This study is a prospective, departmental funded study examining the outcomes of simulated Low Dose CT scans compared to Conventional Dose CT scans in patients who present to Duke University for total shoulder arthroplasty or reverse shoulder arthroplasty.

The purpose of this study is to compare the use of a conventional dose computed tomography scan (C-CT) to a simulated low dose computed tomography scan (L-CT) for preoperative planning in patients who are anticipated to undergo a total shoulder arthroplasty (TSA) or reverse shoulder arthroplasty (RSA) with the goal to reduce the radiation exposure to future patients undergoing preoperative planning. L-CT scans for analysis will be obtained prospectively as derived data from a C-CT scan performed on a dual source CT scanner. Briefly, a C-CT scan will be conducted, with scan images representing a reconstruction of simultaneous scans at two sensors. L-CT images will be derived from single source data (ie the scan data gathered by one of the emitters rather than a reconstruction from both). For additional validation, prospectively collected scans will be compared to retrospectively gathered scans of patients of similar demographics (age, sex, BMI) and degenerative changes who underwent a C-CT scan for an anticipated shoulder arthroplasty in the past. The reviewers will investigate the following outcome measures including 1) Are L-CT images of sufficient quality to be used for preoperative planning 2) Can accurate measurements including glenoid inclination, version, implant selection and humeral head subluxation be made on L-CT images 3) Do proposed treatment plans change with the use of L-CT relative to the chosen plans base on C-CT images. The investigators hypothesize L-CT images will be of sufficient image quality for diagnostic purposes, with similar measurements, and treatment outcomes.

Inclusion Criteria:

• Subjects are planned to undergo total or reverse shoulder arthroplasty
• Subject must be 18 years or older
• Subjects who have capacity to give informed consent

Exclusion Criteria:

• Subjects who are pregnant
• Subjects under the age of 18
• Subjects who do not have the capacity to give informed consent.

All individuals who are scheduled for a shoulder CT for the purpose of preoperative planning for a total shoulder arthroplasty are eligible to be included in this study assuming they meet the eligibility requirements as listed above.

Data is not planned to be shared outside of the collaborators of this project within the Duke University Medical Center. The data will only be reviewed by the study personnel listed on the Institutional Review Board (IRB), and not intended to be shared with an external institution or industry.

However, when submitting data for manuscripts and publication purposes, all data will be deidentified of any public health information. All Protected Health Information (PHI) will be kept in a locked cabinet in the PI's office at Duke University and/or in a protected/encrypted folder in a file separate from the study information. Data will be analyzed by study team members using a computer that is password protected, and stored securely in encrypted Duke servers.

Study files will be backed up onto Dr. Klifto's folder in a secure server provided to faculty in the Department of Orthopaedic Surgery. The subjects will not be identified in any reports or publications from this study.