Predicting Delivery Error Using a DICOM-RT Plan for Volumetric Modulated Arc Therapy


The purpose of this study was to investigate the prediction of mechanical error using DICOM-RT plan parameters for volumetric modulated arc therapy (VMAT). We created plans for gantry rotation arcs of 360° and 180° (full-arc and half-arc VMAT) for six maxillary sinus cancer cases using a Monaco treatment planning system, and delivered the doses with a linear accelerator. We calculated DICOM-RT plan parameters, including gantry, multileaf collimator (MLC) positions and Monitor Units (MU). We compared plans with regard to gantry angle per MU (degrees/MU) and MLC travel per MU (mm/MU) for each segment. Calculated gantry angle/MLC position speeds and errors were evaluated by comparison with the log file. On average, the half-arc VMAT plan resulted in 47% and 35% fewer degrees/MU and mm/MU than the full-arc VMAT plan, respectively. The root mean square (r.m.s.) gantry and MLC speeds showed a linear relationship with calculated degrees/MU and mm/MU, with coefficients of determination (R2) of 0.86 and 0.72, respectively. The r.m.s. gantry angle and MLC position errors showed a linear relationship with calculated degrees/MU and mm/MU with R2 of 0.63 and 0.76, respectively. Deviations from plan parameters were related to mechanical error for VMAT, and provided quantitative information without the need for VMAT delivery. These parameters can be used in the selection of treatment planning.

Share and Cite:

Miura, H. , Tanooka, M. , Fujiwara, M. , Takada, Y. , Doi, H. , Odawara, S. , Kosaka, K. , Kamikonya, N. and Hirota, S. (2014) Predicting Delivery Error Using a DICOM-RT Plan for Volumetric Modulated Arc Therapy. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 3, 82-87. doi: 10.4236/ijmpcero.2014.32013.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Otto, K. (2008) Volumetric Modulated Arc Therapy: IMRT in a Single Gantry Arc. Medical Physics, 35, 310-317.
[2] Pasler, M., Wirtz, H. and Lutterbach, J. (2011) Impact of Gantry Rotation Time on Plan Quality and Dosimetric Verification-Volumetric Modulated Arc Therapy (VMAT) vs. Intensity Modulated Radiotherapy (IMRT). Strahlenther Onkol, 187, 812-819.
[3] Masi, L., Casamassima, F., Doro, R. and Francescon, P. (2011) Quality Assurance of Volumetric Modulated Arc Therapy: Evaluation and Comparison of Different Dosimetric Systems. Medical Physics, 38, 612-621.
[4] Gloi, A.M., Buchana, R.E., Zuge, C.L. and Goettler, A.M. (2011) Rapid Arc Quality Assurance through Map Check. Journal of Applied Clinical Medical Physics, 12, 3251.
[5] Létourneau, D., Publicover, J., Kozelka, J., Moseley, D.J. and Jaffray, D.A. (2009) Novel Dosimetric Phantom for Quality Assurance of Volumetric Modulated Arc Therapy. Medical Physics, 36, 1813-1821.
[6] Korreman, S., Medin, J. and Kjaer-Kristoffersen, F. (2009) Dosimetric Verification of Rapid Arc Treatment Delivery. Acta Oncology, 48, 185-191.
[7] Rowshanfarzad, P., Sabet, M., Barnes, M.P., O’Connor, D.J. and Greer, P.B. (2012) EPID-Based Verification of the MLC Performance for Dynamic IMRT and VMAT. Medical Physics, 39, 6192-6207.
[8] Sun, B., Rangaraj, D., Boddu, S., et al. (2012) Evaluation of the Efficiency and Effectiveness of Independent Dose Calculation Followed by Machine Log File Analysis against Conventional Measurement Based IMRT QA. Journal of Applied Clinical Medical Physics, 13, 3837.
[9] Litzenberg, D.W., Moran, J.M. and Fraass, B.A. (2002) Verification of Dynamic and Segmental IMRT Delivery by Dynamic Log File Analysis. Journal of Applied Clinical Medical Physics, 3, 63-72.
[10] Tyagi, N., Yang, K., Gersten, D. and Yan, D. (2012) A Real Time Dose Monitoring and Dose Reconstruction Tool for Patient Specific VMAT QA and Delivery. Medical Physics, 39, 7194-7204.
[11] Miura, H., Fujiwara, M., Tanooka, M., et al. (2012) Dosimetric and Delivery Characterizations of Full-Arc and Half-Arc Volumetric-Modulated Arc Therapy for Maxillary Cancer. Journal of Radiation Research, 53, 785-790.
[12] Jeleń, U. and Alber, M. (2007) A Finite Size Pencil Beam Algorithm for IMRT Dose Optimization: Density Corrections. Physics in Medicine and Biology, 52, 617-633.
[13] Fippel, M. (1999) Fast Monte Carlo Dose Calculation for Photon Beams Based on the VMC Electron Algorithm. Medical Physics, 26, 1466-1475.
[14] Fippel, M., Haryanto, F., Dohm, O., Nüsslin, F. and Kriesen, S. (2003) A Virtual Photon Energy Fluence Model for Monte Carlo Dose Calculation. Medical Physics, 30, 301-311.
[15] Haga, A., Nakagawa, K., Shiraishi, K., et al. (2009) Quality Assurance of Volumetric Modulated Arc Therapy Using Elekta Synergy. Acta Oncology, 8, 1193-1197.
[16] Chen, F., Rao, M., Ye, J.S., Shepard, D.M. and Cao, D. (2011) Impact of Leaf Motion Constraints on IMAT Plan Quality, Deliver Accuracy, and Efficiency. Medical Physics, 38, 6106-6118.
[17] Webb, S. (2003) 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. Physics in Medicine and Biology, 48, 2051-2062.
[18] Mohan, R., Arnfield, M., Tong, S., Wu, Q. and Siebers, J. (2000) The Impact of Fluctuations in Intensity Patterns on the Number of Monitor Units and the Quality and Accuracy of Intensity Modulated Radiotherapy. Medical Physics, 27, 1226-1237.
[19] McNiven, A.L., Sharpe, M.B. and Purdie, T.G. (2010) A New Metric for Assessing IMRT Modulation Complexity and Plan Deliverability. Medical Physics, 37, 505-515.
[20] Masi, L., Doro, R., Favuzza, V., Cipressi, S. and Livi, L. (2013) Impact of Plan Parameters on the Dosimetric Accuracy of Volumetric Modulated Arc Therapy. Medical Physics, 40, 2013.

Copyright © 2022 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.