Optimisation of radiation dose and image quality for AP pelvis radiographic examination

Background and rationale:Optimising radiation dose and image quality in medical imaging is essential in minimising radiation risk and ensuring images are fit for purpose. This thesis uses novel methods for image quality assessment and radiation dose/image quality optimisation. The antero-posterior (AP) pelvis projection was used as a focus for optimisation.Methods:In the first part of this thesis a visual grading image quality assessment scale is developed and validated in order to assess radiographic image quality. The scale validation is conducted in two phases; the initial phase uses phantom images and is further tested in phase two with cadaveric images. The scale development and validation is guided by psychometric theory and in particular Bandura’s guidelines. In the second part of this thesis a framework is developed to systematically optimise the radiation dose and image quality for AP pelvis radiographic examinations. The methodology development for this section is guided by the factorial based experimental design. The optimisation includes manual and automatic exposure control modes. The image quality is visually assessed using the previously developed (novel) image quality scale and physically using a signal to noise ratio. The optimisation work is conducted with the aim of achieving two objectives: 1) identifying the optimum practice that would produce images with suitable quality and low radiation dose; 2) conducting a systematic investigation into the main effect of the primary acquisition factors on the response variables (e.g. image quality (IQ) and effective dose (E)).Results:A scale of 24 items was produced. These scale items had good inter-item correlation (≥0.2) and high factor loadings (≥0.32). Cronbach's alpha (reliability) revealed that the scale has acceptable levels of internal reliability for both phantom and cadaver (α= 0.8 and 0.9, respectively). The factor analysis suggested that the scale is multidimensional (assessing multiple quality themes). Accordingly, it is likely that this scale will be applicable in both clinical and research practices. The optimum practice was identified, resulting in suitable quality images with a lower dose (i.e. 88 to 94 % less than the UK average adult AP pelvis dose of 0.7 mSv) for both manual and AEC modes. Furthermore, it was identified that kVp had the biggest effect on radiation dose, image quality and figure of merit (P˂0.05) when compared with mAs and SID. The factorial design proved to be an efficient approach in optimising the radiation dose and image quality, and also for exploring the main effect of acquisition factors on radiation dose and image quality.Conclusion:This novel method for developing and validating image quality assessment scale shows promise. As such it is a recommended model for developing scales for other radiographic projections. The factorial design should be considered for use in future work due to its efficiency in optimising the radiation dose and image quality systematically. Finally, the AP pelvis scale, in its current form, could be used in future assessments of AP pelvis image quality

Estimation of Radiation Dose from Most Common Pediatrics Radiographic Examinations within Main Central Hospitals in Najaf City, Iraq

          تضمنت هذه الدراسة تقييم جرعة الدخول الاشعاعية المستلمة من قبل المرضى الاطفال الذين يجرون بعض فحص التصوير الطبي للصدر، البطن، والجمجمة. تمت الدراسة في مستشفيين رئيسيين في محافظة النجف حيث تضمنت الدراسة ثلاثة اجهزة شعاعية للتصوير الطبي. تم تقسيم عينة الدراسة الى اربعة فئات عمرية 0-1 , 1-5 , 5-10   و10-15 سنة. اجريت الحسابات باستخدام عوامل التعرض الاشعاعي والتي تشمل فرق الجهد والتيار الكهربائي لأنبوبة الاشعة السينية والمسافة بين مركز الاشعة وسطح جلد المريض بالإضافة الى عمر المريض. وقد حسبت جرعة الدخول الاشعاعية لكل من الفحص الامامي الخلفي للصدر والبطن والجمجمة. وتم تحليل النتائج ومقارنتها مع الحدود المسموحة دوليا لكل فحص شعاعي. وقد وجدت الدراسة ان الجرعة الاشعاعية الناتجة عن أي فحص تزداد بزيادة عمر الطفل.  وقد سجلت المستشفى رقم 1 بجهازها رقم 2 اقل الجرع الاشعاعية حيث كانت جرع الدخول الاشعاعية لها 19.93-67.66 ملي كري لأشعة الصدر، 39.03-82.63 ملي كري لأشعة البطن، و35.47-94.27 ملي كري لفحص الجمجمة. بينما اعلى الجرع الاشعاعية سجلت في المستشفى رقم 2 بالجهاز ذو الرقم 1 وكما يلي: بالنسبة لأشعة الصدر كانت اقل جرعة247.51 ملي كري واعلى جرعة 2393.12 ملي كري، ولأشعة البطن كانت اقل جرعة 269.05 ملي كري واعلى جرعة 5106.15 ملي كري، اما لأشعة الجمجمة كانت اقل جرعة 430.96 ملي كري والاعلى كانت 3072.77 ملي كري. وقد استنتجت الدراسة ان معظم الجرع الاشعاعية المسجلة للأطفال ضمن الحدود المسموح بها دوليا مع بعض القيم اعلى من ذلك.In this study the Entrance Surface Dose (ESD) received by pediatrics patients undergoing chest, abdomen and skull X-ray examinations was estimated. The study was conducted in two hospitals in Najaf city where three radiographic systems were considered. The study participants were classified into four age groups 0-1 ,  1-5 ,  5-10  and  10-15  years. Calculations were performed using exposure factors, kVp, mAs and focal-skin distance, together with patient data age. The ESD was calculated for the involved patients who underwent an Antero-posterior (AP) chest, abdomen and skull X-ray examination. The resulted data were analyzed and compared with international dose references. For all studied radiographic examinations and all X-ray machines, the ESD increases with age. The lowest recorded radiation dose was from hospital 1 machine 2. In this facility ESD ranged from 19.93  µGy to  67.66  µGy for chest X-ray, from  39.03  µGy to  82.63  µGy for abdomen (AP), and from  35.47  µGy to  94.27  µGy for skull (AP). In contrast the highest dose levels are recorded from hospital 2 machine 1; the minimum ESD for chest X-ray is 247.51  µGy and the maximum is  2393.12  µGy; for abdomen X-ray the lowest ESD is  269.05  µGy and the highest value is  5106.15  µGy; and for skull X-ray minimum values is  430.96  µGy and the maximum value is  3072.77  µGy. In conclusion, for the considered pediatrics examinations, most of ESD values are within the international acceptable level and some are higher >100%

Gonad dose in AP pelvis radiography : impact of anode heel orientation

Purpose: For antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female / male gonad dose. Methods: High sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures. A dose profile was also generated using Unfors Mult-O-Meter 401 along the long axis of the phantom. Results: A decrease in dose from the central ray toward the anode was noted, with a marked increase toward the cathode. A significant reduction in dose was received by the testes with feet towards the anode compared with feet towards cathode (P˂0.001). No difference was seen for ovarian dose (P˃0.05). kVp, mAs and SID all have an effect on male and female gonad dose. Conclusion: For male pelvis imaging, placing feet towards the anode can be used as a simple dose reduction method

Development and validation of a psychometric scale for assessing PA chest image quality

Purpose - To develop and validate a psychometric scale for assessing image quality for chest radiographs

Dose optimisation in paediatric radiography - using regression models to investigate the relative impact of acquisition factors on image quality and radiation dose

Objective: To investigate the optimum pelvis X-ray acquisition factors for a 10-year-old child. Secondly, to evaluate the impact of each acquisition factor on image quality (IQ) and radiation dose. Method: Images were acquired using a pelvis phantom and a range of acquisition parameters; e.g. tube potential, additional filtration and source-to-image distance (SID). Automatic exposure control (AEC) was used with two orientations (head towards/away from two outer chambers) and three different chamber selections. Visual IQ was evaluated using relative and absolute-VGA methods. Radiation doses were measured by placing a dosimeter on the anterior surface of the phantom. Regression analysis was used to determine optimum parameters. Results: The optimised technique (178.8 µGy), with diagnostic IQ, was with 89kVp, 130 cm SID and with 1 mm Al + 0.1 mm Cu filtration. This technique was with the head towards the two outer AEC chambers. Regression analysis showed that SID had the lowest impact on IQ (β = 0.002 95% CI −0.001 to 0.005) and dose (β = −0.96 95% CI −0.40 to −1.53). The impact of filtration on dose (β = −76.24 95% CI −86.76 to −85.72) was higher than tube potential (β = −13.44 95% CI −14.34 to −12.53). The following impact ratios were higher on IQ than radiation dose: filtration/kVp; 11.28 times, filtration/SID; 7.01 times and kVp/SID; 0.62 times. Conclusion: Optimised parameters were identified as 89 kVp, 130 cm SID and with 1 mm Al + 0.1 mm Cu additional filtration. Regression analysis demonstrated that filtration and tube potential had the greatest effect on radiation dose and IQ, respectively

Can the anode heel effect be used to optimise radiation dose and image quality for AP pelvis radiography?

Introduction: A study was conducted to determine whether the anode heel effect can be used to influence optimisation of radiation dose and image quality (IQ) for AP pelvis radiography. Methods: ATOM dosimetry phantom and an anthropomorphic phantom were positioned for AP pelvis. Using a CR system, images were acquired and doses were measured with phantom feet toward anode and then feet toward cathode. Exposure factors (kVp, mAs and SID) were systematically generated using a factorial design. Images were scored visually for quality using relative visual grading together with a 3 point Likert scale. Signal to noise ratio was also calculated as a physical measure of image quality. Dosimetry data were collected for the ovaries and testes. Results: The optimum technique for male, which resulted in lower dose and suitable image quality, was with feet positioned toward the anode (0.80±0.03 mGy; SNR of 38±2.9; visual IQ score 3.13± 0.35). The optimum technique for female was with feet toward anode (0.23±0.02 mGy; SNR of 34.7±2.6; visual IQ score 3.15± 0.26). kVp had the biggest effect on both visual and physical image quality metrics (p˂0.001) for both tube orientations, whereas SID had the lowest effect on both visual and physical image quality metrics compared with mAs and kVp (p˂0.001). The effect of SID on the SNR was not significant (p>0.05) with feet toward anode. Conclusion: Positioning the patient with feet toward the anode, as opposed to the cathode, has no adverse effect on visual image quality assessment but it does have an effect on physical image quality. Implications for Practice:This study would add a new clinical concept in positioning of AP pelvis radiography especially for male positioning

DETERMINING THE RADIUM CONCENTRATION IN VEGETABLES AND FRUITS IN Al-NAJAF, IRAQ

Amount of pollution radiation in foodstuffs and feedstuffs are very necessary to measure because it is a direct contact with human and animal health. Therefore, the present investigation is useful for the health and environmental data base. The study included measurement of effective radium-226 content (CRa) in some chosen samples of vegetables and fruits (local and imported) in Najaf governorate. The CRa were measured in samples of vegetables and fruits using Solid State Nuclear Track Detectors (LR-115 Type II). Also, the annual effective dose (AED) associated with the exposure due to annual intake of 226Ra were calculated from ingestion of vegetables and fruits samples for adults. The results were revealed that the average value of CRa in vegetables and fruits samples in the present study was 3.98±1.08 Bq/kg and 1.73±0.11 Bq/kg, respectively. While, the average of AED (mSv/y) for vegetables and fruits samples was 0.067±0.018 and 0.082±0.005, respectively. Also, the results showed that the average value of AED from fruits consumption is larger than in vegetables, but the result is not significant. All results of the CRa and AED of the studied samples had been compared with the worldwide reported value (median). Accordingly, it was found that all findings were lower than that of the recommended limits of the UNSCEAR 2000. Finally, based on present investigations, no health risk expected when considering eating vegetables and fruits of Al-Najaf of Iraq. © 2022. Online Journal of Animal and Feed Research. All Rights Reserved.The authors would like to staff of university of Kufa and the Islamic University in Al-Najaf, Iraq

10 kVp rule - an anthropomorphic pelvis phantom imaging study using a CR system : impact on image quality and effective dose using AEC and manual mode

Purpose: This study aims to investigate the influence of tube potential (kVp) variation in relation to perceptual image quality and effective dose for pelvis using automatic exposure control (AEC) and non-AEC in a Computed Radiography (CR) system. Methods and Materials: To determine the effects of using AEC and non-AEC by applying the 10 kVp rule in two experiments using an anthropomorphic pelvis phantom. Images were acquired using 10kVp increments (60-120kVp) for both experiments. The first experiment, based on seven AEC combinations, produced 49 images. The mean mAs from each kVp increment were used as a baseline for the second experiment producing 35 images. A total of 84 images were produced and a panel of 5 experienced observers participated for the image scoring using the 2AFC visual grading software. PCXMC software was used to estimate the effective dose. Results: A decrease in perceptual image quality as the kVp increases was observed both in non-AEC and AEC experiments, however no significant statistical differences (p>0.05) were found. Image quality scores from all observers at 10 kVp increments for all mAs values using non-AEC mode demonstrates a better score up to 90kVp. Effective dose results show a statistical significant decrease (p=0.000) on the 75th quartile from 0.3 mSv at 60 kVp to 0.1 mSv at 120kVp when applying the 10 kVp rule in non-AEC mode. Conclusion(s): No significant reduction in perceptual image quality is observed when increasing kVp whilst a marked and significant effective dose reduction is observed

Inspiring radiographers to engage in research

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