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Radiation dose distribution under the area protected using a Cerrobend block during external beam radiotherapy: a film study

  • Mohammad Mohammadi (a1) (a2), Amir Taherkhani (a3) (a4) and Mohmmadsaeed Saboori (a5)



In radiation therapy, to spare normal surrounding tissues, either Multileaf Collimators or Cerrobend blocks are used.


The current study focuses on the relative dose distribution under the areas protected by Cerrobend blocks.

Materials and methods

A dual-energy linear accelerator and a Cobalt-60 machine were utilised as radiation sources. Several blocks were designed using commercially available materials to shield radiation fields. The relative dose distribution was then evaluated using extended dose range 2 films.


Results showed that the dose distribution under protected areas depends on several parameters including the width and height of protecting blocks, incident photon beam energy, radiation field size and source to surface distance. An increase in Cerrobend block height from 80 to 95 mm significantly decreases the dose at the protected areas.


An increase in the block width and photon energy decreases the relative dose deposition at the protected area. However, electron and neutron contaminations should also be taken into consideration.


Corresponding author

Correspondence to: Mohammad Mohammadi, Department of Medical Physics, Faculty of Medicine, Hamadan University of Medical Sciences, 65178-38678 Hamadan, Iran. Tel: +98 8381037; Fax: +98 8381017. E-mail:


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Radiation dose distribution under the area protected using a Cerrobend block during external beam radiotherapy: a film study

  • Mohammad Mohammadi (a1) (a2), Amir Taherkhani (a3) (a4) and Mohmmadsaeed Saboori (a5)


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