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Table 4. Comparison of IDRLs for CTA examinations with published DRL values. Dosimetric quantities

This study CTDI vol( HospitalA) DLP

CTDI vol( Hospital B) DLP

CTDI vol( Hospital C) DLP

CTDI vol( Hospital D) DLP

DRLs Upper Limb

Brain	Carotids	Pulmonary
		embolism

Abdominal aorta

Total aorta

Lower Limb

16.05 26.1 13.95 3.18 9.69 5.12 7.49

1059.81	1370.48	1303.85	321.38	1453.79	1346.47	600.3
–	51.22	19.45	6.97	12.14	–-	16.07

–	1412.73	1384.85	717.24	1338.02	–-	1261.46
–	–	9.07	11.52	9.41	10.74	9.4

–	–	819.49	487.56	1018.17	1860.74	860.98
–	–	5.98	3.87	–	–	6.53

–			–	596	357	–	–	724
( MacGregor et al., 2015)	CTDI vol	–	–	–	16	–	–
	DLP	–	–	–	579	–	–	–
( Salama et al., 2017)	CTDI vol	–	–	–	–-	36.7	–	36.7
	DLP	–	–	–	–-	1317.8	–	1317.8
( Qurashi et al., 2015)	CTD Ivol	–	–	–	18	–	–	–
	DLP	–	–	–	480	–	–	–
( Harun et al., 2020)	CTDI vol	–	–	–	9	–	–	–

	DLP	–	–	–	329	–	–	–
( Treier et al., 2010)	CTDI vol	–	65	20	15	15	–	–
	DLP	–	1000	500	450	650	–	–
( Foley et al., 2012)	CTDI vol	–	–	–	12.5	–	–	–
	DLP	–	–	–	432	–	–	–
( Matsunaga et al., 2019)	CTDI vol	–	73.5	–	–-	–	–	–
	DLP	–	1223.8	–	–-	–	–	–
( Shrimpton et al., 2018)	CTD Ivol	–	–	–	13	15	–	–
	DLP	–	–	–	441	1042	–	–
( Kim et al., 2015)	CTDI voL	–	42.7	–	–	–	–	–
	DLP	–	1854	–	–	–	–	–
( Zensen et al., 2021)	CTDI vol	–	13.7	–	–	–	–	–
	DLP	–	478.3	–	–	–	–	–
( Cho, 2013)	CTDI vol	–	26.7	–	–	–	–	–
	DLP	–	1816	–	–	–	–	–
( Aberle et al., 2020)	CTDI vol	–	–	11	–	–	–	–
	DLP	–	–	360	–	–	–	–
( Sulieman et al., 2024)	CTDI vol	–	–	–	–	–	–	17
	DLP	–	–	–	–	–	–	3562

other hospitals, favorably affecting the dose received by patients. Additionally, the protocols are 100 % monophasic, which is not the case in the other hospitals. During data collection, it was observed that all CT examinations at Hospital D were conducted in the presence of a radiologist, ensuring optimization of the scan length.

In contrast to Hospital D, Hospital B generally exhibited the highest DLP values. For the Brain CTA protocol, an analysis of acquisition parameters between Hospitals A and B revealed that they are nearly identical, except for the number of phases used. Hospital A employed two phases in 86 % of exams, whereas Hospital B used two phases in 97 % of exams. This increase accounts for the 9 % rise in DLP values( 1117.85 mGy x cm vs. 1233.17 mGy x cm). Furthermore,

LDRLs values in terms of CTDI vol experienced a substantial increase of approximately 45 %( 24.5 vs 45.06), which could be attributed to differences in the phantoms used for scanner calibration or the use of body phantoms for calibrating Brain CTA protocols. The differences in CTDI vol values can be significant due to variations in the radiation dose absorbed per unit length in a CT scan, influenced by factors like machine model and acquisition parameters( Ouma et al., 2023). Conversely, DLP values may not show significant differences because they represent the total radiation dose received by the patient over the entire scan. This is calculated by multiplying the CTDI vol by the scan length, which is greatly affected by the scan length and the number of series performed during the CT examination. In this regard, Benmessaoud et al.,( 2021b)

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