Dynamic beam modulation by using a single computer-controlled absorber

C. Fiorino, A. Lev, H. Fusca, G. M. Cattaneo, F. Rudello, R. Callandrino

Research output: Contribution to journalArticlepeer-review


The authors have developed an apparatus able to generate to intensity-modulated beams, using only one moving absorber within the irradiation held. A procedure for deriving optimized absorber-speed profiles in order to produce the desired fluence/dose profiles has been suggested. Experimental tests show that the system should be sufficiently reliable in reproducing modulated beam profiles of different shape: expected relative doses against measured relative doses have been found to be in agreement in a number of situations within 3% using a non-focused device. A better agreement should be expected using a focused apparatus (which is currently being developed). Beam modulation by single absorber cannot modulate the beam fluence in any way one wishes, due to physical constraints, which depend on the absorber and field widths and on the shape of the desired fluence profile. However, the authors show that this simple and low-cost tool could offer, with a sufficient degree of accuracy, the possibility of modulating the beam fluence with a high degree of versatility. In particular, a procedure for performing tissue-missing compensation by single-absorber dynamic beam modulation is suggested. Moreover, 'strongly' modulated beam profiles can be created, showing that this simple technique could also have some interesting applications in the field of conformal radiotherapy by non-uniform dose delivery.

Original languageEnglish
Article number002
Pages (from-to)221-240
Number of pages20
JournalPhysics in Medicine and Biology
Issue number2
Publication statusPublished - 1995

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy (miscellaneous)
  • Biomedical Engineering

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