Abstract:
:Dynamic modulation can be affected by inaccuracies when the required acceleration is larger than the highest allowed by the mechanical characteristics of the whole apparatus. In this study, inertia effects have been investigated with regard to the single absorber 1D modulation, analysing primarily how the acceleration performed by the modulating system affects the realization of 'single absorber' fluence profiles and the type of correction which could be devised. The observed percentage deviations from desired modulation at the lowest fluence coordinate of single minimum fluence profiles, when no correction is applied, were almost negligible for 'easy' modulations of the incident fluence (i.e. slow gradients); deviations became increasingly relevant as the moving absorber executed steeper gradients (a 17.6% higher dose being delivered in the minimum position when a 0.2 modulation is required). By applying the proposed corrections, the single absorber performances were improved to a satisfactory level, with a maximum deviation from desired modulation in the minima within 1.6%.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Corletto D,Broggi S,Fiorino C,Mangili P,Calandrino R,Lev A,Gennari D,Rudello Fdoi
10.1088/0031-9155/44/11/401subject
Has Abstractpub_date
1999-11-01 00:00:00pages
N233-41issue
11eissn
0031-9155issn
1361-6560journal_volume
44pub_type
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