Open diamonds are implanted air kerma strength for 103Pd implants as a function of PTV diameter, while the filled circles are the implanted air kerma strength of 131Cs implants. The expression in the solid box is the nomogram relating the implanted air kerma strength to the PTV diameter for 103Pd, while the expression in the dashed box relates the same for 131Cs.
This is a graphical comparison between 103Pd and 131Cs implants comparing the V100 [Fig. 2(a)] and the V200 [Fig. 2(b)] preimplantation dosimetric parameters. The dashed line corresponds to the unity line, which represents the point where both of the implants are equivalent for that specific dosimetric parameter.
This is a graphical comparison between 103Pd and 131Cs implants comparing the V100 [Fig. 3(a)] and the V200 [(Fig. 3(b)] two month postimplant dosimetric parameters.
Postimplant dose distribution of a typical PBSI patient with a 131Cs and a 103Pd implant. It is immediately evident that the V200% (red) is significantly smaller for the 131Cs implant. The V9Gy [the volume within the target that receives 9 Gy or more] (grey) and the V4.5Gy [the volume within the target that receives 4.5 Gy or more] (white) covers a larger amount of lung in the 131Cs implant compared to the 103Pd implant. This is a result of the higher energy photons emitted by 131Cs. Isodose legend is in Gy bracketed term is in percentage of the prescribed dose.
The average V100, V90, D90, V150, and V200 dosimetric parameters for 131Cs and 103Pd on preimplant and postimplant dose distributions. Both the absolute volumetric and relative percentage data have been tabulated where appropriate. The differences between 131Cs and 103Pd in the relative percentage data for all of the dosimetric parameters were statistically significant with a p-value of <0.05. The average volume of the PTV and surgical scar for the preimplant and postimplant treatment plans has been evaluated. The preimplant PTV used a 15 mm margin expansion on the surgical scar for treatment planning, while the postimplant PTV used a 10 mm margin expansion for evaluation.
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