TY - JOUR
T1 - 0° vs. 180° CT localiser
T2 - The effect of vertical off-centring, phantom positioning and tube voltage on dose optimisation in multidetector computed tomography
AU - Al-Hayek, Yazan
AU - Zheng, Xiaoming
AU - Davidson, Rob
AU - Hayre, Christopher
AU - Al-Mousa, Dana
AU - Finlay, Campbell
AU - Spuur, Kelly
N1 - Funding Information:
I would like to acknowledge all the staff working in I-MED Radiology Network / Wagga Wagga for their timely support, and I would like to give my special thanks to The Hashemite University for their generosity with my PhD scholarship.
Publisher Copyright:
© 2021 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology
PY - 2022/3
Y1 - 2022/3
N2 - Introduction: Patient positioning is an essential consideration for the optimisation of radiation dose during CT examinations. The study objectives seek to explore the effects of vertical off-centring, localiser direction (0° and 180°), and phantom positioning (supine and prone) on radiation dose, using three different tube voltages in multidetector computed tomography (MDCT) imaging. Methods: The trunk of a PBU-60 anthropomorphic phantom was imaged using a Discovery CT750 HD – 128 slice (GE Healthcare). Images employing 0° and 180° localisers were acquired in supine and prone orientation for each combination of vertical off-centring (±100, ±60 and ±30 mm) and different tube voltages (80, 120 and 140 kVp), using the system’s automatic tube current modulation (ATCM) function. The displayed volume CT dose index (CTDI
vol) and dose length product (DLP) were recorded. Results: With incremental table off-centring of ±100 mm, the dose at 120 kVp in the supine position ranged from 63% to 196% (0° localiser) and from 66% to 191% (180° localiser) as compared to iso-centre. While in the prone position, the dose ranged from 62% to 195% (0° localiser); and 62% to 193% (180° localiser), with a notable dose increase at higher tube voltages. Dose variation and vertical off-centring showed a significant relationship for both 0° and 180° localisers (r = 0.94 and 0.96, respectively, P < 0.001). The CTDI
vol variation between supine and prone phantom positions at ±100 mm off-centring was 0.22 mGy (2.9%), and 0.19 mGy (2.3%) when the 0° and 180 ° localisers were utilised, respectively. Conclusions: Phantom off-centring and localiser direction evidenced large dose variation. It is recommended that the 0° localiser is employed during CT examinations, in order to minimise the potential additional radiation dose which may result from off-centring and the use of lower tube voltages where clinically appropriate.
AB - Introduction: Patient positioning is an essential consideration for the optimisation of radiation dose during CT examinations. The study objectives seek to explore the effects of vertical off-centring, localiser direction (0° and 180°), and phantom positioning (supine and prone) on radiation dose, using three different tube voltages in multidetector computed tomography (MDCT) imaging. Methods: The trunk of a PBU-60 anthropomorphic phantom was imaged using a Discovery CT750 HD – 128 slice (GE Healthcare). Images employing 0° and 180° localisers were acquired in supine and prone orientation for each combination of vertical off-centring (±100, ±60 and ±30 mm) and different tube voltages (80, 120 and 140 kVp), using the system’s automatic tube current modulation (ATCM) function. The displayed volume CT dose index (CTDI
vol) and dose length product (DLP) were recorded. Results: With incremental table off-centring of ±100 mm, the dose at 120 kVp in the supine position ranged from 63% to 196% (0° localiser) and from 66% to 191% (180° localiser) as compared to iso-centre. While in the prone position, the dose ranged from 62% to 195% (0° localiser); and 62% to 193% (180° localiser), with a notable dose increase at higher tube voltages. Dose variation and vertical off-centring showed a significant relationship for both 0° and 180° localisers (r = 0.94 and 0.96, respectively, P < 0.001). The CTDI
vol variation between supine and prone phantom positions at ±100 mm off-centring was 0.22 mGy (2.9%), and 0.19 mGy (2.3%) when the 0° and 180 ° localisers were utilised, respectively. Conclusions: Phantom off-centring and localiser direction evidenced large dose variation. It is recommended that the 0° localiser is employed during CT examinations, in order to minimise the potential additional radiation dose which may result from off-centring and the use of lower tube voltages where clinically appropriate.
UR - http://www.scopus.com/inward/record.url?scp=85112680029&partnerID=8YFLogxK
U2 - 10.1002/jmrs.535
DO - 10.1002/jmrs.535
M3 - Article
SN - 2051-3895
VL - 69
SP - 5
EP - 12
JO - Journal of Medical Radiation Sciences
JF - Journal of Medical Radiation Sciences
IS - 1
M1 - jmrs.535
ER -