Implementation of Quality Assurance Protocols for an Advanced Linear Accelerator with Volumetric Modulated Arc Therapy Features Using Electronic Portal Imaging Device (EPID)

Authors

  • C. P. Bhatt Department of Allied Sciences Graphic Era (Deemed to be University), Dehradun, India
  • Kiran Sharma Department of Allied Sciences Graphic Era (Deemed to be University), Dehradun, India
  • Manoj K. Semwal Army Hospital (Research and Referral), New Delhi, India

Keywords:

Radiotherapy, Quality Assurance (QA), Volumetric Modulated Arc Therapy (VMAT), Dynamic Multileaf Collimator (DMLC), Electronic Portal Imaging Device (EPID).

Abstract

To use Electronic Portal Imaging Device (EPID), an integral feature of a TrueBeam linear accelerator (linac)
system, for implementing dosimetry based comprehensive Quality Assurance (QA) protocol needed for
Volumetric Modulated Arc Therapy (VMAT) modality. Varian makes TrueBeam Version 2.0 linac system with
Intensity Modulated Radiotherapy (IMRT), and VMAT treatment modalities were used in the study. The linac is
equipped with a Multileaf Collimator (MLC) having 120 leaves (millenium MLC) and an EPID (aS1000)
having megavoltage photon (MV) detector system. The EPID has an active imaging area of 40 cm x 30 cm with
1024 x 768-pixel matrix with a pixel resolution of 0.39 mm. It is capable of capturing 14-bit images at 30frames
per second. We carried out the following QA tests using the EPID: i) Dynamic MLC (DMLC) dosimetry test ii)
DMLC positional accuracy test (Picket Fence test) for fixed and rotating gantry modes iii) DMLC positional
accuracy test during rotation with intentional errors iv) dose rate and gantry speed tests during RapidArc
delivery and v) DMLC leaf speed test during RapidArc delivery. All the tests were analysed with Microsoft
Excel application. Deviations of the EPID pixel values from known regions of interest during the various tests
with respect to open fields were estimated for accuracy assessment. DMLC dosimetry test showed a maximum
deviation of 0.16 % with respect to reference condition at 0º gantry. The maximum positional accuracy of
DMLC was found to be 0.28 mm for fixed gantry and 0.26 mm for rotating gantry. For varying dose rate and
gantry speed, the average of the absolute value of all deviations Diff(x) was 0.43. The MLC leaf speed variation
during RapidArc resulted in the average of the absolute value of all Diff(x) of 0.20. Similar results have been
obtained with a film based QA tests. The time taken in performing the above tests with EPID is far less as
compared to the conventional methods. EPID based QA tests are reliable and quick. We believe that protocols
developed for performing QA tests with EPID can replace the conventional methods of QA. EPID based QA
will result in considerable time saving and thus helpful in increasing the patient throughput in a clinic. Also, the
quicker and automated QA procedure based on EPID lends itself to better compliance and hence better
treatment quality

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References

Bedford, J. L., & Warrington, A. P. (2009). Commissioning of volumetric modulated arc therapy (VMAT).

International Journal of Radiation Oncology Biology Physics, 73(2), 537-545.

Bedford, J. L., Lee, Y. K., Wai, P., South, C. P., & Warrington, A. P. (2009). Evaluation of the Delta4 phantom

for IMRT and VMAT verification. Physics in Medicine and Biology, 54(9), N167-176.

Boggula, R., Birkner, M., Lohr, F., Steil, V., Wenz, F., & Wertz, H. (2011). Evaluation of a 2D detector array

for patient-specific VMAT QA with different setups. Physics in Medicine and Biology, 56(22), 7163-7177.

Essers, M., de Langen, M., Dirkx, M. L., & Heijmen, B. J. (2001). Commissioning of a commercially available

system for intensity-modulated radiotherapy dose delivery with dynamic multileaf collimation. Radiotherapy

and Oncology, 60(2), 215-224.

Greer, P. B., & Popescu, C. C. (2003). Dosimetric properties of an amorphous silicon electronic portal imaging

device for verification of dynamic intensity modulated radiation therapy. Medical Physics, 30(7), 1618-1627.

Hardcastle, N., Tomé, W. A., Foo, K., Miller, A., Carolan, M., & Metcalfe, P. (2011). Comparison of prostate

IMRT and VMAT biologically optimised treatment plans. Medical Dosimetry, 36(3), 292-298.

Journal of Graphic Era University

Vol. 6, Issue 1, 109-122, 2018

ISSN: 0975-1416 (Print), 2456-4281 (Online)

Klein, E. E., Hanley, J., Bayouth, J., Yin, F. F., Simon, W., Dresser, S., Serago, C., Aguirre, F., Ma, L.,

Arjomandy, B., Liu, C., Sandin, C., & Holmes, T. (2009). Task Group 142 report: quality assurance of medical

accelerators. Medical Physics, 36(9), 4197-4212.

Kumar, R., Sharma, S. D., Deshpande, S., Sresty, N. M., Bhatt, C. P., Amols, H. I., Chourasiya, G., & Mayya,

Y. S. (2014). Analysis of patient specific dosimetry quality assurance measurements in intensity modulated

radiotherapy: A multi centre study. Journal of Cancer Research and Therapeutics, 10(3), 611-617.

Ling, C. C., Zhang, P., Archambault, Y., Bocanek, J., Tang, G., & LoSasso, T. (2008). Commissioning and

quality assurance of RapidArc radiotherapy delivery system. International Journal of Radiation Oncology

Biology Physics, 72(2), 575-581.

LoSasso, T. (2008). IMRT delivery performance with a varian multileaf collimator. International Journal of

Radiation Oncology Biology Physics, 71(1), S85-S88.

Oliver, M., Ansbacher, W., & Beckham, W. A. (2009). Comparing planning time, delivery time and plan quality

for IMRT, RapidArc and Tomotherapy. Journal of Applied Clinical Medical Physics, 10(4), 117-131.

Petoukhova, A. L., Van Egmond, J., Eenink, M. G. C., Wiggenraad, R. G. J., & Van Santvoort, J. P. C. (2011).

The ArcCHECK diode array for dosimetric verification of HybridArc. Physics in Medicine and Biology, 56(16),

-5428.

Rangaraj, D., Oddiraju, S., Sun, B., Santanam, L., Yang, D., Goddu, S., & Papiez, L. (2010). Fundamental

properties of the delivery of volumetric modulated arc therapy (VMAT) to static patient anatomy. Medical

Physics, 37(8), 4056-4067.

Rowshanfarzad, P., McGarry, C. K., Barnes, M. P., Sabet, M., & Ebert, M. A. (2014). An EPID-based method

for comprehensive verification of gantry, EPID and the MLC carriage positional accuracy in Varian linacs

during arc treatments. Radiation Oncology, 9(1), 249-259.

Schreibmann, E., Dhabaan, A., Elder, E., & Fox, T. (2009). Patient‐specific quality assurance method for

VMAT treatment delivery. Medical Physics, 36(10), 4530-4535.

Sharma, D. S., Dongre, P. M., Mhatre, V., & Heigrujam, M. (2011). Physical and dosimetric characteristic of

high‐definition multileaf collimator (HDMLC) for SRS and IMRT. Journal of Applied Clinical Medical Physics,

(3), 142-160.

Unkelbach, J., Bortfeld, T., Craft, D., Alber, M., Bangert, M., Bokrantz, R., Chen, D., Li, R., Xing, L., Men, C.,

Nill, S., Papp, D., Romeijn, E., & Salari, E. (2015). Optimization approaches to volumetric modulated arc

therapy planning. Medical Physics, 42(3), 1367-1377.

Van Elmpt, W., McDermott, L., Nijsten, S., Wendling, M., Lambin, P., & Mijnheer, B. (2008). A literature

review of electronic portal imaging for radiotherapy dosimetry. Radiotherapy and Oncology, 88(3), 289-309.

Wang, H. C., Chui, C. S., Tsai, H. Y., Chen, C. H., & Tsai, L. F. (2008). Dose deviations caused by positional

inaccuracy of multileaf collimator in intensity modulated radiotherapy. Radiation Measurements, 43(2), 925-

Winkler, P., Hefner, A., & Georg, D. (2005). Dose‐response characteristics of an amorphous silicon EPID.

Medical Physics, 32(10), 3095-3105

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Published

2023-02-28

How to Cite

Bhatt, C. P., Sharma, K., & Semwal, M. K. (2023). Implementation of Quality Assurance Protocols for an Advanced Linear Accelerator with Volumetric Modulated Arc Therapy Features Using Electronic Portal Imaging Device (EPID). Journal of Graphic Era University, 6(1), 109–122. Retrieved from https://www.journal.riverpublishers.com/index.php/JGEU/article/view/95

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