Comparison of Axxent-Xoft, (192)Ir and (60)Co high-dose-rate brachytherapy sources for image-guided brachytherapy treatment planning for cervical cancer.

OBJECTIVE

To evaluate the dosimetric differences and similarities between treatment plans generated with Axxent-Xoft electronic brachytherapy source (Xoft-EBS), (192)Ir and (60)Co for tandem and ovoids (T&O) applicators.

METHODS

In this retrospective study, we replanned 10 patients previously treated with (192)Ir high-dose-rate brachytherapy. Prescription was 7 Gy × 4 fractions to Point A. For each original plan, we created two additional plans with Xoft-EBS and (60)Co. The dose to each organ at risk (OAR) was evaluated in terms of V(35%) and V(50%), the percentage volume receiving 35% and 50% of the prescription dose, respectively, and D(2cc), highest dose to a 2 cm(3) volume of an OAR.

RESULTS

There was no difference between plans generated by (192)Ir and (60)Co, but the plans generated using Xoft-EBS showed a reduction of up to 50% in V(35%), V(50%) and D(2cc). The volumes of the 200% and 150% isodose lines, however, were 74% and 34% greater than the comparable volumes generated with the (192)Ir source. Point B dose was on average only 16% of the Point A dose for plans generated with Xoft-EBS compared with 30% for plans generated with (192)Ir or (60)Co.

CONCLUSION

The Xoft-EBS can potentially replace either (192)Ir or (60)Co in T&O treatments. Xoft-EBS offers either better sparing of the OARs compared with (192)Ir or (60)Co or at least similar sparing. Xoft-EBS-generated plans had higher doses within the target volume than (192)Ir- or (60)Co-generated ones.

ADVANCES IN KNOWLEDGE

This work presents newer knowledge in dosimetric comparison between Xoft-EBS, (192)Ir or (60)Co sources for T&O implants.