AbstractID: 6690 Title: Dosimetric study of the new InterSource palladium and iodine seed
The use of low energy photon emitters for brachytherapy applications, to treat prostate or of eye
tumors, has seriously increased these last few years. New seed models for 103Pd and 125I have
been introduced as the InterSource1.
To determine the dosimetric parameters as recommended in the TG43, measurements were made
with LiF thermoluminescent micro-dosimeters in two types of solid water phantoms to obtain the
dose rate constant, the radial dose function and the anisotropy function. The same dose
parameters are also obtained by Monte Carlo calculations (MCNP4b) in liquid water in addition
to both solid media.
Our calculated and measured TG43 functions for solid water are in excellent agreement. We have
then calculated these functions in liquid water to obtain the dosimetric information for clinical
applications. For Palladium, the calculated dose rate constant is 0.657+/-1% in WT1 and 0.682+/1% in RW1, the measured values are respectively 0.671+/-7% and 0.687+/-7%. The calculated
value for water is 0.692+/-1%. For Iodine, the calculated dose rate constant is 0.99+/-1% in WT1,
the measured values is 1.02+/-7%. The calculated value for water is 1.02+/-1%.
We were also interested in the ratio between the doses obtained in the three media to analyse the
water equivalence of these commercially available solid water media at these low energies. To
confirm the calculated data by measurements, we have calculated the ratios between the doses
measured in each solid waters; the differences between the calculated ratios and the measured
ratios are always inside the range of the experimental error.
1
Furnished by IBt, Seneffe, Belgium