CT radiation dose optimization and reduction for routine head, chest and abdominal CT examination

Abstract

The purpose of this study is to find an optimization approach to minimize the absorbed dose to adult patients undergoing CT examination, while maintain the diagnostic image quality. A single detector CT was considered, to represent typical practice in King Hamad University Hospital. We included 626 patients in this study and investigated radiation dose for three anatomical regions, head, chest and abdomen and pelvis. For each type of CT examination, two groups of patients were considered. 383 patients in Group I: were imaged according to the protocols set by the manufacturer. Group II: 243 patients were imaged according to the protocols set by our team after optimization. We were able to adjust the adjustable factors such as noise index, scan time, pitch, rotation time and slice thickness. For each examination the weighted volume CT dose index (CTDIvol) and dose length product (DLP) were recorded and noise is measured. Each study was also reviewed for image quality. Measured (CTDIvol, DLP) were compared to international reference levels. For Group I, the CTDIvol and DLP values were higher than the reference levels. After Dose optimization the CTDIvol and DLP values were significantly reduced to have lower values than the reference levels. The results of our study showed that the CTDIvol and DLP values taken from images done using the protocols set by the Ct machine developers are higher than the reference levels which indicate that manufacturers are focusing their efforts toward improving image quality rather than the minimizing the dose that can be given to the patient.

Utilization of sinogram affirmed iterative reconstruction on 128 multi slice computed tomography scan to reduce radiation dose and improve image quality on thorax multi slice computed tomography scan: chest phantom study

“…After reconstruction with SAFIRE, the image obtained was smoother. 1 The level of noise reduction is adjusted to the SAFIRE strength level setting, wherein increasing SAFIRE strength level will cause noise to decrease. In previous studies it was mentioned that the use of SAFIRE was able to reduce noise by 50-60% compared to using FBP.…”

“…Nowadays, medical equipment has experienced very rapid progress followed by technological developments that present one of the diagnostic imaging modalities called multi slice computed tomography (MSCT scan). 1 MSCT scan is capable of producing digital tomographic images, has good speed and volume coverage, provides better image quality especially at spatial resolution and temporal resolution, and has a faster scan time compared to other imaging modalities. 2 One of the MSCT scan tests is the 'thorax MSCT' which is capable of imaging the lungs and respiratory tract organs as well as being able to display both normal and pathological lung parenchyma.…”

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“…In this work it was used two different chest adult phantoms to observe the dose distribution and to obtain the dose index. Different protocols were used in the phantom CT scans using two X-ray tube voltages [12][13][14].…”

“…Air Kerma in PMMA (C k,100P,MMA ) was performed using a RADCAL ACCU-GOLD dosimetry set with a pencil ionizing chamber model 10 × 6-3CT. The protocol used to irradiate the central slice is presented in Table 2 [12,15].…”

“…In the examination room, the adult phantoms have been placed on the table and, with the aid of laser lights; they were oriented so that their central axis passed through the isocenter of the gantry during the table displacement [19,20]. They central area of the phantoms were scanned in helical mode with voltages of 120 and 135 kV using the system automatic control, electrical current in automatic, in the rage of 50 to 500 mA [12,13,20]. The scan distance was 10 cm, with pitch of 1,388 using 80 detectors of 0.5 mm.…”