Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-28T02:02:27.176Z Has data issue: false hasContentIssue false
  • English
  • Français

Clinical experience using Delta 4 phantom for pretreatment patient-specific quality assurance in modern radiotherapy

Published online by Cambridge University Press:  15 November 2018

R. P. Srivastava  and
C. De Wagter
R. P. Srivastava*
Affiliation:
Department of Radiation Oncology, Ghent University Hospital, Gent, Belgium Radiotherapy Association Meuse Picardie, Centre Hospitalier Mouscron, Mouscron, Belgium
C. De Wagter
Affiliation:
Department of Radiation Oncology, Ghent University Hospital, Gent, Belgium Department of Radiation Oncology and Experimental Cancer Research, Ghent University Hospital, Gent, Belgium
*
Author for correspondence: R. P. Srivastava, Department of Radiation Oncology, Ghent University Hospital, C. Heymanslaan 10, Radiotherapiepark, 9000 Gent, Belgium. Tel: +3293323030. E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Purpose

In advanced radiotherapy techniques such as intensity-modulated radiation therapy (IMRT), the quality assurance (QA) process is essential. The aim of the study was to assure the treatment planning dose delivered during delivery of complex treatment plans. The QA standard is to perform patient-specific comparisons between planned doses and doses measured in a phantom.

Materials and method

The Delta 4 phantom (Scandidos, Uppsala, Sweden) has been used in this study. This device consists of diode matrices in two orthogonal planes inserted in a cylindrical acrylic phantom. Each diode is sampled per beam pulse so that the dose distribution can be evaluated on segment-by-segment, beam-by-beam, or as a composite plan from a single set of measurements. Ninety-five simple and complex radiotherapy treatment plans for different pathologies, planned using a treatment planning system (TPS) were delivered to the QA device. The planned and measured dose distributions were then compared and analysed. The gamma index was determined for different pathologies.

Results

The evaluation was performed in terms of dose deviation, distance to agreement and gamma index passing rate. The measurements were in excellent agreement between with the calculated dose of the TPS and the QA device. Overall, good agreement was observed between measured and calculated doses in most cases with gamma values above 1 in >95% of measured points. Plan results for each test met the recommended dose goals.

Conclusion

The delivery of IMRT and volumetric-modulated arc therapy (VMAT) plans was verified to correspond well with calculated dose distributions for different pathologies. We found the Delta 4 device is accurate and reproducible. Although Delta4 appears to be a straightforward device for measuring dose and allows measure in real-time dosimetry QA, it is a complex device and careful quality control is required before its use.

Keywords

gamma indexintensity-modulated radiation therapymulti-leaf collimatorquality assurancevolumetric-modulated arc therapy
Type
Technical Note
Information
Journal of Radiotherapy in Practice , Volume 18 , Issue 2 , June 2019 , pp. 210 - 214
Check for updates
Copyright
© Cambridge University Press 2018 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Cite this article: Srivastava RP, De Wagter C (2019) Clinical experience using Delta 4 phantom for pretreatment patient-specific quality assurance in modern radiotherapy. Journal of Radiotherapy in Practice18: 210–214. doi: 10.1017/S1460396918000572

References

1. Palta, JR, Liu, C, Li, J G. Quality assurance of intensity-modulated radiation therapy. Int J Radiat Oncol 2008; 71 (Suppl 1): S108–S112.Google Scholar
2. Scandidos. Delta4PT User’s Guide. Uppsala, Sweden: Scandidos, 2013.Google Scholar
3. Low, D A, Harms, W B, Mutic, S, Purdy, J A. A technique for the quantitative evaluation of dose distributions. Med Phys 1998; 25 (5): 656–661.Google Scholar
4. Low, D A. Gamma dose distribution evaluation tool. J Phys Conf Series 2010; 250 (012071), 1–11.Google Scholar
5. Myers, P, Stathakis, S, Gutiérrez, A, Esquivel, C, Mavroidis, P, Papanikolaou, N. Evaluation of PTW Seven29 for tomotherapy patient-specific quality assurance and comparison with ScandiDos Delta4. J Med Phys Assoc Med Phys India 2012; 37 (2): 72.Google Scholar
6. Bedford, J, Lee, Y, Wai, P, South, C, Warrington, A P. Evaluation of the Delta4 phantom for IMRT and VMAT verification. Phys Med Biol 2009; 54 (9): N167–N176.Google Scholar
7. Nilsson, G. Delta4—a new IMRT QA device. Med Phys 2007; 34 (6): 2432–2432.Google Scholar
8. Daci, L, Malkaj, P. Implementation of IMRT and VMAT using Delta4 phantom and portal dosimetry as dosimetry verification tools. AIP Conf Proc 2016; 1722 (1): 030002.Google Scholar
9. Nelms, B, Zhen, H, Tomé, W A. Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors. Med Phys 2011; 38 (2): 1037–1044.Google Scholar
10. Sadagopan, R, Bencomo, J, Martin, R, Nilsson, G, Matzen, T, Balter, P A. Characterization and clinical evaluation of a novel IMRT quality assurance system. J Appl Clin Med Phys 2009; 10 (2): 104–119.Google Scholar
11. Paelinck, L, Vanderstraeten, B, Srivastava, R, Olteanu, L, De Wagter, C. The effect of the table top modeling on calculations and measurements for the Delta4 phantom. ESTRO 2016; 35: S705–S706.Google Scholar
12. Nilsson, J, Hauer, A, Bäck, A. IMRT patient-specific QA using the Delta4 dosimetry system and evaluation based on ICRU 83 recommendations. J Phys Conf Series 2013; 444 (012048), 1–4.Google Scholar
13. Prescribing, recording, and reporting photon-beam intensity-modulated radiation therapy (IMRT): contents. J ICRU 2010; 10 (1), NP.3-NP.Google Scholar
14. Chandraraj, V, Stathakis, S, Manickam, R, Esquivel, C, Supe, S, Papanikolaou, N. Comparison of four commercial devices for RapidArc and sliding window IMRT QA. J Appl Clin Med Phys 2011; 12 (2): 338–349.Google Scholar