Highlights
- •Comparing Iris and MLC plan quality for 56 CyberKnife abdominal and prostate SBRT cases.
- •Comparison based on a overall mathematical scoring index and on clinical scoring.
- •Iris and MLC comparison was not straightforward when based on multiple parameters.
- •Mathematical and clinical scoring proved essential to evaluate MLC plans advantages.
- •Time reduction achievable by MLC is highly variable among different published studies.
Abstract
Purpose
This study evaluated the plan quality of CyberKnife MLC-based treatment planning in
comparison to the Iris collimator for abdominal and pelvic SBRT. Multiple dosimetric
parameters were considered together with a global scoring index validated by clinical
scoring.
Methods and materials
Iris and MLC plans were created for 28 liver, 15 pancreas and 13 prostate cases including
a wide range of PTV sizes (24–643 cm3). Plans were compared in terms of coverage, conformity (nCI), dose gradient (R50%),
homogeneity (HI), OAR doses, PTV gEUD, MU, treatment time both estimated by TPS (tTPS) and measured. A global plan quality score index was calculated for IRIS and MLC
solutions and validated by a clinical score given independently by two observers.
Results
Compared to Iris, MLC achieved equivalent coverage and conformity without compromising
OAR sparing and improving R50% (p < 0.001). MLC gEUD was slightly lower than Iris
(p < 0.05) for abdominal cases. MLC reduced significantly MU (−15%) and tTPS (−22%). Time reduction was partially lost when measured. The global score index was
significantly higher for MLC solutions which were selected in 73% and 64% of cases
respectively by the first and second observer.
Conclusion
Iris and MLC comparison was not straightforward when based on multiple dosimetric
parameters. The use of a mathematical overall score index integrated with a clinical
scoring was essential to confirm MLC plans advantages over Iris solutions.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Physica Medica: European Journal of Medical PhysicsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- The CyberKnife® robotic radiosurgery system in 2010.Technol Cancer Res Treat. 2010; 9: 433-452https://doi.org/10.1177/153303461000900502
- A feasibility dosimetric study on prostate cancer: are we ready for a multicenter clinical trial on SBRT?.Strahlenther Onkol. 2015; 191: 573-581
- Stereotactic body radiotherapy for prostate cancer.Clin Oncol. 2015; 27: 270-279https://doi.org/10.1016/j.clon.2015.01.011
- Stereotactic body radiotherapy for localized prostate cancer: pooled analysis from a multi-institutional consortium of prospective phase II trials.Radiother Oncol. 2013; 109: 217-221
- Stereotactic body radiation therapy for patients with heavily pretreated liver metastases and liver tumors.Front Oncol. 2012; 2: 1-8https://doi.org/10.3389/fonc.2012.00023
- Stereotactic Body Radiotherapy (SBRT) for liver metastasis – clinical outcomes from the international multi-institutional RSSearch® Patient Registry.Radiat Oncol. 2018; 13: 26
- Five-fraction stereotactic body radiation therapy (SBRT) and chemotherapy for the local management of metastatic pancreatic cancer.J Gastrointest Cancer. 2018; 49: 116-123https://doi.org/10.1007/s12029-016-9909-2
- Stereotactic body radiotherapy (SBRT) reirradiation for recurrent pancreas cancer.J Cancer. 2016; 7: 283-288
- Gated volumetric-modulated arc therapy vs. tumor-tracking cyberknife radiotherapy as stereotactic body radiotherapy for hepatocellular carcinoma: a dosimetric comparison study focused on the impact of respiratory motion managements.PLoS One. 2016; 11 (e0166927)https://doi.org/10.1371/journal.pone.0166927
- Potential dosimetric benefits of adaptive tumor tracking over the internal target volume concept for stereotactic body radiation therapy of pancreatic cancer.Radiat Oncol. 2017; 12: 1-9https://doi.org/10.1186/s13014-017-0906-9
- Dosimetric comparison of volumetric modulated arc therapy with robotic stereotactic radiation therapy in hepatocellular carcinoma.Radiat Oncol J. 2015; 33: 233-241https://doi.org/10.3857/roj.2015.33.3.233
- Prescribing, recording, and reporting of stereotactic treatments with small photon beams.J ICRU. 2014; 14: 1-160https://doi.org/10.1093/jicru/ndx009
- Resampling: an optimization method for inverse planning in robotic radiosurgery.Med Phys. 2006; 33: 4005-4011
- The design, physical properties and clinical utility of an iris collimator for robotic radiosurgery.Phys Med Biol. 2009; 54: 5359-5380https://doi.org/10.1088/0031-9155/54/18/001
- Investigating the clinical advantages of a robotic linac equipped with a multileaf collimator in the treatment of brain and prostate cancer patients.J Appl Clin Med Phys. 2015; 16: 284-295https://doi.org/10.1120/jacmp.v16i5.5502
- Variable circular collimator in robotic radiosurgery: a time-efficient alternative to a mini-multileaf collimator?.Int J Radiat Oncol Biol Phys. 2011; 81: 863-870https://doi.org/10.1016/j.ijrobp.2010.12.052
- Dosimetric and radiobiological comparison of CyberKnife M6 TM InCise multileaf collimator over IRIS TM variable collimator in prostate stereotactic body radiation therapy.J Med Phys. 2016; 41: 135https://doi.org/10.4103/0971-6203.181638
- Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT.J Appl Clin Med Phys. 2017; 18: 124-133https://doi.org/10.1002/acm2.12128
- Comparison of multileaf collimator and conventional circular collimator systems in Cyberknife stereotactic radiotherapy.J Radiat Res. 2017; 58: 693-700https://doi.org/10.1093/jrr/rrw130
- Dosimetric and delivery efficiency investigation for treating hepatic lesions with a MLC-equipped robotic radiosurgery-radiotherapy combined system.Med Phys. 2016; 43: 727-733https://doi.org/10.1118/1.4939259
- SPIDERplan: a tool to support decision-making in radiation therapy treatment plan assessment.Reports Pract Oncol Radiother. 2016; 21: 508-516https://doi.org/10.1016/j.rpor.2016.07.002
- Variation in external beam treatment plan quality: an inter-institutional study of planners and planning systems.Pract Radiat Oncol. 2012; 2: 296-305https://doi.org/10.1016/j.prro.2011.11.012
- Treatment planning for spinal radiosurgery.Strahlenther Onkol. 2018; 194: 843-854https://doi.org/10.1007/s00066-018-1314-2
- Inverse treatment planning for spinal robotic radiosurgery: an international multi-institutional benchmark trial.J Appl Clin Med Phys. 2016; 17: 313-330
- Unified dosimetry index (UDI): a figure of merit for ranking treatment plans.J Appl Clin Med Phys. 2008; 9: 99-108https://doi.org/10.1120/jacmp.v9i3.2803
- Automatic planning of head and neck treatment plans.J Appl Clin Med Phys. 2016; 17: 272-282https://doi.org/10.1120/jacmp.v17i1.5901
- Stereotactic body radiation therapy: the report of AAPM Task Group 101.Med Phys. 2010; 37: 4078-4101https://doi.org/10.1118/1.3438081
- Treatment precision of image-guided liver SBRT using implanted fiducial markers depends on marker–tumour distance.Phys Med Biol. 2011; 56: 5445-5468https://doi.org/10.1088/0031-9155/56/17/001
Prostate Advances in Comparative Evidence – Full Text View – ClinicalTrials.gov n.d.
- The design and physical characterization of a multileaf collimator for robotic radiosurgery.Biomed Phys Eng Express. 2016; 2017003https://doi.org/10.1088/2057-1976/2/1/017003
- Stepwise multi-criteria optimization for robotic radiosurgery.Med Phys. 2008; 35: 2094-2103https://doi.org/10.1118/1.2900716
- Treatment planning for MLC based robotic radiosurgery for brain metastases: plan comparison with circular fields and suggestion for planning strategies.Curr Dir Biomed Eng. 2017; 3: 151-154
- Dose calculation algorithm accuracy for small fields in non-homogeneous media: the lung SBRT case.Phys Med. 2017; 44: 157-162https://doi.org/10.1016/j.ejmp.2016.11.104
- A finite size pencil beam for IMRT dose optimization.Phys Med Biol. 2005; 50: 1747-1766https://doi.org/10.1088/0031-9155/50/8/009
- Stereotactic radiosurgery-radiotherapy: should Monte Carlo treatment planning be used for all sites ?.Pract Radiat Oncol. 2011; 1: 251-260https://doi.org/10.1016/j.prro.2011.03.001
- A free program for calculating EUD-based NTCP and TCP in external beam radiotherapy.Phys Med. 2007; 23: 115-125https://doi.org/10.1016/j.ejmp.2007.07.001
- Simultaneous tumour dose escalation and liver sparing in Stereotactic Body Radiation Therapy (SBRT) for liver tumours due to CTV-to-PTV margin reduction.Radiother Oncol. 2008; 87: 432-438https://doi.org/10.1016/j.radonc.2007.11.015
- Potential for dose-escalation and reduction of risk in pancreatic cancer using IMRT optimization with lexicographic ordering and gEUD-based cost functions.Med Phys. 2007; 34: 521-529https://doi.org/10.1118/1.2426403
- CyberKnife® M6™: peripheral dose evaluation for brain treatments.Phys Med. 2017; 37: 88-96https://doi.org/10.1016/j.ejmp.2017.04.015
- Optimization of normalized prescription isodose selection for stereotactic body radiation therapy: conventional vs robotic linac.Med Phys. 2013; 40051705https://doi.org/10.1118/1.4798944
- The efficacy of stereotactic body radiation therapy on huge hepatocellular carcinoma unsuitable for other local modalities.Radiat Oncol. 2014; 9: 1-8https://doi.org/10.1186/1748-717X-9-120
- Solutions that enable ablative radiotherapy for large liver tumors: fractionated dose painting, simultaneous integrated protection, motion management, and computed tomography image guidance.Cancer. 2016; 122: 1974-1986https://doi.org/10.1002/cncr.29878
- Plan delivery quality assurance for CyberKnife: statistical process control analysis of 350 film-based patient-specific QAs.Phys Med. 2017; 39: 50-58https://doi.org/10.1016/j.ejmp.2017.06.016
- High resolution ion chamber array delivery quality assurance for robotic radiosurgery: commissioning and validation.Phys Med. 2016; 32: 838-846https://doi.org/10.1016/j.ejmp.2016.05.060
Article info
Publication history
Accepted:
November 17,
2018
Received in revised form:
November 13,
2018
Received:
June 13,
2018
Identification
Copyright
© 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
