Andrew K. H. Robertson

• Doctor of Philosophy
• Medical Physicist - Radiation Oncology at BC Cancer Vancouver

To design a postprocessing 3D adaptive median filter that minimizes streak artifacts and improves soft-tissue contrast in postoperative CT images of brachytherapy seed implantations. The filter works by identifying voxels that are likely streaks and estimating more reflective voxel intensity by using voxel intensities in adjacent CT slices and appl...

Effective use of the ²²⁵Ac decay chain in targeted internal radioimmunotherapy requires the retention of both ²²⁵Ac and progeny isotopes at the target site. Imaging-based pharmacokinetic tests of these pharmaceuticals must therefore separately yet simultaneously image multiple isotopes that may not be colocalized despite being part of the same deca...

Background: The development of radiopharmaceuticals containing 225Ac for targeted alpha therapy is an active area of academic and commercial research worldwide. Objectives: Despite promising results from recent clinical trials, 225Ac-radiopharmaceutical development still faces significant challenges that must be overcome to realize the widesprea...

Recent clinical results have demonstrated remarkable treatment responses of late-stage cancer patients when treated with alpha-emitting radionuclides such as actinium-225 (225 Ac). The resulting intense global effort to produce greater quantities of 225 Ac has triggered a number of emerging technologies to produce this rare, yet important, radionuc...

Thorium targets were irradiated with 438-MeV protons, resulting in spallation and high-energy fission reactions. The measured production cross sections of 38 nuclides in the mass range 83 to 233 are reported. These cross-section data are useful for validating nuclear interaction models and are compared to simulated cross sections calculated using t...

Background Lead-212 ( ²¹² Pb, t 1/2 = 10.6 h) and lead-203 ( ²⁰³ Pb, t 1/2 = 51.9 h) are an element-equivalent, or a matched theranostic radioisotope pair that show great potential for application in targeted radionuclide therapy (TRT) and single-photon emission computed tomography (SPECT), respectively. At TRIUMF we have produced both ²⁰³ Pb and ²...

Background: Lead-212 (²¹²Pb, t1/2 = 10.6 h) and lead-203 (²⁰³Pb, t1/2 = 51.9 h) are an element-equivalent, or a matched theranostic radioisotope pair that show great potential for application in targeted radionuclide therapy (TRT) and single-photon emission computed tomography (SPECT), respectively. At TRIUMF we have produced both ²⁰³Pb and ²¹²Pb u...

Targeted alpha‐therapy (TAT) has great potential for treating a broad range of late‐stage cancers by delivering a focused and lethal radiation dose to tumors. Actinium‐225 (²²⁵Ac) is an emerging alpha emitter suitable for TAT; however, the availability of chelators for Ac remains limited to a small number of examples (DOTA and macropa). Herein, we...

Herein, we present the syntheses and characterization of a new undecadendate chelator, H4py4pa, and its bifunctional analog H4py4pa-phenyl-NCS, conjugated to the monoclonal antibody, Trastuzumab, which targets the HER2+ cancer. H4py4pa possesses excellent affinity for 225Ac (, t1/2 = 9.92 d) for targeted alpha therapy (TAT), where quantitative rad...

The ISAC facility (Isotope Separation and Acceleration) at TRIUMF has recently started to provide isotopes for pre-clinical nuclear medicine studies. By irradiating ISOL (Isotope Separation OnLine) targets with a 480 MeV proton beam from the TRIUMF H- cyclotron, the facility can deliver a large variety of radioactive isotope beams (RIB) for researc...

Background: Actinium-225 (225Ac, t1/2 = 9.9 d) is a promising candidate radionuclide for use in targeted alpha therapy (TAT), though the currently limited global supply has hindered the development of a suitable Ac-chelating ligand and 225Ac-radiopharmaceuticals towards the clinic. We at TRIUMF have leveraged our Isotope Separation On-Line (ISOL)...

With recent impressive clinical results of targeted alpha therapy using 225Ac, significant effort has been directed towards providing a reliable and sufficient supply of 225Ac to enable widespread using of 225Ac-radiopharmaceuticals. TRIUMF has begun production of 225Ac via spallation of thorium metal with 480 MeV protons. As part of this program,...

The development of alpha-emitting radiopharmaceuticals using ²¹¹At requires quantitative determination of the time-dependent nature of the ²¹¹At biodistribution. However, imaging-based methods for acquiring this information with ²¹¹At have not found wide-spread use because of its low abundance of decay emissions suitable for external detection. In...

TRIUMF has a long history of medical isotope production. For more than 40 years, the Life Sciences Division at TRIUMF has produced isotopes for Positron Emission Tomography (PET) for the local hospitals. Recently, the division has taken on the challenge to expand the facility's isotope repertoire to isotopes for imaging to treatment. At the smalles...

H2macropa, an 18-membered macrocycle, was investigated for 225Ac chelation in targeted alpha therapy (TAT). Radiolabeling studies showed that macropa, at submicromolar concentration, complexed all 225Ac (26 kBq) in 5 min at RT. [225Ac(macropa)]+ remained intact over 7-8 days when challenged with either excess La3+ ions or human serum, and did not a...

H2macropa, an 18-membered macrocycle, was investigated for 225Ac chelation in targeted alpha therapy (TAT). Radiolabeling studies showed that macropa, at submicromolar concentration, complexed all 225Ac (26 kBq) in 5 min at RT. [225Ac(macropa)]+ remained intact over 7-8 days when challenged with either excess La3+ ions or human serum, and did not a...

There is growing interest in finding new sources of ²²⁵Ac, an isotope with potential use in the treatment of metastatic disease. Proposed production alternatives include the proton irradiation of thorium above 100 MeV, however, concerns exist about the co-production of the long-lived and toxic ²²⁷Ac. This work describes the design and simulated yie...

To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 (125)I sources. For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of i...

Purpose: To determine the impact of seed thickness on post‐operative CT image quality, seed detection and dosimetry, with and without breathing motion. Methods: An acrylic prostate phantom mounted to a computer controlled motion platform was created for both standard (5 × 1 mm)‐ and small (5 × 0.5 mm)‐diameter non‐radioactive I‐125 seeds (Oncura In...