Browsing by Author "Kraft, Susan, committee member"
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Item Open Access Evaluation of 64Cu-ATSM in cell culture for potential use as a radiotherapy agent(Colorado State University. Libraries, 2014) McMillan, Dayton Datteri, author; Kato, Takamitsu, advisor; Callahan, Gerald, committee member; Kraft, Susan, committee memberOxygen status of tumors is an important clinical factor when considering treatment and potential outcomes. In radiotherapy applications, hypoxic tumors display resistance to traditional low linear energy transfer (LET) external beam radiotherapy (EBRT), instigating interest in finding alternative and more effective means to treat these tumors. 64Cu-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM) has shown clinical usefulness in imaging and experimental radiotherapy of solid state tumors due to its ability to concentrate in hypoxic tissue regions and emit radiations of multiple types, energies, and LET. Intrinsic to the potential use of 64Cu-ATSM for radiotherapy purposes is the decay mechanism of 64Cu which emits high LET Auger electrons. Presently, the biological mechanism for cell killing and DNA damage due to high LET electrons released in the decay of 64Cu is unknown. To evaluate how high LET Auger electrons play a role in cell death and DNA damage, Chinese hamster ovary (CHO) cell lines proficient and deficient in DNA nonhomologous end joining (NHEJ) DNA repair (10B2 and xrs-5 cells, respectively) were treated with 64Cu-ATSM. Colony formation assay results show similar cell survival for both cell lines treated with similar activities of 64Cu-ATSM, indicating cell lethality due to high LET radiation. Survival curves were compared for radiations of known LET to generally characterize the effective LET of 64Cu-ATSM. Additionally, chromosome aberration and H2AX DNA double strand break (DSB) studies were performed to examine DNA damage from 64Cu-ATSM. 64Cu-ATSM was also administered to multiple additional cell lines under various -oxic states to evaluate how efficiently 64Cu-ATSM is incorporated. These findings indicate better 64Cu-ATSM uptake in cancerous, canine, and potentially osteosarcoma cell lines. This research offers experimental support for various characteristics of 64Cu-ATSM that may provide potential clinical advantages over traditional EBRT to more effectively treat hypoxic tumors.Item Open Access Occupational dose assessment of 64Cu-ATSM in a veterinary setting(Colorado State University. Libraries, 2014) Hetrick, Lucas, author; Johnson, Thomas, advisor; Kraft, Susan, committee member; Biller, Barbara, committee member64Cu-ATSM is an emerging radiopharmaceutical for diagnostic use in Positron Emission Tomography (PET) and has potential utility for radiation therapy but to date there are no studies that assess the occupational doses delivered to workers in either a hospital or veterinary environment. This study consisted of canine patients that were recruited at the Colorado State University James L. Voss Veterinary Teaching Hospital (VTH). The study was aimed at determining the radiation dose to veterinary workers from clinical PET/CT procedures using 64Cu-ATSM. To determine the dose to the workers, each worker was assigned two Electronic Personal Dosimeters (EPDs) to be worn on the chest and waist during the entirety of each procedure. The workers monitored during this study involved included a radiobiologist, a nuclear medicine technician, an anesthesiologist, and a veterinary surgeon. Seven canine patients were imaged over a ten month period with an average mass of 33.7 kg (a range of 20.0 - 55.1 kg) with an average injected activity of 5 MBq kg-1. The dose range for the radiobiologist was 2 -17 µSv, for the nuclear medicine technician 0 -14 µSv, for the anesthesiologist 0 - 12 µSv, and for the surgeon 0 -10 µSv. In a comparison between the results of this study and published literature on occupational exposures from human/veterinary FDG PET/CT procedures, 64Cu-ATSM veterinary PET/CT procedures, on a per patient bias, exposed workers to less radiation.Item Unknown Occupational radiation dose to persons involved in veterinary positron emission tomography(Colorado State University. Libraries, 2011) Martinez, Nicole, author; Johnson, Thomas, advisor; Kraft, Susan, committee member; Ryan, Stewart, committee memberSeveral studies have been conducted concerning the dose to hospital personnel from positron emission tomography (PET) radiopharmaceuticals, but to date no specific parallel studies have been done for veterinary PET technologists. Compared to human PET imaging, veterinary personnel are potentially interacting with animal patients for a longer time period, sometimes in close physical proximity, because of the need for anesthetizing patients. There is no equivalent data on personnel exposure from human PET imaging; human patients are not anesthetized and are kept in an isolated room after injection until their imaging procedure. Although veterinary personnel may be interacting more closely with animal patients undergoing PET imaging, radiopharmaceutical doses are generally smaller for animal patients because they weigh less on average. Considering these and other differences between human and veterinary practice, this study aimed to determine, on a per patient basis, the dose to personnel working with PET at Colorado State University's (CSU) James L. Voss Veterinary Teaching Hospital (VTH). Electronic personal dosimeters (EPDs) and supplemental optically stimulated luminescence (OSL) dosimeters were used (in addition to regular dosimetry) to determine radiation doses to veterinary personnel over a period of four months. Participants in the study included nuclear medicine technologists, the on-duty anesthesiology technologist, and occasionally an observer. Individual doses, along with the details of the staff member's activities, were recorded for available personnel for each PET study. Twenty-five scans were conducted over the course of this study: thirteen different dogs, six different cats, and a sheep (with two cats and three dogs having repeat scans). The mass range of the animals was 2.8 to 76.5 kg, with an average of 28.9 kg. The average amount of activity injected was 6 MBq per kg. The dose range for the nuclear medicine technologists was 0 to 30 μSv (7.8 μSv average), for the anesthetist 1 to 22 μSv (8.3 μSv average), and for the observer 0 to 2 μSv (0.4 μSv average).