3.1. Study Design and Setting
This descriptive study used a cross-sectional design. The research setting included university-affiliated teaching hospitals across seven provinces, in collaboration with the Deputy Offices for Treatment and Food and Drug Affairs of the participating Universities of Medical Sciences. This study was approved by the Ethics Committee of Kermanshah University of Medical Sciences (Approval Code: IR.KUMS.REC.1402.036). All participants provided informed consent, and institutional confidentiality was maintained through de-identification of hospital and participant data in accordance with the approved protocol.
The study population comprised 30 medical equipment experts purposively selected from seven university hospitals and from the Deputy for Treatment and the Deputy for Food and Drug of the country's Universities of Medical Sciences. Of the 30 medical equipment experts, five hospitals had 4 experts each (5 × 4 = 20), and two hospitals had 5 experts each (2 × 5 = 10); thus, the difference in expert counts between any two hospitals was at most one. The hospitals were selected from seven different provinces with a relatively uniform geographical distribution nationwide. A purposive sampling strategy was used to ensure representation across major geographical regions. "Uniform geographical distribution" was operationally defined as selecting one tertiary-level university teaching hospital from each of seven distinct provinces spanning northern, southern, eastern, western, and central areas of the country, to minimize regional bias in equipment maintenance practices.
All participating sites were accredited teaching hospitals with established radiology residency programs. To balance institutional confidentiality with scientific transparency, aggregated and de-identified facility characteristics are reported. Each hospital operated 1 - 3 CT scanners, with equipment ages ranging from 2 to 15 years. Annual CT examination volumes ranged from 6,200 to 18,500 procedures, and each site trained between 5 and 8 radiology residents annually across all training years. Given administrative and logistical constraints, a national census was not feasible; therefore, purposive sampling was used to identify institutions with accessible maintenance records and active clinical training programs.
In accordance with the approved ethical protocol (IR.KUMS.REC.1402.036), all institutional identifiers were removed to protect organizational privacy and prevent potential administrative repercussions. However, de-identified operational and demographic data were systematically retained and reported to satisfy STROBE requirements for reproducibility, methodological transparency, and cross-study comparability. In addition, all hospitals had comparable conditions in terms of bed distribution and the number of CT scanners. Radiology residents were trained at these hospitals. Expert questionnaire data, maintenance records, and resident satisfaction data were matched by hospital identifier. Due to existing sensitivities, participants' occupational positions, and ethical commitments, more detailed information about the research setting is not reported.
3.2. Data Collection Instruments
Data collection instruments included a questionnaire, observation, and review of documents and records. The 46-item questionnaire was structured across five domains: 1) maintenance management and organization (10 items), 2) planning and coordination with higher authorities (9 items), 3) equipment selection and procurement (8 items), 4) quality control and evaluation (11 items), and 5) repair processes (8 items). Each item was scored on a 5-point Likert scale, ranging from 1 = strongly disagree to 5 = strongly agree. Domain scores were calculated as the mean of constituent items, yielding a possible range of 1 - 5 per domain. For interpretation, scores were categorized as follows: 1.00 - 2.49 = poor management practice, 2.50 - 3.49 = moderate practice, and 3.50 - 5.00 = optimal practice. Higher scores indicated more favorable equipment-management processes.
Content validity was established through a panel of experts comprising three radiology program directors, two medical education specialists, and four biomedical engineering faculty members. The Content Validity Index (CVI) and Content Validity Ratio (CVR) were calculated for each item, yielding an overall scale CVI of 0.88 and CVR of 0.75, indicating acceptable content validity. To assess reliability, a test-retest method was used with a 10-day interval among 10 experts not included in the main study. The internal consistency of the questionnaire was assessed using Cronbach's alpha, which yielded a coefficient of 0.87, indicating high reliability. The intraclass correlation coefficient (ICC) for test-retest reliability was 0.89. Domain scores were calculated as the mean of constituent items, with higher scores reflecting more favorable equipment-management practices.
To assess satisfaction with CT-related training, a nationwide survey was conducted among 48 radiology residents. Residents were asked to respond to the following primary item: "Overall, how satisfied are you with the quality, availability, and hands-on training opportunities related to CT scanner operation during your clinical rotation?" To capture multidimensional aspects of the training experience, three supplementary items assessed: 1) exposure to standardized acquisition protocols, 2) frequency of supervised scanning practice, and 3) consistency of image quality and equipment readiness. Responses to these items were aggregated into a composite CT-related educational satisfaction score on a 1 - 10 scale.
The satisfaction instrument was developed specifically for this study based on a review of established radiology training evaluation frameworks. Content and face validity were confirmed through expert review by three radiology program directors and two medical education specialists. A pilot test (n = 10) was conducted among residents not included in the final sample, yielding a Cronbach's alpha of 0.84, indicating acceptable internal consistency. The instrument was administered anonymously to minimize response bias. The respondent cohort comprised radiology residents across all training years. At the time of survey administration, a proportion of residents were actively rotating through the CT imaging unit, while others reported having accumulated at least 3 months of CT scanner exposure during their training.
Data were collected anonymously via a secure institutional platform to ensure participant confidentiality. Demographic characteristics and training-exposure variables, including residency year and clinical rotation history, were examined to assess potential confounding effects on educational satisfaction scores. All maintenance metrics were extracted from institutional records covering a 24-month period from March 2021 to February 2023, corresponding to the Iranian calendar years 1401 - 1402. This time window was selected to capture a complete cycle of seasonal variation in equipment utilization while ensuring data completeness across all participating hospitals.
3.3. Process Implementation
The questionnaire was developed through library- and internet-based searches, and its validity was confirmed using specialized texts and by collecting the opinions of faculty members and experts. After the questionnaire was designed, a test-retest method was applied to establish confidence in the data collection tool. Accordingly, after 10 questionnaires were distributed, the same questionnaires were redistributed and collected again after a 10-day interval. The questionnaire demonstrated high internal consistency (Cronbach's α = 0.87) and stability over time (ICC = 0.89), confirming its suitability for data collection.
On a specified date, the questionnaires were distributed to the study population and, based on participants' agreement, were collected by the researchers on the predetermined date. Participants were assured that their information would remain confidential and that no identifying information would be reported that could disclose their identity or jeopardize their occupational position. In addition, based on the documentation obtained from these educational centers, RC, CT, MTTR, and the ratio of preventive programs to total repairs (PM) were calculated. Three key maintenance metrics were extracted from institutional records for each hospital:
1) MTTR was defined as the average duration from equipment failure notification to full operational restoration, calculated as:
MTTR = Σ(Repair completion time - Failure report time) / Total number of repair events
Units: hours per repair event. For analysis, MTTR values were aggregated at the hospital level over the study period.
2) RC was defined as the total direct expenditure incurred for unscheduled repairs, including parts, labor, and external service contracts, calculated as:
Units: local currency (IRR). Costs were adjusted for inflation using the national consumer price index to ensure comparability across the study period.
3) The PM ratio was defined as the proportion of scheduled preventive maintenance activities relative to total maintenance interventions, including preventive and corrective interventions, calculated as:
Units: percentage (%). A higher PM ratio indicates a more proactive maintenance strategy.
The 48 radiology residents in the educational centers were asked to rate their views regarding CT-related educational satisfaction on a scale from 1 = dissatisfied to 10 = complete satisfaction. The distribution of radiology residents across the seven university hospitals was as follows: six hospitals had 7 residents each (6 × 7 = 42), and one hospital had 6 residents (1 × 6 = 6). The difference in resident counts between any two hospitals was at most one. All residents were assured that their information would remain confidential. Ultimately, the mean score of CT-related educational satisfaction was calculated for each teaching hospital.
3.4. Evaluation and Statistical Analysis
Data analysis of the 30 completed questionnaires was performed using descriptive statistics and appropriate software, including SPSS and Matlab. For analysis, items were scored on a 5-point scale, with a maximum score of 5 and a minimum score of 1 for each question. The statement obtaining the highest score was considered the medical equipment authorities' proposed recommendation. Furthermore, associations between repair metrics and mean resident evaluation scores were calculated to examine the effect of downtime duration on radiology residents' educational satisfaction.
Before calculating the Pearson correlation coefficient, assumptions of linearity and normality were assessed using scatterplot visualization and Shapiro-Wilk tests for the aggregated hospital-level variables. Given the small sample size (n = 7) and potential deviation from normality, a sensitivity analysis was also conducted using Spearman's rank-order correlation. The Spearman correlation coefficient was ρ = -0.857 (P = 0.018), consistent in direction and magnitude with the Pearson result, supporting the robustness of the observed inverse association.
The primary unit of analysis for the correlation between equipment maintenance metrics and educational satisfaction was the hospital level (n = 7). For each participating hospital, data were aggregated from three sources: 1) maintenance records (MTTR, CR, and PM) were extracted and averaged across the 24-month study period, 2) expert questionnaire responses (n = 4 - 5 per hospital) were averaged to produce a consensus-based assessment of equipment-management practices, and 3) resident satisfaction scores (n = 6 - 7 per hospital) were averaged to generate a hospital-level mean satisfaction score. All linkage was performed using de-identified hospital codes to preserve institutional confidentiality. Consequently, the Pearson correlation coefficient (r = -0.875; P = 0.012) reflects the association between hospital-aggregated CT downtime and hospital-aggregated resident satisfaction across seven independent institutions.