Patient Perceptions and Knowledge of Ionizing Radiation From Medical Imaging

Key Points Question What are the patient perceptions and knowledge about ionizing radiation used for medical imaging? Findings In this survey study among 2866 patients undergoing radiological examinations in Italian hospitals, a substantial proportion of respondents perceived their medical radiation knowledge as inadequate and had misconceptions about basic aspects of radiation protection. Better knowledge was associated with receiving such information from medical staff and having a higher educational level. Meaning These findings suggest that interventions to improve patients’ knowledge about radiation protection risks would be beneficial, with communication from medical staff potentially playing a determinant role.


Introduction
Owing to the development and widespread availability of cross-sectional imaging, in the last several decades, radiology has become pivotal in the diagnosis and management of many diseases. The use of medical imaging, including ionizing radiation-based modalities, continues to increase, raising concerns about patients' radiation exposure, [1][2][3][4] with reported cumulative effective doses exceeding 100 mSv for single procedures. [5][6][7][8] Although accounting for only 17% of all medical examinations, multidetector computed tomography (CT) alone makes up approximately 50% of the total radiation burden for medical purposes, and a large multicenter trial by Rehani et al 9 revealed that more than 1% of patients undergoing multiple CT examinations over 1 to 5 years received a cumulative effective dose above 100 mSv.
The European Council Directive 2013/59/Euratom has emphasized the need for "safety standards for protection against the dangers arising from exposure to ionizing radiation." 10 Technical advances aimed to optimize radiation dose use, and awareness campaigns for health care professionals (including general practitioners, clinicians, radiologists, nuclear medicine physicians, and radiographers) and patients are the main ways to minimize unnecessary radiation exposure.
Several studies have reported a lack of knowledge about medical radiation and related risks among both health care professionals and patients. [11][12][13][14][15][16] In particular, patients' knowledge about medical radiation is limited, and the perception of radiation risks is variable depending on age and educational level. [17][18][19] In Italy, this issue is of special interest owing to the European Council Directive 2013/59/ Euratom having become effective starting on August 27, 2020. 11,20 In this context, a nationwide survey might help to more thoroughly assess patients' knowledge about medical radiation and its potential risks. Our purpose was to develop and validate a questionnaire aimed to assess such knowledge among Italian patients and identify any differences related to patient sex, age, educational level, information received, and radiological procedures performed.

Population and Data Collection
A multicenter, nationwide survey study with prospective data collection was performed between June 1, 2019, and May 31, 2020, with patients in waiting rooms for medical imaging examinations in 16 Italian academic and nonacademic hospitals. Radiography students were trained as interviewers to achieve more generalized respondent comprehension and avoid misunderstanding. A web platform containing an informative brochure, a user's guide, and the online questionnaire was implemented for easier collection of the survey results. Inclusion criteria were provision of written and individually signed patient informed consent, patient ability and willingness to adhere to all study requirements, and age 18 years or older. Exclusion criteria were mental illness, physical inability to respond and/or no or limited legal capacity, and age younger than 18 years.
Our study was approved by the regional ethical committee for clinical trials (Comitato Etico di Area Vasta Nord Ovest), and all of the involved radiology departments agreed to participate in the study. All patients gave their written informed consent to take the survey and were assured about the anonymity of responses; participants did not receive compensation. The survey was anonymously completed only once by each volunteer.

Questionnaire Development
This study followed the American Association for Public Opinion Research (AAPOR) reporting guideline for survey studies. The survey consisted of 23 items grouped into 3 sections (eAppendix in the Supplement). The first section of the survey contained questions on factors such as sex, age, marital status, and educational level. The second section contained questions aimed to explore the patient's knowledge about ionizing radiation risks (Knowledge About Ionizing Radiation Questionnaire [KIRQ]) and was divided into 3 steps. The first step identified survey questions (items generation) based on a review of current biomedical and life sciences literature (eTable 1 in the Supplement), which resulted in creation of the first KIRQ version. In the second step, semantic structure and content of each item in terms of statement relevance, clarity, and appropriateness were assessed by 5 radiologists with more than 10 years of experience in radiation protection policies (first questionnaire version). After modification and optimization of the selected items, 10 questions were included in the second version and validated by an independent panel of radiology educators. The third step involved pretesting the questionnaire on 20 nonmedical volunteers to assess its comprehensibility (pilot test). A reliability test-retest was performed on 50 volunteers and reapplied 2 weeks later to ensure the stability of questionnaire scores over time. 21 The third section of the survey contained questions aimed to explore expectations and communication gaps between health care professionals and survey respondents The full survey questions are reported in the eAppendix in the Supplement.

Statistical Analysis
Sample characteristics from the 3 questionnaire sections are assessed using descriptive statistics, whereas categorical variables are expressed as percentages and continuous variables are reported as mean (SD). The Italian regions were grouped into 3 territorial subareas: north, center, and south/islands. 22 The educational level of the survey respondents was classified as low ( We performed exploratory factor analysis and confirmatory factor analysis via structural equation modeling to identify latent factors underlying the psychometric properties of the 10-item KIRQ. 23 To quantify the reliability of the questionnaire, we calculated the Cronbach index (α) as a measure of internal consistency. Several goodness-of-fit criteria were used, including the standardized root mean square residual, root mean square error of approximation (cutoff Յ0.10), comparative fit index, and Tucker-Lewis index (cutoff >0.90). 24,25 Respondents' scores were recorded using a binary classification of the KIRQ score with a 75thpercentile threshold separating high knowledge (Ն75th percentile, binary value 1) from low to moderate knowledge (<75th percentile, binary value 0). Binary logistic models were applied to evaluate the association between personal data, communication, and information aspects and respondents' knowledge. Setting the binary KIRQ score as the dependent variable and personal data, communication, and information items as independent variables, we performed univariable logistic regression as a first step to identify predictive variables and subsequently performed a multivariable logistic regression to simultaneously test the combinations of variables selected by univariable multinomial logistic regression (adjusted for sex and age). Results are reported as odds ratios (ORs) and their 95% CIs.
Statistical analysis was performed using Stata/SE, version 15 (StataCorp LLC) and SPSS, version 24 (IBM Corp). All P values were 2-sided, and P < .05 was set as the threshold for statistical significance.

Results
Our survey was conducted among 3039 individuals, with a response rate of 94.3% (n = 2866 A total of 2525 of the 2866 respondents (88.1%) wanted to be informed about the amount of radiation received after the radiological examination was completed. The most appreciated methods of communication were via a quantitative dose measurement using a specific radiation unit (eg,

Psychometric Properties of the 10-Item KIRQ
Exploratory factor analysis highlighted the presence of 1 latent factor underlying the 10-item questionnaire on ionizing radiation knowledge. The questionnaire showed acceptable internal consistency (Cronbach α, 0.742) (eTable 2 in the Supplement).
Confirmatory factor analysis revealed that the items related to ionizing radiation exposure from specific imaging modalities (question B5) were the most important variables, with a value equal to 0.478 for CT and 0.382 for MRI. Other variables with optimal specific validity index values were those related to the amount of radiation in association with specific imaging examinations (question B6; 0.374), natural sources of ionizing radiation (question B4; 0.342), and radiation emission after radiological tests (question B7; 0.313).

Factors Associated With Knowledge of Radiation Protection
The KIRQ score greater than or equal to the 75th percentile was equal or above 7 points and the median was 5 points. The KIRQ score was significantly lower in patients older than 65 years (median, 4; IQR, 3-6 years) than in those aged 18 to 64 years (median, 5; IQR, 4-7) (P < .001).
Univariable analysis (  Multivariable logistic regression (Figure 2)   sections. Items labeled as "B" indicate knowledge, and items labeled as "C" indicate communication.

OR (95% CI)
The reference category for educational level was low level, and the reference category for self-perceived knowledge was inadequate knowledge. OR indicates odds ratio. Statistically significant associations were also observed for lifetime number of radiological examinations (OR, 1.51; 95% CI, 1.110-2.061; P < .01) and information received from health care professionals (OR, 1.30; 95% CI, 1.072-1.565; P < .01). No statistically significant association was observed for sex, whereas younger age was associated with a greater knowledge level (OR, 0.99; 95% CI, 0.987-0.999; P = .02).
Overall, multivariable analysis showed that the most relevant factors associated with ionizing radiation knowledge were a higher educational level, an adequate self-perception of radiation knowledge, a higher number of imaging examinations performed, and having received radiation information from a health care professional. Although exposure to radiation information from various news sources (eg, television, radio, and newspapers) was also associated with a higher radiation knowledge on univariate analysis, such association was not confirmed by multivariate analysis.

Discussion
Despite the fact that 98.5% of the respondents had undergone imaging, few had an understanding of radiation dose or risk and had gained their knowledge from outside the health care system, and most requested more information. These results suggest the need for new strategies even with the presence of many public radiation protection and awareness campaigns for more than a decade.
This study was designed to be a national-level survey of adults undergoing medical imaging procedures aimed to evaluate their knowledge and awareness about ionizing radiation, with the dual purpose of understanding their concerns and informing policy makers and radiation protection professionals about gaps in education and training of all stakeholders. To our knowledge, this is the first multicenter survey on this topic performed on a large population, as studies published so far have included a limited number of patients and/or single imaging centers. 17,18,26 Our results revealed a lack of knowledge in the general population about radiation doses associated with common radiological examinations and basic radiation protection issues. In particular, the existence of natural background radiation and the dose burden of the most frequent imaging examinations were largely unknown by our surveyed patients. This lack of information was not due to having no experience with radiological procedures. In fact, nearly all of the respondents had previously received at least 1 imaging examination, including radiation-free imaging modalities, and about two-thirds of the patients had undergone at least 3 imaging tests; there was a prevalence of men in the number of total radiological examinations (72.9%), whereas women had undergone ultrasonographic examinations more frequently than other imaging tests, including mammography.
Such a female prevalence of ultrasonographic examinations could be due to breast screening and follow-up testing for urogynecological concerns.
Although most patients had undergone an ultrasonographic or MRI examination at least once, most were unaware of the absence of ionizing radiation in MRI (57%), and to a lesser extent, this finding also applied to ultrasonography (15%). Moreover, 71.0% of surveyed patients knew that CT relies on ionizing radiation, whereas only 38.4% (men and women combined) knew that mammography uses ionizing radiation, with women knowing that mammography is radiation based more frequently than men (46.4% vs 29.2%; P < .001). To this latter point, a questionnaire-based study conducted by Hollada et al 27 on 1725 patients presenting for a mammogram showed that, although 65% of the patients responded that they had been informed of the risks and benefits of the examination, 60% overestimated the amount of radiation in a mammogram, suggesting that targeted patient education for those undergoing any type of imaging procedure should be heightened. More generally, our findings are in line with those from previous studies, revealing an unmet need for awareness campaigns about medical radiation addressed to the general population. [26][27][28][29][30] Efforts to improve patient awareness about CT and radiation protection have yielded some results, 28 yet much remains to be done. In addition, our findings highlighted patients' limited knowledge about the association between body mass index and delivered CT radiation dose, with more than half believing that radiation dose is unrelated to body size, and about the association between patient age and radiation risk.

JAMA Network Open | Imaging
Furthermore, most surveyed patients were unaware of the potential radiation risks to which they may have been exposed if their imaging had required ionizing radiation, with more than half of the respondents receiving no radiation information before, during, or after imaging examinations despite more stringent legal requirements about delivering patient information and recording and reporting of doses on medical procedures. Improved communication between medical staff and patients may be useful if it is the main and mandatory focus of further informative campaigns because more than 40% of the respondents had received information about ionizing radiation mainly from mass media and deemed the knowledge received from those sources to be inadequate.
Approximately 80% of the respondents stated they would like to receive information from medical staff, attesting to their willingness to be properly informed about the potential risks of radiological procedures.
In particular, most patients (68.6%) would like to be given information on this topic by radiologists. This preference could be explained by assuming that patients prefer to be informed by physicians who, owing to the medical and technological skills that pertain to their professional specialty, will supervise their imaging procedures and interpret the findings in combination with their clinical history to reach a diagnosis, hence being directly involved in clinical management and communication with other medical specialists. Although to a lesser extent, patients would also like to be informed by their general practitioners, with whom they usually have a closer relationship than with other health care professionals, or by radiographers, probably owing to their specific technical expertise. Nonetheless, several factors may align to prevent satisfactory communication between health care professionals and patients in a busy radiology setting. 26 In line with Hartwig et al, 31 who found an association between patients' educational level and awareness of potential negative effects from medical imaging, our study found that educational level, self-perceived knowledge about ionizing radiation, and number of imaging examinations performed were associated with a higher degree of awareness and knowledge about the risks of radiation exposure. Moreover, the fact that these patients were more likely to seek radiation protection information through mass media might suggest that proper information given by the radiological staff at imaging appointments could trigger patients' interest about radiation protection issues. This practice could possibly improve patient knowledge and awareness and, in the long run, ease the educational tasks of radiology personnel.

Limitations
The study has limitations. The first limitation of our survey is that it was administered in waiting rooms of different hospitals without any differentiation based on imaging modality, potentially introducing a selection bias in the recruitment of survey respondents. Second, the sample selection and total number of respondents were not representative of the general patient population. Third, although our survey included a question on whether respondents who had undergone prior imaging examinations had been informed about radiation risks, it lacked more specific questions to assess whether such information was adequate. Fourth, although the survey had been tested and validated before being distributed to our final patient population, it cannot be considered as a standardized tool. Further studies with larger samples are needed, possibly via a nationwide or, even better, international standardized questionnaire, to get a more accurate representation of the general population's radiation knowledge and awareness.