Assessment of Volumetric Computed Tomography Dose Index (CTDIvol) for selected computed tomography scanners in Uganda

doi:10.21203/rs.3.rs-3849436/v1

Download PDF

Research Article

Assessment of Volumetric Computed Tomography Dose Index (CTDIvol) for selected computed tomography scanners in Uganda

https://doi.org/10.21203/rs.3.rs-3849436/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

The Atomic Energy Council conducted routine inspections on 42 facilities with Computed Tomography (CT) scanners in Uganda to verify the compliance of their CTDIvol with the established regulatory machine performance standards. The findings of the inspections revealed that most scanners complied with the recommended regulatory dose limits for the adult abdomen, adult head, and pediatric abdomen examinations. The mean optimal doses deduced from the study were 5 mGy, 15 mGy, and 50 mGy for pediatric abdomen, adult abdomen, and head examinations respectively. However, a considerable number of scanners, 4%, 6%, and 20% produced doses exceeding the regulatory limits for pediatric abdomen, adult abdomen, and adult head respectively. It was established that some of the corrective actions for scanners that produced high doses exceeding the regulatory limit were (1) varying of tube current parameters, and (2) varying of pitch. The scanners Y and Z produced exceedingly very high doses compared to the regulatory limit and were recommended for immediate suspension to correct for the dose irregularity. The study also established that about 50% of CTs were of the modern era with improved technologies of dose optimization and minimization. However, the operators had limited access rights to interact and utilize these technological advancements. It was therefore, recommended that all stakeholders involved in supplying, acquiring, and operating these machines to ensure that the end users (radiation workers) acquire adequate end-user training and retraining programs. We also recommend the facilities to perform acceptance and commissioning tests and periodic quality control tests to ensure compliance of the CT machines with the regulatory dose limits.

CTDIvol

pitch

dose optimization

diagnostic imaging

regulatory dose limit

compliance

The mean optimal doses from the study were 5 mGy, 15 mGy, and 50 mGy for pediatric abdomen, adult abdomen, head examinations respectively.
The variation of pitch and tube current parameters has a considerable effect on the CT dose output.
Most CTs complied with the regulatory dose limit of 80, 30, and 25 for adult head and abdomen, and pediatric abdomen respectively.

Since the introduction of Computed Tomography (CT) in the 1970s as a diagnostic tool, CT examinations have become the most viable tools for diagnostic imaging applications. According to [1], Japan statistically has the highest density of CT scanners per million people followed by Australia. This is generally attributed to the medical personnel preferring the use of CT for different diagnostic imaging scenarios [2–6]. This is because of the assurance of a better and improved image quality of 3D cross-section CT images combined with the less requirement of patient preparation for scanning [7–9].

The most concern with the increased use of CT is the associated dose resulting from radiation exposure mostly incurred by patients as studied in several cases [9–15]. This justifies the need for ensuring dose optimization in CT practices. While the traditional principles of radiation protection like the ALARA principles still apply [16–18], the modern CTs are designed with techniques of dose optimization. For example the use of Automatic Exposure Control mode (AEC) [19], iterative image reconstruction [20, 21], and others discussed extensively by [22].

The International Commission on Radiation Protection (ICRP) recommends at least each country to develop Dose Reference Levels (DRLs) for each imaging modality or adopt applicable international recommended standards for dose levels [23–25]. Some of the recent works tempting to develop DLRs in the African region include [26] in Kenya, [27, 28] in Uganda, [29] in Ghana, and others. However, generally it was found out that locally developed DRLs tend to deviate from the ICRP recommended dose levels [26, 28, 30, 31].

The CT dose is determined by the number of X-rays generated at different energies depending on the kilovoltage (kV). For any absorbing medium, the absorbed dose in each scan is the weighted computed tomography dose index (CTDIw). This is a measure of the air karma K(z) over a 100 mm length with the total collimated beam width of NT (N representing slice number, and T as the nominal detector width). The volumetric computed tomography dose index (CTDIvol) accounts for the spacing created during axial and helical scans while the normalized value of CTDI accounts for pitch which is the unit tube exposure in a single scan, refer to [25] for details of the equations and derivations. For daily CT dose measurements, we use CTDIvol as a representative of the average dose along x, y, and z planes for a scanned length of 100 mm per scan rotation of each couch increment. However, it’s not effective in representing the absorbed dose that quantifies the stochastic risk to the patient [32, 33]. We should note that there are other parameters for quantifying CT dose for example dose length product (DLP), size specific dose (SSD) and effective dose [7, 32, 34, 35].

In a recent audit of radiology facilities, [36] established that the number of CT facilities in Uganda had risen to about 25 in 2020. Currently according to Atomic Energy Council database, the CT facilities have risen to about 50 in a period of 3 years, with most of them spread in the greater Kampala region and a few facilities scattered in the Northern, Eastern and Western regions. The Atomic Energy Council which is mandated to regulate the peaceful application of ionizing radiation conducts inspections on these facilities to verify the compliance of their practices with respect to the established regulatory standards. These standards include dose limits for different practices, authorization, and other requirements of the Atomic Energy Act, No 24 of 2008 [37] and Atomic Energy Regulations, 2012 [38]. Therefore, this study is aimed at assessing and analyzing the CT dose output for different CT scanners in different CT facilities in Uganda. Also, this is significant for contributing to the establishment of national DRLs.

The data collected included CT specific exposure parameters (kV, mA, scan time (s), pitch, effective mA, and number of slices), scanner specifications (manufacturer, model & serial number, and manufacturer date), and the dose parameters (CTDI and DLP). The PMMA head and body phantoms were placed on a couch to simulate the head and abdomen of the male adult patients aged between 30–50 years respectively. These were scanned in a helical mode using the pre-set protocols at each scan for different positions of CT sensor in the phantom (centre, 12 o’clock, 3 o’clock, 6 o’clock and 9 o’clock) respectively. For each scan, the CTDI was measured using a Raysafe-X2 CT Sensor (Model: 8252030-3, S/N: 269736) and a recording made on a computer. The head phantom was also used to simulate the pediatrics’ abdomen aged between 8–15 years and the above procedure repeated.

For every scan, the displayed and measured CTDI values were recorded in addition to the scanner pre-set protocols (kV, mA, scan/ exposure time, pitch, rotation time). The displayed CTDI on the console was used as a quality control test for our measurements. The CTDI values to be considered for further analysis had to comply with the limit of < 20% deviation calculated as shown in Eq. 1.

$Percentage devaition= \frac{\left|measured-displayed\right|}{displayed} x100$ 1

The CTDIvol for each examination was calculated using equations 2 and 3 and compared with the regulatory limit [39] as shown in Table 1 to verify the compliance. A statistical study using MATLAB (version R2022a – academic use, MathWorks Inc.) was also done.

$CTDIw=\left(\frac{1}{3}x\text{C}\text{T}\text{D}\text{I}\text{c}\text{e}\text{n}\text{t}\text{r}\text{e}\right)+\left(\frac{2}{3}xCTDIperiphery (average of 12 o’clock +3 o’clock+6 o’clock+9 o’clock positions)\right)$ 2

$CTDIvol=\raisebox{1ex}{$CTDIw$}\!\left/ \!\raisebox{-1ex}{$Pitch$}\right.$ 3

Table 1

A table showing the recommended regulatory CTDIvol limits for different examinations.
Examination	Regulatory limit of CTDIvol (mGy)
Adult head	80
Adult abdomen	30
Pediatric abdomen	25

Figure 1 shows the comparison of the computed dose (CTDIvol) values for different CT examinations in different CT facilities with the regulatory limit provided in Table 1. It was observed that 71% of the inspected facilities complied with the regulatory dose limits. The CTDI values of the pediatric abdomen and adult abdomen examinations showed the highest compliance rate compared to the adult head examinations.

Only 2 scanners (A and C) produced a dose exceeding the regulatory limit for pediatric abdomen. The CTDI value of scanner C was 31.8 mGy which was 27% above the regulatory limit while the CTDI value of Scanner A was about 8% above the limit. Most of the dose values were within a range of about 3–5 mGy when compared to the recommended limit of 25 mGy. The scanners FF, HH and R had much lower doses of about 1 mGy. While the very low doses are significantly important for dose minimization to pediatric patients, they may affect the image quality which is an important consideration for the purpose of imaging. The appropriate imaging technique should provide the maximum information to aid further diagnosis at a minimal dose [40, 41].

Three scanners (E, Y & Z) produced a dose exceeding the recommended limit of adult abdomen, that’s 33.6, 107.5 & 40.1 mGy which results in an excess dose of about 12%, 258% and 33%, respectively above the recommended limit. The dose of scanner Y is very high, and immediate action was recommended to correct this anomaly. From the discussion by [7], several factors contribute to patient dose (effective dose). These include patient parameters, protocol attributes, application of dose minimization techniques and scanner parameters. For this study, the interest is on scanner properties like kV, mA, scan/exposure time, pitch, and number of slices which contribute to CTDI for a specific scanner. The pitch of scanner Y was 0.6 which was the lowest when compared with the selected scanners as shown in Fig. 2. Most adult abdomen CTDI values lie in a range between 10–15 mGy from which we can conclude as an optimal value of dose for this examination based on the study. From a perspective of dose optimization and purpose of the examination, the adult abdomen dose exhibits a better variation when compared with the pediatric abdomen dose. The scanner F has a very low dose of about 2 mGy which may not be appropriate for the examination purpose.

Nine CT scanners accounting for 20% of the total selected CTs produced a dose exceeding the recommended dose of 80 mGy as shown in Table 2.

Table 2

A table showing the list of CT scanners with dose exceeding the recommended limit.
CT scanner	% above the recommended limit	Pitch	kV
B	27	0.55	130
F	25	0.55	130
G	19	0.55	130
V	28	0.55	130
X	31	0.55	130
Y	138	0.55	130
Z	120	0.297	120
BB	41	0.531	120
II	29	0.55	130

For the purposes of optimizing patient doses, an immediate action is required for the scanners Y and Z which produced the highest doses above the recommended limit to correct. From the table, we study other dose contributing parameters [7] like pitch and kV for the 9 scanners and note the following;

The kV variation is generally constant for all the scanners.

All the scanners exhibit a nearly constant pitch of about 0.55 except scanner Z with the lowest pitch of 0.297.

The pitch values of the scanners in Table 2 are lower compared to other scanners that complied with the regulatory limit.

We shall discuss the variation of specific scanner parameters with respect to dose contribution later in the discussion. Otherwise for other scanners, the adult head dose values were in a range of about 40–60 mGy which gives an appropriate optimal dose compared to the recommended value of 80 mGy.

CTDI is the dose output of the CT machine which later contributes to the patient dose (effective dose) depending on the patient factors like age, weight, sex, and body organ being exposed. Therefore, what solely determines CTDI are scanner specific factors as already highlighted in the previous literature [7, 42, 43]. From the results, most CT scanners generally complied with the regulatory limits of dose for adult abdomen (93%), pediatric abdomen (96%) and adult head (80%). This represents a significant percentage of compliance for purposes of dose optimization to patients. From the analysis in section 3, we deduce the mean optimal dose values for each examination, that is about 5 mGy, 15 mGy, and 50 mGy for pediatric abdomen, adult abdomen, and adult head examinations respectively.

However, we identified some scanners that produced very high doses exceeding the recommended dose limits. The isolated cases were scanners Y for the adult abdomen, and Y and Z for the adult head. We noticed that scanner Y consistently produced higher doses at all examinations. In the analysis, we singled out pitch which might be contributing to the dose. Figure 3 shows the pitch values for each CT and examination under the study.

For a certain considerable percentage of CT scanners under study, their dose values increase with a decrease in pitch values. However, scanners A, C, L, N, and T have the same pitch for different examinations and yet their doses were within the regulatory limits. Note that pitch accounts for the factor of table increment per scan rotation in helical mode. Therefore, pitch decreases as the couch distance increases per scan rotation, and this increases the dose to the patient. Hence, a clear relationship of inverse proportionality between the dose and pitch exists [25, 44, 45]. However, this is different in the modern CT designs like multi slice CTs which offer effective compensation to high doses resulting from low pitch values. Such provisions of dose compensation include use of automatic exposure control and tube current modulation to maintain a constant effective mA and variation of rotation time. A detailed discussion of these misconceptions about pitch relationship with dose can be found in [46]. Additionally, pitch is an important factor for image quality; lower pitch offers a high contrast and hence better image quality with reduced artifacts [47]. Therefore, from a perspective of justification, the radiation worker may opt to use a lower pitch for some examinations at a minimal high CT dose, and this is mostly recommended for head examinations [25].

We made recommendations for the scanners that produced doses to be investigated by qualified biomedical engineers to correct the anomaly. Table 3 shows results of the follow up. It was observed that new examination protocols were developed using the different tube current factors for all the 3 scanners (BB, F and MM) and pitch values for scanner F. Studies have shown that increasing tube current linearly increases CT dose [48]. The tube current determines the rate of production of X-ray (photon per second) and hence reduces the noise in the CT images. This relationship is complicated in the modern CT designs which use effective mAs given in Eq. 4. This is used as for dose compensation tool in the automatic exposure control mode for very low pitch values as discussed by [25, 46].

$effective mAs= \frac{mA*rotation time}{pitch}$ 4

We were limited in the study by the variation of tube current parameters recorded during the study. However, we can deduce a clear relationship existing between dose, pitch, mA, and rotation time. While tube potential is an important parameter for dose, we did not discuss its variation since it was generally constant for most CTs for a specific examination under the study.

Table 3

A table showing the findings from the follow up exercises on the previously noncompliance facilities.
CT scanner	Examination		kV	Tube current variation	Pitch	CTDI (mGy)
BB	Adult head	Initial	120	151mA	0.531	112.59
BB	Adult head	After	120	100mA	0.533	64.0
F	Adult head	Initial	130	30mA	0.55	100.05
F	Adult head	After	130	230mA	0.80	73.180
MM	Adult head	Initial	130	96mAs	0.55	103.12
MM	Adult head	After	130	13mA	0.55	71.8

A further study is required to examine how other factors contribute to the dosage above for the selected scanners. This aids in the assessment of the expected doses subject to the patients during treatment planning and preparation. Other factors of consideration include the scanner type, for example single slice versus the multi slice scanners [44, 49, 50], dose reduction techniques like automatic exposure control, use of interactive image reconstruction, tube current modulation techniques and others detailed by [22]

The factors discussed above are all variable factors that may be applied for dose minimization. Their applicability and utilization however depends on facility specifics which are detailed in quality assurance (QA) and radiation protection (RP) programs. For example, the provisions of using a lower pitch for a minimal high dose for specific CT examination should be clearly documented in a QA program and provisions for compensation of such high dose. Therefore, the QA and RP programs should be maintained up to date with provisions of improved technologies for dose minimization [22, 51], and image quality [20, 52]. One of the most important components of these programs is the quality control tests done routinely to check machine performance with respect to established regulatory limits. While the regulatory body established a fairly high rate of compliance with the dose limits during the study, the other cases of noncompliance should have been identified by the facilities if control tests were implemented on a routine basis. One notable challenge was the knowledge gap for the radiation workers to fully interact and utilize the sophisticated technology of the new modern scanners, yet they have a considerable percentage of about 50% of the total CTs in the Country.

In conclusion therefore, the scanners Y and Z need immediate attention to correct for the very high dose output for the adult head for the two scanners and the adult abdomen for only Y. Additionally, the other CT scanners that produced doses exceeding the recommended regulatory limit also require action to correct for the noncompliance in dose limit. We note that our study has a limitation that there was no consideration of other factors of image quality, scanner types and others. Therefore, we may not conclusively deduce the most appropriate action for each scanner that produced high dose. However, we expect the facilities with their qualified experts to investigate and make corrective actions and decisions on how to ensure that the CTDI complies with the regulatory limit. The practical applicability of dose limitation, optimization and justification principles forms a basis for radiation protection programs in any medical facility utilizing ionizing radiation [53, 54]. And hence the role of Atomic Energy Council as a regulatory body of ionizing radiation practices in Uganda is to ensure that the radiation protection and quality assurance programs are implemented appropriately and effectively.

Acknowledgements

The authors of this paper wish to acknowledge the efforts of all technical staff of Atomic Energy Council in activities of data collection during inspections. These are Birungi Joshua, Byamukama Abdul, Asaba Ruth, Mukyaala Kevin, Menya Richard, Emong Christine Edna, Kagulire Daniel, Sekyanzi Deo, Kisaakye John, Kukiriza Grace, Maberi Wattisa Samuel, Katusiime Dornum, Nasuuna Susan, Sekyaya Charles, Nalumansi Susan, Nabalayo Cate, and Senyonga Maclian.

Author contributions

WR did the data analysis and the drafted the manuscript, LN and NN developed the proposal, developed the data collection sheet, and supervised the data collection, and NDL supervised the whole process of the research. All authors reviewed the manuscript and endorsed it.

Funding

No fundings was received for this study.

Availability of data and materials

All the necessary data and materials have been included in this manuscript.

Ethics approval and consent to participate: Not applicable.

Consent for publication: Not applicable

Competing interests: None

Stewart C. Computer tomography scanner density by country 2021. Statista. 2023.
Maxwell S, Ha NT, Bulsara MK, Doust J, Mcrobbie D, O’Leary P, et al. Increasing use of CT requested by emergency department physicians in tertiary hospitals in Western Australia 2003–2015: an analysis of linked administrative data. BMJ Open. 2021;11:e043315.
Randen A, Van, Bipat S, Zwinderman AH, Ubbink DT, Stoker J, Boermeester MA. Acute Appendicitis: Meta-Analysis of Diagnostic Performance of CT and Graded Compression US Related to Prevalence of Disease. Radiology. 2008;249:97–106.
Hricak H, Brenner DJ, Adelstein SJ, Frush DP, Hall EJ, Howell RW, et al. Managing radiation use in medical imaging: A multifaceted challenge. Radiology. 2011;258:889–905.
Helena N, Bastos P, Felipe A, Alves F, Luiza A, Pavan M, et al. ABDOMEN–PELVIS COMPUTED TOMOGRAPHY PROTOCOL OPTIMIZATION: AN IMAGE QUALITY AND DOSE ASSESSMENT. Radiat Prot Dosimetry. 2018;184:66–72.
Sookpeng S, Martin CJ, Butdee C. The investigation of dose and image quality of chest computed tomography using different combinations of noise index and adaptive statistic iterative reconstruction level. Indian J Radiol Imaging. 2021;29:53–60.
Thakur Y, Mclaughlin PD, Mayo JR. Strategies for Radiation Dose Optimization. Curr Radiol Rep. 2013;:1–10.
Power SP, Moloney F, Twomey M, James K, O’Connor OJ, Maher MM. Computed tomography and patient risk: Facts, perceptions and uncertainties. World J Radiol. 2016;8:902.
Smith-Bindman R, Miglioretti DL, Johnson E, Lee C, Feigelson HS, Flynn M, et al. Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996–2010. JAMA. 2012;307:2400–9.
Mettler FA, Bhargavan M, Faulkner K, Gilley DB, Gray JE, Ibbott GS, et al. Radiologic and nuclear medicine studies in the United States and worldwide: Frequency, radiation dose, and comparison with other radiation sources – 1950–2007. Radiology. 2009;253:520–31.
Fazel R, Krumholz HM, Wang Y, Ross JS, Chen J, Ting HH, et al. Exposure to Low-Dose Ionizing Radiation from Medical Imaging Procedures. N Engl J Med. 2009;361:849–57.
Mettler FAJ, Wiest PW, Locken JA, Kelsey CA, Mettler J, Wiest PW, et al. CT scanning: Patterns of use and dose. J Radiol Prot. 2000;20:353–9.
Schauer DA, Linton OW. National Council on Radiation Protection and Measurements report shows substantial medical exposure increase. Radiology. 2009;253:293–6.
Freudenberg LS, Beyer T. Subjective perception of radiation risk. J Nucl Med. 2011;52 SUPPL. 2:29–35.
Sakhnini L. CT radiation dose optimization and reduction for routine head, chest and abdominal CT examination. Radiol Diagn Imaging. 2017;2:1–4.
Solomon DZ, Ayalew B, Dellie ST, Admasie D. Justification and Optimization Principles of ALARA in Pediatric CT at a Teaching Hospital in Ethiopia. Ethiop J Health Sci. 2020;30:761–6.
England A, Alzyoud K, Yi XT, Zanardo M, Gerasia R. Optimization of the procedure ALARP / ALARA. International Covid-19 support for Radiographers and Radiological Technologists. 2020; December:1–7. https://www.learning.isrrt.org/course/view.php?.
Krupinski EA. Optimisation in daily practice – it’s more than just radiation dose. J Med Radiat Sci. 2020;67:2–4.
Söderberg M, Gunnarsson M, Sderberg M, Gunnarsson M. Automatic exposure control in computed tomography an evaluation of systems from different manufacturers. Acta radiol. 2010;51:625–34.
Greffier J, Frandon J, Larbi A, Beregi JP, Pereira F. CT iterative reconstruction algorithms: a task-based image quality assessment. Eur Radiol. 2020;30:487–500.
Nesteruk KP, Bobić M, Sharp GC, Lalonde A, Winey BA, Nenoff L, et al. Low-Dose Computed Tomography Scanning Protocols for Online Adaptive Proton Therapy of Head-and-Neck Cancers. Cancers (Basel). 2022;14:5155.
Kaza RK, Platt JF, Goodsitt MM, Al-Hawary MM, Maturen KE, Wasnik AP, et al. Emerging Techniques for Dose Optimization in Abdominal CT. Radiographics. 2014;34:4–17.
Kumsa MJ, Nguse TM, Ambessa HB, Gele TT, Fantaye WG, Dellie ST. Establishment of local diagnostic reference levels for common adult CT examinations: a multicenter survey in Addis Ababa. BMC Med Imaging. 2023;23:1–9.
International Atomic Energy Agency (IAEA). Dosimetry in Diagnostic Radiology: An International Code of Practice. 2007.
IAEA. Quality Assurance Programme for Computed Tomography: Diagnostic and Therapy Applications. Vienna: INTERNATIONAL ATOMIC ENERGY AGENCY; 2012.
Korir GK, Wambani JS, Korir IK, Tries MA, Boen PK, NATIONAL DIAGNOSTIC REFERENCE LEVEL INITIATIVE FOR COMPUTED TOMOGRAPHY EXAMINATIONS IN KENYA. Radiat Prot Dosimetry. 2015;168:ncv020.
Ayugi G, Oruru B, Kiragga F, Kisembo H, Kyagulanyi H. Establishment of Computed Tomography Diagnostic Reference Levels on Paediatric Patients in Uganda. J Med Diagnostic Methods. 2018;07:189–92.
Erem G, Ameda F, Otike C, Olwit W, Mubuuke AG, Schandorf C, et al. Adult Computed Tomography examinations in Uganda: Towards determining the National Diagnostic Reference Levels. BMC Med Imaging. 2022;22:1–12.
Inkoom S, Emi-Reynolds G, Nkansah A, Schandorf C, Boadu M. Adult medical x-ray dose assessments for computed tomography procedures in Ghana: a review. J Appl Sci Technol. 2014;19:1–9.
Muhogora W, Rehani MM. Review of the current status of radiation protection in diagnostic radiology in Africa. J Med Imaging. 2017;4:031202.
Kawooya MG, Kisembo HN, Remedios D, Malumba R, Del Rosario Perez M, Ige T et al. An Africa point of view on quality and safety in imaging. Insights Imaging. 2022;13.
Lee C. How to estimate effective dose for CT patients. Eur Radiol. 2020;30:1825–7.
The International Commissionon on Radiological Protection (ICRP). The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Annals of the ICRP; 2007.
Brenner D, Huda W. Effective dose: A useful concept in diagnostic radiology. Radiat Prot Dosimetry. 2008;128:503–8.
Gharbi S, Labidi S, Mars M, Chelli-Bouaziz M, Ladeb F. Effective Dose and Size Specific Dose Estimation with and without Tube Current Modulation for Thoracic Computed Tomography Examinations: A Phantom Study. Int J Medical, Heal Biomed Bioeng Pharm Eng, 2017. 2017;Vol:11:55–9.
Elsie K-M, Rosemary B, Michael Grace K, Aloysius Gonzaga M, Roy Clark B, Richard P, et al. An audit of registered radiology equipment resources in Uganda. Pan Afr Med J. 2020;37:295.
Atomic Energy Council (AEC). THE ATOMIC ENERGY ACT., 2008. Uganda; 2008.
Atomic Energy Council (AEC). The Atomic Energy Regulations., 2012. Uganda; 2012.
Faulkner K, Christofides S, Lillicrap S, Horton P, Malone J. Criteria for Acceptability of Medical Radiological Equipment used in Diagnostic Radiology, Nuclear Medicine and Radiotherapy. 2012.
EL MANSOURI M, Choukri A, Talbi M, Hakam OK. Impact of Tube Voltage on Radiation Dose (CTDI) and Image Quality at Chest CT Examination. Atom Indones. 2021;47:105–9.
Elnour H, Ahmed Hassan H, Mustafa A, Osman H, Alamri S, Yasen A. Assessment of Image Quality Parameters for Computed Tomography in Sudan. Open J Radiol. 2017;07:75–84.
Fernanda Stephanie S, Arnaldo Prata M. Dose Evaluation of Head CT Scans Using Phantom for Optimization Protocols. Int J Radiol Imaging Technol. 2022;8:1–6.
Goldman LW. Principles of CT: Radiation Dose and Image Quality. J Nucl Med Technol. 2007;35:213–25.
Mahesh M, Scatarige JC, Cooper J, Fishman EK. Dose and pitch relationship for a particular multislice CT scanner. AJR Am J Roentgenol. 2001;177:1273–5.
Wang G, Vannier MW. The effect of pitch in multislice spiral/helical CT. Med Phys. 1999;26:2648–53.
Ranallo F, Szczykutowicz T. The Correct Selection of Pitch and Rotation Time for Optimal CT Scanning – The Big Misconception; The Effects of Pitch on Image Quality and Patient Dose in Both Manual mA and AEC - mA Modulation Scanning Modes. In: Radiological Society of North America 2014 Scientific Assembly and Annual Meeting. Chicago; 2014.
Lestariningsih I, Lubis LE, Nurlely, Soejoko DS. Effect of pitch on CT image quality based on SNR evaluation using in house phantom. J Phys Conf Ser. 2019;1248:0–6.
Lira D, Padole A, Kalra MK, Singh S. Tube potential and CT radiation dose optimization. AJR Am J Roentgenol. 2015;204:W4–10.
Bashir U, Murphy A, Bell D. Pitch (CT). Reference Article: Radiopaedia.orgRadiopaedia.org. 2023. https://doi.org/10.53347/rID-18984.
Brix G, Nagel HD, Stamm G, Veit R, Lechel U, Griebel J, et al. Radiation exposure in multi-slice versus single-slice spiral CT: Results of a nationwide survey. Eur Radiol. 2003;13:1979–91.
Ginat DT, Gupta R. Advances in computed tomography imaging technology. Annu Rev Biomed Eng. 2014;16:431–53.
Wu M, Yin Z, De Man B. Model-based dose reconstruction for CT dose estimation. Med Phys. 2017;44:e255–63.
Do K-HH. General Principles of Radiation Protection in Fields of Diagnostic Medical Exposure. J Korean Med Sci. 2016;31(Suppl 1):6.
Kim JH. Three principles for radiation safety: time, distance, and shielding. Korean J Pain. 2018;31:145–6.

No competing interests reported.

Download PDF

Reviews received at journal
07 Aug, 2024
Reviews received at journal
31 Jul, 2024
Reviewers agreed at journal
30 Jul, 2024
Reviewers agreed at journal
29 Jul, 2024
Reviews received at journal
29 Jul, 2024
Reviewers agreed at journal
29 Jul, 2024
Reviewers agreed at journal
29 Jul, 2024
Reviewers agreed at journal
04 Feb, 2024
Reviewers invited by journal
30 Jan, 2024
Editor invited by journal
19 Jan, 2024
Submission checks completed at journal
19 Jan, 2024
Editor assigned by journal
19 Jan, 2024
First submitted to journal
09 Jan, 2024

You are reading this latest preprint version

Assessment of Volumetric Computed Tomography Dose Index (CTDIvol) for selected computed tomography scanners in Uganda

Status:

Version 1

Abstract

Figures

Highlights

1. INTRODUCTION

2. DATA AND METHODS

3. RESULTS AND ANALYSIS

4. DISCUSSION AND CONCLUSION

Declarations

References

Additional Declarations

Status:

Version 1