/two‐lesion lung stereotactic body radiation therapy

Automation and integration of a novel restricted single‐isocenter stereotactic body radiotherapy (a‐RESIST) method for synchronous two lung lesions

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