Speakers
Description
In
2002, Martin Ebert proposed the theoretical concept of Intensity Modulated
Brachytherapy, which uses brachytherapy sources that emit radiation anisotropically to
achieve dose intensity modulation [1]. To perform the dosimetric tests, a phantom was
constructed from an acrylic box filled with acrylate water gel and a 3D-printed inner box
made of polylactic acid or PLA. This phantom was irradiated with an iridium-192 source at
an energy of 373 keV. The treatment plan was created in BrachyVision's Treatment
Planning System - TPS (Version 16, Varian Medical Systems, Palo Alto CA) and the dose
distribution was calculated using the tomographic images of the constructed phantom and
the dose calculation algorithm based on TG 43[2]. The results of the dosimetric tests on the
radiochromic film in the upper and lower region compared to the TPS, upper region: 823.4
cGy ± 0,85%; 649.9 cGy ± 1,07%; 575.8 cGy ± 1,21%; 540.1 cGy ± 1,3%, estimated
TPS:700 cGy; lower region: 691.1 cGy ± 1,01%; 990.8 cGy ± 0,70%; 649.8 cGy 1,07%;
768.3 cGy ± 0,91%, estimated TPS: 700 cGy. The planning system conditions are the most
ideal, which may have caused the dose variation. The upper and lower simulated regions
may refer to the dose to the bladder and rectum. The tests carried out on this phantom for
the vaginal canal can also be adapted for the rectal canal.
[1] EBERT MA. Possibilities for intensity-modulated brachytherapy: technical limitations on the
use of non-isotropic sources. Phys Med Biol. 2002; 47:2459–2509
[2] Ravinder, N; Anderson, L L; Luxton, G; et al. Dosimetry of interstitial brachytherapy sources:
Recommendations of the AAPM Radiation Therapy Committee Task Group No. 43. Med Phys, v.
22, n. 2, pp. 209-234, 1995
Keywords: brachytherapy, dosimetric tests, absorbed dose.