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 - 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
includes bibliographical references
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.
KW - Humans
KW - Multidetector Computed Tomography
KW - Patient Positioning/methods
KW - Phantoms, Imaging
KW - Radiation Dosage
UR - http://www.scopus.com/inward/record.url?scp=85112680029&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85112680029&partnerID=8YFLogxK
U2 - 10.1002/jmrs.535
DO - 10.1002/jmrs.535
M3 - Article
C2 - 34402591
AN - SCOPUS:85112680029
SN - 2051-3909
VL - 69
SP - 5
EP - 12
JO - Journal of Medical Radiation Sciences
JF - Journal of Medical Radiation Sciences
IS - 1
ER -