Computed tomography (CT), originally known as computed axial tomography (CAT) and body section roentgenography, is a medical imaging method employing tomography where digital geometry processing is used to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation.
A full-body scan can theoretically catch deadly diseases (e.g. cancer) in early stages, which can save lives. However in practice, the benefits may not outweight the risks (see sections below). Thus, controversy arises from the use of full-body scans in the screening of patients who have not been diagnosed with a disease, or who do not have symptoms suggestive of a disease, As with any test that screens for disease, the risks of full-body CT scans need to be weighed against the benefit of identifying a treatable disease at an early stage.
Advantages over traditional radiography
There are several advantages that CT has over traditional 2D medical radiography. First, CT completely eliminates the superimposition of images of structures outside the area of interest. Second, because of the inherent high-contrast resolution of CT, differences between tissues that differ in physical density by less than 1% can be distinguished. Finally, data from a single CT imaging procedure consisting of either multiple contiguous or one helical scan can be viewed as images in the axial, coronal, or sagittal planes, depending on the diagnostic task. This is referred to as multi planar reformatted imaging.
CT is regarded as a moderate to high radiation diagnostic technique. The improved resolution of CT has permitted the development of new investigations, which may have advantages; compared to conventional for example, CT angiography avoids the invasive insertion of an CT colonography (also known as virtual colonoscopy or VC for short) may be as useful as a barium enema for detection of tumors, but may use a lower radiation dose. CT VC is increasingly being used in the UK as a diagnostic test for bowel cancer and can negate the need for a colonoscopy.
The radiation dose for a particular study depends on multiple factors: volume scanned, patient build, number and type of scan sequences, and desired resolution and image quality. Additionally, two helical CT scanning parameters that can be adjusted easily and that have a profound effect on radiation dose are tube current and pitch. Computed tomography (CT) scan has been shown to be more accurate than radiographs in evaluating anterior interbody fusion but may still over-read the extent of fusion.
Health risks
- Compared to most other diagnostic X-ray procedures, CT scans result in relatively high radiation exposure. This exposure may be associated with a very small increase in the possibility of developing cancer later in a person's life. This risk is greatly outweighed by the benefits of diagnostic and therapeutic CT, however is questionable when used on asymptomatic individual.
Diagnosis benefits
- Allows a transparent view of the body, which normally is not transparent. Many possible malignancies are discovered with a full-body scan, but these are almost always benign.These may not be related to any disease, and may be benign growths, scar tissue, or the remnants of previous infections. CT scanning for other reasons sometimes identifies these "incidentalomas".
Other issues
- Low rate of finding disease.
- Confusion regarding "incidentalomas" (see above): It is uncertain how to treat some of them, or if treatment is even necessary.
- Possibly high cost: At a cost of US$600 to $3000 full-body scans are expensive, and are rarely covered by insurance. However, in December 2007, the IRS stated that full-body scans qualify as deductible medical expenses, without a doctor's referral. This will likely lead employer-sponsored, flexible-spending plans to make the cost of the scans eligible for reimbursement.
- May not be able to detect colors, unlike for example a colonoscopy.
Alternatives
Partial-body scans
Other CT scans may be used in screening for disease in high risk groups. These scans are more localized and are identical to those used in the course of treating a disease, the only difference being that these scans are done before any disease is found.
Low-dose CT scanning of the lungs may be done to screen for lung cancer, but it has showed varied success. CT colography, or virtual colonoscopy is a CT scan that looks for polyps that may develop into colon cancer. It has shown detection rates for polyps of size greater or equal to 8 mm that are comparable to traditional or "optical" colonoscopy. One of the downsides of imaging is that although they provide comparable detection rates, they have no inherent capability of treatment. For example, if polyps are found on virtual colonoscopy the next step is to perform a traditional colonoscopy to remove the polyps; however the initial diagnosis is significantly less invasive.
Other types of scans include Heart, Brain, Bone density, Angiogram, Carotid artery
Magnetic resonance imaging (MRI) scans are associated with a lesser radiation risk than CT scans, and are being evaluated for their use in screening.
Safety concerns:
The increased use of CT scans has been the greatest in two fields: screening of adults (screening CT of the lung in smokers, virtual colonoscopy, CT cardiac screening and whole-body CT in asymptomatic patients) and CT imaging of children. Shortening of the scanning time to around 1 second, eliminating the strict need for subject to remain still or be sedated, is one of the main reasons for large increase in the pediatric population (especially for the diagnosis of appendicitis). CT scans of children have been estimated to produce non-negligible increases in the probability of lifetime cancer mortality, leading to calls for the use of reduced current settings for CT scans of children. These calculations are based on the assumption of a linear relationship between radiation dose and cancer risk; this claim is controversial, as some but not all evidence shows that smaller radiation doses are not harmful. Estimated lifetime cancer mortality risks attributable to the radiation exposure from a CT in a 1-year-old are 0.18% (abdominal) and 0.07% (head)—an order of magnitude higher than for adults—although those figures still represent a small increase in cancer mortality over the background rate. In the United States, of approximately 600,000 abdominal and head CT examinations annually performed in children under the age of 15 years, a rough estimate is that 500 of these individuals might ultimately die from cancer attributable to the CT radiation. The additional risk is still very low (0.35%) compared to the background risk of dying from cancer (23%). However, if these statistics are extrapolated to the current number of CT scans, the additional rise in cancer mortality could be 1.5 to 2%. Furthermore, certain conditions can require children to be exposed to multiple CT scans. Again, these calculations can be problematic because the assumptions underlying them could overestimate the risk.
In 2009 a number of studies appeared that further defined the risk of cancer that may be caused by CT scans. One study indicated that radiation by CT scans is often higher and more variable than cited and each of the 19,500 CT scans that are daily performed in the US is equivalent to 30 to 442 chest x-rays in radiation. It has been estimated that CT radiation exposure will result in 29,000 new cancer cases just from the CT scans performed in 2007. The most common cancers caused by CT are thought to be lung cancer, colon cancer and leukemia with younger people and women more at risk. These conclusions, however, are criticized by the American College of Radiology (ACR) that maintains that the life expectancy of CT scanned patients is not that of the general population and that the model of calculating cancer is based on total body radiation exposure and thus faulty.
CT scans can be performed with different settings for lower exposure in children, although these techniques are often not employed. Surveys have suggested that currently, many CT scans are performed unnecessarily. Ultrasound scanning or magnetic resonance imaging are alternatives (for example, in appendicitis or brain imaging) without the risk of radiation exposure. Although CT scans come with an additional risk of cancer (it can be estimated that the radiation exposure from a full body scan is the same as standing 2.4 km away from the WWII atomic bomb blasts in Japan), especially in children, the benefits that stem from their use outweighs the risk in many cases. Studies support informing parents of the risks of pediatric CT scanning.
2. RESEARCH PROBLEM
The research problem of the study is to analyze the turnaround time in Radiology (CT scan). It is observed that the turnaround time is too long in CT scan. This clearly implies that the total revenue gets affected. Also the HR department highlights that the turnaround time in CT scan was high. Hence it was decided to conduct a research on minimizing turnaround the time in the Radiology (CT scan).
3. RESEARCH OBJECTIVE
1. To measure the turnaround time in Radiology (CT Scan).
2. To identify the causes of any delay in generation of report.
3. To find out the delay with respect to specific process to CT scan.
4. To find out the potential causes of the defect.
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