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A top-down view of a cross-section through the central plane of the simulation of 117m Sn. The tissue block is the same as in the other simulations. The joint is a stylized ball and socket joint. Layers of cartilage lie between the ball to the left and the socket to the right in the figure. The synovium in which the radioactivity was uniformly distributed is transparent in this figure. It is a thin cylindrical layer that surrounds the joint between the solid cylinders of bone. The bone and joint are 1.5 cm in radius. The superficial tissue is 2 mm thick.
Source publication
The treatment of pets, service animals, and pre-clinical research subjects with radionuclides raises concern for the safety of the people who interact with the animals after their treatment. Three treatments of skeletal conditions in dogs are considered in this study: Sm-1,4,7,10-tetraazacylcododecanetetramethylenephosphonic acid, which is a bone-s...
Context in source publication
Context 1
... the 117m Sn radiosynoviorthesis simulation, a stylized ball and socket joint as shown in Fig. 3 and Fig. 4 was modeled. The activity was concentrated on the surfaces of the synovial membrane, which was modeled as a cylindrical surface surrounding the rest of the joint. Concentrating the activity in the synovium is consistent with measurements showing that there is negligible remaining activity in the synovial fluid within a few ...
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Citations
... Although additional study is warranted, interest in modelling and/or measuring doses to owners/handlers from veterinary nuclear medicine procedures has seemingly increased over the past few years (e.g. Davila, 2019;Wendt et al., 2020;Arno and Smith, 2021;Smith and Krimins, 2022;Suwannasaeng et al., 2022). ...
Veterinary use of radiation in the diagnosis, management, and treatment of disease has expanded and diversified, as have the corresponding radiological protection concerns. Radiological exposure of personnel involved in veterinary procedures and, where applicable, members of the public providing assistance (e.g. owners or handlers) has always been included within the system of radiological protection. Veterinary practice is now addressed explicitly as the modern complexities associated with this practice warrant dedicated consideration, and there is a need to clarify and strengthen the application of radiological protection principles in this area. The Commission recommends that the system of radiological protection should be applied in veterinary practice principally for the protection of humans, but with explicit attention to the protection of exposed animals. Additionally, consideration should be given to the risk of potential contamination of the environment associated with applications of nuclear medicine in veterinary practice. This publication focuses primarily on justification and optimisation in veterinary practice, and sets the scene for more detailed guidance to follow in future Recommendations. It is intended for a wide-ranging audience, including radiological protection professionals, veterinary staff, students, education and training providers, and members of the public, as an introduction to radiological protection in veterinary practice.
... An exposure rate measurement post administration is used as justification for outpatient release . Adding together the elements of an emerging technology, gamma emission, half-life, and amount of radioactivity injected, a legitimate concern is controlling the radiation dose to the general public and maintaining license conditions that follow the ALARA principle (Wendt et al. 2020;Arno and Smith 2021). ALARA is an acronym that stands for "as low as reasonably achievable." ...
A novel device in the veterinary market uses a colloid containing radioactive 117mSn to treat osteoarthritis in the synovial joints of canines. The technique of injecting a radioisotope to restore synovia is referred to as radiosynoviorthesis. The outpatient canine procedure uses a maximum administration of 222 MBq of 117mSn injected into one or more joints. Due to the 13.91 d half-life and 158.6 keV gamma output of 117mSn, abiding by the annual public dose limit of 1 mSv is of primary regulatory concern. The therapy protocol starts with a pre-screening questionnaire to establish owner and animal behavior patterns. The questionnaire is used to determine the duration of written time and distance limitations post therapy. In this study, external radiation doses to owners were measured by providing optically stimulated luminescent dosimeters (OSLD) for up to 30 d post-treatment of the pet. Twelve owners were measured over various time frames at two licensed locations independent of each other. In one location, the average (OSLD) measured 0.029 mSv over a 14-d wear period. In the second location, the average (OSLD) measured 0.057 mSv over a 30-d wear period; both values were well below the recommended annual public dose. The overall average extrapolated external radiation dose was estimated at 0.092 mSv, while the maximum dose estimate was 0.25 mSv. The (OSLD) results and extrapolated owner doses provide reasonable assurance that the public dose limits will be met.
... To demonstrate compliance with the public dose limits, time and motion studies are needed to prospectively calculate the dose to members of the public, of which the people that share a household with the dog are the critical group. Earlier human dose assessments had used relatively simple assumptions regarding interactions and the geometry of those interactions (Wendt et al. 2020). Additional refinement of those assumptions, both with regard to dose rate and the geometry of those interactions, was needed to address NRC's concerns. ...
... The mathematical model for a dog joint from Wendt et al. (2020) was used to model the radiation source. This model consists of a cartilage-lined bony ball-and-socket joint connected to cylindrical bone masses covered by an annular layer of skin as shown in Fig. 3. ...
Tin-117 m (117mSn) is used to treat dogs with osteoarthritic joints by radiosynoviorthesis. The decay process for 117mSn is internal conversion wherein IC electrons and auger electrons provide the therapeutic effect. Additionally, the most prominent gamma emission is 158.6 keV. The effective dose rate received by a person interacting at close distances with a treated dog is needed to determine the person's total dose and thus regulatory compliance. Simple measurement of the dose rate at a given distance does not provide an accurate measurement of the effective dose to a person due to the non-uniform nature of the radiation field at close distances. MNCP models of the interactions of five ages of humans at three distances were created to determine the effective dose rates using the methodology from NRC Regulatory Guide 8.40. Ratios of the effective dose rate to the person to the measured dose rate at 1 m from the same source were calculated.
... To demonstrate compliance with the public dose limits, time and motion studies are needed to prospectively calculate the dose to members of the public, of which the people that share a household with the dog are the critical group. Earlier human dose assessments had used relatively simple assumptions regarding interactions and the geometry of those interactions (Wendt et al. 2020). Additional refinement of those assumptions, both with regard to dose rate and the geometry of those interactions, was needed to address NRC's concerns. ...
Tin-117m (117mSn) is used to treated dogs with osteoarthritic joints by radiosynoviorthesis. The internal conversion and Auger electrons emitted by the 117mSn provide the therapeutic effect. Sn-117m also emits gamma rays, of which the most significant is 158.6 keV. The external radiation field around a treated dog is of interest to limit the dose to the owners/caretakers of the dog. The dog's torso attenuates the radiation being emitted toward the opposite side of the dog's body. This leads to a radiation field that is significantly non-isotropic. This study characterizes the anisotropy of this field to permit maximum dose rate measurements to be used to calculate the dose to individuals in the vicinity of the dog. Measurements were made in nine directions and at two distances, 0.3 and 1.0 m, to characterize common distances and spatial orientations for human-dog interactions. From these measurements, the percent reduction in the average dose rate compared to the maximum dose rate was determined. From a radiation safety perspective, the important factor is the minimum amount of shielding effectiveness or percent reduction that can be expected. A reasonable measure for this value is the fifth percentile of the shielding effectiveness distribution. The fifth percentile shielding effectiveness measures are 27% and 21% at 0.3 and 1.0 m, respectively.
Intra-articular injections are a nonsurgical treatment modality that can be used to manage osteoarthritis, naturally occurring or surgically induced acute synovitis, and intra-articular ligamentous or tendon injury. This option may be assistive for patients in which other conservative modalities are ineffective, or in conjunction with other forms of treatment. It may also be used as the primary treatment. Injectates labeled for use in companion animal joints include corticosteroids and viscosupplements. Additional injectates, that are not specifically approved for use in companion animals are but are reported in the literature, include orthobiologics and a radioisotope of Tin-117m.
With the introduction of biologics in the treatment of rheumatoid arthritis (RA), the main indications for radiosynovectomy (RSO) changed from the treatment of RA to include other types of arthritis, and from typical affected joints of RA, such as MCP and PIP’s, to other small joints, e.g., basal joint of the thumb or acromioclavicular joints. Depending on the joint size, ¹⁶⁹Erbium-colloid is used for small joints (15–37 MBq) and ¹⁸⁶Rhenium-colloid (37–111 MBq) in medium joints. However, the main issue which impedes the of worldwide use of RSO is the limited availability of radiocolloids outside from Europe. Here other radionuclides such as ³²P-, ¹⁵³Sm-, ¹⁷⁷Lu-colloids or colloidal 117mSn could be useful.
In RSO of small and medium joints, accurate diagnosis of arthritis is highly important with careful identification of the affected joints. Pre-therapeutic diagnostics include medical history, clinical examination, and two-phase bone scan with local planar scans. The differentiation of affected joints in the foot, hand and ankle is essential for a good response. A whole-body scan alone is not sufficient to differentiated between metacarpophalangeal joint (MCP), proximal interphalangeal joint (PIP), distal interphalangeal joint (DIP), ankle, subtalar and cuneonavicular joints. Symptoms in these joints may require additional local scans.
The procedure of RSO itself is similar to that of an intraarticular administration of glucocorticoids. Intraarticular position must be verified by arthrography before administering radiocolloid. After RSO the affected joint requires immobilization, 2 days of inactivity, and post-therapeutic evaluation by clinical examination and bone scan.
The reported response rate of RSO ranging from 54% to 100% is caused by a lack of gold standard to evaluate the response. A variety of simple subjective scoring instruments have been used to evaluate response. More detailed clinical and additional objective scorings such as semi-quantification of blood pool phase in bone scan could helpful for more statistic power of response evaluation.
Laboratory animals play an important role in biomedical research and act as a backbone of new drug research and development. Biomedical research is primarily dependent on laboratory rodents. There is a steady shift of therapeutic strategies for diseases from physiological to cellular and presently molecular targets. There is a huge advancement in personalized medicine and ways of drug research in the recent past that is primarily due to the implementation of 3Rs in animal study design and looking into molecular insights of the disease processes with the help of precise tools such as noninvasive imaging. Imaging technologies proved extremely important in diagnosis and evaluating human diseases in clinics. Besides, it has an important role in biomedical research in oncology and other research areas including stem cell research, bone metabolism, endocrinology, neurology, cardiology, and nanotechnology. The complex pathways involved in the initiation and progression of the disease can be visualized and quantitatively monitored using noninvasive imaging technologies. The strong preclinical data is the backbone of biomedical research, and new drug development and imaging technologies provide relevant accurate information. This chapter is focused on the dedicated noninvasive preclinical imaging modalities for their present role in laboratory animal science. This chapter also deals with protocols for positron emission tomography (PET), single-photon emission computed tomography (SPECT), and X-ray computed tomography (CT) for rodent imaging.
Purpose:
To evaluate the clinical effects of an intra-articular injection of 117mSn-colloid for management of canine grade 1 or 2 elbow osteoarthritis (OA).
Patients and methods:
This was a prospective study in 23 dogs with grade 1 or 2 elbow OA. An orthopedic examination and elbow radiographs were performed to confirm the presence of OA. Dogs were randomly assigned to receive unilateral intra-articular (IA) injection of low-dose (LD: 1.0mCi, n =8), medium-dose (MD: 1.75mCi, n =6), or high-dose (HD: 2.5mCi, n =9) of 117mSn-colloid. The primary outcome measure was peak vertical force (PVF) from force-plate gait analysis and secondary outcome measures included the Canine Brief Pain Inventory score (CBPI) and elbow goniometry. The CBPI was evaluated at pretreatment and then monthly post treatment for 1 year, and goniometry and PVF were evaluated at pretreatment, and at 1, 3, 6, 9 and 12 months post treatment.
Results:
PVF improved at 3, and 9 months compared to pretreatment values in the HD group. CBPI scores improved at most of the time points in all dose groups. There was no significant difference in elbow goniometry between treated and untreated elbows. There were no self-reports of any adverse effects of the injection by the owners and none were noted by the examining veterinarian at the time of regularly scheduled re-evaluations.
Conclusion:
117mSn IA injection was free of any obvious adverse effects, improved CBPI scores, and increased weight bearing in limbs with elbow OA providing preliminary evidence that 117mSn may be beneficial in the management of elbow OA in dogs. Although 17mSn appeared to be effective for management of elbow OA in these dogs, this pilot study has inherent limitations; therefore, future studies with larger numbers and with placebo group are needed.
