Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study

Abstract

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics.

Mechanical and Imaging Properties of a Clinical-Grade Kidney Phantom Based on Polydimethylsiloxane and Elastomer

“…Based on Table 5, greater attenuation occurred at 120 kVp, reducing the signal received by the detector, which explained the lower SNR values. In a noisy image, the image contrast is low; this is caused by a large amount of background signal due to the Compton scattering effect, consequently reducing the CNR of the image [21]. This explains why the 140 kVp scan reduced the CNR by 90%, compared with the 120 kVp value.…”

“…The obtained value was then compared to the typical CT numbers of normal human tissue, particularly that of the kidney. The information regarding the CT numbers and noise was used to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) [21]. In a digital image, the signal is defined as a resultant exposure demonstrated on the image display monitor.…”

“…Along with the exposure, there is an electronic noise that may be visualized along with the displayed image. The signal-to-noise ratio (SNR) is a method of measuring object detectability relative to noise in the digital image [21]. Higher image quality can be obtained by increasing the strength of the signal, which results in higher SNR than the amount of noise.…”

Applications of Medical Physics

“…The study of Muhammad et al [7] focuses on the possibility of reducing organ doses in pediatric CT chest-abdominal pelvis examination by optimizing the CT protocols. The effect of scan parameters such as tube voltage, tube current, slice collimation, pitch, and tube current modulation on image quality indices and organ doses are accordingly investigated.…”

Dose Estimation by Geant4-Based Simulations for Cone-Beam CT Applications: A Systematic Review

“…Nevertheless, these advances have resulted in a rise in radiation dose, being the medical exposure to ionizing radiation from CT examinations a major issue of concern nowadays [30][31][32][33][34][35][36]. Ionization radiation exposure can induce harmful biological effects, depending on the radiosensitivity of the organ, radiation dose, dose distribution, age, gender, or genetic factors [37].…”