Regarding published studies on
evaluation radiation doses for CT examinations, Kanal et al 38
calculated the DRLs and median values of CTDIvol, and DLP for CT from
1310727 of ten most common examinations
in the United States. They found an insignificant relationship between the patient size and DRLs and achievable doses
for head and neck examinations, however, the CTDIvol, DLP, and DRLs increased
with patient’s size for body examinations.
Toori et al 39
establish local reference levels for
patients undergoing common CT examinations Including chest, sinus, brain,
pelvic and abdomen in Iran. They reported differing values of the DLP, CTDIw,
and CTDIvol for the same examination among different centers. For example, the
CTDIw for pelvic was ranged from 7 to 16.3 and the DRLs defined to be 11
In 2014, Alzimami 40 assessed the dose in
182 paediatric patients undergoing
abdomen, chest, and brain helical CT examinations in Sudan. The range of age in
Alzimami study range between one month and ten years and weight between 5 and
29 kg. They reported the highest value of
DLP for the brain with 321 mGy·cm (effective dose = 2.05 mSv) and found a significant
relationship between patient dose and
technologist experience and CT protocol.
Concerning published studies on
evaluation radiation doses during routine fluoroscopy examinations, Wambani et
reported 83% of kerma area product for 455 adult patients using the integrated
measuring system were below international DRLs and 60% of 195 paediatric
patients below international DRLs, except the examination performed with longtime
found to be above international DRLs. Regarding the interventional radiology
examinations, Urairat et al 42
calculated the entrance skin dose to 120 patients undergoing brain
arteriovenous malformations, dural-arteriovenous fistula, transarterial oily-chemoembolisation
and femoral angiography in Thailand using built-in air kerma area product meter.
They found a difference between radiations doses in most interventional
examinations, but they detected the highest ESDs in therapeutic cerebral
angiography examinations with about 363 cGy.
Regarding published studies on
evaluating image quality and estimations radiation doses for mammography
examinations, ?lusarczyk-Kacprzyk et al 43
calculated the MGD for patients in Poland for 47 systems using ACR
accreditation phantom with methods described by Perry et al 24.
They calculated the MGD for breast simulated by 4.5 cm of PMMA and reported
only the large doses in computer radiography mammography systems, comparing
with several screen-film and fully digital systems. It is worth noting that
?lusarczyk-Kacprzyk et al 43
noticed that the image quality in the fully digital systems higher than other
systems, despite the relatively low doses recorded.
Methodology (not less than 1000 = 1004)
Eight major hospitals in Najran
will include in this study, namely, Maternity and Children Hospital, King
Khalid Hospital, Najran University Hospital, Najran General Hospital, Najran
Health Center – National Guard Health Affairs, Armed Forces Hospital, Habona General Hospital and Sharurah Hospital
(SH) to evaluate image quality and to measure the radiation doses for patients
undergoing common examinations in X-ray, fluoroscopy, mammography and CT.
For diagnostic x-ray equipment
the exposure parameters such as kVp, mAs and focus to skin distance (FSD) and
the patients’ anthropometric data will record directly by the technologist at
the time of examination. The tube output will be measured using an Unfors Xi
dosemeter. ESD will calculate for five routine radiographic examinations:
abdomen (AP), chest (AP), skull (AP), pelvis (AP), and cervical spine (LAT)
from the eight hospitals using DoseCal and CALDose
software. Regarding conventional x-ray units, this study will be a
complementary to a previous one that evaluated the ESDs for chest and lumbar
spine examinations 44,
but on a scale covering all hospitals in the Najran area as well as using an
additional software (CALDose, version X 5.0) to verify the obtained results.
The CALDose is standing for CALculation
of Dose for X-ray diagnosis and is Windows software based on EGSnrc Monte Carlo
code calculation to determine the organ absorbed doses, and cancer risks for
patients undergoing radiological procedures. It’s developed by the Department
of Nuclear Energy, Federal University of Pernambuco, Brazil. The software requires
the user to input the patients’ anthropometric data and technical exposure recorded
at the time of examination. Based on the tube output of the x-ray unit and
entrance surface air kerma, the software will calculate the incident air kerma.
This study will also be a
complementary to a previous one that evaluated the CTDIw for chest and head
examinations 45 and will be the second in a series of
reviews the dose collects from all hospitals in Najran using the same
fabricated phantoms developed locally in Najran University. The radiation dose
in CTs at all hospitals will be measured using an ionization chamber (type
Unfors Xi CT) and the image quality will be evaluated using Gammex 464 ACR CT
accreditation phantom. The quality of the image
will include evaluating the following: CT number, slice thickness, position,
alignment, CT number uniformity, low and high contrast resolution.
The radiation dose in terms
of MGD will be evaluated for all mammography systems in all hospitals with the
same method described by Perry et al 24.
The description of this method was explained below.
standard breast can be simulated using 5 cm thickness of PMMA, however, it’s
recommended to calculate the glandular dose for different PMMA
thicknesses. The exposure parameters
such as kVp, mAs, target and filter material (in the automatic exposure control
mode) should be recorded after exposing 2, 3, 4, 4.5, 5, 6 and 7 cm thickness
of PMMA. The average glandular dose (AGD) can be calculated to typical PMMA
thickness by the following equation:
AGD = Ka,i × g × c × s