A Novel Minimally Invasive Tumour Localization Device

Lung cancer is one of the leading causes of death, by cancer. The usual treatment is surgical resection of tumours. However, patients who are weak or have poor pulmonary function are deemed unfit for surgery. For these patients, a minimally-invasive approach is desired. A major problem associated with minimally-invasive approaches is tumour localization in real time and accurate measurement of tool--tissue forces. This thesis describes the design, analysis, manufacturing and validation of a minimally-invasive instrument for tumour localization, named Palpatron. The instrument has an end effector that is able to support two previously designed jaws, one containing an ultrasound sensor and the other a tactile sensor. The jaws can move with two degrees of freedom to palpate tissue and rotate about the central axis of the instrument. The Palpatron has uncoupled jaw motion that allows for optimal alignment of sensors to improve data acquisition. The instrument can be easily assembled and disassembled allowing it to be cleaned and sterilized. The mechanism is articulated using push rods, each actuated by a motor. A semi-automatic control system was created for palpation. It is composed of a microcontroller that controls four motors via serial communication. In addition, the Palpatron has the ability to prevent tissue damage by measuring tool--tissue forces. Finite element analysis was used to guide material selection for designed components. Grade 5 titanium was selected for end effector links to provide a factor of safety of 1.2 against yielding under a 10 N point load at the tip of a jaw. The design was fabricated and validated by conducting experiments to test articulation and load carrying capacity. An 8-N force was applied to the instrument, which was successfully supported. The semi-automatic control system was used to perform basic maneuvering tasks to verify jaw motion capabilities. With positive testing results, the Palpatron forms the next step towards a comprehensive robotic-assisted palpation technology

Impaired bone healing at tooth extraction sites in CD24-deficient mice: A pilot study

<div><p>Aim</p><p>To use a micro-computed tomography (micro-CT) to quantify bone healing at maxillary first molar extraction sites, and test the hypothesis that bone healing is impaired in <i>CD24</i>-knockout mice as compared with wild-type C57BL/6J mice.</p><p>Materials and methods</p><p>Under ketamine-xylazine general anaesthesia, mice had either extraction of the right maxillary first molar tooth or sham operation. Mice were sacrificed 1 (n = 12/group), 2 (n = 6/group) or 4 (n = 6/group) weeks postoperatively. The right maxillae was disected. Micro-CT was used to quantify differences in bone microstructural features at extrction sites, between <i>CD24</i>-knockout mice and wild-type mice.</p><p>Results</p><p><i>CD24</i>-Knockout mice displayed impaired bone healing at extraction sites that was manifested as decreased trabecular bone density, and decreased number and thickness of trabeculae.</p><p>Conclusions</p><p>This pilot study suggests that CD24 plays an important role in extraction socket bone healing and may be used as a novel biomarker of bone quality and potential therapeutic target to improve bone healing and density following alveolar bone injury.</p></div

Study groups and number of animals per group.

<p>Study groups and number of animals per group.</p

Bone healing parameters at 4-weeks.

<p><b>A</b>. Trabecular thickness; <b>B</b>. Trabecular separation; <b>C</b>. Trabecular number; <b>D</b>. Bone surface/Bone volume. In wild type <i>C57BL</i>/6J mice, as compared with <i>CD24</i>-knockout mice, the bone surface was significantly smoother (p = 0.017); the trabeculae were significantly thicker (p = 0.035) and there was less bone marrow space (p = 0.014).</p

Bone density expressed as the fraction of bone volume out of the total volume.

<p>Bone density in wild-type (WT) <i>C57BL</i>/6J mice at 4 weeks post-extraction was significantly larger than the bone densities at 1 week and 2 weeks post-extraction (Duncan’s p<0.001, p = 0.003, respectively). At 4 weeks after tooth extraction, WT mice had a significantly larger bone density than the <i>CD24</i>-knockout mice (p = 0.004).</p

Impaired bone healing at tooth extraction sites in CD24-deficient mice: A pilot study - Fig 1

<p><b>A.</b> Micro-CT 2D cross sections through extraction sockets and adjacent molar teeth in representative wild-type (WT) <i>C57BL/6J</i> mice (<b>A and D</b>) and a <i>CD24</i>-knockout (KO) mouse (<b>C</b>). White line in A marks the region of interest which includes the complete vertical dimension of the socket within the maxilla and 1 mm of bone length distal to the adjacent molar tooth; <b>B.</b> 3D cubic sub-volume of the bone contained in the area marked in A. White arrow in C points to large socket concavities in the KO mouse as compared with a bone-filled socket in the WT mouse in D; <b>E-F</b>. Micro-CT surface images in a representative <i>CD24</i>-KO mouse (<b>E</b>) and a WT mouse (<b>F</b>); the images show a more rough surface morphology in the KO mouse as compared to the WT mouse.</p