TY  - JOUR
AU  - Gimenez-Alventosa, V.
AU  - Gimenez, V.
AU  - Ballester, F.
AU  - Vijande, J.
AU  - Andreo, P.
PY  - 2018
DA  - 2018//
TI  - Correction factors for ionization chamber measurements with the 'Valencia' and 'large field Valencia' brachytherapy applicators
T2  - Phys. Med. Biol.
JO  - Physics in Medicine and Biology
SP  - 125004 - 10pp
VL  - 63
IS  - 12
PB  - Iop Publishing Ltd
KW  - skin applicator
KW  - Valencia applicator
KW  - large field Valencia applicator
KW  - HDR brachytherap
KW  - brachytherapy dosimetry
KW  - Monte Carlo
AB  - Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the 'Valencia' and 'large field Valencia' shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber active volume with a Type A uncertainty of the order of 0.1%. The average energies of the photon spectra arriving at the surface of the water phantom differ by approximately 10%, being 384 keV for the 'Valencia' and 343 keV for the 'large field Valencia'. The ionization chamber correction factors have been obtained for both applicators using three methods, their values depending on the applicator being considered. Using a depth-independent global chamber perturbation correction factor and no shift of the effective point of measurement yields depth-dose differences of up to 1% for the 'Valencia' applicator. Calculations using a depth-dependent global perturbation factor, or a shift of the effective point of measurement combined with a constant partial perturbation factor, result in differences of about 0.1% for both applicators. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each shielded brachytherapy applicator and ionization chamber.
SN  - 0031-9155
UR  - https://doi.org/10.1088/1361-6560/aac27a
DO  - 10.1088/1361-6560/aac27a
LA  - English
N1  - WOS:000434682500004
ID  - Gimenez-Alventosa_etal2018
ER  -