Reducing Radiation Dose to the Female Breast during CT Coronary Angiography: A Simulation Study Comparing Breast Shielding, Angular Tube Current Modulation, Reduced kV, and Partial Angle Protocols Using an Unknown-location Signal-detectability Metric

Purpose: The authors compared the performance of five protocols intended to reduce dose to the breast during computed tomography (CT) coronary angiography scans using a model observer unknown-location signal-detectability metric. Methods: The authors simulated CT images of an anthropomorphic female thorax phantom for a 120 kV reference protocol and five “dose reduction” protocols intended to reduce dose to the breast: 120 kV partial angle (posteriorly centered), 120 kV tube-current modulated (TCM), 120 kV with shielded breasts, 80 kV, and 80 kV partial angle (posteriorly centered). Two image quality tasks were investigated: the detection and localization of 4-mm, 3.25 mg/ml and 1-mm, 6.0 mg/ml iodine contrast signals randomly located in the heart region. For each protocol, the authors plotted the signal detectability, as quantified by the area under the exponentially transformed free response characteristic curve estimator (AˆFE), as well as noise and contrast-to-noise ratio (CNR) versus breast and lung dose. In addition, the authors quantified each protocol\u27s dose performance as the percent difference in dose relative to the reference protocol achieved while maintaining equivalentAˆFE. Results: For the 4-mm signal-size task, the 80 kV full scan and 80 kV partial angle protocols decreased dose to the breast (80.5% and 85.3%, respectively) and lung (80.5% and 76.7%, respectively) withAˆFE= 0.96, but also resulted in an approximate three-fold increase in image noise. The 120 kV partial protocol reduced dose to the breast (17.6%) at the expense of increased lung dose (25.3%). The TCM algorithm decreased dose to the breast (6.0%) and lung (10.4%). Breast shielding increased breast dose (67.8%) and lung dose (103.4%). The 80 kV and 80 kV partial protocols demonstrated greater dose reductions for the 4-mm task than for the 1-mm task, and the shielded protocol showed a larger increase in dose for the 4-mm task than for the 1-mm task. In general, the CNR curves indicate a similar relative ranking of protocol performance as the correspondingAˆFEcurves, however, the CNR metric overestimated the performance of the shielded protocol for both tasks, leading to corresponding underestimates in the relative dose increases compared to those obtained when using theAˆFEmetric. Conclusions: The 80 kV and 80 kV partial angle protocols demonstrated the greatest reduction to breast and lung dose, however, the subsequent increase in image noise may be deemed clinically unacceptable. Tube output for these protocols can be adjusted to achieve a more desirable noise level with lesser breast dose savings. Breast shielding increased breast and lung dose when maintaining equivalentAˆFE. The results demonstrated that comparisons of dose performance depend on both the image quality metric and the specific task, and that CNR may not be a reliable metric of signal detectability

Patient doses in ct, dental cone beam ct and projection radiography in Finland, with emphasis on paediatric patients

Diagnostic radiology represents the largest man-made contribution to population radiation doses in Europe. To be able to keep the diagnostic benefit versus radiation risk ratio as high as possible, it is important to understand the quantitative relationship between the patient radiation dose and the various factors which affect the dose, such as the scan parameters, scan mode, and patient size. Paediatric patients have a higher probability for late radiation effects, since longer life expectancy is combined with the higher radiation sensitivity of the developing organs. The experience with particular paediatric examinations may be very limited and paediatric acquisition protocols may not be optimised. The purpose of this thesis was to enhance and compare different dosimetric protocols, to promote the establishment of the paediatric diagnostic reference levels (DRLs), and to provide new data on patient doses for optimisation purposes in computed tomography (with new applications for dental imaging) and in paediatric radiography. Large variations in radiation exposure in paediatric skull, sinus, chest, pelvic and abdominal radiography examinations were discovered in patient dose surveys. There were variations between different hospitals and examination rooms, between different sized patients, and between imaging techniques; emphasising the need for harmonisation of the examination protocols. For computed tomography, a correction coefficient, which takes individual patient size into account in patient dosimetry, was created. The presented patient size correction method can be used for both adult and paediatric purposes. Dental cone beam CT scanners provided adequate image quality for dentomaxillofacial examinations while delivering considerably smaller effective doses to patient compared to the multi slice CT. However, large dose differences between cone beam CT scanners were not explained by differences in image quality, which indicated the lack of optimisation. For paediatric radiography, a graphical method was created for setting the diagnostic reference levels in chest examinations, and the DRLs were given as a function of patient projection thickness. Paediatric DRLs were also given for sinus radiography. The detailed information about the patient data, exposure parameters and procedures provided tools for reducing the patient doses in paediatric radiography. The mean tissue doses presented for paediatric radiography enabled future risk assessments to be done. The calculated effective doses can be used for comparing different diagnostic procedures, as well as for comparing the use of similar technologies and procedures in different hospitals and countries.Diagnostisen röntgensäteilyn osuus ihmisen aiheuttamasta väestön keskimääräisestä säteilyannoksesta on kaikkein suurin. Jotta diagnostisen hyödyn ja säteilyhaitan välinen suhde voidaan pitää mahdollisimman suurena, on tärkeää ymmärtää kvantitatiivisesti potilaan säteilyannoksen ja siihen vaikuttavien tekijöiden, kuten kuvausarvojen, kuvausmenetelmien ja potilaiden kokojen välinen suhde. Lapsipotilailla on aikuisia suurempi riski säteilyn myöhäisiin haittavaikutuksiin, mikä on seurausta pitkästä odotettavissa olevasta eliniästä sekä kehittyvien elinten korkeasta säteilyherkkyydestä. Henkilökunnan kokemus tietyissä lasten tutkimuksissa voi olla rajallinen eikä lasten kuvausmenetelmiä välttämättä ole optimoitu. Työn tarkoituksena oli kehittää ja vertailla eri annosmittausmenetelmiä tietokonetomografiatutkimuksissa (TT) ja lasten natiiviröntgentutkimuksissa, edistää lasten vertailutasojen käyttöönottoa sekä tuottaa uutta potilasannostietoa röntgentutkimusten optimointia varten. Potilasannoskartoituksissa todettiin suuria vaihteluita kuvaustekniikoissa eri sairaaloiden, tutkimushuoneiden ja eri kokoisten potilaiden välillä. Tutkimustekniikoiden vaihtelusta aiheutuneet erot potilasannoksissa osoittivat tarvetta kuvausmenetelmien optimoinnille sekä kansallisella, että kansainvälisellä tasolla. Tietokonetomografiatutkimuksia varten kehitettiin korjauskerroin, joka ottaa potilaan koon huomioon aikuisten ja lasten potilasannoksia määritettäessä. Tietokonetomografiatutkimuksissa lapset, naiset ja pienikokoiset potilaat absorboivat säteilyä suhteellisesti isokokoisia potilaita voimakkaammin. Hampaiston kuvantamisessa käytettävien rajoitetun kartiokeilan TT-laitteiden kuvanlaatu todettiin riittäväksi potilasannosten ollessa oleellisesti pienempiä kuin monileike-TT-laitteilla. Eri kartiokeila-TT-laitteiden potilasannoksissa oli kuitenkin suuria eroja kuvanlaadusta riippumatta, mikä osoitti tarvetta kuvaustekniikoiden jatkokehitykselle. Lasten keuhkokuvauksia varten annettiin graafiset vertailutasot, joiden avulla sairaalat voivat suoraan verrata eri kokoisten potilaiden säteilyannoksia vertailutasoon. Vertailutasot annettiin myös lasten nenän sivuontelokuvauksia varten. Yksityiskohtaiset tiedot kerätystä aineistosta, kuvausarvoista ja -menetelmistä antoivat työkalut potilasannosten vähentämiseksi lasten natiiviröntgentutkimuksissa. Kudoksiin absorboituvien annosten määrittäminen mahdollistaa jatkossa potilaskohtaiset riskiarvioinnit. Määritettyjä efektiivisiä annoksia voidaan käyttää diagnostisten menetelmien ja kuvaustekniikoiden vertailuun eri sairaaloiden ja valtioiden välillä

Adolescent Idiopathic Scoliosis. The Role of Low Dose Computed Tomography.

Continuous implementation of new operative methods for correction and stabilization of spinal deformities in young patients with AIS demands a detailed morphological analysis of the vertebral column. CT spine according to protocols available in daily clinical practice means high radiation dose to these young individuals. All examinations included in this thesis were performed on a 16-slice CT scanner. Examination of the chest phantom in paper I showed that the radiation dose of the spine (including 15 vertebrae) was 20 times lower than that of routinely used protocols for CT examination of the spine in children (0.38 mSv vs 7.76 mSv). In paper II the radiation dose and the impact of dose reduction on image quality were evaluated in 113 consecutive examinations with low-dose spine CT and compared with that of 127 CTs after trauma and 15 CTs performed according to a previously used ANV-protocol of a limited part of the vertebral column. The effective dose of the low-dose spine CT (0.01 mSv/cm scan length) was 20 times lower than that of the standard CT for trauma (0.20 mSv/cm scan length). The absorbed doses to the breasts, genital organs, and thyroid gland in the low-dose spine CT was 8, 265, and 22 times lower than the corresponding doses in CT for trauma. This significant dose reduction conveyed no impact on image quality with regard to answering the clinical questions at issue for the preoperative CTs and for the postoperative CTs after posterior corrective surgery. In paper III the low-dose CT showed to be a reliable method in the evaluation of screw placement in patients with AIS after posterior scoliosis surgery with titanium implants, using the new grading system for screw misplacement. Our proposed grading system for screw misplacement has shown to be feasible, practical, and easy to perform and is in line with the general agreement about the harmlessness of misplacement with minor pedicle breach. In paper IV the evaluation of the clinical and radiological outcome of 49 patients with AIS operated on with titanium “all-pedicle screw construct” showed an overall misplacement rate of 17 %. No evidence of neurovascular complications was reported. In parity with most of the reports in the literature the lateral- and medial cortical perforation were the most common types of screw misplacement (8 % and 6.1 % respectively)

MONTE CARLO MODELING BASED PATIENT DOSE OPTIMIZATION IN DIAGNOSTIC RADIOLOGY

Radiation doses are caused by the energy deposited in unit mass of matter from ionizing radiation. In the US, radiation doses from medical imaging increased six-fold in the past generation. Among medical exposures to patients, computed tomography (CT) composes about half of the collective doses, and interventional fluoroscopy composes 14%. Radiation exposure to patients undergoing diagnostic radiological procedures causes increased lifetime carcinogenic risks, especially for pediatric patients who are more radiosensitive than adults. The correlation between procedural x-ray techniques and the radiation doses to patients, as well as the resultant image quality, is not well understood, and therefore the focus of the performed studies. High radiation dose levels can occur as an outcome of complex procedures requiring additional imaging, or when a patient undergoes multiple radiological procedures. Accumulated occupational doses, caused by the scattered radiation from the patient to the staff during the procedures, are also of concern. There are many factors that affect the patient radiation doses, such as different combinations of technical parameter settings and patient characteristics. Due to the complexities and time-consuming nature of clinical dose/exposure measurements, the Monte Carlo technique is the only realistic tool to investigate patient doses and occupational exposure. Therefore, the objective of this Dissertation is to investigate the possible optimization methods of the irradiation technical factors in order to lower radiation doses to patients undergoing diagnostic radiological examinations using Monte Carlo algorithm-based software. Our general hypothesis is that incident x-ray photon energy used in a diagnostic radiological procedure can be optimized to reduce patient doses without sacrificing image quality, and therefore can lower radiation-induced lifetime carcinogenic risks for patients. Our results will be valuable for medical physicists to analyze dose distributions, and for the cardiology clinicians to maximize image guidance capabilities while minimizing potential carcinogenic and deterministic risks to pediatric patients. Firstly, the impact of irradiation parameters on patient doses during CT scans was investigated and possible optimization methods were discussed. Our results about cone beam CT scans showed that there were major differences in organ and effective dose as the x-ray tube rotates around the patient. This suggested that the use of x-ray tube current modulation could produce substantial reductions in organ and effective dose for body imaging with cone beam CT. For chest CT, our results showed that the existing x-ray tube current modulation schemes are expected to reduce patient effective doses in chest CT examinations by about 10%, with longitudinal modulation accounting for two thirds and angular modulation for the remaining one third. It was also shown that the choice of the scanned region affects organ doses in CT. Secondly, the radiation-induced cancer risks from body CT examinations for adult patients were estimated. For patients who differ from a standard sized adult, correction factors based on the patient weight and antero-posterior dimension are provided to adjust organ doses and the corresponding risks. Our results showed that at constant incident radiation intensity, for CT examinations that include the chest, risks in females are markedly higher than those for males, whereas for examinations that include the pelvis, risks in males were slightly higher than those in females. In abdominal CT scans, risks for males and female patients are very similar. A conclusion was reached that cancer risks in body CT can be estimated from the examination Dose Length Product by accounting for sex, age, as well as patient physical characteristics. Thirdly, a set of innovative Monte Carlo models were developed to investigate the role of x-ray photon energy in determining skin dose, energy imparted, and image quality in pediatric interventional radiology using the MCNP5 platform. Contrast, relative noise, and contrast-to-noise ratio (CNR) were obtained for diagnostic imaging with and without the utilization of grids. Our results indicated that using Monte Carlo methods, the optimized x-ray tube voltage for a relatively low patient dose under the desired image quality could be obtained for any specific patient undergoing a certain type of diagnostic examination. Lastly, we investigated the changes in the pattern of energy deposition in patient phantoms following the use of iodinated contrast media using Monte Carlo models built on MCNP5 platform. Relative energy imparted to the volume of interest with iodine contrast agent, as well as to the whole patient phantom, was calculated. Changes in patterns of energy deposition around the contrast-filled volume were also investigated. Our results suggested that adding iodine can result in values of localized absorbed dose increasing by more than an order of magnitude, but the total energy deposition is generally very modest. Furthermore, our results also showed that adding iodine primarily changes the pattern of energy deposition in the irradiated region, rather than increasing the corresponding patient doses. The goal of this project was to establish a better understanding of the roles of different technique factors in the patient doses from diagnostic radiological procedures. Based on these studies, the limitations of the current Monte Carlo software were analyzed and our own Monte Carlo model was proposed for simulations of patient doses during pediatric interventional radiology procedures. The ultimate goal of this study is to develop a comprehensive dosimetry database using Monte Carlo technique, with the output of patient doses, operator doses, and the corresponding radiation-induced carcinogenesis risks for pediatric interventional radiology procedures

3D Imaging for Planning of Minimally Invasive Surgical Procedures

Novel minimally invasive surgeries are used for treating cardiovascular diseases and are performed under 2D fluoroscopic guidance with a C-arm system. 3D multidetector row computed tomography (MDCT) images are routinely used for preprocedural planning and postprocedural follow-up. For preprocedural planning, the ability to integrate the MDCT with fluoroscopic images for intraprocedural guidance is of clinical interest. Registration may be facilitated by rotating the C-arm to acquire 3D C-arm CT images. This dissertation describes the development of optimal scan and contrast parameters for C-arm CT in 6 swine. A 5-s ungated C-arm CT acquisition during rapid ventricular pacing with aortic root injection using minimal contrast (36 mL), producing high attenuation (1226), few artifacts (2.0), and measurements similar to those from MDCT (p\u3e0.05) was determined optimal. 3D MDCT and C-arm CT images were registered to overlay the aortic structures from MDCT onto fluoroscopic images for guidance in placing the prosthesis. This work also describes the development of a methodology to develop power equation (R2\u3e0.998) for estimating dose with C-arm CT based on applied tube voltage. Application in 10 patients yielded 5.48┬▒177 2.02 mGy indicating minimal radiation burden. For postprocedural follow-up, combinations of non-contrast, arterial, venous single energy CT (SECT) scans are used to monitor patients at multiple time intervals resulting in high cumulative radiation dose. Employing a single dual-energy CT (DECT) scan to replace two SECT scans can reduce dose. This work focuses on evaluating the feasibility of DECT imaging in the arterial phase. The replacement of non-contrast and arterial SECT acquisitions with one arterial DECT acquisition in 30 patients allowed generation of virtual non-contrast (VNC) images with 31 dose savings. Aortic luminal attenuation in VNC (32┬▒177 2 HU) was similar to true non-contrast images (35┬▒177 4 HU) indicating presence of unattenuated blood. To improve discrimination between c

3D Imaging for Planning of Minimally Invasive Surgical Procedures

Novel minimally invasive surgeries are used for treating cardiovascular diseases and are performed under 2D fluoroscopic guidance with a C-arm system. 3D multidetector row computed tomography (MDCT) images are routinely used for preprocedural planning and postprocedural follow-up. For preprocedural planning, the ability to integrate the MDCT with fluoroscopic images for intraprocedural guidance is of clinical interest. Registration may be facilitated by rotating the C-arm to acquire 3D C-arm CT images. This dissertation describes the development of optimal scan and contrast parameters for C-arm CT in 6 swine. A 5-s ungated C-arm CT acquisition during rapid ventricular pacing with aortic root injection using minimal contrast (36 mL), producing high attenuation (1226), few artifacts (2.0), and measurements similar to those from MDCT (p\u3e0.05) was determined optimal. 3D MDCT and C-arm CT images were registered to overlay the aortic structures from MDCT onto fluoroscopic images for guidance in placing the prosthesis. This work also describes the development of a methodology to develop power equation (R2\u3e0.998) for estimating dose with C-arm CT based on applied tube voltage. Application in 10 patients yielded 5.48┬▒177 2.02 mGy indicating minimal radiation burden. For postprocedural follow-up, combinations of non-contrast, arterial, venous single energy CT (SECT) scans are used to monitor patients at multiple time intervals resulting in high cumulative radiation dose. Employing a single dual-energy CT (DECT) scan to replace two SECT scans can reduce dose. This work focuses on evaluating the feasibility of DECT imaging in the arterial phase. The replacement of non-contrast and arterial SECT acquisitions with one arterial DECT acquisition in 30 patients allowed generation of virtual non-contrast (VNC) images with 31 dose savings. Aortic luminal attenuation in VNC (32┬▒177 2 HU) was similar to true non-contrast images (35┬▒177 4 HU) indicating presence of unattenuated blood. To improve discrimination between c

Evaluation of cone beam computed tomography with respect to effective radiation dose and diagnostic properties

Cone beam computed tomography (CBCT) is an x-ray modality providing three-dimensional x-ray images. CBCT devices have high resolution compared to traditional medical CT, making them suitable for examination of fine details. However, CBCT devices are worse at showing contrast differences, making them less suitable for examinations of soft tissue such as the brain and many other internal organs. An x-ray modality suitable for imaging of small details and hard tissue fits dental and maxillofacial radiology well. After the introduction of dentomaxillofacial CBCT in 1998, CBCT examinations have spread to become a common and important diagnostic tool in odontology. Today, CBCT examinations complement or replace examinations previously performed by other methods. When choosing an x-ray imaging modality and examination parameters, concern must be taken for the diagnostic value and the radiation dose. The examination should be chosen to provide as low radiation dose as possible while not sacrificing the diagnostic value. In order to provide guidelines on the use of CBCT, scientific knowledge on CBCT and alternative examinations are needed. What is the radiation dose for different examinations and how does the examination affect diagnosis and treatment? This thesis aims to provide additional information in this field, to provide reference data when considering the choice of examination and the establishment of guidelines. In the first paper, examinations of the temporomandibular joint, using CBCT and traditional medical multi-detector CT (MDCT), were compared to determine if CBCT examinations would result in lower radiation dose. The examinations were optimized to find the lowest suitable dose levels, and at these optimized dose levels no significant difference was found between CBCT and MDCT. The second paper investigated the radiation dose from multiple different x-ray examinations of possible resorption impacted maxillary canines in children. CBCT examinations were compared to two-dimensional examinations using intraoral radiographs, and in some cases panoramic radiographs. CBCT examinations ranged from 15 to 140 times higher radiation dose, depending on x-ray device. The third paper investigated the possibility of reducing the image size, and therefore the x-ray dose, in panoramic radiographs. A full-size panoramic radiograph was required in 20% of adult patient cases. The introduction of two different image sizes for adult patients would reduce the collective radiation dose from panoramic examinations by about 40% in our university clinic. The fourth paper investigated radiation doses from different examinations and settings using the Newtom 5G CBCT device. This CBCT model use automatic exposure control and does not allow manual adjustment of exposure parameters. The resulting effective doses should be applicable to examinations of adult patients using this CBCT model

Radiation doses, cancer risks and optimization process of routine computed tomography (ct) examinations in Johor

The concerns towards radiation–induced cancer from Computed Tomography (CT) examinations have led to the encouragement of CT dose monitoring and further optimization of the scanning parameters. Therefore, in this study, radiation dose from CT scan and its related risks to the patients from current CT practice were analysed. In the first stage, this thesis started the discussion on the level of current knowledge among radiology personnel towards CT radiation risk and its optimization. There is no significant difference of the current knowledge of CT optimization between the two professions of interest herein, the medical and the allied health groups. A CT dose survey was conducted in 8 CT facilities for a 6-month period, encompassing data for 1024 patients with various CT examinations that included regions of the abdomen, brain and thorax. CT-EXPO (Version 2.3.1, Germany) software was used to validate the dose information such as CT Dose Index (CTDI) and dose-length product (DLP). The proposed Diagnostic Reference Levels (DRLs) were indicated by rounding off the third quartiles (Q3s) of whole dose distributions for weighted CTDI (CTDIw) (in mGy), volume CTDI (CTDIvol) (in mGy) and DLP (in mGy.cm) and their values were; 16, 17, and 650 respectively for CT abdomen; 70, 70, and 1030 respectively for CT Brain and 15, 16, and 670 respectively for CT thorax. In the second stage, the cancer risks of the CT examinations were estimated and the calculation was based on International Commission on Radiation Protection (ICRP) Publication 103 Report and Biological Effects of Ionizing Radiation (BEIR) VII Report. Based on BEIR VII recommendation, the study discovered that the lifetime attributable risks (LARs) of 100,000 populations who underwent abdominal CT examinations for stomach cancer were 2.3 for male and 1.0 for female; while for colon cancer the LARs were 2.3 for male and 0.7 for female. The effectiveness of optimization of CT parameters and application of shielding in routine CT procedures were evaluated. Of 7 protocols (P1 – P7), the k factors were constant for all protocols and decreased by ~8% compared to the universal k factor. It is of interest that k factors from CT-EXPO were found to vary between 0.010 for protocol P5 and 0.015 for protocol P3 due to inconsistency in tube potential and pitch factor. The application of breast shielding to routine CT thorax protocols reduced by 14% the breast’s equivalent dose. Hence, this study supports the importance of initiating protection and optimization processes of routine CT examinations in order to offer safer imaging practices

Radiation doses, cancer risks and optimization process of routine computed tomography (CT) exminations in Johor

ABSTRACT The concerns towards radiation–induced cancer from Computed Tomography (CT) examinations have led to the encouragement of CT dose monitoring and further optimization of the scanning parameters. Therefore, in this study, radiation dose from CT scan and its related risks to the patients from current CT practice were analysed. In the first stage, this thesis started the discussion on the level of current knowledge among radiology personnel towards CT radiation risk and its optimization. There is no significant difference of the current knowledge of CT optimization between the two professions of interest herein, the medical and the allied health groups. A CT dose survey was conducted in 8 CT facilities for a 6-month period, encompassing data for 1024 patients with various CT examinations that included regions of the abdomen, brain and thorax. CT-EXPO (Version 2.3.1, Germany) software was used to validate the dose information such as CT Dose Index (CTDI) and dose-length product (DLP). The proposed Diagnostic Reference Levels (DRLs) were indicated by rounding off the third quartiles (Q3s) of whole dose distributions for weighted CTDI (CTDIw) (in mGy), volume CTDI (CTDIvol) (in mGy) and DLP (in mGy.cm) and their values were; 16, 17, and 650 respectively for CT abdomen; 70, 70, and 1030 respectively for CT Brain and 15, 16, and 670 respectively for CT thorax. In the second stage, the cancer risks of the CT examinations were estimated and the calculation was based on International Commission on Radiation Protection (ICRP) Publication 103 Report and Biological Effects of Ionizing Radiation (BEIR) VII Report. Based on BEIR VII recommendation, the study discovered that the lifetime attributable risks (LARs) of 100,000 populations who underwent abdominal CT examinations for stomach cancer were 2.3 for male and 1.0 for female; while for colon cancer the LARs were 2.3 for male and 0.7 for female. The effectiveness of optimization of CT parameters and application of shielding in routine CT procedures were evaluated. Of 7 protocols (P1 – P7), the k factors were constant for all protocols and decreased by ~8% compared to the universal k factor. It is of interest that k factors from CT-EXPO were found to vary between 0.010 for protocol P5 and 0.015 for protocol P3 due to inconsistency in tube potential and pitch factor. The application of breast shielding to routine CT thorax protocols reduced by 14% the breast’s equivalent dose. Hence, this study supports the importance of initiating protection and optimization processes of routine CT examinations in order to offer safer imaging practices