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Retrospective Audit of Patient Specific Quality Assurance Results Obtained Using Helical Diode Arrays

  • Liting Yu
  • Tanya Kairn
  • Scott B. CroweEmail author
Conference paper
Part of the IFMBE Proceedings book series (IFMBE, volume 68/3)

Abstract

A retrospective audit was performed for existing patient specific quality assurance (PSQA) results measured on two ArcCheck helical diode arrays (Sun Nuclear Corporation). Twenty-five volumetric modulated arc therapy (VMAT) and thirty-two helical tomotherapy (HT) treatment plans were re-analysed using SNC patient software (version 6.2) and in-house gamma analysis code (developed in Python). Global gamma analyses were performed on the measured and calculated data (2%/2 mm) to identify the registration shift which provided the greatest gamma agreement index (GAI). Audit results indicated that when the ArcCheck devices were used for VMAT and HT, 1 mm longitudinal (Y) registration shifts frequently provided better GAI results than no shift. Specifically, the SNC and Python codes both identified a significant trend for longitudinal shifts for both ArcCheck devices. No significant trend was observed for roll (X) registration shifts. Measurements performed with physical shifts of the ArcCheck device improved the GAI results with no shift applied, suggesting that unless there is a co-incidental offset in the position of the radiation isocentre on both the TomoTherapy unit and the linac, there may be an actual displacement of the centre of the diode array and the marking lines on the two ArcCheck devices. This behaviour is dependent on gamma evaluation criteria used. The results of this study confirm the necessity of undertaking regular audits of QA results, as well as the need to consider sources of geometric uncertainty when selecting gamma evaluation criteria and when applying automatic geometric shifts to measured data.

Keywords

ArcCheck Shift PSQA VMAT Tomotherapy 

References

  1. 1.
    Childress NL, White RA, Bloch C, Salehpour M, Dong L, Rosen II (2005) Retrospective analysis of 2D patient‐specific IMRT verifications. Medical physics 32 (4):838–850Google Scholar
  2. 2.
    Crowe S, Kairn T, Middlebrook N, Sutherland B, Hill B, Kenny J, Langton CM, Trapp J (2015) Examination of the properties of IMRT and VMAT beams and evaluation against pre-treatment quality assurance results. Physics in Medicine & Biology 60 (6):2587Google Scholar
  3. 3.
    Crowe SB, Sutherland B, Wilks R, Seshadri V, Sylvander S, Trapp JV, Kairn T (2016) Relationships between gamma criteria and action levels: Results of a multicenter audit of gamma agreement index results. Medical physics 43 (3):1501–1506Google Scholar
  4. 4.
    Steers JM, Fraass BA (2016) IMRT QA: Selecting gamma criteria based on error detection sensitivity. Medical physics 43 (4):1982–1994Google Scholar
  5. 5.
    Koren S, Ma C (2011) Gamma Analysis Criteria for Planar and Cylindrical Dose Arrays. International Journal of Radiation Oncology Biology Physics 81 (2):S834Google Scholar
  6. 6.
    Lin MH, Koren S, Veltchev I, Li J, Wang L, Price RA, Ma CM (2013) Measurement comparison and Monte Carlo analysis for volumetric‐modulated arc therapy (VMAT) delivery verification using the ArcCHECK dosimetry system. Journal of applied clinical medical physics 14 (2):220–233Google Scholar
  7. 7.
    Vieillevigne L, Molinier J, Brun T, Ferrand R (2015) Gamma index comparison of three VMAT QA systems and evaluation of their sensitivity to delivery errors. Physica Medica 31 (7):720–725Google Scholar
  8. 8.
    Yang W, Wallace R, Huang K, Cook R, Fraass B (2012) SU‐E‐T‐363: Sensitivity of ArcCheck to Delivery Errors in IMRT/VMAT Treatment. Medical Physics 39 (6):3787–3787Google Scholar
  9. 9.
    Fan Q, Park C, Lu B, Barraclough B, Lebron S, Li J, Liu C, Yan G (2015) SU‐E‐T‐584: Optical Tracking Guided Patient‐Specific VMAT QA with ArcCHECK. Medical physics 42 (6):3470–3470Google Scholar
  10. 10.
    Templeton AK, Chu JC, Turian JV (2015) The sensitivity of ArcCHECK - based gamma analysis to manufactured errors in helical tomotherapy radiation delivery. Journal of applied clinical medical physics 16 (1):32–39Google Scholar
  11. 11.
    Ahmed S, Nelms B, Kozelka J, Zhang G, Moros E, Feygelman V (2016) Validation of an improved helical diode array and dose reconstruction software using TG‐244 datasets and stringent dose comparison criteria. Journal of applied clinical medical physics 17 (6):163–178Google Scholar
  12. 12.
    Hussein M, Clark C, Nisbet A (2017) Challenges in calculation of the gamma index in radiotherapy–towards good practice. Physica Medica: European Journal of Medical Physics 36:1–11Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Royal Brisbane and Women’s HospitalBrisbaneAustralia
  2. 2.Queensland University of TechnologyBrisbaneAustralia

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