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eLQ : A biologically-equivalent dose calculator available on iPhone, Android, and the web

2011; Elsevier BV; Volume: 1; Issue: 3 Linguagem: Inglês

10.1016/j.prro.2011.04.001

1879-8519

Jean‐Emmanuel Bibault, Pierre Blanchard, Bernard Dubray, Éric Lartigau,

Advances in Oncology and Radiotherapy

The French Society of Young Radiation Oncologists (SFjRO) has created an iPhone application (Fig 1) that allows for calculation of biologically equivalent doses in clinical radiotherapy using the linear-quadratic model. An English version was made available in November 2010, downloaded by more than 900 people over the world (United States, United Kingdom, Germany, The Netherlands, etc).1SFjRO eLQ available on the App Store.http://itunes.apple.com/us/app/elq/id398906906?mt=8Google Scholar It is available on iOS for iPhone, iPod Touch, and iPad. A web version (in French, English, German, and Spanish) can be used inside any browser (http://www.sfjro.fr). The application is also available for Google's mobile OS Android. The application was developed with 2 goals in mind: (1) To provide radiation oncologists with a ready-to-use tool fitting in a lab coat pocket; and (2) to sensitize young radiation oncologists to radiobiology and the influence of fractionation. The calculator was created using Apple's Xcode Developer Tool Technology with the PhoneGap open source framework and jQtouch. It is the first free calculator that is academically supported. Inside the application, the user is invited to choose an organ at risk or a predefined α/β value, and enter total prescribed dose, initial dose per fraction, and new dose per fraction. The equivalent dose is then calculated. Alerts based on linear-quadratic model limitations and dose constraints for each organ are activated, should any parameters be out of the defined boundaries. The linear-quadratic model is used to predict biological response to radiation when fractionation is altered.2Thames Jr, H.D. Withers H.R. Peters L.J. Fletcher G.H. Changes in early and late radiation responses with altered dose fractionation: implications for dose-survival relationships.Int J Radiat Oncol Biol Phys. 1982; 8: 219-226Abstract Full Text PDF PubMed Scopus (682) Google Scholar, 3Joiner M.C. Bentzen S.M. Fractionation: the linear-quadratic approach.in: Joiner M.C. van der Kogel A. Basic clinical radiobiology. 4th ed. Hodder Arnold, London2009: 102-118Crossref Google Scholar, 4Hall E.J. Time, dose, and fractionation in radiotherapy.in: Radiobiology for the radiologist. 5th ed. Lippincott Williams & Wilkins, Philadelphia2000: 397-418Google Scholar, 5Scalliet P. Cosset J.M. Wambersie A. Application of the LQ model to the interpretation of absorbed dose distribution in the daily practice of radiotherapy.Radiother Oncol. 1991; 22: 180-189Abstract Full Text PDF PubMed Scopus (26) Google Scholar Each organ is characterized by 2 parameters: α represents the cell kill per Gy of the initial linear component and β the cell kill per Gy of the quadratic component of the survival curve. α/β is inversely proportional to biological sensitivity to different fractionation regimens. If α/β >10 Gy, the biological response would be unlikely changed by modified fractionation. Conversely, an α/β value <10 Gy would be associated with a significant impact of dose per fraction alteration, especially when late reactions of organs at risk are considered.5Scalliet P. Cosset J.M. Wambersie A. Application of the LQ model to the interpretation of absorbed dose distribution in the daily practice of radiotherapy.Radiother Oncol. 1991; 22: 180-189Abstract Full Text PDF PubMed Scopus (26) Google Scholar Since the validity of the linear-quadratic model has only been established for doses per fraction between 1 and 6-8 Gy,2Thames Jr, H.D. Withers H.R. Peters L.J. Fletcher G.H. Changes in early and late radiation responses with altered dose fractionation: implications for dose-survival relationships.Int J Radiat Oncol Biol Phys. 1982; 8: 219-226Abstract Full Text PDF PubMed Scopus (682) Google Scholar, 3Joiner M.C. Bentzen S.M. Fractionation: the linear-quadratic approach.in: Joiner M.C. van der Kogel A. Basic clinical radiobiology. 4th ed. Hodder Arnold, London2009: 102-118Crossref Google Scholar, 4Hall E.J. Time, dose, and fractionation in radiotherapy.in: Radiobiology for the radiologist. 5th ed. Lippincott Williams & Wilkins, Philadelphia2000: 397-418Google Scholar, 5Scalliet P. Cosset J.M. Wambersie A. Application of the LQ model to the interpretation of absorbed dose distribution in the daily practice of radiotherapy.Radiother Oncol. 1991; 22: 180-189Abstract Full Text PDF PubMed Scopus (26) Google Scholarour application should not be used for largely hypofractionated regimens. Additionally, we did not include correction for incomplete repair between fractions or for cell proliferation; our application should not be used when the interval between 2 treatment sessions is shorter than 6 to 8 hours or in the case of accelerated treatments. We thank the boards of SFRO and SFjRO for their help and remarks. We would like to invite the journal readership to test eLQ and let us know their comments and suggestions.