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Updated: Jul 14, 2026

Use of a Linear Accelerator for Conducting In Vitro Radiobiology Experiments
Published on: May 26, 2019
Linearity of the dose monitor system at low monitor units
Peter Mohr1, Sabrina Brieger, Jürgen Stahl
1Strahlentherapie, Diakoniekrankenhaus Schwäbisch Hall, Diakoniestrasse 10, 74523 Schwäbisch Hall, Germany. Peter.Mohr@diaksha.de
Background And Purpose:
The accuracy of the dose monitor system of a medical electron accelerator is of crucial importance for the precise delivery of the prescribed dose. Special attention is given to the case of low monitor units (MU). The long-term stability of the dose monitor system is analyzed.
Material And Methods:
Photon and electron fields with monitor units between 1 and 500 MU were measured with field sizes of 10 x 10 cm(2) and 20 x 20 cm(2) at source-skin distances (SSDs) of 100 cm and 95 cm, respectively. The relative dose per MU [see text] was determined for an Elekta linear accelerator.
Results:
The relative dose per MU was measured to be constant within about 1% down to fields with only 2 MU. The deviation remained below 2% down to 1 MU which is the minimum setting of the accelerator. The long-term stability is better than 0.2% per month.
Conclusion:
No therapeutically relevant deviation of the prescribed dose could be detected for the Elekta linear accelerator. This is a prerequisite for the implementation of intensity-modulated radiotherapy (IMRT) techniques.
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