Compare The Grid And Air Gap Techniques Information Technology Essay

Comp be The Grid And Air Gap Techniques Information engine room EssayThe search design for this take on is of a comparative quantitative, quasi- observational nature. The principle for this comparative rent is to see what effect two different anti- crack up proficiencys strike on plan flavour. The properties that make this a quasi-experimental theatre argon habit of specialised inconsistents and rig in experimentation and exam (Parahoo, 2006). True experimental research is characterised by three properties manipulation, picture and randomisation (Parahoo, 2006). As the investigator will non randomise any variables, this athletic field is considered as quasi-experimental and not a true experimental cartoon.In this research manipulation was achieved since a standard anti-scatter proficiency was equalized to an channelize pass technique adapted for the acoustic projection of the rose hip in the lateral position. Expo trusted factor variables were also manipulat ed employ an automatic depiction control (AEC). Control was maintained by testing the two techniques under the homogeneous conditions victimization the equal research tools. Further more, the research worker unbroken control of the study by testing only the anti-scatter techniques on one specific projection. thusly the results achieved by this study atomic number 18 specific to the lateral hip projection. However, the principle could be applied to other projections in order to discover which technique works better in providing reasoned mental picture prime(a) in that specific projection.3.3 Research Method3.3.1 priming of the studyThe fol impressioning methodology was adapted from a study carried let on in the United Kingdom by Goulding (2006) who looked at the atm jailbreak and the football fieldiron technique apply to image the hip laterally in the University Hospital she trained in. The study was conducted with the help of pieceing radiographers in the cam str oke and Emergency (AE) department where they serveed some(prenominal) control control grid and product line snap technique as routine projections on forbearings. Goulding (2006) looked at image eccentric by attaining the hip radiographs performed with both anti scatter techniques separately. Goulding (2006) amass her information by asking proclaiming radiographers to comment on these radiographs. In Gouldings (2006) study the radiographs on which she based her findings and results were conducted on tolerants of different size and this may live with lacked reliableness due to different pictorial matter factors apply for individually examination, different patient pane of glass depending on patient size as well as image choice.Using a similar methodology in this study the police detective assessed image lineament utilise a timbre control darkness and an humanlike phantom. In doing so the researcher will make sure that tests through with(p) on both anti-scatter techniques to assess for image quality were more precise. The methodology for this research and the tools apply to measure image quality in both grid and mail recess technique are ex seeming(a)ed in the following sub- theatrical roles.3.3.2 Research toolsIn this study the tools discussed in this section were utilize to gather the entropy. They were customd to test the anti-scatter techniques being compared and investigated in this study which will be explained situated ahead on in this chapter.Since this research looks at image quality in two anti-scatter techniques, a lead quality control phantom (PTW Normi 13) was a very important tool utilize to collect the data. According to Carlton Adler (2006), spatial solving and severalize settlement are the most important properties upon which devices and techniques can be tested. The lead quality control phantom (Appendix B) is designed to perform constancy and acceptance tests on plain digital roentgenogram governing bodys a nd is able to test image receptors for their homogeneity, spatial steadiness and line solving (PTW-Freiburg, 2005). However, in this research, spatial resolution and contrast resolution were the two relevant key tests for image quality. Spatial resolution is mensurable by counting the largest amount of line p transfers per milli touchstone (Lp/mm) trance contrast resolution is deliberate by the low contrast steps seen on the resultant image. The areas on the phantom that are use to measure spatial and contrast resolution are shown in Appendix B.In stack away the data, the researcher made use of an anthropomorphous pixy phantom AR10A (Appendix B) to image the hip laterally using a horizontal circulate. This phantom was used so that the exposures of both grid and disseminate disruption technique performed on the quality control phantom could be done to image a hip that resembles that of a human. As the anthropomorphic phantom used had the resembling attenuation coefficient of a human body, it stops the shaft of light passing finished it in the same way that a human body would.Although this study evaluates image quality in two anti-scatter techniques, the radiation syndrome given to the field of force/object at apiece exposure using the air gap and grid technique was also save and compared. The amount of radiation unfastened by the tube at to each one exposure was also measured using a dose area product (DAP) metre. This was important in order to see how some(prenominal) radiation was being used at each exposure to pee an image using the grid and air gap technique.All the exposures (in this experimental testing) were made using an automatic exposure control (AEC) which is incorporated in the erect bucky in the digital roentgen ray system used. This device determined how much mAs was used in each exposure so that the right amount of x-ray photons irradiated the image receptor to create an image with adequate quality. This device was used sin ce the mAs that is used in an exposure determines how good the image quality is as well as the patient dose. Therefore when the readings using the tools mentioned were ga on that pointd from all exposures, the researcher could compare these results and identify the ideal technique and exposure that should be used in imaging the hip laterally. This technique and exposure should ideally produce a good quality image with as low a dose as possible.3.3.3 MethodThe following two subsections will explain in detail how the data was collected during the experimentation on the anti scatter techniques. The researcher made sure that the tools used in the testing were kept the same to test both techniques. The same digital x-ray system was also used throughout the entire experimentation.3.3.3.1 The Grid Technique interrogatory for this technique was divided in two periods. In the first point in time the researcher made use of the quality control phantom (PTW Normi 13). The phantom was set on a custom made table in contact with the erect imaging receptor. A stationary parallel grid was placed surrounded by the phantom and the receptor since this is the type of grid used in a lateral hip shoot through projection. In this technique, the object to image distance (OID) was that of 0cm since the phantom was in contact with the grid and image receptor. The source to image distance (SID) used was that of one metre (100 cm) since this is the standard SID used in such a projection in the radiology department of the topical anaesthetic hospital. The kV used was kept unvarying at 75 kV and the phantom was centred to the central AEC. The light beam diaphragm was set around the contours of the quality control phantom. A further exposure was made using the same grid technique position. However, this conviction the grid was removed. This was done in order to find out whether the grid was working effectively in absorbing scatter radiation, which in patch could affect image quality . The DAP metre was recorded so that the researcher could have an approximate idea of the dose given to the phantom.The second stage in testing the grid technique was done by using the anthropomorphic phantom. The researcher set up the pixy phantom AR10A with the hip in contact with the grid and receptor. The hip was centred with the central AEC and exposed. The kV and the SID were the same as the ones used in testing the quality control phantom 75kV and 100cm SID. The set-ups used to test the grid techniques using both phantoms can be show in Appendix B.3.3.3.2 The Air Gap TechniqueTo test for the air gap technique the researcher also divided the tests into two stages. The same quality control phantom used previously in the grid technique was also utilised in this test/experiment. The PTW Normi 13 was placed on a custom-made table. However, in this technique, an air gap between the phantom and the image receptor was applied. There were a total of sise air gaps applied, varying f rom 10cm to 60cm. This was done in order to see which air gap was more effective in reducing scatter radiation reaching the receptor. To achieve this aim the object to image distance (OID) was increase by 10 cm after each exposure to a maximum of 60 cm. The source to object distance (SOD) was kept at 100 cm to reduce object magnification as much as possible since this may create a loss in image sharpness. The source to image distance (SID) depended on what OID was used. Therefore when an OID of 20cm was applied, the SID was that of 120cm. This was done to ensure that the distance of the source to the object remained at 100cm. In each exposure the phantom was centred to the central AEC and the light beam diaphragm was set around the contours of the quality control phantom. The researcher also made use of the DAP metre to see which air gap produced a good quality image with a reasonably low dose. This was done so that the air gap exposures could be compared with the standard grid tech nique.In the second stage of testing for the air gap technique the researcher also used the same anthropomorphic phantom. The setting of the technique to image the hip laterally was adapted from Gouldings (2006) study by using the same patient position that the author used in her study. This setting knobbed applying an air gap between the phantoms hip and the receptor, keeping the SOD at 100cm. A total of six exposures were also performed on the pixy phantom AR10A with the same OIDs and cot death used to image the quality control phantom. The researcher made sure that the phantoms hip was centred with the central AEC of the erect image receptor. Both settings used to perform testing on the air gap technique can be found in Appendix B.3.4 Data CollectionThe data was collected during February 2010. The data record sheets used to record the data can be found in Appendix A. Exposure FactorsThe exposure factors used to produce the images in the grid and air gap technique were recorded. The kV was a constant factor while the mAs changed according to the technique used and its setting. The mAs was manipulated by intends of the AED. This was done so that the amount of x-ray photons needed to produce the image andthe length of the exposure was recorded depending on the technique used. quarry to Image Distance (OID)The OID used in testing the grid and air gap technique was recorded. This was important, particularly in the application of the air gap technique. This is because the OID in the air gap technique determined the magnitude of the air gap that should be used to achieve a good quality image while keeping the radiation dose as low as possible. Therefore the researcher could see and analyse the effect on the image quality each time a specific OID was used in recounting to exposure factors. In the air gap technique the SID depended on what OID was used. The researcher kept the SOD at 100cm to reduce as much as possible magnification of the resultant image. Dose orbit Product (DAP)The DAP metre was recorded at each exposure for both grid and air gap techniques. Although this metre does not measure the radiation dose given to the phantoms at each exposure, it gives an indication of whether the dose would be low or gamey. A high DAP reading would mean that more radiation was used in the exposure and therefore the resultant patient dose may be higher. The readings from this metre for both techniques were compared in relation to image quality of the radiographs. Signal to racket ratio (SNR)The signal to noise ratio (SNR) consists of the un-attenuated photons that have penetrated the subject without interaction (signal) and the Compton scatter and other factors that tear down image quality (noise). The SNR was used to determine how much contrast resolution an image had after each exposure. The higher the SNR the better the contrast resolution of an image (Dendy Heaton, 2006). However a high SNR also means high mAs and consequently a high p atient dose. The SNR was calculated by dividing the mean picture element value by the standard deviation of the signal of each exposure. The mean pixel value and standard deviation of the signal were recorded after each exposure provided by the digital x-ray system. Therefore the equation used wasSignal to Noise ratio = mean pixel value/standard deviation (reference) Spatial colony and Contrast ResolutionThe spatial and contrast resolution readings were recorded by the researcher from the radiographs achieved using the quality control phantom in the grid and air gap technique. The line pairs per millimetre (Lp/mm) were measured to test for spatial resolution, while for contrast resolution the low contrast steps were counted. The data recorded was tabulated in tables 2a and 2b respectively in the data record sheet. This recorded data enabled the researcher to compare the image quality in both techniques.Unlike Goulding (2006) in this study two nonsymbiotic radiologists that were ch osen randomly from the researcher were asked to report on image quality on all the radiographs performed on the anthropomorphic pixy phantom AR10A. Radiologists were chosen in this study since in Malta there are no reporting radiographers that report on the appendicular skeleton. The radiologists were asked to report on the images by answering a likert scale (1=very unretentive and 5=very good) to assess image quality. The results were tabulated in table 3 of the data record sheet.3.5 hardihood and ReliabilityValidity refers to the degree the research instrument used in the study measures what it is intended to measure. ThereforeValidity reflects the accuracy with which the findings reflect the phenomenon being studied (Parahoo, 2006, p.80)In this study, the researcher consulted with the medical examination physicist at the local hospital who was asked to assess the content validity of the research tools used to collect the data. The medical physicist considered the research tool s valid since the same tools are used in the medical imaging department to test for image quality on the digital x-ray systems. As the research tools were deemed to be totally valid, the data collected to measure image quality in the grid and air gap technique can also be said to be valid.Reliability refers to how consistent an instrument is in measuring what it is intended to measure (Parahoo, 2006). To maintain the equivalence reliability of the lead quality control phantom used for assessment of image quality, two independent observers were asked to measure both spatial and contrast resolution of the two images achieved using the same exposure factors, OID and SID. The researcher tested for the reliability of the automatic exposure device used. This was done by exposing the lead phantom twice without manipulating the setting or exposure factors and the results were recorded. The spatial resolution, contrast resolution and DAP metre readings were the same in both images and so th e AEC was considered reliable enough to use in the testing and data collection.3.6 Ethical ConsiderationsEthics is defined by Polit Beck (2006) as a system of moral values that are designed to comfort the participant from the research procedures as the researcher has professional, legal and social obligations towards the participants involved in the study. However, in this research, no human subjects were involved in the experimentation and collection of data, so there were no ethical issues regarding the exposures done on the PTW NORMI 13 phantom and the anthropomorphic phantom pixy AR10A. Permission was seek for the use of the x-ray equipment from Medical Imaging Department at the local hospital. Experimentation was performed under supervision and precautions were taken to ensure that radiation would not harm any other members of the staff or public where the study was performed.3.7 Limitations of the studyLimitations were encountered by the researcher throughout this study. Th e study was conducted using a quality control phantom and an anthropomorphic phantom. Although both phantoms are make to mimic and represent a patient as well as to produce equivalent scatter radiation, patient size was a variable that could not be added to the study. The DAP metre was used in this study so that the researcher could have an idea of the dose being attenuated by the phantoms used. Ideally the actual patient dose should be measured exactly this could not be done since no human subjects were used. Expansion of this study would lead to a better understanding of the dose given to patients while comparing the air gap and grid technique for the lateral hip shoot through.This study was carried out using a digital x-ray system in the radiology department at the local hospital. provide output and technique setup may be different when using other systems. In the radiology department, computed radiography is used to perform a lateral hip shoot through examination rather than a digital system which is what the researcher used in this study. In data analysis the readings from the quality control phantoms were understand by the researcher himself and not by a number of people. If more than one person interpreted the results, the results may have varied. Although these limitations are valid, they had no effect on the data collected and the results achieved.3.8 ConclusionThis chapter described the methodology and the research design of this study. The following(a) chapter consists of presentation, analysis and discussion of the data.