Dissertationen zum Thema „Pelvis radiographs“

The Rotation Ratios Method

En metode for beskrivelse av endret romlig bekkeninnstilling svedsekvensielle røntgenopptak av samme bekken

Sammendraget:

Sekvensielle røntgenopptak av ett og samme bekken blir rutinemessig brukt bl.a. innen ortopedisk kirurgi. Ofte sammenliknes korresponderende røntgenmål for å vurdere sykdomsutvikling eller vurdere effekten av en behandling. Tre-dimensjonale objekt blir transformert til to-dimensjonale bilder ved røntgenopptak. Både den romlige innstillingen av objektet og fokusering av røntgenrøret i forhold til objektet påvirker avbildingen. Endringer i disse innstillingene kan derfor påvirke aktuelle røntgenmål og representere en feilkilde når korresponderende røntgenmål sammenliknes. I en serie av fire arbeid presenteres utviklingen av en målemetode som beskriver endringer i bekkeninnstilling om to akser, basert på standard frontale (AP) bekkenopptak.

To parametre som beskriver endring i bekkeninnstilling eller endring i røntgenfokusering ble validert ved bruk av definerte røntgenopptak av et bekkenfantom.

Et dataprogram for simulering av røntgenopptak av rigide objekt ble utviklet og validert. Dette programmet representerer et virtuelt røntgenlaboratorium der objektorientering, røntgenfokusering, mm. kan endres.

Dette dataprogrammet ble brukt til simulering av 4653 røntgenbilder av 141 utvalgte bekken, representerende en normalpopulasjon. Simulerte røntgenmål fra disse bildene ble brukt i utviklingen av et formelapparat for klinisk bruk. Korreksjonsfaktorer for kjønn og bekkenstørrelse ble innarbeidet.

Metoden, som er en algoritme inkluderende både manuelle og matematiske prosedyrer ble validert. Først ble de manuelle delene validert enkeltvis før en samlet validering ble gjort der en sammenliknet 1020 beregnede bekkenrotasjoner mot korresponderende reelle.

Metoden synes å ha god nok nøyaktighet for klinisk bruk.

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.

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Total hip arthroplasty is a surgery with a high success rate, providing pain relief and improvement of the articular mobility. Long-term success is related to the position and orientation of the acetabular and femoral components. Traditional preoperative planning entails radiographic analysis of the pelvis, in which a template is placed on the image, allowing an analysis of the appropriate size of the Exeter cemented prosthesis. Objective: To evaluate the effectiveness of traditional preoperative planning with the use of templating. Patients and Method: Forty-three anteroposterior X-rays were analyzed by three experienced surgeons. The evaluation of each surgeon was compared with the actual prosthesis used in the surgery and also compared with the assessment of the other two surgeons. Cohen's Kappa concordance test and weighted Kappa indexes using quadratic weighting were used for statistical analysis with a confidence interval of 95%. Results: The preoperative evaluations of Surgeons A, B and C were divided into the analysis of the sizes of the acetabular cup, stem and plug of the distal femoral canal. Surgeon A obtained a moderate agreement in relation to the acetabular component and substantial agreements in relation to the stem and plug. Surgeon B had moderate agreement in relation to both the acetabulum and the stem and substantial agreement in relation to the plug. Surgeon C obtained moderate agreement in relation to the analysis of the acetabulum and the plug and substantial agreement for the stem. The intra-observer agreement test demonstrated a prevalence of slight agreement in relation to the acetabulum and substantial agreement in relation to the stem and to the plug. Conclusion: Templating used in preoperative planning proved effective; however, there was a prevalence of slight and moderate agreement in relation to the size of the acetabular component according to the inter- and intra-observer analysis.
A artroplastia total do quadril é uma cirurgia com alto índice de sucesso, atuando no alívio da dor e melhora da mobilidade articular e seu êxito a longo prazo relaciona-se à posição e orientação do componente acetabular e femoral. O planejamento pré-operatório tradicional consiste na análise radiográfica da bacia, na qual será sobreposto um templating , o que permite a análise do tamanho adequado da prótese Exeter cimentada. Objetivo: Avaliar a eficácia do planejamento pré-operatório tradicional pelo uso do templating . Casuística e Método: Quarenta e três radiografias na posição antero-posterior e foram analisadas por três cirurgiões experientes; as avaliações de cada cirurgião foram comparadas com a prótese utilizada na cirurgia e cada resultado comparado com os resultados dos outros dois. Para avaliação, utilizou-se o teste de concordância do Capa de Cohen e do Capa ponderado, com ponderação quadrática e intervalo de confiança de 95%.Resultados: Os resultados pré-operatório encontrados pelo examinadores A, B e C foram divididos como análise do tamanho do acetábulo, haste e plug do canal femoral distal. O cirurgião A obteve em relação ao componente acetabular uma concordância moderada, e em relação à haste e ao plug uma concordância substancial. O cirurgião B apresentou resultado de concordância moderada em relação ao acetábulo e à haste e substancial em relação ao plug. O cirurgião C na análise acetabular e do plug obteve concordância moderada e substancial quanto à haste. O teste de concordância intra-observador apresentou uma prevalência da concordância leve em relação ao acetábulo e substancial em relação à haste e ao plug. Conclusão: O templating utilizado no planejamento pré-operatório mostrou-se eficaz, no entanto, em relação ao tamanho do componente acetabular houve um predomínio de concordância leve e moderada na análise inter e intraobservador.

A estimativa da idade é um elemento importante na investigação antropológica, sendo uma das fontes preliminares dos dados para estabelecer a identidade de pessoas vivas ou restos mortais desconhecidos. Os métodos mais utilizados para este fim são os baseados no desenvolvimento ósseo e dentário dos indivíduos. Neste sentido, o presente trabalho apresentou como objetivo, estabelecer valores de referência na população brasileira para a estimativa da idade, por meio de dois métodos: a análise da mineralização dos terceiros molares; e a mensuração da altura do ramo mandibular. Para isso, foram escaneadas radiografias (407 panorâmicas e 289 cefalométricas em norma lateral) de pacientes, de 6 a 25 anos de idade, atendidos na Faculdade de Odontologia de Bauru. As imagens radiográficas panorâmicas foram utilizadas para análise da mineralização dos terceiros molares inferiores, através do método proposto por Demirjian, Goldstein e Tanner (1973), e as imagens radiográficas cefalométricas utilizadas para medir a altura do ramo da mandíbula. Os resultados indicam uma forte correlação entre a idade cronológica e ambos os métodos utilizados, proporcionando a elaboração de fórmulas para o cálculo da idade aproximada dos indivíduos na população estuda. Não houve diferença estatisticamente significante para o desenvolvimento dos terceiros molares entre os sexos. Já para a altura do ramo da mandíbula, essa diferença ocorreu entre os 16 e 25 anos de idade. A probabilidade de afirmamos que um indivíduo tem 18 anos ou mais de idade, com base nas duas metodologias proposta neste trabalho, é extremamente alta (>90%). Concluiu-se que ambos os métodos estariam aptos a serem utilizados para estimar a idade na população brasileira, entretanto, pelo fato do Brasil ser um país com extenso território e apresentar uma população bastante miscigenada, novos estudos devem ser realizados, aumentando a amostra dessa população, e permitindo o aprimoramento dos valores aqui informados.
Age determination is an important element in anthropological research, one of the primary sources of data to establish the person living identity or unknown remains. The aim of this paper was to establish reference values in Brazilian population to estimate chronological age by two methods: mineralization of third molars and measurement of the mandible ramus height. Therefore, radiographs from patients between 6 to 25 years, were scanned (407 panoramics and 289 cephalometrics). The patients were from School of Dentistry at Bauru. The panoramic radiographs were used for analysis the mineralization of the mandibular third molars. Moreover, cephalometric radiographs were used to measure the mandibular height. The results indicated a strong correlation between chronological age and both methods, providing the development of formulas for calculating the approximate real age of individuals by radiographs. There was no statistically significant difference for the third molars development between sexes. There was a significant difference between men and women for ramus height of the mandible for the range between 16 and 25 years. The probability of a claim that an individual is 18 years or older, based on the two methodologies proposed in this work was extremely high (>90%). It was concluded that both methods were suitable to be used to estimate the age in Brazilian population. However, as Brazil is a country with vast territory and present a fairly mixed population, it is necessary further studies to confirm the values reported.

Yes
Objectives: Pelvis radiographs are usually acquired supine despite standing imaging reflecting functional anatomy. We compared supine and erect radiographic examinations for anatomical features, radiation dose and image quality. Methods: 60 patients underwent pelvis radiography in both supine and erect positions at the same examination appointment. Measures of body mass index and sagittal diameter were obtained. Images were evaluated using visual grading analysis and pelvic tilt was compared. Dose–area product values were recorded and inputted into the CalDose_X software to estimate effective dose (ED). The CalDose_X software allowed comparisons using data from the erect and supine sex-specific phantoms (MAX06 & FAX06). Results: Patient sagittal diameter was greater on standing with an average 20.6% increase at the iliac crest (median 30.0, interquartile range [26.0 to 34.0] cm), in comparison to the supine position [24.0 (22.3 to 28.0) cm; p < 0.001]. 57 (95%) patients had posterior pelvic tilt on weight-bearing. Erect image quality was significantly decreased with median image quality scores of 78% (69 to 85) compared to 87% for the supine position [81 to 91] (p < 0.001). In the erect position, the ED was 47% higher [0.17 (0.13 to 0.33) mSv vs 0.12 (0.08 to 0.18) mSv (p < 0.001)], influenced by the increased sagittal diameter. 42 (70%) patients preferred the standing examination. Conclusion: Patient diameter and pelvic tilt were altered on weightbearing. Erect images demonstrated an overall decrease in image quality with a higher radiation dose. Optimal acquisition parameters are required for erect pelvis radiography as the supine technique is not directly transferable.
College of Radiographers Industry Partnership Scheme grant.

Yes
We read with interest the recent article by Yun et al. [1] comparing acetabular and hip measurements across pelvis, hip and lumbar spine radiographs. The authors assert that lumbar radiographs can be utilised in place of routine pelvis radiographs for these measurements. The example lumbar spine radiograph (figure 2) appears to be an abdominal image, with a contrast urogram. Indeed, standard texts [2,3] confirm that the anteroposterior lumbar spine radiograph should not include any coverage of the hips as appropriate collimation should limit the anatomy to T12 superiorly, lower sacrum inferiorly and the sacroiliac joints laterally, which would exclude the hip joints. Thus assessing any hip measurements on an appropriately collimated lumbar spine radiograph should not be possible. This is further compounded by the description of the centring point within their study (iliac crest), which varies from the internationally recognised standard of lower costal margin/L3 [2,3].

Yes
Aim: Pelvic radiography is used for the identification of hip joint changes, including pathologies such as osteoarthritis. Several studies have recommended that the position for this radiological procedure should be standing, not supine, to reflect the functional appearances of the hip joint. The aim of this review was to evaluate pelvis radiography positioning with respect to the image appearances and information provided for clinical decision-making. Aside from this, potential recommendations to the radiographic technique for an erect pelvis projection will be considered. Method: A literature search was performed using databases/abstract systems (ScienceDirect, Web of Science, PubMed, and MEDLINE). Only articles written in English were included. Results: Twenty-five articles were identified. Findings from the review describe the effect of repositioning from supine to erect on a series of specific hip measurements. These include pelvic tilt, joint space width, and the acetabular component. Conclusion: Evidence within the literature illustrates that in several studies, there were differences when repositioning from supine to standing for a number of pelvic metrics. Standing positioning is promoted by some authors since this may facilitate the early diagnosis of hip joint pathology and assist in the planning of surgical interventions. Literature is very limited on how to optimally perform erect pelvis radiography, and this should be an area for future research.

Yes
Introduction: To investigate the reliability and variability of Video Rasterstereography (VR) measurements of the spine and pelvis, for eight proposed standing postures, in order to help define an optimal standing position for erect pelvis radiography. Methods: Surface topography data were collected using the formetic 4D dynamic modelling (Diers) system. 61 healthy participants were recruited; each participant performed eight different standing positions. Four positions were performed with the feet shoulder width apart and parallel, and four positions were performed with the feet shoulder width apart and internally rotated. For the upper extremity, each of the (two sets of) four positions were performed with different arm positions (arms by the sides, arms crossed over the chest, arms 30° flexed and touching the medial end of the clavicle, arms 30° flexed with the hands holding a support). Three sets of surface topography were collected in the eight positions (n = 24). The variability was assessed by calculating standard error of the measurement (SEm) and the coefficient of variation (CV). Reliability was assessed using intra-class correlation coefficients (ICC ± 95% CI). Results: No significant differences in the SEm were found between the three paired measurements for all standing positions (P > 0.05). ICC values demonstrated excellent reliability for all measurements across the eight standing positions (range 0.879–1.00 [95% CI 0.813–1.00]). Conclusion: Evaluating eight standing positions radiographically would be unethical as it would involve repeat radiation exposures. Using the formetic 4D dynamic modelling (Diers) system, provides an alternative and has shown that there was only a minimal, non-statistically significant, differences between the eight different standing positions.
KA is supported by the Hashemite University/ Jordan.

Yes
Introduction: Pelvic radiographs remain an essential investigation in orthopaedic practice. Although it is recognised that acquisition techniques can affect image appearances and measurement accuracy, it remains unclear what variation in practice exists and what impact this could have on decision making. Method: This was a cross sectional survey of UK radiology departments utilising an electronic tool. An introductory letter and link was distributed. Responses were received from 69 unique hospital sites within the specified timeframe, a response rate of 37.9%. Results: There was no consistent technique for the positioning of patients for pelvic radiographs. The distance varied between 90 and 115 cm and 10 different centering points were described. In relation to leg position, the feet are usually internally rotated (65 of 69 [94.2%]). Only 1 teaching hospital (1 of 69 [1.4%]) uses a weight-bearing position as standard. Orthopaedic calibration devices were not in routine use, with only 21 using on pelvic x-rays (30.4%). Further, the type of device and application criteria were inconsistent. Conclusions: To our knowledge this is the first study to directly compare radiographic positioning across hospital sites. Our data demonstrated marked variation in technique for pelvis radiographs with associated implications for clinical decision making. Research is required to determine the standard technique and quality outcome measures to provide confidence in diagnostic interpretation particularly for serial radiographs.
College of Radiographers Industry Partnership Scheme (CoRIPS).

Yes
Introduction: Within medical imaging variations in patient size can generate challenges, especially when selecting appropriate acquisition parameters. This experiment sought to evaluate the impact of increasing body part thickness on image quality (IQ) and effective dose (E) and identify optimum exposure parameters. Methods: An anthropomorphic pelvis phantom was imaged with additional layers (1e15 cm) of animal fat as a proxy for increasing body thickness. Acquisitions used the automatic exposure control (AEC), 100 cm source to image distance (SID) and a range of tube potentials (70e110 kVp). IQ was evaluated physically and perceptually. E was estimated using PCXMC software. Results: For all tube potentials, signal to noise ratio (SNR) and contrast to noise ratio (CNR) deceased as body part thickness increased. 70 kVp produced the highest SNR (46.6e22.6); CNR (42.8e17.6). Visual grading showed that the highest IQ scores were achieved using 70 and 75 kVp. As thickness increases, E increased exponentially (r ¼ 0.96; p < 0.001). Correlations were found between visual and physical IQ (SNR r ¼ 0.97, p < 0.001; CNR r ¼ 0.98, p < 0.001). Conclusion: To achieve an optimal IQ across the range of thicknesses, lower kVp settings were most effective. This is at variance with professional practice as there is a tendency for radiographers to increase kVp as thickness increases. Dose reductions were experienced at higher kVp settings and are a valid method for optimisation when imaging larger patients.
Hashemite University in Jordan, College of Radiographers Industry Partnership (CoRIPS)