CT Scan - Assignment (PDF)
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Added on 2021-05-31
CT Scan - Assignment (PDF)
Added on 2021-05-31
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CT SCANSCT SCANSStudent’s NameINTRODUCTIONThere has been new technology coming up to reduce the CT Scan dose in recent light of the result outcomes to exposing kids to more radiation. The cells in children mutate different and thus their radiation needs are different from those of adults. Therefore, there is need for more optimization to reduce risks to children from the dosages. There has been acknowledgement that the scans are in high dosages than necessary.The radiation dose is measured in units if the dose that the body absorbs per unit mass. (Gray1J/Kg). some of the body tissues are more sensitive than others and thus an effective dose needs to be determined with consideration of risks from the radiation, measured in (SV) sieverts. The determination of effective dose is measured from the amount absorbed by critical organs of the body. The Es can be compared between different types of parameters (Sarabjeet Singh, 2009). The CT dose is determined using the CTDI (CT dose index) in volume. LITERATURE REVIEWFactors affecting dose reductionPitchThe ratio of gantry rotation to beam width over some distance is inversely proportional to the dose. Exposure lengthThe distance of patient anatomy in the Z direction when exposed to the X ray should be limited to specific organ.Scan Phases.The number of times a body is radiated in a multi-liver study needs to be maintained to specific organs as opposed to multiphase scans. Helical Over-RangingThere should be an important tissue for pediatric parings need to have shorter acquisition distances when compared to adults (Racadio, 2014). Course:Approved by the Human Research Committee (HRC) in compliance with the Health Insurance Portability and Accountability Act guidelines, gradual incremental stepwise reduction method was used for kids. This involved analysis the noisier images associated with lower radiation doses. Each CT scan was divided into 6 color zones with pink for rule out, green for follow-up, red for bone evaluation, yellow for kidney stone, blue for small lesions and gray for vascular assessments. The radiation optimization was then centered around four phases that fell between different weight ranges. By studying the CT scans on adults and then kids, the result showed that lower nose index could be used for children who weighed less than 27.2 kgs. From the studies, the image noise was graded from 1 to where 1 was minimal noise and 65 was unacceptable noise. Compared to the noncompliant examinations used in CT scan, the color noise examination showed use of lesser radiation doses for chest sections ad abdominal sections as well. .RISKSAs the age increases, so does the risk of cancer induction as well. The risk with radiation scans comes in from the population of patients involved.The risk versus benefit assessment for ach CTY study and lastly,Diseases that are independent of radiation can develop from weakening body immunity.CONCLUSION.•Based on the cylinder tests and color tests for reduction of dose in CT scan its velar that using physical measured data, the use of the parameters stated above will enable reduction of dosages while the CNR is preserved. METHODOLOGYRational Approaches to Dose ReductionThere has been attempts made to reduce the dosages through determining dependent size technique factors from computed tomography (CT), using physically measured objective data. Experiments using cylinders have been made by passing them through CT and studying the noise reflected from them. Similarly, diluted iodine and tissue contracts were determined from computer calculation. The doses, noise reflected and contrast offered by iodine were used to optimize the radiation for pediatric CT, especially for abdominal and head examinations (Boone, 2003). There has been successful research that has shown that aorta, renal, hepatic and superior mesenteric arteries to showing noise reduction technologies while maintaining the standard references in ensuring pairwise ration doses and image quality comparison. The image noise showed at interference point intervention using air kerma, there was reduction in dosages. This technique is referred to as image localization. More strategies include the fixed tube strategy that considered children’s weight to reduce the peak voltage of the CT in order to reduce the radiation dose. Exposure techniques including current modulation have also been employed where the size of the child is directly linked to the radiation dose offered. This is done while maintaining desired images quality and the tests have been successfully carried out among volunteering patients for kidney stone evaluations, bone indicators and follow-up head scans for conditions such as hydrocephalus and chest conditions like cystic fibrosis. Other conditions successfully conducted considering size of the child in CT scans include bronchiectasis, and pulmonary nodules follow-ups (Boone, 2003). Dose Reduction Techniques Coronary CT angiography is reliable as it’s a non-invasive imaging modality for evaluating heart diseases using the right clinical settings. With the increase of the condition among many people, the issue of the radiation dosing has come to light. Therefore, advances have been made to achieve lowest angiography protocols that consist of low radiation and highly defined images. This has been achieved through tube potential modulation, where lower volts are used and thus radiation exposure is reduced as well. Iodine induced contrast is enhanced which makes the method appropriate for CT angiography (Nelson, 2014). DEMERITS.The method tends to have a lot of image noise which makes the quality of the image poor. The method when using current-time depends on the body mass index (BMI). The radiation dose is reduced through reducing current and peak voltage as well as table speed and gantry rotation. This method has been known to have high noise levels for images and also causes poor image quality. ACTM (Automatic tube current modulation) in the CT helps in achieving good image quality using the noise index (NI). The higher the NI, the lower the radiation (Nelson, 2014). Image noise can also be reduced using advanced reconstruction algorithms which include ASIR or MBIR (newer model-based iterative reconstruction). Filtered back projection (FBP) help reduce noise though maintaining spatial resolution and image quality. Another effective method is image reconstruction. The initial image quality is edited through reducing quantum noise and artifacts which improves the quality of CT image quality. Image quality is computed using combined adaptive statistical iterative reconstruction (ASIR). An image is set under different ASIR ranges from 0-80% ASIR and the image assessed for image noise, image artifacts and visibility. Through recording of ED (Effective dose) from the image noise to the signal to noise ration (SNR), ASIR can be increased or reduced to optimum levels. Different ASIR levels are suitable for different scans. E.g. 50% ASIR is recommended for CT protocol (Nelson, 2014). •COMPARISON.•ASIR, ATCM and FBP work through image reconstruction while CT angiography voltage modulation work by reducing image noise. •MBIR uses image analysis to determine the image quality with 1 as excellent and 4 as severe reduction in image quality.
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