Clinical radiotherapy application of N-vinylpyrrolidone-containing 3D polymer gel dosimeters with remote external MR-reading

Marek Kozicki; Andreas Berg; Piotr Maras; Malwina Jaszczak; Mariusz Dudek

doi:10.1016/j.ejmp.2019.11.014

Clinical radiotherapy application of N-vinylpyrrolidone-containing 3D polymer gel dosimeters with remote external MR-reading

Phys Med. 2020 Jan:69:134-146. doi: 10.1016/j.ejmp.2019.11.014. Epub 2020 Jan 3.

Authors

Marek Kozicki¹, Andreas Berg², Piotr Maras³, Malwina Jaszczak⁴, Mariusz Dudek⁵

Affiliations

¹ Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Lodz University of Technology, Lodz, Poland; GeVero Co., Lodz, Poland(1). Electronic address: marek.kozicki@p.lodz.pl.
² High Field MR-Center, Medical University of Vienna, Austria.
³ Medical Physics Department, Copernicus Hospital, Lodz, Poland.
⁴ Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Lodz University of Technology, Lodz, Poland.
⁵ Institute of Materials Science and Engineering, Lodz University of Technology, Lodz, Poland.

PMID: 31901838
DOI: 10.1016/j.ejmp.2019.11.014

Abstract

Purpose: Advanced 3D dosimetry is required for verifications of complex dose distributions in modern radiotherapy. Two 3D polymer gel dosimeters, coupled with magnetic resonance (MR) imaging (3 T MRI) readout and data processing with polyGeVero® software, were tested for the verification of calculated 3D dose distributions by a treatment planning system (TPS) and ArcCHECK®-3DVH®, related to eradication of a lung tumour.

Methods: N-vinylpyrrolidone-containing 3D polymer gel dosimeters were used: VIC (containing ascorbic acid and copper sulfate pentahydrate) and VIC-T (containing tetrakis(hydroxymethyl)phosphonium chloride). Three remote centers were involved in the dosimeters preparation and irradiation (Poland), and MRI (Austria). Cross beam calibration of the dosimeters and verification of a 3D dose distribution calculated with an Eclipse External Beam TPS and ArcCHECK®-3DVH® were performed. The 3D-to-3D comparisons of the VIC and VIC-T with TPS and ArcCHECK®-3DVH® along with ArcCHECK®-3DVH® versus TPS dose matrixes were performed with the aid of the polyGeVero® by analyzing dose profiles, isodoses lines, gamma index, gamma angle, dose difference, and related histograms.

Results: The measured MR-relaxation rate (R₂ = 1/T₂) for the dosimeters relates to the dose, as follows: R₂ = 0.0928 ± 0.0008 [Gy^-1 s^-1] × D [Gy] + 2.985 ± 0.012 [s^-1] (VIC) and 0.1839 ± 0.0044 [Gy^-1 s^-1] × D [Gy] + 2.519 ± 0.053 [s^-1] (VIC-T). The 3D-to-3D comparisons revealed a good agreement between the measured and calculated 3D dose distributions.

Conclusions: VIC and VIC-T with 3T MRI readout and polyGeVero® showed potential for verifications of calculated irradiation plans. The results obtained suggest the implementation of the irradiation plan for eradication of the lung tumour.

Keywords: 3D radiotherapy dosimetry; 3T MRI; ArcCHECK–3DVH verification; TPS verification; VIC; VIC-T; polyGeVero software.

MeSH terms

Calibration
Gelatin / chemistry
Humans
Imaging, Three-Dimensional
Lung Neoplasms / diagnostic imaging*
Lung Neoplasms / radiotherapy*
Magnetic Resonance Imaging*
Polymers
Pyrrolidinones*
Radiometry / instrumentation*
Radiometry / methods
Radiotherapy / methods*
Software

Substances

Polymers
Pyrrolidinones
N-vinyl-2-pyrrolidinone
Gelatin