Monte Carlo Modeling of Dynamic Tumor Tracking on a Gimbaled Linear Accelerator

Carpentier, EmilieE; Mcdermott, RonanL; Su, Shiqin; Rostamzadeh, Maryam; Popescu, IAntoniu; Bergman, AlanahM; Mestrovic, Ante

doi:10.4103/jmp.jmp_108_22

Cited by 1 publication

(1 citation statement)

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“…A 4D dose calculation requires modelling the beam's tracking motion while re‐calculating the plan on multiple breathing phases, subsequently accumulating these dose distributions on a reference phase CT image. A 4D dose calculation can be conducted in the TPS 14 or with Monte Carlo (MC) 15 using 2 or 10 breathing phases from a patient's 4DCT image set. Using only 2 breathing phases, the inhale (0%) and exhale (50%) phases, with patient‐specific weightings gives similar results as using all 10 breathing phases but requires less time and resources 14 .…”

Section: Introductionmentioning

confidence: 99%

Four‐dimensional treatment planning strategies for dynamic tumor tracking

Carpentier,

McDermott,

Camborde

et al. 2024

J Applied Clin Med Phys

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IntroductionDynamic tumor tracking (DTT) is a motion management technique where the radiation beam follows a moving tumor in real time. Not modelling DTT beam motion in the treatment planning system leaves an organ at risk (OAR) vulnerable to exceeding its dose limit. This work investigates two planning strategies for DTT plans, the “Boolean OAR Method” and the “Aperture Sorting Method,” to determine if they can successfully spare an OAR while maintaining sufficient target coverage.Materials and methodsA step‐and‐shoot intensity modulated radiation therapy (sIMRT) treatment plan was re‐optimized for 10 previously treated liver stereotactic ablative radiotherapy patients who each had one OAR very close to the target. Two planning strategies were investigated to determine which is more effective at sparing an OAR while maintaining target coverage: (1) the “Boolean OAR Method” created a union of an OAR's contours from two breathing phases (exhale and inhale) on the exhale phase (the planning CT) and protected this combined OAR during plan optimization, (2) the “Aperture Sorting Method” assigned apertures to the breathing phase where they contributed the least to an OAR's maximum dose.ResultsAll 10 OARs exceeded their dose constraints on the original plan four‐dimensional (4D) dose distributions and average target coverage was V100% = 91.3% ± 2.9% (ranging from 85.1% to 94.8%). The “Boolean OAR Method” spared 7/10 OARs, and mean target coverage decreased to V100% = 87.1% ± 3.8% (ranging from 80.7% to 93.7%). The “Aperture Sorting Method” spared 9/10 OARs and the mean target coverage remained high at V100% = 91.7% ± 2.8% (ranging from 84.9% to 94.5%).Conclusions4D planning strategies are simple to implement and can improve OAR sparing during DTT treatments. The “Boolean OAR Method” improved sparing of OARs but target coverage was reduced. The “Aperture Sorting Method” further improved sparing of OARs and maintained target coverage.

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Section: Introductionmentioning

confidence: 99%