Which factor does NOT influence dose delivery by a brachytherapy source implant?

The factor that does not influence dose delivery by a brachytherapy source implant is the source depth. In brachytherapy, the dose delivery is primarily determined by the characteristics of the radioactive source, its placement within or around the tumor, and the surrounding tissue.

While the depth of the source may seem relevant, the actual positioning of the source and the energy of the radiation emitted are more critical factors in calculating the dose. The radiation dose delivered to the targeted area is a function of the source's strength, the distance to the target tissue, and the duration of the implant.

Total AKS, duration of the implant, and perturbation of the implant medium all directly affect the calculated dose. Total AKS (air kerma strength) relates to the output of the source, influencing the dose delivered. Duration affects the total dose received based on the time the source remains active. Perturbation of the implant medium can alter dose distribution due to changes in tissue density or composition surrounding the source, which would also influence the effectiveness of the treatment.