DICOM-RT Plan Complexity Verification for Volumetric Modulated Arc Therapy

The purpose of this study was to investigate the relationship between plan parameters verified with DICOM-RT and dosimetric results for volumetric modulated arc therapy (VMAT). We investigated three treatment locations: prostate cancer (ten cases), maxillary sinus cancer (four cases), and malignant pleura mesothelioma (four cases) with treatment plans generated by a MonacoTM treatment planning system (TPS), and delivered with an Elekta SynergyTM linear accelerator. We calculated plan parameters, including gantry and multileaf collimator (MLC) positions, Monitor Units (MU), and millimeters of MLC motion per degree of gantry rotation (mm/degree), and performed quality assurance (QA) with a DICOM-RT plan verification system. We measured the VMAT dose with a two-dimensional diode array detector. The average gamma passing rate with percent dose acceptance criteria and distance to agreement criteria of 2 mm and 2% (2 mm/2%) were 97.4%, 97.8% and 92.0% for prostate cancer, maxillary sinus cancer, and malignant pleural mesothelioma, respectively. The mean 95th percentile value for DICOM-calculated mm/degree was 4.0, 5.2, and 11.1 for prostate cancer, maxillary sinus cancer, and malignant pleural mesothelioma, respectively. The gamma passing rate showed a correlation with calculated mm/degree, with a coefficient of determination (R2) of 0.60. Higher calculated mm/degree values led to increased dosimetric errors. We conclude that dose distribution calculated by a TPS is more reliable at smaller mm/degree.

[1]  James L Bedford,et al.  Evaluation of the Delta4 phantom for IMRT and VMAT verification , 2009, Physics in medicine and biology.

[2]  Daliang Cao,et al.  Impact of leaf motion constraints on IMAT plan quality, deliver accuracy, and efficiency. , 2011, Medical physics.

[3]  J. Cygler,et al.  Commissioning and quality assurance of treatment planning computers. , 1993, International journal of radiation oncology, biology, physics.

[4]  Lorenzo Livi,et al.  Impact of plan parameters on the dosimetric accuracy of volumetric modulated arc therapy. , 2013, Medical physics.

[5]  Andrea L McNiven,et al.  A new metric for assessing IMRT modulation complexity and plan deliverability. , 2010, Medical physics.

[6]  David A Jaffray,et al.  Novel dosimetric phantom for quality assurance of volumetric modulated arc therapy. , 2009, Medical physics.

[7]  S Webb,et al.  Use of a quantitative index of beam modulation to characterize dose conformality: illustration by a comparison of full beamlet IMRT, few-segment IMRT (fsIMRT) and conformal unmodulated radiotherapy. , 2003, Physics in medicine and biology.

[8]  Rajat J Kudchadker,et al.  Quantification of beam complexity in intensity-modulated radiation therapy treatment plans. , 2014, Medical physics.

[9]  R Mohan,et al.  The impact of fluctuations in intensity patterns on the number of monitor units and the quality and accuracy of intensity modulated radiotherapy. , 2000, Medical physics.

[10]  Conor K McGarry,et al.  Assessing software upgrades, plan properties and patient geometry using intensity modulated radiation therapy (IMRT) complexity metrics. , 2011, Medical physics.

[11]  Volker Steil,et al.  Evaluation of a 2D detector array for patient-specific VMAT QA with different setups. , 2011, Physics in medicine and biology.

[12]  Karl Otto,et al.  Volumetric modulated arc therapy: IMRT in a single gantry arc. , 2007, Medical physics.

[13]  J. Bedford,et al.  Commissioning of volumetric modulated arc therapy (VMAT). , 2009, International journal of radiation oncology, biology, physics.

[14]  Benedick A Fraass,et al.  Penalization of aperture complexity in inversely planned volumetric modulated arc therapy. , 2012, Medical physics.

[15]  Masao Tanooka,et al.  Predicting Delivery Error Using a DICOM-RT Plan for Volumetric Modulated Arc Therapy , 2014 .

[16]  Dosimetric and delivery characterizations of full-arc and half-arc volumetric-modulated arc therapy for maxillary cancer , 2012, Journal of radiation research.