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Neurological application validation for photon counting spectral CT

Periodic Reporting for period 1 - NEUROSPECT (Neurological application validation for photon counting spectral CT)

Reporting period: 2015-07-01 to 2015-12-31

Computed tomography (CT) is the most widely used x-ray imaging modality. The basic detection technology has not changed for many years; indirect conversion with scintillators that convert the x-ray quanta to visible light is still the universal solution and this does not make maximal use of the information content of the x rays. Pushed by a demand for better dose utilization and the emergence of new clinical applications, a technological shift towards photon counting CT with energy sensitive detectors is underway. Hypothesized new applications include the possibility to characterize vulnerable carotid plaques by means of tissue quantification and better stroke treatment planning by better detecting partial perfusion after thrombus induced vessel occlusion. The new technology also has the potential to eliminate some fundamental image artefacts (from beam hardening) that limits the utility of CT in important clinical applications such as imaging cerebral bleeding in the posterior fossa (in the middle of the brain).
Since major advantages are foreseen with the new technology it is no surprise that all major system vendors are participating in the race towards photon counting spectral CT. All proposed implementations, except that of Prismatic Sensors AB, are based on cadmium telluride (or cadmium zink telluride, CZT) as the direct conversion material. CZT is a relatively new material and it has proved difficult to manufacture clean enough crystals for efficient and complete charge collection. Without complete and efficient charge collection, the detection efficiency goes down (and the dose increases) and the spectral capabilities deteriorate. CZT detectors, although they have desirable theoretical characteristics such as high detection efficiency and high fraction of photo events, are to date not able to handle the large x-ray fluence rates encountered in practice and indeed, despite more than a decade of development efforts, not a single clinical installation exists. The manufacturing of silicon wafers is however a mature technology and charges can be collected efficiently at much higher rates than possible with CZT.
This is the business opportunity Prismatic has addressed in this Feasibility study. With a photon counting detector based on silicon conversion diodes we can handle all clinically encountered fluence rates without deterioration in performance. Prismatic intends to sell to (one of the) large system vendors; Philips, GE, Siemens and Toshiba. We plan to offer a modularized detector system for integration into the existing detector cradle and gantry. This would allow the system vendors to offer their customers, the radiology clinics, the first technically viable photon counting system unlocking the benefits of spectral CT.

The overall objective of this project was to conduct a feasibility study and plan for the finalization and integration of a newly developed x-ray detector module for photon counting spectral computed tomography (CT) into a vendor-supplied high-end commercial CT gantry. The goal was to develop a business plan on performance of the final development and commercial steps to enable introduction of a new detector technology to the market which will result in increased image quality and allow for new applications to meet currently unmet clinical needs.
The specific objectives of the feasibility assessment were:
1. A technical layout with competitive cost structure.
At the beginning of the project, it was unclear how large vendors consider detector cost. During the course of the phase-1 investigation, we have been able to accurately price our product, and dramatically reduce the projected cost of production.

2. A technical requirement specification
Our initial design has been improved to aspects of manufacturability, assembly and cost – vital for the vendors with which we want to close a deal. This was achieved in an iterative process where the design (hardware and dataflow architecture) was overhauled in close cooperation with industry consultants and suppliers. In high-level meetings with both some of the major vendors, we have scrutinized the technical system requirements. The goal has been to ensure that our technical solution is a good match for integration into a large system vendor’s CT portfolio.

3. Elaboration of business plan
During the feasibility project we have evaluated our business proposition with a special emphasis on the following items:
a) Competitor analysis
We have a clear global picture of the competitor companies and their technologies which are primarily based in the USA, Canada, Japan.

b) Further IPR analysis and Freedom to Operate
Prismatic has established a patent portfolio protecting all patentable aspects of technology. To date Prismatic has three granted patent families and four patent applications submitted.
The patents focus is on protecting key aspects of the photon counting silicon detectors and the subsequent data treatment.
We have performed extensive patent searches and have not identified any patent infringements. We have also performed a thorough FTO analysis and have found no foreseen problems with patent infringement issues.

c) Market strategy development, including which clinical segment to address
Our concept is to implement a development project, based on the findings of this Phase-1 feasibility study to commercialize a detection system that can be integrated into existing gantries in order to improve and speed up imaging diagnostics, initially focusing on stroke patients. Based on this feasibility assessment, the business approach is to collaborate with a downstream partner that can be intrinsically involved in the development of the detector as soon as possible. This is motivated by an in-depth analysis that has identified the advantages of this approach.

d) COGS projection, product development roadmap and financial forecasts
The global CT market was valued at 3.6 billion USD in 2012 and is expected to grow to 6 billion USD in 2019. This corresponds to a compounded annual growth rate of 10%, i.e. a very attractive market growth figure. This project targets the high-end stroke segment where a price premium can be claimed. A COGS projection has been calculated and has provided a potential EBITDA levelling out at 14 million EUR per year for the company.

e) Identification of vital resources (staffing need)

We have identified which parts of the production will need to be outsourced, and which parts will take place in-house at Prismatic Sensors. After completion of development (approx. 2-3 years), we estimate the need to expand to a production staff of 32, and a team of 6 for quality assurance and calibration of the detectors. Together with support staff and experienced physicists and electrical engineers the total staff is estimated to 56.
There is no other company in the world beside Prismatic Sensors AB that is developing silicon sensors for computed tomography applications. Combined with its low manufacturing cost there is a good chance that photon counting technology, with all its benefits, will be an asset to the market. The main economic benefit for the end-user (the hospitals) will be a significantly improved quality of care at the same cost. The unique selling points include:

* higher spatial resolution
*complete removal of beam hardening artefacts
*the ability to quantify small iodine concentrations.
* reduction in time-to-treatment at major hospitals and corresponding reduction in mortality and severe handicap

Progress of the business innovation project

In summary, this innovation project has allowed us to progress the project as follows:

• Updated business plan and feasibility assessment including technical, financial and commercial requirements, on how to move the project forward to the market
• Plan for System integration including validation of system stability (electromechanical integration of modules, calibration etc.)
• Plan for Integration of image reconstruction chain
• Plan for completion of the in vitro system validation
• An in vivo clinical validation plan
• Partnership with neuroradiologists at Karolinska University Hospital
• A plan for commercialization of the sensors in collaboration with a CT vendor
Stacking of the sensor diodes in edge-on geometry.
Dose-efficiency comparison of current CT technology and Prismatic.
Illustration of the edge-on concept. X-rays enter in the “paper plane” and passes 30 mm of silicon.