A Method for In Vivo Dosimetry Using an Electronic Portal Imaging Device

Abstract:

The implementation of advanced radiotherapy techniques such as Intensity-Modulated RadiationTherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) allows much more accuratecontrol of the irradiation area and more conformal dose delivery. Since these treatments are characterizedby high dose gradients and hence small error margins, they also require advanced and highlyeffective treatment verification techniques. Fortunately, an imaging modality, originally intended forset-up verifications, called the Electronic Portal Imaging Device (EPID) was reported to have hugepotential for dosimetry and treatment verification applications. However, methods and algorithmspreviously developed for EPID dosimetry are not yet widely adopted in cancer centers due to complexitiesin the implementation. These motivate more investigation and development of new methodsto encourage cancer centers to practice EPID dosimetry and improve patient safety.This research generally aims to develop an in-vivo dosimetry method that can be used in the future toapproximate the actual dose delivered inside the target by utilizing the transmitted fluence detectedby the EPID. In this study, Monte Carlo simulations are carried out using the Geant4 Application forTomographic Emission (GATE) to implement a virtual set-up composed of a water target irradiatedwith a monoenergetic 2 MeV photon beam and an EPID model to detect the total transmitted fluence.A mathematical model has been proposed to calculate the target absorbed dose by utilizing the transmittedprimary fluence. This involves back-projection of the transmitted fluence to determine fluencevalues at certain depths inside the irradiated homogeneous medium. This is followed by the calculationof the collision kerma using the back-projected fluence and the values of the linear attenuation coefficientand mass energy absorption coefficient in the National Institute of Standards and Technology(NIST) database. The results show accurate prediction of the fluence values inside the target, calculationof the corresponding values of the collision kerma, and determination of the proportionalityconstant β that relates the collision kerma to the target absorbed dose.

• Periodical: Materials Science Forum (Volume 1102)
• Pages: 169-177
• DOI: https://doi.org/10.4028/p-t9isN3
• Online since: October 2023
• Authors: Dainna Recel S. Pamisa*, Catherine Therese J. Quiñones
• Keywords: EPID, GATE, In Vivo Dosimetry, Monte Carlo

References

[1] W. Renner, K. Norton, and T. Holmes, A method of deconvolution of integrated electronic portal images to obtain incident fluence for dose reconstruction, J Appl Clin Med Phys 6 (2005) 22-39.

DOI: 10.1120/jacmp.2026.25359

[2] K. Pasma, S. Vieira, and B. Heijmen, Portal dose image prediction for dosimetric treatment verification in radiotherapy. II. An algorithm for wedged beams, Med Phys 29 (2002) 925-31.

DOI: 10.1118/1.1463064

[3] W. van Elmpt, S. Nijsten, B. Mijnheer, A. Dekker, and P. Lambin, The next step in patientspecific QA: 3D dose verification of conformal and intensity modulated RT based on EPID dosimetry and Monte Carlo dose calculations, Radiother Oncol 86 (2008) 86-92.

DOI: 10.1016/j.radonc.2007.11.007

[4] M. Wendling, L. McDermott, A. Mans, J. Sonke, M. van Herk, and B. Mijnheer, A simple backprojection algorithm for 3D in vivo EPID dosimetry of IMRT treatments, Med Phys 36 (2009) 3310-21.

DOI: 10.1118/1.3148482

[5] P. Francois, P. Boissard, L. Berger, and A. Mazal, In vivo dose verification from back projection of a transit dose measurement on the central axis of photon beams, Physica Medica 27 (2011) 1-10.

DOI: 10.1016/j.ejmp.2010.06.002

[6] B. McCurdy and S. Pistorius, A two-step algorithm for predicting portal dose images in arbitrary detectors, Med Phys 27 (2000) 2109-16.

DOI: 10.1118/1.1289375

[7] K. Chytyl-Prax K. Chytyk-Praznik, E. VanUytven, T. vanBeek, P. Greer, and B. McCurdy, Model-based prediction of portal dose images during patient treatment, Med Phys 40 (2013) 1-11.

DOI: 10.1118/1.4792203

[8] I. Olaciregui-Ruiz, S. Beddar, P. Greer, N. Jornet, B. McCurdy, G. Paiva-Fonseca, B. Mijnheer, and F. Verhaegen, In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice, Physics and Imaging in Radiation Oncology 15 (2020) 108-16.

DOI: 10.1016/j.phro.2020.08.003

[9] L. Antonuk, J. Yorkston, W. Huang, H. Sandler, J. Siewerdsen, and Y. El-Mohri, Megavoltage imaging with a large-area, flat-panel amorphous silicon imager, Int J Radiat Oncol Biol Phys 36 (1996) 661-672.

DOI: 10.1016/s0360-3016(96)00358-6

[10] Epiqa in clinical practice. http://www.wienkav.at/kav/kfj/9

[11] M. Held, J. Cheung, A. Andujar, F. Husson, and O. Morin, Commissioning and evaluation of an Electronic Portal Imaging Device-based in-vivo dosimetry software, Cureus 10 (2018).

DOI: 10.7759/cureus.2139

[12] A. Sait, J. Figueredo, G. Jones, K. Jones, T. McGowan, J. Kapatoes, and R. Ramaseshan, Validation of three-dimensional Electronic Portal Imaging Device-based PerFRACTIONTM software for patient-specific quality assurance, J Med Phys 44 (2019) 16-20.[13] W. Nailon, D. Welsh, K. McDonald, D. Burns, J. Forsyth, G. Cooke, F. Cutanda, L. Carruthers, D. McLaren, J. Vaqué, T. Kehoe, and S. Andiappa, EPID-based in vivo dosimetry using Dosimetry CheckTM: Overview and clinical experience in a 5-yr study including breast, lung, prostate, and head and neck cancer patients, J Appl Clin Med Phys (2019) 6-16.

DOI: 10.1002/acm2.12441

[14] B. Mijnheer, S. Beddar, J. Izewska, and C. Reft, In vivo dosimetry in external beam radiotherapy, Med Phys 40 (2013).

DOI: 10.1118/1.4811216

[15] D. Sarrut et al, Advanced Monte Carlo simulations of emission tomography imaging systems with GATE, Phys Med Biol 66 (2021) 10TR03.

[16] I. Sumida, H. Yamaguchi, I. Das, H. Kizaki, K. Aboshi, M. Tsujii, Y. Yamada, O. Suzuki, Y. Seo, F. Isohashi, and K. Ogawa, Intensity-modulated radiation therapy dose verification using fluence and portal imaging device, Journal of Applied Clinical Medical Physics 17 (2016).

DOI: 10.1120/jacmp.v17i1.5899

[17] D. Dance, S. Christofides, A. Maidment, I. McLean, and K. Ng, Diagnostic Radiology Physics: A Handbook for Teachers and Students, International Atomic Energy Agency, Vienna International Centre, Vienna, Austria, 2014.