McGill.CA / Medical Physics Unit / People / Faculty & Staff / Shirin A. Enger

Radiobiology and Microdosimetry

From left to right: Shirin A. Enger (Assistant Professor), Behnaz Behmand (Postdoctoral Fellow), Yuji Kamio (PhD Student), Joseph DeCunha (MSc Candidate)

 

In radiotherapy, ionizing radiation is used to cause irreparable damage to the DNA and inhibit cell cycling of the cancer cells. However, radiation does not just cause selective damage in cancerous cells but also injures healthy tissue. Many strategies have been developed for delivering dose in radiotherapy to maximize the effect of radiation on tumour cells and to spare the surrounding healthy tissues. In brachytherapy radiation is administered from radiation sources located within the tumour or nearby body cavities giving a high radiation dose to the tumour while sparing healthy surrounding tissue. High precision external radiotherapy can be delivered by protons and other ions with a strongly increasing energy deposition that creates a narrow peak of dose, called the Bragg peak at the end of the particle’s range and with sharp lateral dose fall-off, allowing to tailor the dose distribution to the malignant volume.

The biological response to radiation is quantified in terms of the relative biological effectiveness (RBE), defined as the ratio between the absorbed dose of a reference radiation such as Cobalt-60 and that of a test radiation for a given biological endpoint i.e. cell type, cell cycle, survival level, radiation dose, dose rate and dose per fraction. Low energy brachytherapy sources, proton and ion beams are associated with high RBE values. RBE does not simply depend on the mean value of energy deposition, but on its stochastic distribution, which, in turn, depends on the target size. When changing radionuclides or radiation modalities with another, it is important to understand the difference in RBE between the two radiation sources/modalities for the same end point.

In this project RBE between different brachytherapy radiation sources and external beam radiotherapy modalities are investigated for different tumours and tumour cell lines, both experimentally through cell irradiation studies and theoretically through microdosimetrical studies by using Monte Carlo track structure codes.

 

Peer reviewed publications and published conference presentations

Journal publications

  • Famulari G, Pater P, Enger SA. Microdosimetric evaluation of alternative high and intermediate energy high dose rate brachytherapy sources - a Geant4-DNA simulation study. Int J Radiat Oncol Biol Phys. 100(1):270-277 (2018).
  • Famulari G, Pater P, Enger SA, Microdosimetry calculations for monoenergetic electrons using Geant4-DNA combined with a weighted track sampling algorithm. Phys Med Biol, 62(13):5495-5508 (2017).
  • Pater P, Bäckstöm G, Villegas F, Ahnesjö A, Enger SA, Seuntjens J and El Naqa Issam, Proton and light ion RBE for the induction of direct DNA double strand breaks. Med phys, 43(5): 2131-2141 (2016).
  • Bernal M, Bordage MC, Brown J, Davidkova M, Delage M, El Bitar Z, SA Enger, Francis Z, Guatelli S, Ivantchenko V, Karamitros M, Kyriakou I, Maigne L, Meylan S, Murakami K, Okada S, Payno H, Perrot Y, Pham T, Tran H, Sasaki T, Stepan V, Villagrasa C, Incerti S, Track structure modeling in liquid water: a review of the Geant4-DNA very low energy extension of the Geant4 Monte Carlo simulation toolkit. European Journal of Medical Physics. 31(8): 861-874. (2016).
  • Poole CM, Ahnesjö A, Enger SA, Determination of subcellular compartment sizes for estimating dose variations in radiotherapy. Radiation Protection Dosimetry. 1-4 (2015).

Conference presentations (oral)

  • Kamio Y, Bavoux M, Zerouali K, Carrier J-F, Deblois F, Wong P, Enger SA. Validation of an orthovoltage based high-throughput microfluidic lab-on-a-chip radiobiological platform using EBT3 GafchromicTM film multichannel dosimetry. 65th COMP annual meeting, 24-27th September (2019).
  • DeCunha J, Villegas-Navarro F, Vallières N, Camilleri-Broët S, Enger SA. Towards Patient Specific Microdosimetry. MCMA. June 21 (2019).
  • Famulari G, Pater P, Enger SA. Microdosimetry calculations for monoenergetic electrons using Geant4-DNA combined with a weighted track sampling algorithm. Physica Medica, 42:8 (2017).
  • Famulari G, Pater P, Enger SA, Microdosimetric evaluation of intermediate-energy brachytherapy sources using Geant4-DNA. Radiotherapy and Oncology, 84:S27–S35 (2017).
  • Pater P, Bäckström G, Villegas, MF, Ahnesjö A, Enger SA, Seuntjens J, and El Naqa I, Influence of Proton Track-Cell Nucleus Incidence Angle On Relative Biological Effectiveness, Med. Phys. 42, 3448 (2015).
  • Pater P, Bäckström G, Villegas, MF, Ahnesjö A, Enger SA, Seuntjens J, and El Naqa I, On the Value of LET as a Radiation Quality Descriptor for RBE, AAPM annual meeting. Med. Phys. 42, 3469 (2015).
  • Bäckström G, Villegas, MF, Enger SA, Ahnesjö A, Impact of the microdosimetric spread on cell survival data analysis, World Congress on Medical Physics and Biomedical Engineering, Toronto. 10/6/2015.
  • Pater P, Bäckström G, Villegas, MF, Ahnesjö A, Enger SA, and Seuntjens J, Exploring RBE Dependence on Proton Track Angular Incidence, World Congress on Medical Physics and Biomedical Engineering, Toronto. (2015).
  • Pater P, Bäckström G, Villegas, MF, Ahnesjö A, Enger SA, and Seuntjens J, Initial DNA damage patterns with MC track structure and ionization clusters, Radiotherapy and Oncology, 115, Supplement 1, S76-S77, (2015).
  • Villegas F, Bäckström G, Enger SA, Ahnesjö A, Impact of the microdosimetric spread on LQ-parameterization of cell survival data for protons and Co-60 photons, Radiotherapy and Oncology, 115, Supplement 1, S803, (2015).
  • Poole  C, Enger SA, Crosbie JC , Determining microdosimetric spread amongst cells subject to microbeam radiotherapy using Monte Carlo simulation. Micro-Mini & Nano Dosimetry and Prostate Cancer Treatment Workshop, MMND-IPCT Conference October 20-25, Port Douglas, Australia (2014).
  • Poole C, Ahnesjö A, Enger SA, Calculation of microdosimetric data due to subcellular compartment sizes determined from histological samples. Radiotherapy and Oncology, Vol. 111, S163–S164 (2014).

Conference presentations (poster)

  • Bavoux M, Kamio Y, Nyjab O, Lafontaine J, Wong P, Gervais T. Optimization of a Microfluidic System for High-Throughput Screening of Combinations of Drugs with Radiotherapy on Spheroids. 18th World Preclinical Congress/WPW, June 17-20th (2019).
  • Truong N, Ybarra N, Evans M, Enger SA, Nuclei Size Distribution as a Predictor for Radiosensitivity with 192Ir Brachytherapy. Brachytherapy,16(3):S83 (2017).

 

Alumni

 

From left to right: Peter Truong

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