Iridium-Knife: Another knife in radiation oncology

Natasa Milickovic; Nikolaos Tselis; Efstratios Karagiannis; Konstantinos Ferentinos; Nikolaos Zamboglou

doi:10.1016/j.brachy.2017.03.005

Iridium-Knife: Another knife in radiation oncology

Brachytherapy. 2017 Jul-Aug;16(4):884-892. doi: 10.1016/j.brachy.2017.03.005. Epub 2017 Apr 6.

Authors

Natasa Milickovic¹, Nikolaos Tselis², Efstratios Karagiannis³, Konstantinos Ferentinos³, Nikolaos Zamboglou³

Affiliations

¹ Department of Medical Physics and Engineering, Sana Klinikum Offenbach, Offenbach, Germany. Electronic address: natasa.milickovic@sana.de.
² Department of Radiation Oncology, Sana Klinikum Offenbach, Offenbach, Germany; Department of Radiotherapy and Oncology, J. W. Goethe University, Frankfurt am Main, Germany.
³ Department of Radiation Oncology, Sana Klinikum Offenbach, Offenbach, Germany.

PMID: 28392144
DOI: 10.1016/j.brachy.2017.03.005

Abstract

Purpose: Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 (¹⁹²Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial ¹⁹²Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife.

Methods and materials: Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk.

Results: Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans.

Conclusions: Both 3D ¹⁹²Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D ¹⁹²Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife.

Keywords: Brachytherapy; High-dose-rate; Iridium-Knife; Stereotactic body radiation therapy; Stereotactic radiosurgery; X-Knife.