Knowledge of endoscopic ultrasound-delivered fiducial composition and dimension necessary when planning proton beam radiotherapy
submitted 20 December 2017
accepted after revision 05 February 2018
05 June 2018 (online)
Background and study aims Little consideration has been given to selection of endoscopic ultrasound-guided fiducials for proton radiotherapy and the resulting perturbations in the therapy dose and pattern. Our aim was to assess the impact of perturbations caused by six fiducials of different composition and dimensions in a phantom gel model.
Materials and methods The phantom was submerged in a water bath and irradiated with a uniform 10 cm × 10 cm field of 119.7 MeV monoenergetic spot scanning protons delivered through a 45 mm range shifter. The proton “Bragg Peak” was evaluated.
Results Dose perturbations manifesting as dose reductions up to 30 % were observed. A carbon composite (1 × 5 mm) and gold (0.4 × 10 mm) fiducial with backload potential rather than dedicated EUS pre-loaded gold fiducial needles had the best performance in terms of minimizing the dose perturbation.
Conclusions Our data demonstrate that a carbon composite fiducial has a less untoward effect on proton therapy dose distribution than dedicated EUS pre-loaded gold fiducial needles. Such information is important to consider when selecting fiducials specifically for proton therapy.
- 1 Newhauser W, Fontenot J, Koch N. et al. Monte Carlo simulations of the dosimetric impact of radiopaque fiducial markers for proton radiotherapy of the prostate. Phys Med Biol 2007; 52: 2937-2952
- 2 Lim YK, Kwak J, Kim DW. et al. Microscopic gold particle-based fiducial markers for proton therapy of prostate cancer. Int J Radiat Oncol Biol Phys 2009; 74: 1609-1616
- 3 Vassiliev ON, Kudchadker RJ, Kuban DA. et al. Dosimetric impact of fiducial markers in patients undergoing photon beam radiation therapy. Phys Med 2012; 28: 240-244
- 4 Khashab MA, Kim KJ, Tryggestad EJ. et al. Comparative analysis of traditional and coiled fiducials implanted during EUS for pancreatic cancer patients receiving stereotactic body radiation therapy. Gastrointest Endosc 2012; 76: 962-971
- 5 Park WG, Yan BM, Schellenberg D. et al. EUS-guided gold fiducial insertion for image-guided radiation therapy of pancreatic cancer: 50 successful cases without fluoroscopy. Gastrointest Endosc 2010; 71: 513-518
- 6 Abu DayyehBK, Vandamme JJ, Miller RC. et al. Esophageal self-expandable stent material and mesh grid density are the major determining factors of external beam radiation dose perturbation: results from a phantom model. Endoscopy 2013; 45: 42-47
- 7 Cheung J, Kudchadker RJ, Zhu XR. et al. Dose perturbations and image artifacts caused by carbon-coated ceramic and stainless steel fiducials used in proton therapy for prostate cancer. Phys Med Biol 2010; 55: 7135-7147