GEM-based Dose Imaging Detectors for Proton Therapy Quality Assurance and Proton Radiography

Main Article Content

Alexander V. Klyachko



Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task and may be challenging, due to the lack of adequate instrumentation. The paper describes the development of a novel dose imaging detectors based on gas electron multiplierz (GEM). Multiple needs are addressed in a single package by applying new detector technology to improve the speed, accuracy and cost-effectiveness of the quality assurance procedures.

A scintillation detector based on a double GEM amplification structure with optical readout was evaluated in pristine and modulated proton beams. The detector's performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115 – 205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based gas mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, in particular in small-field applications.

Scintillation GEM detector is also well suited for proton radiography applications, particularly in proposed efficient method for proton radiography-based QA of patient-specific devices based on the developed detector with the goal of improving accuracy, completeness and cost-effectiveness of the QA process in comparison with available alternatives.

Article Details

How to Cite
KLYACHKO, Alexander V.. GEM-based Dose Imaging Detectors for Proton Therapy Quality Assurance and Proton Radiography. Quarterly Physics Review, [S.l.], v. 3, n. 3, oct. 2017. ISSN 2572-701X. Available at: <>. Date accessed: 23 mar. 2018.
Review Articles


1. de Moor, J.S., et al., Cancer survivors in the United States: prevalence across the survivorship trajectory and implications for care. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2013. 22(4): p. 561-570.
2. Nichiporov, D., L. Coutinho, and A.V. Klyachko, Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams. Phys. Med. Biol., 2015. 61(8): p. 2972 - 2990.
3. Sauli, F., Development and applications of gas electron multiplier detectors. Nucl. Instrum. Meth. A, 2003. 505(1-2): p. 195-198.
4. Smith, A.R., Vision 20∕20: Proton therapy. Medical Physics, 2009. 36(2): p. 556-568.
5. McDonald, M.W. and M.M. Fitzek, Proton therapy. Current problems in cancer, 2010. 34(4): p. 257-296.
6. MEDraysintell. Proton Therapy World Market Report Edition 2015. 2015;
7. P.J. Kim and H.A. Shih, The Place of Ion Beams in Clinical Applications, and references therein, in Ion Beam Therapy: Fundamentals, Technology, Clinical Applications, U. Linz, Editor. 2012, Springer-Verlag: Berlin. p. 17.
8. Reinhardt, S., et al., Comparison of Gafchromic EBT2 and EBT3 films for clinical photon and proton beams. Med Phys, 2012. 39(8): p. 5257-5262.
9. Boon, S.N., et al., Performance of a fluorescent screen and CCD camera as a two-dimensional dosimetry system for dynamic treatment techniques. Medical Physics, 2000. 27(10): p. 2198-2208.
10. LYNX PT. IBA Dosimetry 2015;
11. Ramm, U., et al., Three-dimensional BANG TM gel dosimetry in conformal carbon ion radiotherapy. Phys. Med. Biol., 2000. 45(9): p. N95.
12. Liyong, L., et al., A novel technique for measuring the low-dose envelope of pencil-beam scanning spot profiles. Phys. Med. Biol., 2013. 58(12): p. N171.
13. Liyong, L., et al., Experimental characterization of two-dimensional spot profiles for two proton pencil beam scanning nozzles. Phys. Med. Biol., 2014. 59(2): p. 493.
14. Arjomandy, B., et al., Verification of patient-specific dose distributions in proton therapy using a commercial two-dimensional ion chamber array. Medical Physics, 2010. 37(11): p. 5831-5837.
15. Arjomandy, B., et al., Use of a two-dimensional ionization chamber array for proton therapy beam quality assurance. Medical Physics, 2008. 35(9): p. 3889-3894.
16. Sauli, F., GEM: A new concept for electron amplification in gas detectors. Nucl. Instrum. Meth. A, 1997. A386(2-3): p. 531-534.
17. Fraga, F.A.F., et al., Optical readout of GEMs. Nucl. Instrum. Meth. A, 2001. 471(1-2): p. 125-130.
18. Fraga, F.A.F., et al., Scintillation neutron detectors with GEMs. Intl. Workshop PSND 2001at HMI, Berlin, Germany 2001,, 2001.
19. Fraga, F.A.F., et al. Imaging detectors based on the gas electron multiplier scintillation light. in Nuclear Science Symposium, 1999. Conference Record. 1999 IEEE. 1999.
20. Timmer, J.H., et al., A scintillating GEM for 2D-dosimetry in radiation therapy. Nucl. Instrum. Meth. A, 2002. 478(1-2): p. 98-103.
21. Fetal, S., et al., Dose imaging in radiotherapy with an Ar-CF4 filled scintillating GEM. Nucl. Instrum. Meth. A, 2003. 513(1-2): p. 42-46.
22. Seravalli, E., et al., 2D dosimetry in a proton beam with a scintillating GEM detector. Phys Med Biol., 2009. 54(12): p. 3755-3771.
23. Klyachko, A.V., et al., Dose Imaging Detectors for Radiotherapy Based on Gas Electron Multipliers. Nucl. Instrum. Meth. A, 2011. 628(1): p. 434-439.
24. Hoppe, R., T.L. Phillips, and M. Roach III, Leibel and Phillips Textbook of Radiation Oncology, 3rd Edition. 2010, Philadelphia: Elsevier/Saunders.
25. Paganetti, H., Proton Therapy Physics. 2012, Boca Raton, FL: CRC Press.
26. Zhao, Q., H. Wu, and I. Das. Quality assurance of proton compensators. in World Congress on Medical Physics and Biomedical Engineering, IFMBE Proceedings. 2012. Berlin, Germany: Springer.
27. Kim, J.S., et al., Image based quality assurance of range compensator for proton beam therapy. Korean J. Med. Phys., 2008. 19: p. 35-41.
28. Yoon, M., et al., Computerized tomography-based quality assurance tool for proton range compensators. Med. Phys. , 2008. 35: p. 3511-3517.
29. Kim, M., et al., Development of a 3D optical scanning-based automatic quality assurance system for proton range compensators. Medical Physics, 2015. 42(2): p. 1071-1079.
30. Park, S., et al., Proton-radiography-based quality assurance of proton range compensator. Phys. Med. Biol., 2013. 58(18): p. 6511.
31. Park, S., et al., Feasibility study of proton-based quality assurance of proton range compensator. Journal of Physics: Conference Series, 2013. 444(1): p. 012056.
32. Gafchromic EBT3 film specifications, Ashland Inc. 2015;
33. Klyachko, A.V., Phenix Medical OptiGEM Dose Imaging Detector User Manual. Phenix Medical LLC internal document, 2014.
34. Klyachko, A.V., et al., A GEM-based dose imaging detector with optical readout for proton radiotherapy. Nucl. Instrum. Meth. A, 2012. 694(0): p. 271-279.
35. Tech-Etch. 2012;
36. QSI, Quantum Scientific Imaging, Inc., 12 Coteau Dr., Poplarville, MS 39470, USA 2013.
37. Fraga, M.M.F.R., et al., The GEM scintillation in He-CF4, Ar-CF4, Ar-TEA and Xe-TEA mixtures. Nucl. Instrum. Meth. A, 2003. A 504: p. 88-92.
38. Farr, J.B., et al., Clinical characterization of a proton beam continuous uniform scanning system with dose layer stacking. Medical Physics, 2008. 35(11): p. 4945-4954.
39. PTW. PTW-Freiburg GmbH. Lörracher Strasse 7, 79115 Freiburg, Germany. 2010;
40. Schulte, R., et al., Conceptual Design of a Proton Computed Tomography System for Applications in Proton Radiation Therapy. Nuclear Science, IEEE Transactions on, 2004. 51(3): p. 866-872.
41. Talamonti, C., et al., Proton radiography for clinical applications. Nucl. Instrum. Meth. A, 2010. 612(3): p. 571-575.
42. Ryu, H., et al., Density and spatial resolutions of proton radiography using a range modulation technique. Phys. Med. Biol., 2008. 53(19): p. 5461.
43. Zygmanski, P., et al., The measurement of proton stopping power using proton-cone-beam computed tomography. Phys. Med. Biol., 2000. 45(2): p. 511.
44. Nichiporov, D., et al., Multichannel detectors for profile measurements in clinical proton fields. Medical Physics, 2007. 34(7): p. 2683-2690.
45. Altunbas, C., et al., Construction, test and commissioning of the triple-gem tracking detector for COMPASS. Nucl. Instrum. Meth. A, 2002. 490(1-2): p. 177-203.
46. Marshall J.L., W.P., Rheault J.-P., Prochaska T., Allen R. D., DePoy D.L., Characterization of the Reflectivity of Various Black Materials. Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 91474F 2014.
47. Equinox Interscience, Pinecliffe, USA. Deep Sky Black. 2016;
48. Surrey NanoSystems, Newhaven, UK. Vantablack. 2016;