WP3. OPTIMISATION

SEDENTEXCT ANNUAL REPORTWORKPACKAGE-SPECIFIC INFORMATION

WORKPACKAGE 3 (NKUA - Kostas Tsiklakis)

To develop tools for Quality Assurance on CBCT in terms of image quality evaluation

• to develop, design and test a phantom for QA tests on dental CBCT equipment.

• to develop software tools for the evaluation of image quality and for routine QA testing

Objectives

WP3 Optimisation

WP3. OPTIMISATIONReport of Progress towards Objectives (Summary)

• The first prototype phantom was scanned on a wide variety of CBCT devices by NKUA and KUL; Improvements to the phantom and insert design were identified. (NKUA, KUL)

•Results from the testing (geometric accuracy, resolution (high and low contrast), MTF calculation and artefact induction) were obtained and reported in Athens in January 2009, and the Deliverable report D3.1 was submitted in June 2009 with extensive information on the necessary phantom design modifications (NKUA, KUL)

•After preliminary analysis of the first prototype phantom, a first version of the QA software was developed by partners KUL and LTO. The software contains a ‘viewer’ and ‘analysis’ part, which was written independently by LTO and KUL, respectively. The two parts were combined into one interface. (KUL, LTO)

WP3. OPTIMISATIONReport of Progress towards Objectives (Summary)

• The development of the 2nd prototype phantom was started right after the preliminary analysis of the first prototype and was achieved on time (by M22) by delivering a 2nd prototype that implements all improvements on the design that were deemed necessary after meeting the objective of task1 (“Testing of 1st prototype QA phantom results M3.3, D3.1”) (NKUA, KUL, LTO)

•Immediately after the 1st version software tests performed by KUL, a number of improvements were assessed and reported. These issues are currently being worked on, enabling the software to be compatible with datasets from each CBCT device, and to successfully perform the matching steps. Also, geometrical drawings of the second prototype inserts are being prepared (KUL, LTO)

WP3. OPTIMISATIONWP 3.1 Phantom design

Several changes were suggested to the original design. These are: - Individual threaded discs for each of the insert recesses, thus allowing easier removal of inserts from a single recess. - Insert guidance slots at 90° intervals in each of the insert recesses, giving much improved positioning of the test inserts. - A 20mm PMMA slice at the bottom of the phantom for contrast resolution and homogeneity tests. -A threaded hole at the bottom of the phantom to allow secure fixing of the phantom.

(All the above are implemented in the 2nd prototype phantom delivered on November 2009 (M22) M3.4)

WP3. OPTIMISATIONWP 3.1 Phantom design

Positioning: Phantom positioning stability is under discussion;

one proposed solution is using the platform of the unit, and if not supplied by the manufacturer a specially developed platform on the patient chair.

Second proposed solution is using a tripod that can be secured using the threaded hole at the bottom of the phantom. (already implemented)

WP3. OPTIMISATIONWP 3.1 Phantom design

Alignment: The phantom now includes:

1. visual markers (white in color) which aid correct alignment with the use of the laser positioning beams of the units.

• (already implemented, needs improvement)

2. a numbering system to aid the placement of individual test inserts.

• (partially implemented, needs improvement)

WP3. OPTIMISATIONWP 3.1 QA inserts design

Limiting spatial resolution MTF: MTF by point spread function. In the 2nd prototype, a larger diameter air-gap is used(already implemented)

MTF by line spread function. The revised line spread function (LSF) insert comprises PTFE (Teflon) and PMMA quarters bonded together (already implemented)

Limiting spatial resolution (line pairs/mm) The insert was totally redesigned by using alternating discs of Aluminium and Polymer going up to 10 lp/mm (already implemented)

WP3. OPTIMISATIONWP 3.1 QA inserts design

Geometric Accuracy: Testing of geometric accuracy was redesigned, by using a grid of small holes drilled into the PMMA body of the phantom. (already implemented)

Artefacts: a second set of artefacts inserts was also included using Lead (as a high atomic number material), in addition to the Titanium artefacts inserts (already implemented),

lead is also recommended

M3.3 and D3.1 Phantom 1st prototype delivery and QA software 1st version test results available. (Month 16).

The Deliverable Report was ready on M18, after successfully resolving issues on software development

M3.4 Second prototype QA phantom delivered. (Month 22).

The 2nd prototype QA phantom was delivered on time (Month 22)

WP3 Milestones and Deliverables

Remaining actions - project plan.

• Completion of internal testing of the second round of software changes and test results (Month 30) (Milestone 3.5 and Deliverable D3.2 “Second prototype QA phantom test results obtained”)

• Validation with external users of the final version of software (Month 33) (Milestone 3.6 and Deliverable D3.3 “Phantom delivered and QA software validated”).

• QA procedure (protocol) ready (Month 36) (Deliverable D3.4)

WP3 Milestones and Deliverables