Khanal, Suraj P.

Synthetic hydroxyapatite HAp bears poor mechanical properties that limit its
applicability in orthopedics. We study the possibility of overcoming such limitations by
incorporating functionalized single walled carbon nanotube fSWCNT and polymerized є-
caprolactam. Sonication method was used to disperse fSWCNT in the HAp. A simple hot
blending method was used to incorporate HAp/fSWCNT powder with melted polymerized
є-caprolactam. The fracture toughness of the composite material was tested in
compliance with ASTM D-5045 standard. A critical stress intensity factor K1C of the composite
material was found to be 3.55 MPa.m1/2, which is a value comparable to the one for cortical
bone.

Hydroxyapatite (HAp) is an ideal bioactive material that is used in orthopedics.
Chemical composition and crystal structure properties of HAp are similar to the natural
bone hence it promotes bone growth. However, its mechanical properties of synthetic
HAp are not sufficient for major load-bearing bone replacement.
The potential of improving the mechanical properties of synthetic hydroxyapatite
(HAp) by incorporating carboxyl functionalized single walled carbon nanotubes
(CfSWCNT) and polymerized ɛ-caprolactam (nylon) is studied. The fracture toughness,
tensile strength, Young’s modulus, stiffness and fracture energy were studied for a series
of HAp samples with CfSWCNT concentrations varying from 0 to 1.5 wt. % without, and
with nylon addition. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM),
Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC)
were used to characterize the samples. The fracture toughness and tensile test was
performed under the standard protocol of ASTM D5045 and ASTM D638-02a respectively. Reproducible maximum values of (3.60 ± 0.3) MPa.m1/2 for fracture
toughness and 65.38 MPa for tensile strength were measured for samples containing 1 wt.
% CfSWCNT and nylon. The Young’s modulus, stiffness and fracture energy of the
samples are 10.65 GPa, 1482.12 N/mm, and 644 J/m2 respectively. These values are
comparable to those of the cortical bone. Further increase of the CfSWCNT content
results to a decreased fracture toughness and tensile strength and formation of a
secondary phase.

The purpose of this research is to compare the surface dose outside the treatment area for different breast cancer irradiation modalities using Thermoluminescence Dosimeters (TLDs). Five different modalities are included in this study: Accuboost, Photon boost, Electron boost, Strut-Adjusted Volume Implant (SAVI), and Mammosite Multi-lumen (ML).Six points of interest (POI) on the breast cancer patients had been selected for the TLDs placement. Data from 25 breast cancer patients at Lynn Cancer Institute of the Boca Raton Regional Hospital were included in the study. The measured percentage ranges of the averaged doses at the six POIs for the different modalities are: Sternum 0.26% - 3.26%, Shoulder 0.33% - 2.79%, Eye 0.26% - 1.32%, Thyroid 0.20% - 2.75%, CLB 0.2% - 5.46%, Lower Abdomen 0.16% - 2.25%.