Introduction
The advent of computed tomography (CT) diagnostic radiology in the 1970s was a welcome milestone in the history of medical x-ray imaging. Its use in the medical field has increased dramatically. It is reported that more than 62 million CT scans per year are presently done in the United States alone [1, 2]. The high spatial resolution and high speed associated with CT are some factors that have allowed physicians to perform diagnosis of diseases and injuries faster, more accurately and safely than with the use of traditional imaging techniques [3]. However, even with these benefits of CT, there are high risks posed by the radiation exposure to patients during the process of CT imaging, including induced malignancy. This may be generally because CT radiation scans exhibit much greater radiation dose in comparison to the traditional X-rays.
In CT scans of the chest, for instance, a patient would be exposed by about 100 times the exposure amount of radiation in x-ray of the same body part, increasing the risk of cancer [1]. Therefore, a challenge exists to manufacturers of CT scanners (tomographs) to produce CT equipments that generate high quality images with low radiation dose exposure to patients. This report examines various CT radiation dose reduction strategies to determine the one which is most suitable for medical uses. There are a number of factors that will be involved, including the scanning parameters that affect CT radiation dose such as scanner geometry; tube current (mAs) and voltage (kVp); length, scanning modes and collimation; gantry rotation time; pitch and table speed; and shielding [2]. Kalra et al [2] notes that a “technologist monitoring the examination can control most of these parameters and modulate them to obtain the desired image quality”. The CT dose index (CTDI), which is the main radiation dose descriptor in computed tomography [2] will also be evaluated.
Aim
The aim of this research project is to identify the appropriate CT radiation dose reduction strategies for use in medical x-ray imaging, the ultimate goal being to identify the most effective strategy.
Significance
The significance of this report project is that it will reveal to manufacturers of CT tomographs the best options available for CT radiation dose reduction, while to medical practitioners it will highlight the possibilities of reducing the amount of radiation exposed to patient. This would in turn reduce the risks associated with radiation and promote CT as an effective tool in medical diagnosis.
Objective
The objective of the study is to discover the most appropriate strategy for CT dose reduction without compromising the image quality of scan, where a comparison of the different strategies that takes into account various CT radiation dose metrics, including scanner radiation output, effective dose and organ dose will be done.
Research methodology
The research study will involve primarily a review of various literatures of the subject matter. A number of peer-reviewed articles will be examined and at least 30 articles with the most relevant information in regards to the subject matter will be used as the source of the project data. The extracted data will involve the reported CT radiation dose achieved through various reduction strategies, and the image quality of these CT reduction strategies. Variables such as patient size, scans numbers, Kvp and mAs will also be sought. A comparison of the reduction strategies will then be done taking into account the radiation dose and the image quality achieved as well as the variables mentioned above.
The search of the peer-reviewed articles will done on renowned journal and information databases such as Science direct, Pubmed/Medline, ProQuest and Curtin library databases. Keywords relating to the eeffectiveness of CT dose reduction strategies will be used. Microsoft Excel 2007 will be used to record the acquired data to facilitate in the analysis processes.
References
Brenner DJ & Hall EJ. Computed tomography – an increasing source of radiation exposure. N Engl J Med. 2007; 357(22):2277-84.
Kalra MK, Maher MM, Toth TL, Hamberg LM, Blake MA & Shepard J-A. Strategies for CT Radiation Dose Optimization1. Radiology. 2004; 230(3): 619-628.
Yu, L, Liu, X, Leng S, Kofler, JM & Ramirez-Girald, JC. Radiation dose reduction in computed tomography: techniques and future perspective. Imagine Med. 2009; 1(1): 65-84.
McCollough CH. Patient dose in cardiac computed tomography. Herz. 2003; 28(1): 1-6.