Intraoperative implantation of a mesh of directional palladium sources (CivaSheet): Dosimetry verification, clinical commissioning, dose specification, and preliminary experience

Publication date: Available online 18 August 2017
Source:Brachytherapy
Author(s): Gil'ad N. Cohen, Karen Episcopia, Seng-Boh Lim, Thomas J. LoSasso, Mark J. Rivard, Amandeep S. Taggar, Neil K. Taunk, Abraham J. Wu, Antonio L. Damato
PurposeTo present the clinical commissioning of a novel ¹⁰³Pd directional brachytherapy device (CivaSheet) for intraoperative radiation therapy.Methods and MaterialsClinical commissioning for the CivaSheet consisted of establishing: (1) source strength calibration capabilities, (2) experimental verification of TG-43 dosimetry parameters, (3) treatment planning system validation, and (4) departmental practice for dose specification and source ordering. Experimental verification was performed in water with radiochromic film calibrated with a 37 kVp X-ray beam. Percentage difference ([measurements − calculation]/calculation) and distance to agreement (difference between film-to-source distance and distance that minimized the percentage difference) were calculated. Nomogram values (in U/100 Gy) for all configurations (up to 20 × 20 sources) were calculated for source ordering. Clinical commissioning was used on patients enrolled in an ongoing Institutional Review Board-approved protocol.ResultsA source calibration procedure was established, and the treatment planning system was commissioned within standard clinical uncertainties. Percentage dose differences (distances to agreement) between measured and calculated doses were 8.6% (−0.12 mm), 0.6% (−0.01 mm), −6.4% (0.22 mm), and −10.0% (0.44 mm) at depths of 2.3, 5.1, 8.0, and 11.1 mm, respectively. All differences were within the experimental uncertainties. Nomogram values depended on sheet size and spatial extent. A value of 2.4U/100 Gy per CivaDot was found to satisfy most cases, ranging from 2.3 to 3.3U/100 Gy. Nomogram results depended on elongation of the treatment area with a higher variation observed for smaller treatment areas. Postimplantation dose evaluation was feasible.CONCLUSIONSCommissioning and clinical deployment of CivaSheet was feasible using BrachyVision for postoperative dose evaluation. Experimental verification confirmed that the available TG-43 dosimetry parameters are accurate for clinical use.



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