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Sunday
August 29
14:15 - 15:30
N105-N106
Next generation of brachytherapy treatment planning systems: What do we want and what do they need?
Elisa Placidi, Italy;
Frank-André Siebert, Germany
Treatment planning systems (TPS) play a central role in brachytherapy. Here, all important data is concentrated as dose prescription, patient image data, clinical goals, etc. TPS is used for decision making when assessing the dose calculation taking into account also clinical considerations. Thus, it is more than a tool for providing dose calculation. In the past brachytherapy TPS used TG-43 formalism, but since a few years also model-based algorithms were implemented in the clinics. In this symposium we want to learn how to efficiently commission a model-based algorithm in brachytherapy and if these modern algorithms are worth the effort when using them in the clinics. Apart from the question of the dose calculation algorithm it should be questioned if the existing TPS can fulfil the clinical requirements. In particular if the needed dose distribution can be prescribed by planning aims and if the typical dose constraints are sufficient input into a TPS or if more input data is needed besides dose values? We want to make an outlook to the next generation of brachytherapy TPS and analyze what we have now and what properties and features are mostly required in the future. This will be done with a closer look to the application of artificial intelligence in brachytherapy TPS.
Symposium
Brachytherapy
How to design, fabricate, and validate a customized COMs-style eye plaque
PO-0258

Abstract

How to design, fabricate, and validate a customized COMs-style eye plaque
Authors:

Christopher Deufel1, Lauren Dalvin2, Jing Qian1, Birjoo Vaishnav1, Sarah McCauley Cutsinger1, Michelle Neben Wittich1, Ivy Petersen1

1Mayo Clinic, Radiation Oncology, Rochester, USA; 2Mayo Clinic, Ophthalmology, Rochester, USA

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Purpose or Objective

A customized COMS-style eye plaque may provide superior dosimetric coverage compared with standard models for certain intraocular tumor locations and shapes.  This work provides a recipe for developing and validating such customized plaques. To date, the publications regarding customized COMS-style plaques have emphasized the customization results, namely the plaque design and dosimetry, and have by and large minimized their description of the methods for creating the customized plaque. The purpose of this paper is to provide a detailed description of the process for creating a customized eye plaque, that is to say a recipe that the reader can follow for the design, prototype, fabrication, and quality assurance tasks. 

Material and Methods

The concept-into-clinical treatment process for a customized COMS-style eye plaque begins with a CAD model design (Figure 1 A, B, C) that meets the specifications of the radiation oncologist and surgeon, as well as a heterogeneity-corrected dose prediction to model the dose distribution. Next, a 3D printed plastic prototype is created and reviewed (Figure 1 D, E).  After design approval, a Modulay plaque is commercially fabricated. Quality assurance is subsequently performed to verify the physical measurements of the Modulay and Silastic as well as dosimetric measurement of the calibration, depth dose, and dose profiles. Sterilization instructions are provided by the commercial fabricator.  This customization procedure and quality assurance is demonstrated with a narrow-slotted plaque that was recently constructed for the treatment of a circumpapillary ocular tumor. 


Results

The production of a customized COMS-style eye plaque is a multistep process that requires requird approximately 30 hours and a cost of $1500.  CAD and dosimetric modeling is recommended to ensure that the design will meet the patient’s needs, and quality assurance is essential to confirm that the plaque has the proper dimensions and dose distribution. The customized narrow-slotted plaque presented herein was successfully implemented in the clinic, and provided superior dose coverage of juxtapapillary and circumpapillary tumors compared with standard or notched COMS-style plaques.  For the Mayo Slotted Plaque, the fabricated Modulay is shown in Figure 2A. The Modulay plaque was tested on two cadaveric eyes to ensure that the plaque would conform to a human optic nerve without damaging the nerve (Figures 2B,C).



Conclusion

Customized eye plaques may be used to treat intraocular tumors that cannot be adequately managed with standard models.  The procedure by which a customized COMS-style plaque may be designed, fabricated, and validated was presented along with a clinical example.