Radiation dose optimization in radiology is a critical aspect of modern healthcare, aimed at balancing the necessity of diagnostic imaging with the imperative of patient safety. This comprehensive review explores the fundamental principles, techniques, and considerations in optimizing radiation dose to safeguard patients while preserving image fidelity. Beginning with acknowledging the inherent risks associated with medical radiation exposure, the review highlights strategies such as the As Low as Reasonably Achievable (ALARA) principle, technological advancements, and quality assurance measures to minimize radiation dose without compromising diagnostic accuracy. Regulatory guidelines and the importance of patient education and informed consent are also discussed. Through a synthesis of current knowledge and emerging trends, the review underscores the pivotal role of radiation dose optimization in radiology practice. Furthermore, it emphasizes the need for ongoing research and collaboration to advance dose reduction strategies, establish standards for radiation safety, and explore personalized dose optimization approaches. By prioritizing radiation dose optimization, healthcare providers can ensure the highest standards of patient care while minimizing potential risks associated with medical radiation exposure.

OBJECTIVE: In contemporary radiotherapy, patient positioning accuracy relies on kV imaging. This study aims at optimizing planar kV image acquisition protocols regarding patient dose without degrading image quality.
METHODS: An image quality test-object was placed in-between PMMA plates, suitably arranged to model head or pelvis. Constructed phantoms were imaged using default protocols, the resultant image quality was assessed and the corresponding radiation dose was measured. The process was repeated using numerous kV/mAs combinations to identify those acquisition settings providing images at lower dose than the default protocols but without deterioration in image quality. Default and dose-optimized protocols were then tested on an anthropomorphic phantom and on 51 patients during two successive treatment sessions. Image quality was independently assessed by two readers. Organ and effective doses were estimated using a Monte Carlo simulation software.
RESULTS: Low-contrast detectability exhibited a stronger dependence on kV/mAs settings, compared to high-contrast resolution. Dose-optimized protocols resulted in significant dose reductions (anteroposterior-head 48.0 %, lateral-head 30.0 %, anteroposterior-pelvis 28.4 %, lateral-pelvis 27.0 %) compared to the default ones, without compromising image quality. Optimized protocols decreased effective doses by 54 % and 29.6 % in head and pelvic acquisitions, respectively. Regarding image quality, anthropomorphic and patient images acquired using the dose-optimized protocols were subjectively evaluated equivalent to those obtained with the corresponding default settings, indicating that the proposed protocols may be routinely used.
CONCLUSIONS: Given the potentially large number of radiotherapy fractions and the pertinent image acquisitions, dose-optimized protocols could significantly reduce patient dose associated with planar imaging without compromising positioning accuracy.

OBJECTIVE: To develop and assess the value and limitations of an image quality scoring criteria (IQSC) for pediatric CT exams.
METHODS: IQSC was developed for subjective assessment of image quality using the scoring scale from 0 to 4, with 0 indicating desired anatomy or features not seen, 3 for adequate image quality, and 4 depicting higher than needed image quality. Pediatric CT examinations from 30 separate patients were selected, five each for routine chest, routine abdomen, kidney stone, appendicitis, craniosynostosis, and ventriculoperitoneal (VP) shunt. Five board-certified pediatric radiologists independently performed image quality evaluation using the proposed IQSC. The kappa statistics were used to assess the interobserver variability.
RESULTS: All five radiologists gave a score of 3 to two-third (67%) of all CT exams, followed by a score of 4 for 29% of CT exams, and 2 for 4% exams. The median image quality scores for all exams were 3 and the interobserver agreement among five readers (acceptable image quality [scores 3 or 4] vs sub-optimal image quality ([scores 1 and 2]) was moderate to very good (kappa 0.4-1). For all five radiologists, the lesion detection was adequate for all CT exams.
CONCLUSIONS: The image quality scoring criteria covering routine and some clinical indication-based imaging scenarios for pediatric CT examinations has potential to offer a simple and practical tool for assessing image quality with a reasonable degree of interobserver agreement. A more extensive and multi-centric study is recommended to establish wider usefulness of these criteria.

Introduction and aim: In case of imaging modalities using ionizing radiation, radiation exposure of the patients is a vital issue. It is important to survey the various dose-reducing techniques to achieve optimal radiation protection while keeping image quality on an optimal level. Method: We reprocessed 105 patients\' data prospectively between February and April 2017. The determination of the radiation dose was based on the effective dose, calculated by multiplying the dose-length product (DLP) and dose-conversation coefficient. In case of image quality we used signal-to-noise ratio (SNR) based on manual segmentation of region of interest (ROI). For statistical analysis, one sample t-test and Wilcoxon signed rank test were used. Results: Using iterative reconstruction, the effective dose was significantly lower (p<0.001) in both native and contrast-enhanced abdominal, contrast-enhanced chest CT scans and in the case of the total effective dose. At native and contrast-enhanced abdominal CT scans, the noise content of the images showed significantly lower (p<0.001) values for iterative reconstruction images. At contrast-enhanced chest CT scans there was no significant difference between the noise content of the images (p>0.05). Conclusion: Using iterative reconstruction, it was possible to achieve significant dose reduction. Since the noise content of the images was not significantly higher using the iterative reconstruction compared to the filtered back projection, further dose reduction can be achievable while preserving the optimal quality of the images. Orv Hetil. 2019; 160(35): 1387-1394.
Absztrakt: Bevezetés és célkitűzés: Az ionizáló sugárzást használó keresztmetszeti képalkotó modalitások alkalmazása során kiemelt szerepe van a pácienseket érő sugárdózis mennyiségének. A betegeket érő sugárterhelés csökkentésére fókuszálva fontos felmérni a különböző dóziscsökkentő technikák adta lehetőségeket a sugárvédelem optimális megvalósítása céljából a képminőség minél magasabb szinten tartása mellett. Módszer: Kutatásunk során az intézetünkben használt iteratív képrekonstrukciót (SAFIRE) és a szűrt visszavetítéses rekonstrukciót (FBP) alkalmazó CT-berendezések sugárterhelését és képminőségét hasonlítottuk össze. Vizsgálatunkban prospektív módon 2017. február–április intervallumban 105 beteg képanyagával dolgoztunk. A CT-vizsgálatok során a beteget érő effektív dózis került meghatározásra a dózis-hossz szorzat (DLP) és a dóziskonverziós együttható szorzataként. A képminőség értékeléséhez manuális terület kijelölés (ROI-) alapú adatfelvételt követően jel-zaj arányt (SNR) számoltunk. A statisztikai elemzést egymintás t-próbával és Wilcoxon-teszttel végeztük el. Eredmények: Az effektív dózis iteratív rekonstrukciót alkalmazva szignifikánsan alacsonyabb (p<0,001) volt natív és kontrasztanyagos hasi, illetve kontrasztanyagos mellkasi CT-vizsgálat esetén, továbbá a betegeket ért összes effektív dózis tekintetében is. A felvételek zajtartalma natív és kontrasztanyagos hasi CT-vizsgálat során szignifikánsan alacsonyabb (p<0,001) értékeket mutatott az iteratív rekonstrukcióval készült képek esetén. A kontrasztanyagos mellkasi CT-vizsgálatok során szignifikáns eltérés nem mutatkozott a kétféle eljárással készült képek zajtartalma között (p>0,05). Következtetés: Az ismételt CT-vizsgálaton átesett betegek körében szignifikáns dóziscsökkentés vált lehetővé az iteratív képrekonstrukció alkalmazásával, a képminőség megtartása mellett. A képek zajtartalma egy régió vizsgálatánál sem volt szignifikánsan magasabb az iteratív rekonstrukció alkalmazásakor a szűrt visszavetítéses rekonstrukcióhoz képest, így felmerül a további dóziscsökkentés lehetősége optimális képminőség megőrzése mellett. Orv Hetil. 2019; 160(35): 1387–1394.

Congenital heart diseases (CHD) belong to the leading causes of infant mortality worldwide. Prognostic improvements result from multimodal therapy strategies leading to an increased demand for noninvasive imaging. The aim of the study was to further optimize cardiac CT radiation dose by omitting the test bolus or bolus tracking scan, which can have a relevant share of radiation exposure, especially in neonates.
This retrospective study included 25 neonates with CHD who received a CT angiography (CTA) from 2009 to 2018. The examinations were performed as a high-pitch CTA (pitch 3.4, 80 kV) with manual contrast administration (1.5 ml/kg body weight) and fixed scan delay depending on the respective heart defect. Diagnosis, adverse events, radiation dose parameters, objective (contrast-to-noise ratio) and subjective (4-point Likert scale) image quality as well as diagnostic accuracy compared to intraoperative findings was assessed.
All examinations were diagnostically evaluable without adverse events. The median CT dose index volume (CTDIvol) was 0.50 mGy (range, 0.15-0.94), the median dose-length product was 8 mGy × cm (range, 3-17). The estimation of the effective dose by Monte Carlo simulation revealed lower median dose levels 0.66 mSv (range, 0.25-1.40 mSv) than previously published in comparable groups. All examinations achieved a very good mean image quality score of 1.2 ± 0.4 with only minimal image noise and mean contrast-to-noise ratio of 16.1 ± 7.0. Diagnostic accuracy was 100 % as cardiac anatomy revealed no new diagnoses or significant differences in the subsequent cardiac surgery.
Cardiac high-pitch CTA of neonates with CHD can be performed safely and dose-reducing without additional test bolus or bolus tracking scan. With very good image quality, it provides a detailed insight into the cardiac anatomy and thus enables a differentiated, noninvasive therapy planning.

Optimal performance of pediatric cardiothoracic computed tomography (CT) is technically challenging and may need different approaches for different types of CT scanners. To meet the technical demands and improve clinical standards, a practical, user-friendly, and vendor-specific guideline for pediatric cardiothoracic CT needs to be developed for children with congenital heart disease (CHD). In this article, we have attempted to describe such guideline based on the consensus of experts in the Asian Society of Cardiovascular Imaging CHD Study Group. This first part describes the imaging techniques of pediatric cardiothoracic CT, and it includes recommendations for patient preparation, scan techniques, radiation dose, intravenous injection protocol, post-processing, and vendor-specific protocols.

To determine whether the body size-adapted volume computed tomography (CT) dose index (CTDvol) in pediatric cardiothoracic CT with tube current modulation is better to be entered before or after scan range adjustment for radiation dose optimization.
In 83 patients, cardiothoracic CT with tube current modulation was performed with the body size-adapted CTDIvol entered after (group 1, n = 42) or before (group 2, n = 41) scan range adjustment. Patient-related, radiation dose, and image quality parameters were compared and correlated between the two groups.
The CTDIvol after the CT scan in group 1 was significantly higher than that in group 2 (1.7 ± 0.1 mGy vs. 1.4 ± 0.3 mGy; p < 0.0001). Image noise (4.6 ± 0.5 Hounsfield units [HU] vs. 4.5 ± 0.7 HU) and image quality (1.5 ± 0.6 vs. 1.5 ± 0.6) showed no significant differences between the two (p > 0.05). In both groups, all patient-related parameters, except body density, showed positive correlations (r = 0.49-0.94; p < 0.01) with the CTDIvol before and after the CT scan. The CTDIvol after CT scan showed modest positive correlation (r = 0.49; p ≤ 0.001) with image noise in group 1 but no significant correlation (p > 0.05) in group 2.
In pediatric cardiothoracic CT with tube current modulation, the CTDIvol entered before scan range adjustment provides a significant dose reduction (18%) with comparable image quality compared with that entered after scan range adjustment.

Background In 1996 the International Commission on Radiological Protection (ICRP) introduced diagnostic reference levels (DRLs) as a quality assurance tool for radiation dose optimization. While many countries have published DRLs, available data are largely from high-income countries. There is arguably a greater need for DRLs in low- and middle-income-countries (LMICs), where imaging equipment may be older and trained imaging technicians are scarce. To date, there has been no critical analysis of the published work on DRLs in LMICs. Such work is important to evaluate data deficiencies and stimulate future quality assurance initiatives. Purpose To review the published work on DRLs in LMICs and to critically analyze the comprehensiveness of available data. Material and Methods Medline, Scopus, and Web of Science database searches were conducted for English-language articles published between 1996 and 2015 documenting DRLs for diagnostic imaging in LMICs. Retrieved articles were analyzed and classified by geographical region, country of origin, contributing author, year of publication, imaging modality, body part, and patient age. Results Fifty-three articles reported DRLs for 28 of 135 LMICs (21%), reflecting data from 26/104 (25%) middle-income countries and 2/31 (6%) low-income countries. General radiography (n = 26, 49%) and computerized tomography (n = 17, 32%) data were most commonly reported. Pediatric DRLs (n = 14, 26%) constituted approximately one-quarter of published work. Conclusion Published DRL data are deficient in the majority of LMICs, with the paucity most striking in low-income countries. DRL initiatives are required in LMICs to enhance dose optimization.

Pediatric CT radiation dose optimization is a challenging process for pediatric-focused facilities and community hospitals alike. Ongoing experience and trial-and-error approaches to dose reduction in the large academic hospital setting may position these centers to help community hospitals that strive for CT quality improvement. We describe our hands-on approach in a pilot project to create a partnership between an academic medical center and a community hospital to develop a toolkit for implementing CT dose reduction. Our aims were to (1) assess the acceptability of an interactive educational program and electronic toolkit booklet, (2) conduct a limited test of the efficacy of the toolkit in promoting knowledge and readiness to change, and (3) assess the acceptability and practicality of a collaborative approach to implementing dose reduction protocols in community hospitals. In partnering with the community hospital, we found that they had size-specific radiation doses two to three times higher than those at our center. Survey results after a site visit with interactive educational presentations revealed an increase in knowledge, stronger opinions about the health risks of radiation from CT scans, and willingness and perceived ability to reduce pediatric CT doses.

OBJECTIVE: To investigate effect of body dimensions obtained from localizer radiograph and transverse abdominal computed tomography (CT) images on Size Specific Dose Estimate.
METHODS: This study was approved by Institutional Review Board and was compliant with Health Insurance Portability and Accountability Act. Fifty patients with abdominal CT examinations (58 ± 13 years, Male:Female 28:22) were included in this study. Anterior-posterior (AP) and lateral (Lat) diameters were measured at 5 cm intervals from the CT exam localizer radiograph (simple X-ray image acquired for planning the CT exam before starting the scan) and transverse CT images. Average of measured AP and Lat diameters, as well as maximum, minimum and mid location AP and Lat were measured on both image sets. In addition, off centering of patients from the gantry iso-center was calculated from the localizers. Conversion factors from American Association of Physicists in Medicine (AAPM) report 204 were obtained for AP, Lat, AP + Lat, and effective diameter (√ AP * Lat) to determine size specific dose estimate (SSDE) from the CT dose index volume (CTDIvol) recorded from the dose reports. Data were analyzed using SPSS v19.
RESULTS: Total number of 5376 measurements was done. In some patients entire body circumference was not covered on either projection radiograph or transverse CT images; hence accurate measurement of AP and Lat diameters was not possible in 11% (278/2488) of locations. Forty one patients were off-centered with mean of 1.9 ± 1.8 cm (range: 0.4-7 cm). Conversion factors for attained diameters were not listed on AAPM look-up tables in 3% (80/2488) of measurements. SSDE values were significantly different compared to CTDIvol, ranging from 32% lower to 74% greater than CTDIvol.
CONCLUSIONS: There is underestimation and overestimation of dose comparing SSDE values to CTDIvol. Localizer radiographs are associated with overestimation of patient size and therefore underestimation of SSDE.