Dosimetric Comparison of Conformal Radiotherapy and Arc-therapy of Ineligible Cervical Cancers for Intracavitary Brachytherapy

Author(s): Bouchra Amaoui, Dounia Mohssine, Malha ait Mohamed Bourhim, Nawal Bouih, Hicham Tamri, Mohamed El Morchid, Slimane Semghouli

Purpose: The purpose of this study was to compare the dosimetric parameters of two radiotherapy techniques for the cervical cancer treatment: three-dimensional conformal radiotherapy and arc-therapy.

Materials and Methods: Twenty patients with locally advanced cervical cancer who had been treated with 50 Gy conformal radiotherapy or arc-therapy, received a further 20 Gy by arc-therapy technique on a Varian treatment planning system. Both techniques were compared on the basis of Dose-Volume Histograms (DVH) for the Planning Target Volume (PTV), Organs At Risk (OAR) as well as homogeneity and conformity indices. Statistical analysis was performed using the SPSS (Statistical Package for the Social Sciences) v23 software (IBM Inc., Chicago, IL).

Results: The results obtained show that there is no significant difference in terms of dose distribution on the planning volumes between these two techniques. For the 50 Gy series, arc-therapy allowed for better OAR savings. V50 was reduced by 85% for the bladder and 89% for the rectum. For the 70 Gy series, the benefit was also in favor of arc-therapy. Indeed, from V30 to V60 the reduction was 15% to 56% for the bladder and rectum. In the small bowels, the reduction was greater than 61% for volumes beyond V40.

Conclusion: In this study, the arc-therapy compared to the conformational radiotherapy, allows a better coverage of the planning target volume, but also a reduction of the doses received by the organs at risk, which suggests a possible improvement of the therapeutic index. Therefore, arc-therapy may be a suitable technology for the treatment of cervical cancer when brachytherapy is not feasible.

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