TY - JOUR
T1 - Validation of calculation algorithms for organ doses in CT by measurements on a 5 year old paediatric phantom
AU - Dabin, Jérémie
AU - Mencarelli, Alessandra
AU - McMillan, Dayton
AU - Romanyukha, Anna
AU - Struelens, Lara
AU - Lee, Choonsik
A2 - Vanhavere, Filip
N1 - Score=10
PY - 2016/5/18
Y1 - 2016/5/18
N2 - Many organ dose calculation tools for computed tomography (CT) scans
rely on the assumptions: (1) organ doses estimated for one CT scanner can
be converted into organ doses for another CT scanner using the ratio of the
Computed Tomography Dose Index (CTDI) between two CT scanners; and (2)
helical scans can be approximated as the summation of axial slices covering
the same scan range. The current study aims to validate experimentally these
two assumptions.
We performed organ dose measurements in a 5 year-old physical anthropomorphic
phantom for five different CT scanners from four manufacturers.
Absorbed doses to 22 organs were measured using thermoluminescent dosimeters
for head-to-torso scans. We then compared the measured organ doses with
the values calculated from the National Cancer Institute dosimetry system for CT
(NCICT) computer program, developed at the National Cancer Institute.
Whereas the measured organ doses showed significant variability
(coefficient of variation (CoV) up to 53% at 80 kV) across different scanner
models, the CoV of organ doses normalised to CTDIvol substantially decreased
(12% CoV on average at 80 kV). For most organs, the difference between
measured and simulated organ doses was within �20% except for the bone
marrow, breasts and ovaries. The discrepancies were further explained by
additional Monte Carlo calculations of organ doses using a voxel phantom
developed from CT images of the physical phantom.
The results demonstrate that organ doses calculated for one CT scanner can
be used to assess organ doses from other CT scanners with 20% uncertainty
(k = 1), for the scan settings considered in the study.
AB - Many organ dose calculation tools for computed tomography (CT) scans
rely on the assumptions: (1) organ doses estimated for one CT scanner can
be converted into organ doses for another CT scanner using the ratio of the
Computed Tomography Dose Index (CTDI) between two CT scanners; and (2)
helical scans can be approximated as the summation of axial slices covering
the same scan range. The current study aims to validate experimentally these
two assumptions.
We performed organ dose measurements in a 5 year-old physical anthropomorphic
phantom for five different CT scanners from four manufacturers.
Absorbed doses to 22 organs were measured using thermoluminescent dosimeters
for head-to-torso scans. We then compared the measured organ doses with
the values calculated from the National Cancer Institute dosimetry system for CT
(NCICT) computer program, developed at the National Cancer Institute.
Whereas the measured organ doses showed significant variability
(coefficient of variation (CoV) up to 53% at 80 kV) across different scanner
models, the CoV of organ doses normalised to CTDIvol substantially decreased
(12% CoV on average at 80 kV). For most organs, the difference between
measured and simulated organ doses was within �20% except for the bone
marrow, breasts and ovaries. The discrepancies were further explained by
additional Monte Carlo calculations of organ doses using a voxel phantom
developed from CT images of the physical phantom.
The results demonstrate that organ doses calculated for one CT scanner can
be used to assess organ doses from other CT scanners with 20% uncertainty
(k = 1), for the scan settings considered in the study.
KW - CT
KW - anthropomorphic phantom
KW - organ dose
KW - Monte Carlo simulation
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/20085476
U2 - 10.1088/0031-9155/61/11/4168
DO - 10.1088/0031-9155/61/11/4168
M3 - Article
SN - 0031-9155
VL - 61
SP - 4168
EP - 4182
JO - Physics in Medicine and Biology
JF - Physics in Medicine and Biology
ER -