Radiation Exposure In Imaging Research Articles

A Simulation-Free Replacement Solution for Radiation Therapy Immobilization Devices Using Computer Numerical Control (CNC) -Milled Polystyrene Molds

In radiation therapy (RT), if an immobilization device is lost or damaged, the patient may need to be brought back for resimulation, device fabrication, and treatment planning, causing additional imaging radiation exposure, inconvenience, cost, and delay. We describe a simulation-free method for replacing lost or damaged RT immobilization devices. Replacement immobilization devices were fabricated using existing simulation scans as design templates by computer numerical control (CNC) milling of molds made from extruded polystyrene (XPS). XPS material attenuation and bolusing properties were evaluated, a standard workflow was established, and 12 patients were treated. Setup reproducibility was analyzed postfacto using Dice similarity coefficient (DSC) and mean distance to agreement (MDA) calculations comparing onboard treatment imaging with computed tomography (CT) simulations. Results showed that XPS foam material had less dosimetric impact (attenuation and bolusing) than materials used for our standard immobilization devices. The average direct cost to produce each replacement mold was $242.17, compared with over $2000 for standard resimulation. Hands-on time to manufacture was 86.3 minutes, whereas molds were delivered in as little as 4 hours and mostly within 24 hours, compared with a week or more required for standard resimulation. Each mold was optically scanned after production and was measured to be within 2-mm tolerance (pointwise displacement) of design input. All patients were successfully treated using the CNC-milled foam mold replacements, and pretreatment imaging verified satisfactory clinical setup reproduction for each case. The external body contours from the setup cone beam CT and the original CT simulation with matching superior-inferior extent were compared by calculating the DSC and MDA. DSC average was 0.966 (SD, 0.011), and MDA average was 2.694 mm (SD, 0.986). CNC milling of XPS foam is a quicker and more convenient solution than traditional resimulation for replacing lost or damaged RT immobilization devices. Satisfactory patient immobilization, low dosimetric impact compared with standard immobilization devices, and strong correlation of onboard contours with CT simulations are shown. We share our clinical experience, workflow, and manufacturing guide to help other clinicians who may want to adopt this solution.

Delayed partial primary hypoadrenalism following therapeutic and imaging radiation exposure of the adrenal glands

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Management of pulmonary nodules in women with pregnant intention: A review with perspective.

The process for the management of pulmonary nodules in women with pregnant intention remains a challenge. There was a certain proportion of targeted female patients with high-risk lung cancer, and anxiety for suspicious lung cancer in early stage also exists. A comprehensive review of hereditary of lung cancer, effects of sexual hormone on lung cancer, natural history of pulmonary nodules, and computed tomography imaging with radiation exposure based on PubMed search was completed. The heredity of lung cancer and effects of sexual hormone on lung cancer are not the decisive factors, and the natural history of pulmonary nodules and the radiation exposure of imaging should be the main concerns. The management of incidental pulmonary nodules in young women with pregnant intention is an intricate and indecisive problem we have to encounter. The balance between the natural history of pulmonary nodules and the radiation exposure of imaging should be weighed.

Cumulative diagnostic imaging radiation exposure in premature neonates

To date, there has been limited work evaluating the total cumulative effective radiation dose received by infants in the neonatal intensive care unit. Most previous publications report that the total radiation dose received falls within the safe limits but does not include all types of ionizing radiation studies typically performed on this vulnerable patient population. We aimed to provide an estimate of the cumulative effective ionizing radiation dose (cED) in microSieverts (μSv) received by premature infants ≤32 weeks from diagnostic studies performed throughout their NICU stay, and predictors of exposures. Retrospective chart review from 2004-2011. Data included demographics, gestational age (GA), birth weight (BW), length of stay (LOS), clinical diagnosis, and radiological studies. 1045 charts were reviewed. Median GA = 30.0 weeks (SD 2.7, range 22.0-32.6). Median BW = 1340.0 grams (SD 445.4, range 420-2470). Median number of radiographic studies = 9 (SD 28.5, range 0-210). Median cED = 162μSv (range 0-9248). The cED was positively associated with LOS (p < 0.001) and inversely correlated with GA (p < 0.001) and BW (p < 0.001). Infants with intestinal perforation had the highest median cED 1661μSv compared to 162μSv for others (p < 0.001). Our results provide an estimate of the cumulative effective radiation dose received by premature infants in a level 4 neonatal intensive care unit from all radiological studies involving ionizing radiation and identifies risk factors and predictors of such exposure. Radiation exposure in NICU is highest among the most premature and among infants who suffer from intestinal perforation.

Abstract 4241: Associations between perceived medical device-related radiation harm and adherence to mammography screening guidelines

Abstract Introduction: Many forms of cancer screening involve imaging technologies utilizing radiation. Broad media coverage of radiation-related health risks may shape the public's perceptions of imaging-based cancer screening, such as mammography. In turn, this may impact patient outcomes by affecting cancer screening decisions. Our primary aim was to evaluate population differences in beliefs about medical radiation exposure in the United States and associations with mammography screening rates in women. Methods: We analyzed data from the National Cancer Institute's Health Information National Trends Survey (HINTS) 2012 administration. Bivariate and multivariate regression analyses were used to evaluate associations of sex, ethnicity, age, annual income, and education with perceptions of harm from medical test radiation exposure. Additional analyses evaluated the role of radiation perception on compliance with current mammography screening recommendations from the United States Preventive Services Task Force. Results: Approximately one-third of respondents indicated that they worried about medical imaging-related radiation exposure. Respondents who perceived medical imaging radiation as harmful to health were more likely to be female, be diagnosed with cancer, have less formal education, report lower socioeconomic status, and identify as an ethnic minority. Most female participants were not in compliance with current breast cancer screening recommendations (weighted percentage = 83.8%). Annual income (p = 0.042) and ethnicity (p = 0.0478) were two variables that were significantly associated with adherence to the recommended mammography screening paradigm. Women without health insurance were more likely to worry about medical imaging-related radiation (p=0.073). Neither health insurance (95%CI = 0.29, 4.99) nor excess worry about radiation exposure from medical imaging devices (95%CI=0.42, 1.89) predicted compliance to mammography screening, after adjusting for relevant sociodemographic variables. Conclusions: These results indicate that some populations may be more concerned about harm from medical device-related radiation than others. Identifying these populations may help improve future cancer patient outcomes by promoting targeted health interventions and communication strategies for these individuals. Women may be more likely to perceive medical imaging radiation exposure as harmful to health, however this alone could not account for why the majority of female respondents were not adhering to recommended mammograms screening guidelines. Future studies are needed to identify the major contributor to low breast cancer screening rates in the United States. Citation Format: Kekoa Taparra, Kay M. Pepin, Alexandra J. Greenberg-Worisek. Associations between perceived medical device-related radiation harm and adherence to mammography screening guidelines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4241.

Advancements in pediatric imaging

Pediatric imaging research has been particularly susceptible to the phenomenon of technologic "leapfrogging", in which advances in technology have outstripped progress in validating and implementing them in a patient-based, clinical setting. This review describes work underway to develop new techniques that can reduce pediatric imaging radiation exposure, principally by investigating new acquisition technologies and adjusting existing techniques, protocols, and practices to better conform to the special imaging needs of pediatric patients. These efforts have already helped develop and bring to the clinic new technologies such as iterative reconstruction for CT, dynamic helical CT, and quantitative susceptibility mapping for MRI. The pieces are also in place for additional future benefits for pediatric imaging. Advances in imaging, particularly for pediatrics, are often achieved late in the product cycle, with the result that new beneficial technologies take years, sometimes an entire market cycle, before they are adopted clinically due to the slow pace of capital equipment acquisition.

The clinical feasibility and performance of an orthogonal X-ray imaging system for image-guided radiotherapy in nasopharyngeal cancer patients: Comparison with cone-beam CT

The demand for greater accuracy of intensity-modulated radiotherapy (IMRT) has driven the development of more advanced verification systems for image-guided radiotherapy (IGRT). The purpose of this study is to investigate setup discrepancies measured between an orthogonal X-ray guidance system (XGS-10) and cone-beam computed tomography (CBCT) of Varian in the IMRT of patients with nasopharyngeal cancer (NPC). The setup errors measured by XGS-10 and CBCT at the treatment unit with respect to the planning CTs were recorded for 30 patients with NPC. The differences in residual setup errors between XGS-10 system and CBCT were computed and quantitatively analyzed. The time of image acquisition and image registration was recorded. The radiation doses delivered by CBCT and XGS-10 were measured using PTW0.6CC ionization chambers and a water phantom. The differences between setup errors measured by the XGS-10 system and CBCT were generally <1.5 mm for translations, indicating a reasonably good agreement between the two systems for patients with NPC in the translation directions of A-P (P = 0.856), L-R (P = 0.856) and S-I (P = 0.765). Moreover, compared with CBCT, XGS-10 took much shorter image acquisition and registration time (P < 0.001) and delivered only a small fraction of extra radiation dose to the patients (P < 0.001). These results indicate that XGS-10 offers high localization accuracy similar to CBCT and additional benefits including prompt imaging process, low imaging radiation exposure, real time monitoring, which therefore represents a potential attractive alternative to CBCT for clinical use.

Radiation Exposure in Imaging of Suspected Child Abuse: Benefits versus Risks

Recent articles on child abuse in this journal discussed the value of ordering a skeletal survey in children age 24-36 months and the need for a computed tomography (CT) of the head in children less than 2 years with an isolated single nonmetaphyseal long bone fracture. The benefits of these and other imaging studies are not merely in the number of positive tests. Negative results can be extremely important. However, both radiography and CT use ionizing radiation (X-rays). Determining the risks of radiation exposure from medical imaging is not straight forward. Language: en

Total Effective Radiation Dose Attributable to Medical Imaging in Patients With Acute Chest Pain: A Single-Center Comparison Study Between Dual-Source Coronary CT Angiography and Usual Care

Introduction: Coronary CT angiography (CCTA) can safely disposition low to intermediate risk chest pain (CP); however, there is conflicting data with respect to cumulative radiation exposure when compared with usual care over short follow-up intervals. Objectives: We report the effective radiation dose from index and downstream testing in low to intermediate risk symptomatic patients evaluated for chest pain in the ED with either CCTA or usual care to define various sources of patient radiation dose and quantify effective dose over a year and a half of follow-up. Patients and Methods: We evaluated radiation exposure from initial and downstream testing in a prospectively collected, matched cohort evaluated for CP in the emergency department (ED) with either CCTA compared with usual care over a median follow-up of 19.6 months. Effective radiation dose was calculated using published conversion factors. Results: Prospective, ECG-triggered acquisition using a 128-slice dual-source multidetector computed tomography (DSCT) scanner was performed in 92.9% of scans with a median effective dose from CCTA of 6.8 mSv (IQR 5.2, 9.1 mSv). CCTA cohort patients were more likely to undergo cardiac testing with exposure to radiation (P < 0.001); however, the median effective dose in patients exposed to radiation from cardiac testing was significantly lower in the CCTA cohort (7.1 mSv vs. 11.8 mSv, P < 0.001). Fewer patients in the CCTA cohort had additional non-cardiac thoracic imaging radiation exposure (40.8%) compared with usual care (92.8%). Total radiation exposure from any source was similar between the CCTA and usual care groups (100% vs 98.4%, P = 0.087), as was median total effective radiation dose (P = 0.105). Upfront CCTA was not associated with higher rates of incidental non-cardiac findings. Conclusions: Initial evaluation of acute chest pain in the ED with CCTA was not associated with an increase in total radiation exposure over a follow-up period of 19 months. CCTA offers a more comprehensive evaluation of multiple thoracic organ systems leading to reduced radiation exposure from non-cardiac thoracic testing and no increase in incidental imaging findings. This may represent an added benefit in this population of patients presenting acutely.

Emergency Radiology Elective Improves Second-Year Medical Students' Perceived Confidence and Knowledge of Appropriate Imaging Utilization

Given recent advances in and wider availability of complex imaging, physicians are expected to understand imaging appropriateness. We introduced second-year medical students to the American College of Radiology Appropriateness Criteria (ACR-AC) in an interactive case-based elective to demonstrate their use in imaging for common emergency department clinical complaints. Prospective pre- and post-test design assessed second-year medical students' performance on case-based knowledge applications and self-assessed confidence related to ACR-AC guidelines compared to second-year students participating in a different concurrent radiology elective. Students participated in a 3-day elective covering the ACR-AC, comparative effective imaging, and risks associated with imaging radiation exposure, with outcomes of perceived confidence using a 5-point Likert scale and knowledge of ACR-AC using case-based multiple choice questions. Analysis included computing mean scores and assessing effect sizes for changes in knowledge. Before the elective, 24 students scored an average of 3.45 questions correct of 8 (43.1%). On course completion, students scored an average of 5.3 questions correct of the same questions (66.3%) (P < .001; effect size [Cohen's d] = 1.3940. In the comparison group, 12 students scored an average of 3.08 questions (38.5%) correctly pretest and 3.09 questions (38.6%) correctly post-test (P > .85; effect size = 0.008). Students' confidence in ordering appropriate imaging improved nearly 2-fold from a range of 1.9 to 3.2 (on a scale of 1.0 to 5.0) to a range of 3.7 to 4.5. Following a short radiology elective, second-year medical students improved their knowledge of appropriate image utilization and perceived awareness of the indications, contraindications, and effects of radiation exposure related to medical imaging.

An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures

There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition procedures were from a Varian on-board imager (OBI) image system. An ionization chamber was used to determine the energy response of nanoDot dosimeters. The chamber calibration factors for x-ray beam quality specified by half-value layer were obtained from an Accredited Dosimetry Calibration Laboratory. The Monte Carlo calculated dose distributions were used to validate the dose distributions measured by using the nanoDot dosimeters in phantom and in vivo. The range of the energy correction factors for the nanoDot as a function of photon energy and bow-tie filters was found to be 0.88–1.13 for different kVp and bow-tie filters. Measurement uncertainties of nanoDot were approximately 2–4% after applying the energy correction factors. The tests of nanoDot placed on a RANDO phantom and on patient's skin showed consistent results. The nanoDot is suitable dosimeter for in vivo dosimetry due to its small size and manageable energy dependence. The dosimeter placed on a patient's skin has potential to serve as an experimental method to monitor and to estimate patient exposure resulting from a kilovoltage x-ray imaging procedure. Due to its large variation in energy response, nanoDot is not suitable to measure radiation doses resulting from mixed beams of megavoltage therapeutic and kilovoltage imaging radiations.

Parental Knowledge of Radiation Exposure in Medical Imaging Used in the Pediatric Emergency Department

We sought to quantify the knowledge base among parents and legal guardians presenting to our pediatric emergency department regarding radiation exposure during medical imaging and potential risks to children resulting from ionizing radiation. We sought to examine if a child's previous exposure to medical imaging changed caregiver knowledge base and discern caregivers' preference for future education on this topic. A prospective convenience sample survey was performed of caregivers who presented with their child to our tertiary pediatric emergency department. Parents or legal guardians (18-89 years) who accompanied a child (0-17 years) were eligible for inclusion and approached for enrollment. A structured questionnaire was administered by trained interviewers, and a chart review was conducted to ascertain if their child had a history of previous imaging. Sixty percent of caregivers interviewed (n = 205 of 340) did not associate any long-term negative effects with medical imaging. Among participants who did express a perceived risk from medical imaging radiation exposure, only 50% could indicate a known negative effect from exposure. We found no significant association between a child having had documented imaging studies and awareness of long-term negative effects (P = 0.22). Participants preferred to learn more about this topic from an Internet-based resource (50%), informational pamphlet (38%), or via treating physician (33%). Parents and legal guardians are largely unaware that exposure to radiation during medical imaging carries an inherent risk for their child. Health care providers wishing to educate caregivers should utilize reliable Internet sources, educational pamphlets, and direct communication.

Computed tomography and positron emission tomography/computed tomography surveillance after combined modality treatment of supradiaphragmatic Hodgkin lymphoma: a clinical and economic perspective

We studied the clinical benefits of radiological imaging, in the follow-up of patients after combined modality treatment for stage I/II classical supradiaphragmatic Hodgkin lymphoma (HL). Imaging data were collected for 78 adults treated during 1996–2008. Median follow-up was 4.6 years. Six of the nine relapses were detected clinically. On average, 31 imaging studies/patient were performed, with an estimated cost of $12 608/patient. Chest computed tomography (CT) scans accounted for 25%, abdominopelvic CT scans 41% and positron emission tomography (PET) or PET/CT scans 22% of this expense. Only one patient recurred infradiaphragmatically. The estimated radiation dose from imaging was 399 mSv and 229 mSv per patient, in relapse and non-relapse groups, respectively. CT scans contributed over 80% of the imaging radiation exposure. The routine use of CT scans in the surveillance of patients with HL after curative treatment adds to healthcare costs and total body radiation exposure with a low yield. History and physical examination remain effective tools for the follow-up of patients.

Medical Imaging Radiation Safety for the Female Patient: Rationale and Implementation

For the modern practitioner of women's imaging, achieving a balance between the positive diagnostic benefits available from current medical imaging on the one hand, and the potentially deleterious effects of ionizing radiation exposure on the other, has become a central issue. Increased public and professional awareness of the side effects of radiation now require a comprehensive understanding of the facts involved, the various risks to which patients are exposed, and the measures that can be implemented to minimize these risks. The major challenges posed by pregnancy, radiosensitive breast tissue, lactation, and an inability to easily exclude ovaries from the imaging field make female patients particularly vulnerable to medical imaging radiation exposure. The nature of this vulnerability changes frequently and depends on the imaging being performed, the age of the patient, and the clinical situation. For this reason, attention to gynecologic imaging radiation exposure across the whole life span is vitally important.

Radiation exposure in children with inflammatory bowel disease

Radiation exposure due to medical imaging has grown exponentially over the past two decades and the awareness has increased in the last few years with a number of articles in scientific publications and lay press. Radiation increases the risk of cancer and is particularly a concern in children. Limiting radiation exposure is most important in children, who are more sensitive to radiation, and specifically in children with a chronic lifelong disease such as inflammatory bowel disease (IBD). Children with IBD and specifically Crohn's disease demonstrate high exposure to ionizing radiation due to medical imaging. The yearly rate of medical imaging radiation exposure may seem small at approximately 3-5 mSv/year, which is only slightly higher than typical background radiation (3 mSv/year). However, this extra yearly radiation exposure to children with a lifelong chronic disease may increase the risk of cancer. Additionally, recent literature suggests that some children with more severe disease are exposed to high radiation doses within the first few years of diagnosis. Imaging modalities that do not utilize radiation, such as MRI and ultrasonography, have demonstrated utility in diagnosing and managing IBD and are particularly important for children. Pediatricians caring for children with chronic diseases should consider radiation exposure and limit exposure when possible. Future quality outcome benchmarks should include limiting exposure to radiation in children with chronic diseases.

Diagnostic Medical Imaging Radiation Exposure and Risk of Development of Solid and Hematologic Malignancy

Limiting patients' exposure to ionizing radiation during diagnostic imaging is of concern to patients and clinicians. Large single-dose exposures and cumulative exposures to ionizing radiation have been associated with solid tumors and hematologic malignancy. Although these associations have been a driving force in minimizing patients' exposure, significant risks are found when diagnoses are missed and subsequent treatment is withheld. Therefore, based on epidemiologic data obtained after nuclear and occupational exposures, dose exposure limits have been estimated. A recent collaborative effort between the US Food and Drug Administration and the American College of Radiology has provided information and tools that patients and imaging professionals can use to avoid unnecessary ionizing radiation scans and ensure use of the lowest feasible radiation dose necessary for studies. Further collaboration, research, and development should focus on producing technological advances that minimize individual study exposures and duplicate studies. This article outlines the research used to govern safe radiation doses, defines recent initiatives in decreasing radiation exposure, and provides orthopedic surgeons with techniques that may help decrease radiation exposure in their daily practice.

A questionnaire study assessing local physicians, radiologists and interns’ knowledge and practice pertaining to radiation exposure related to radiological imaging

To assess the knowledge and practice pertaining to radiation exposure related to radiological imaging among medical doctors, in relation to specialty and year of experience. Questionnaires as recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) were distributed to doctors in tertiary hospitals by convenience sampling. Their knowledge of radiation doses of common radiological investigations was assessed by any significant difference from correct answers by sampled t-test. Comparison between specialties and between the more (>6 years experience) and less experienced doctors was made by pairwise comparisons of 'right answer minus mean difference (RMD)' using Wilcoxon Signed Ranks Test. Descriptive analysis of their knowledge of harmful effects of radiation and the practices pertaining were also performed. Total 93 questionnaires were sent out and 82 (88.2%, 40 interns, 24 clinicians, 18 radiologists) were returned. Radiologists had the least deviation from correct answers compared to interns (1.29 vs. 2.40, p=0.018) and physicians (1.29 vs. 2.57, p=0.046). More-experienced doctors also performed better than the less-experienced (1.69 vs. 2.57, p=0.027). 12/80 (15%) and 4/80 (5%) failed to recognize MR and US as radiation-free modalities. Only 10/80 (12.5%) knew the risk of carcinogenesis from abdominal CT and only 4/81 (5%) will discuss radiation-related hazard with patients routinely. Knowledge of medical doctors, including radiologists, towards radiation exposure of imaging is unsatisfactory and could imply a tendency of radiation misuse and under-utilization of alternative radiation-free methods. On-job training and discussion of the radiation risk with patients are advised.

Managing Radiation Use in Medical Imaging: A Multifaceted Challenge

This special report aims to inform the medical community about the many challenges involved in managing radiation exposure in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options.

Cumulative Imaging Radiation Exposure Following Breast-Conservation Therapy

Radiation from medical imaging may induce cellular damage and increase the risk of cancer. While health care workers are restricted to an annual dose of 50 milliSieverts (mSv), the exposure to patients is not typically recorded. After breast-conservation therapy (BCT), patients are subjected to screening mammography, diagnostic breast imaging, and systemic surveillance imaging (SSI). Our objectives are to determine the cumulative radiation exposure of breast cancer survivors after completion of BCT, and to compare exposure levels in two historical cohorts. We also evaluated the indications of SSI. We performed a retrospective study of 68 patients with stage I or II breast cancer who received BCT in 1997 or 2002. Cumulative radiation exposure during follow-up from all imaging attributable to the breast cancer diagnosis was recorded, including both breast and non-breast imaging. The indications for SSI were recorded. In the first 5 years after BCT, patients received a median annual dose of 0.92 mSv with no difference between the 1997 and 2002 cohorts. A median of 90% of radiation exposure was due to mammography. From 1997 to 2002, the percentage of patients receiving computed tomography (CT) scans increased. Additional SSI occurred in 65% of patients, with the majority of tests ordered in the asymptomatic patient. Patients with nodal positivity were more likely to receive SSI (p = 0.03). In the first 5 years after BCT, annual radiation exposure due to imaging was low. However, it seems prudent to consider the risks of radiation exposure when ordering potentially low-yield screening studies in asymptomatic patients.