Time motion study to evaluate the impact of flattening filter free beam on overall treatment time for frameless intracranial radiosurgery using Varian TrueBeam® linear accelerator
Abstract
Background: The aim was to study the impact of the flattening filter free (FFF) beam on overall treatment time for frameless intracranial radiosurgery using TrueBeam® LINAC. The development of frameless stereotactic radiosurgery (SRS) is possible due to the incorporation of image guidance in the delivery of treatment. It is important to analyze the cost and benefits of FFF beams for treating SRS by understanding the impact of FFF beams in reducing the treatment time.
Materials and methods: Dynamic conformal arc (DCA) and volumetric arc therapy (VMAT) plans were generated using 6 MV with a flattening filter (FF) and FFF beams. Overall treatment time was divided into beam on time (BOT) and beam off time (BFT). Percentage beam on time reduction (PBOTR) and Percentage total time reduction (PTTR) factors were defined for the comparison.
Results: BOT reduction was observed to be significant for higher dose per fraction but subjected to the treatment technique and modulation differences. PBOTR values are much higher than PTTR values. The 39.9% of PBOTR resulted in only 8% PTTR for DCA and 65.3% resulted in 15.9% PTTR for VMAT.
Conclusion: Major BFT was utilized for imaging and verification. FFF beam significantly reduced the beam on time and was found to be most effective if the fractional dose was as high as that for SRS. Newly defined PBOTR and PTTR factors are very useful indicators to evaluate the efficacy of FFF beams in terms of time reduction.
Keywords: time motion studyflattening filter freestereotactic radiosurgerytreatment timeframeless SRS
References
- Schell MC, Bova FJ, Larson DA. Stereotactic radiosurgery. American Association of Physicists in Medicine Report No. 54. American Institute of Physics, Woodbury 1995: 1–88.
- Lightstone AW, Benedict SH, Bova FJ, et al. American Association of Physicists in Medicine Radiation Therapy Committee. Intracranial stereotactic positioning systems: Report of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group No. 68. Med Phys. 2005; 32(7Part1): 2380–2398.
- Lunsford LD, Leksell D. The Leksell System. In: Lunsford LD. ed. Modern Stereotactic Neurosurgery. Topics in neurological surgery. Vol 1. Springer, Boston 1988: MA.
- Lutz W, Winston KR, Maleki N. A system for stereotactic radiosurgery with a linear accelerator. Int J Radiat Oncol Biol Phys. 1988; 14(2): 373–381.
- Ramakrishna N, Rosca F, Friesen S, et al. A clinical comparison of patient setup and intra-fraction motion using frame-based radiosurgery versus a frameless image-guided radiosurgery system for intracranial lesions. Radiother Oncol. 2010; 95(1): 109–115.
- Masi L, Casamassima F, Polli C, et al. Cone beam CT image guidance for intracranial stereotactic treatments: comparison with a frame guided set-up. Int J Radiat Oncol Biol Phys. 2008; 71(3): 926–933.
- Ruschin M, Nayebi N, Carlsson P, et al. Performance of a novel repositioning head frame for gamma knife perfexion and image-guided linac-based intracranial stereotactic radiotherapy. Int J Radiat Oncol Biol Phys. 2010; 78(1): 306–313.
- Ali I, Tubbs J, Hibbitts K, et al. Evaluation of the setup accuracy of a stereotactic radiotherapy head immobilization mask system using kV on-board imaging. J Appl Clin Med Phys. 2010; 11(3): 3192.
- Babic S, Lee Y, Ruschin M, et al. To frame or not to frame? Cone-beam CT-based analysis of head immobilization devices specific to linac-based stereotactic radiosurgery and radiotherapy. J Appl Clin Med Phys. 2018; 19(2): 111–120.
- AlDahlawi I, Prasad D, Podgorsak MB. Evaluation of stability of stereotactic space defined by cone-beam CT for the Leksell Gamma Knife Icon. J Appl Clin Med Phys. 2017; 18(3): 67–72.
- Fu W, Dai J, Hu Y, et al. Delivery time comparison for intensity-modulated radiation therapy with/without flattening filter: a planning study. Phys Med Biol. 2004; 49(8): 1535–1547.
- Mamballikalam G, Senthilkumar S, Jayadevan PM, et al. Evaluation of dosimetric parameters of small fields of 6 MV flattening filter free photon beam measured using various detectors against Monte Carlo simulation. J Radiothera Pract. 2020: 1–1.
- Mamballikalam G, Senthilkumar S, Bos RCJ, et al. Stereotactic radiotherapy for small and very small tumours (≤1 to ≤3 cc): evaluation of the influence of volumetric-modulated arc therapy in comparison to dynamic conformal arc therapy and 3D conformal radiotherapy as a function of flattened and unflattened beam models. J Radiother Pract. 2020: 1–7.
- Stieler F, Fleckenstein J, Simeonova A, et al. Intensity modulated radiosurgery of brain metastases with flattening filter-free beams. Radiother Oncol. 2013; 109(3): 448–451.
- Dang TM, Peters MJ, Hickey B, et al. Efficacy of flattening-filter-free beam in stereotactic body radiation therapy planning and treatment: A systematic review with meta-analysis. J Med Imaging Radiat Oncol. 2017; 61(3): 379–387.
- Lopetegui M, Yen PY, Lai A, et al. Time motion studies in healthcare: what are we talking about? J Biomed Inform. 2014; 49: 292–299.
- Gevaert T, Verellen D, Engels B, et al. Clinical evaluation of a robotic 6-degree of freedom treatment couch for frameless radiosurgery. Int J Radiat Oncol Biol Phys. 2012; 83(1): 467–474.
- Andreo P, Burns DT, Hohlfeld K. Absorbed dose determination in external beam radiotherapy: An international code of practice for dosimetry based on standards of absorbed dose to water. IAEA TRS-398, Vienna 2001.
- IAEA, AAPM. Dosimetry of small static fields used in external beam radiotherapy: an international code of practice for reference and relative dose determination. Technical reports series no. 483. IAEA, Vienna 2017.
- Ling CC, Gerweck LE, Zaider M, et al. Dose-rate effects in external beam radiotherapy redux. Radiother Oncol. 2010; 95(3): 261–268.
- Lohse I, Lang S, Hrbacek J, et al. Effect of high dose per pulse flattening filter-free beams on cancer cell survival. Radiother Oncol. 2011; 101(1): 226–232.
- Verbakel WF, van den Berg J, Slotman BJ, et al. Comparable cell survival between high dose rate flattening filter free and conventional dose rate irradiation. Acta Oncol. 2013; 52(3): 652–657.
- Kerns JR, Childress N, Kry SF. A multi-institution evaluation of MLC log files and performance in IMRT delivery. Radiat Oncol. 2014; 9: 176.
- Park JM, Wu HG, Kim JH, et al. The effect of MLC speed and acceleration on the plan delivery accuracy of VMAT. Br J Radiol. 2015; 88(1049): 20140698.
- Prendergast BM, Fiveash JB, Popple RA, et al. Flattening filter-free linac improves treatment delivery efficiency in stereotactic body radiation therapy. J Appl Clin Med Phys. 2013; 14(3): 4126.
- Boda-Heggemann J, Mai S, Fleckenstein J, et al. Flattening-filter-free intensity modulated breath-hold image-guided SABR (Stereotactic ABlative Radiotherapy) can be applied in a 15-min treatment slot. Radiother Oncol. 2013; 109(3): 505–509.
- Scorsetti M, Alongi F, Castiglioni S, et al. Feasibility and early clinical assessment of flattening filter free (FFF) based stereotactic body radiotherapy (SBRT) treatments. Radiat Oncol. 2011; 6: 113.