Evaluation Of Organ Doses Research Articles

Evaluation of organ dose, effective dose and cancer risk of head and neck dual-energy computed tomography

PurposeDual-energy computed tomography (DECT) is an emerging imaging modality with the aim of evaluating oncologic or vascular imaging diseases. Despite the benefits, the growing trend of DECT scans in recent decades is a major concerns regarding the induction of diseases such as cancer due to the use of a second radiation source. So, this survey was conducted to evaluate radiation dose and estimated the cancer risk of head and neck DECT examination.Methods: This investigation was performed on 122 patients who underwent head and neck DECT examination. The organ doses and effective doses for each patient were estimated using the ImpactDose program. The cancer risk values were calculated by using models developed in the BEIR VII (Biological Effects of Ionizing Radiation VII)-Phase 2 report. ResultsThe highest organ dose in both females and males were observed in thyroid. The overall mean effective dose in the females was higher than that in the males (1.78 vs. 1.36 mSv). The mean REID values were 55.07 per million males and 120.66 per million females. REID values decreased with the increasing age of patients in both genders and were much higher for younger females. ConclusionThe findings of this study will help referring physicians to justify requesting a DECT examination by considering its benefits for the diagnosis on the one hand and awareness of cancer risk on the other.

Estimating organ dose with optimized peak dose index in cone-beam CT scans

PurposeOrgan dose evaluation is important for optimizing cone beam computed tomography (CBCT) scan protocols. However, an evaluation method for various CBCT scanners is yet to be established. In this study, we developed scanner-independent conversion coefficients to estimate organ doses using appropriate peak dose (f(0)) indices. MethodsThis study included various scanners (angiography scanners and linear accelerators) and protocols for the head and body (thorax, abdomen, and pelvis) scan regions. f(0) was measured at five conventional positions (center position (f(0)c) and four peripheral positions (f(0)p) at 90° intervals) in the CT dose index (CTDI) phantom. To identify appropriate measurement positions for organ dose estimation, various f(0) indices were considered. Organ doses were measured by using optically stimulated luminescence dosimeters positioned in an anthropomorphic phantom. Thereafter, the conversion coefficients were calculated from each obtained f(0) value and organ or tissue dose using a linear fit for all scanners, and the coefficient of variation (CV) of the conversion coefficients was calculated for each organ or tissue. The f(0) index with the minimum CV value was proposed as the appropriate index. ResultsThe appropriate f(0) index was determined as f(0)c for the body region and a maximum of four f(0)p values for the head region. Using the proposed conversion coefficients based on the appropriate f(0) index, the organ/tissue doses were well estimated with a mean error of 14.2% across all scanners and scan regions. ConclusionsThe proposed scanner-independent coefficients are useful for organ dose evaluation using CBCT scanners.

Evaluation of organ dose using size-specific dose estimation (SSDE) and related cancer risk due to chest CT scan during the COVID-19 pandemic.

This study aimed to estimate lung and breast doses for individual patients using the size-specific dose estimate (SSDE) method, as well as calculating effective doses, in patients who underwent chest CT scans during the COVID-19 pandemic. Cancer risk incidence was estimated using excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) models from the Biological Effects of Ionizing Radiation Report VII (BEIR-VII). Data from about 570 patients who underwent CT scans for COVID-19 screening were utilized for this study. Using the header of the CT images in a Python script, SSDE and effective dose were calculated for each patient. The SSDE obtained by water equivalent effective diameter (wSSDE) was considered as lung and breast dose, and applied in organ-specific cancer risk estimation. The mean wSSDE value for females (13.3mGy) was slightly higher than that for males (13.1mGy), but the difference was not statistically significant (P value=0.41). No significant differences were observed between males and females in terms of calculated EAR and ERR for lung cancer at 5 and 30years after exposure (P value=0.47, 0.46, respectively). Similarly, there was no significant difference in lung cancer LAR values between females and males (P value=0.48). The results also indicated a decrease in LAR values for both lung and breast cancers with increasing exposure age. In accordance with the ALARA (as low as reasonably achievable) principle, it is important for medical staff and the general public to consider the benefits of CT imaging in detecting such infections. Additionally, imaging medical physicists and CT scan experts should optimize imaging protocols and strike a balance between image quality for detecting abnormalities and radiation dose, all while adhering to the ALARA principle.

Organ dose in CT: Comparison between measurements and computational methods

PurposeThis study aims to compare two methods for the organ dose evaluation in computed tomography (CT) in the head- and thorax regions: an experimental method, using radiochromic films, and a computational one, using a commercial software. MethodsGafchromic® XR-QA2 and EBT-3 were characterized in terms of energetic, angular, and irradiation configurations dependence. Two free-in-air irradiation calibration configurations were employed using a CT scanner: with the sensitive surface of the film orthogonal (OC) and parallel (PC) to the beam axis. Different dose–response curves were obtained by varying the irradiation configurations and the beam quality (BQ). Subsequently, films were irradiated within an anthropomorphic phantom using CT-thorax and -head protocols, and the organ dose values obtained were compared with those provided by the commercial software. ResultsAt different configurations, an unchanged dose response was achieved with EBT-3, while a dose response of 15% was obtained with XR-QA2. By varying BQ, XR-QA2 showed a different response below 10%, while EBT-3 showed a variation below 5% for dose values >20 mGy. For films irradiation angle equal to 90°, the normalized to 0° relative response was 41% for the XR-QA2 model and 83% for the EBT-3 one. Organ dose values obtained with EBT-3 for both configurations and with XR-QA2 for OC were in agreement with the DW values, showing percentage discrepancies of less than 25%. ConclusionsThe obtained results showed the potential of EBT-3 in CT patient dosimetry since the lower angular dependence, compared to XR-QA2, compensates for low sensitivity in the diagnostic dose range.

Diagnostic reference level quantities for adult chest and abdomen-pelvis CT examinations: correlation with organ doses

ObjectivesTo evaluate correlations between DRL quantities (DRLq) stratified into patient size groups for non-contrast chest and abdomen-pelvis CT examinations in adult patients and the corresponding organ doses.MethodsThis study presents correlations between DRLq (CTDIvol, DLP and SSDE) stratified into patient size ranges and corresponding organ doses shared in four groups: inside, peripheral, distributed and outside. The demographic, technical and dosimetric parameters were used to identify the influence of these quantities in organ doses. A robust statistical method was implemented in order to establish these correlations and its statistical significance.ResultsMedian values of the grouped organ doses are presented according to the effective diameter ranges. Organ doses in the regions inside the imaged area are higher than the organ doses in peripheral, distributed and outside regions, excepted to the peripheral doses associated with chest examinations. Different levels of statistical significance between organ doses and the DRLq were presented.ConclusionsCorrelations between DRLq and target-organ doses associated with clinical practice can support guidance’s to the establishment of optimization criteria. SSDE demonstrated to be significant in the evaluation of organ doses is also highlighted. The proposed model allows the design of optimization actions with specific risk-reduction results.

Proposing Intelligent Approach to Predicting Air Kerma within Radiation Beams of Medical X-ray Imaging Systems.

The air kerma is a key parameter in medical diagnostic radiology. Radiologists use the air kerma parameter to evaluate organ doses and any associated patient hazards. The air kerma can be simply described as the deposited kinetic energy once a photon passes through the air, and it represents the intensity of the radiation beam. Due to the heel effect in the X-ray sources of medical imaging systems, the air kerma is not uniform within the X-ray beam's field of view. Additionally, the X-ray tube voltage can also affect this nonuniformity. In this investigation, an intelligent technique based on the radial basis function neural network (RBFNN) is presented to predict the air kerma at every point within the fields of view of the X-ray beams of medical diagnostic imaging systems based on discrete and limited measured data. First, a diagnostic imaging system was modeled with the help of the Monte Carlo N Particle X version (MCNPX) code. It should be noted that a tungsten target and beryllium window with a thickness of 1 mm (no extra filter was applied) were used for modeling the X-ray tube. Second, the air kerma was calculated at various discrete positions within the conical X-ray beam for tube voltages of 40 kV, 60 kV, 80 kV, 100 kV, 120 kV, and 140 kV (this range covers most medical X-ray imaging applications) to provide the adequate dataset for training the network. The X-ray tube voltage and location of each point at which the air kerma was calculated were used as the RBFNN inputs. The calculated air kerma was also assigned as the output. The trained RBFNN model was capable of estimating the air kerma at any random position within the X-ray beam's field of view for X-ray tube voltages within the range of medical diagnostic radiology (20-140 kV).

Relative Error between Organ Doses and Size-specific Dose Estimates for a Specific Location When the Mean CTDIvol Value Is Used for Calculation

Size-specific dose estimates (SSDEs) are dose indices that account for differences in body shape in computed tomography (CT) scans, allowing the evaluation of approximate absorbed doses in any cross section that could not be obtained with the volume CT dose index (CTDIvol). When using automatic exposure control (AEC), CTDIvol is modulated in the body axis direction, but the value displayed after the examination is the mean CTDIvol for the entire scan, and it is expected that the SSDE value will change depending on which value is used in the calculation. In this study, using a human body phantom, we examined the influence of whether the mean CTDIvol or the modulation value for each slice is used to calculate the SSDE on local organ dose evaluation. A program to calculate water equivalent diameter according to the procedure in the American Association of Physicists in Medicine Report No. 220 was developed and compared. As a result, SSDE calculated using the mean CTDIvol (local-SSDEmean) overestimated organ doses in the lung region by 18%-56% compared with those calculated by a web system for evaluating CT exposure doses (WAZA-ARIv2, Japan). In contrast, local-SSDEmodulated, which was calculated using the modulated value of the CTDIvol, was able to estimate the organ dose with a relative error of 10%-13%. The average local-SSDE over the entire body axis direction was not significantly different between the two methods, regardless of which method was used for CTDIvol. If the mean CTDIvol is stored in the Digital Imaging and Communications in Medicine (DICOM) header tag (0018, 9345) of the CT image and the modulated CTDIvol value is not available for each slice, the calculated local SSDE will contain many errors and will not correctly reflect the organ doses at the scan region. In such cases, it is available to use the method of evaluating local organ doses by multiplying the SSDE, which is the average of the SSDE for the entire scan, by a factor for each organ.

ASSESSMENT OF PCXMC MONTE CARLO SIMULATIONS IN SLOT-SCANNING-BASED EXAMINATIONS: COMPARISON WITH IN-PHANTOM THERMOLUMINESCENT DOSIMETRY.

Slot-scanning technology is nowadays a valid solution for the follow-up of chronic musculoskeletal disorders on children and adolescent patients, but there is no commercial software designed for simulating this X-ray beam geometry. PC Program for X-ray Monte Carlo (PCXMC) is a widespread Monte Carlo software developed for dose computation in projection radiography. In this study, experimental measurements were performed to evaluate its applicability in examinations with a slit-beam device. Physical phantoms corresponding to an adult and a 5-y-old child with calibrated thermoluminescent dosemeters were used for experiments. Different simulation approaches were investigated. Differences between measured and calculated organ doses ranged from -95 to 67% and were statistically significant for almost all organs. For both patients, PCXMC underestimated the effective dose of about 25%. This study suggests that PCXMC is not suited for organ dose evaluation in examinations with slot-scanning devices. It is still a useful tool for effective dose estimation when a proper correction factor is applied.

Calculation of scan length and size-specific dose at longitudinal positions of body CT scans using dose equilibrium function.

Dose evaluation at longitudinal positions of body computed tomography (CT) scans is useful for CT quality assurance programs and patient organ dose evaluation. Accurate estimates depend on both patient size and scan length. To propose practical evaluation of the average dose to the transverse slab of an axial image slice for adult body CT examinations, considering not only patient size but also scan length, and to compare the results with those of Monte Carlo (Geant4) simulation [Dsim (z)] and size-specific dose estimates at longitudinal positions of scans [SSDE(z)] from international standards (IEC publication no. 62985). In a scan series, the total dose at each z-axis location was calculated using the input information identical to the SSDE(z) evaluation. Each axial image slice (slice thickness, 2.5 or 5mm) was first considered independently. Its z-axis coverage and CTDIvol (from the DICOM headers) were used to directly calculate a z-axis dose profile for the average dose over the cross-section of a water phantom, using the approach to equilibrium function. The phantom diameter was taken to be equal to the patient water equivalent diameter at that slice. The above was repeated at all slices and the dose at each z-axis location was accumulated from all profiles, referred to as Dcalc (z). For validation, we considered a cohort of 65 patients, who underwent chest and abdominopelvic examinations. The resultant Dcalc (z) was compared with Dsim (z) and SSDE(z), both available in a previous paper. Dcalc (z) evaluation could be used to accurately assess the scan range average dose, with an accuracy of 7.1%-8.7% for 65 patients in two examinations. On individual image slices, the maximum difference in magnitude between Dcalc (z) and Dsim (z) [and between SSDE(z) and Dsim (z) in parentheses] was 37.5% (85%) [two edges (2×5cm) of chest scan range], 17.8% (35.2%) (the remaining central region of chest scan), 26.8% (74.1%) [two edges (2×5cm) of abdominopelvic scan range], and 14.2% (22.5%) (the remaining central region of abdominopelvic scan). Identical input data are used for Dcalc (z) and SSDE(z) evaluations. The latter is limited to the z-axis locations within scan range. At each image slice, SSDE(z) is equivalent to the midpoint dose of a fixed-mA scan of 15-30cm (scan length). In contrast, Dcalc (z) considers dose accumulation from varying scan length (from sub-centimeter to about 1m) and tube current, and dose profile is also computed outside scan range. Besides greatly improving dose evaluation for individual image slices, Dcalc (z) allows for evaluating dose accumulation from multiple series, which typically span different scan ranges. Our proposal may assist CT manufacturers and dose index monitoring software in assessing dose at longitudinal positions of body CT scans.

Monte Carlo study of organ doses and related risk for cancer in Algeria from scattered neutrons in prostate treatment involving 3D-CRT

The present study aimed to evaluate organ doses and related risk for cancer from scattered neutrons involving 3D Conformational Radiotherapy (3D−CRT) for patients with prostate cancer in Algeria based on Monte Carlo technique and to estimate the secondary cancer risks. To this purpose, a detailed geometric Monte Carlo (MC) modeling of the LINAC Varian 2100C combined with a computational whole-body phantom was carried out. The neutron equivalent doses were calculated in-field and out-of field of patient's organs using the phase-space method. The obtained neutron equivalent doses were used to estimate the Lifetime Attributable Risks (LARs) for cancer incidence in out of field organs. LARs was evaluated assuming Biological Effects of Ionizing Radiation VII (BEIR VII) risk model for exposure age in the range 35–70 years, according to the interval's age of treated patients in Algeria. The baselines cancer risks and survival data were associated with the statistical data for the Algerian population. The results showed that the neutrons equivalent doses per prescribed dose (Photon Dose) mostly depend on the distance of organs from the treated volume. The highest and lowest equivalent doses of 1.18 mSv/Gy and 0.25 mSv/Gy were recorded in the bladder and heart, respectively. The highest estimated lifetime attributable risk per 100,000 population was found for 35 yrs’ exposure age in colon 49.94, lung 16.63 and stomach 11.17. The lowest risks were found for 70 yrs’ age, in spine 0.06 and thyroid 0.14. The results showed that LARs values decrease with the increase of the exposure age and cancer incidence risk is lower than the baseline cancer risk incidence for all organs. The present study may help in providing a database on the impact of radiotherapy-induced secondary cancer incidence during 3D-CRT for prostate cancer in Algeria.

OD121 - Organ dose evaluation in radiological monitoring of paediatric Ollier disease

OD121 - Organ dose evaluation in radiological monitoring of paediatric Ollier disease

Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics.

An Evaluation of Radiation Dose for Wide Volume Scan during Chest CT

A volume scan can cover a range of 160 mm with a single gantry rotation. It can be performed sequentially (a wide volume [WV] scan) to cover more than 160 mm, and volume Xact+ (Xact+) can be used when volume scan is done to extend the reconstruction area. The purpose of this study was to investigate the dose distribution and organ doses for a WV scan during chest CT. We arranged radiophotoluminescence glass dosimeters (RPLDs) linearly on the surface and inside of the phantom to evaluate the dose distribution along the z-axis. We also placed RPLDs at the lens, thyroid, and breast positions to evaluate organ doses. We performed WV and helical scans and WV scan using Xact+. The absorbed doses increased at the borders of the volume scans, and dose peaks were observed there. The organ doses for the WV scan outside the acquisition range were lower than those for the helical scan. The organ doses inside the acquisition range changed by the locations of borders. The WV scan increases the absorbed doses at the overlapping scanned regions, which can be reduced by using Xact+.

Dosimetry of inhaled 219Rn progeny.

During prostate cancer treatment with 223Ra. 219Rn (actinon) occurs and may be exhaled by the patient. Nurses and other hospital employees may inhale this radionuclide and its decay products. The alpha-emitting decay products of actinon deposited within a body will irradiate tissues and organs. Therefore. it is necessary to evaluate organ doses of actinon progeny. The purpose of this study is to set up a dosimetric method to assess dose coefficients for actinon progeny. The effective dose coefficients were calculated separately for three modes. The unattached mode which concerned the activity median thermodynamic diameter (AMTD) of 1 nm. and the nucleation and accumulation modes which are represented by activity median aerodynamic diameters (AMAD) of 60 and 500 nm respectively. The recent biokinetic models of actinon progeny developed in the Occupational Intakes of Radionuclides (OIR) publications series of the International Commission of Radiological Protection (ICRP) were implemented on BIOKMOD (Biokinetic Modeling) to calculate the number of nuclear transformations per activity intake of actinon progeny. The organ equivalent and effective dose coefficients were determined using the dosimetric approach of the ICRP. The inhalation dose coefficients of actinon progeny are dominated by the contribution of lung dose. The calculated dose coefficients of 211Pb and 211Bi are 5.78 × 10−8 and 4.84 × 10−9 Sv.Bq−1 for unattached particles (AMTD = 1 nm). and 1.4 × 10−8 and 3.55 × 10−9 Sv.Bq−1 for attached particles (AMAD = 60 nm). and 7.37 × 10−9 and 1.91 × 10−9 Sv.Bq−1 for attached particles (AMAD = 500 nm). These values are much closer to those of the recently published ICRP 137.

Evaluation of organ doses following prostate treatment with permanent brachytherapy seeds: a Geant4 Monte Carlo simulation study

This study aimed to evaluate the absorbed doses received by the organs at risk (OARs) following prostate treatment with permanent Iodine-125 (125I) brachytherapy seeds. In order to simulate an enlarged abnormal prostate due to malignancy, the MIRD5 adult male anthropomorphic phantom (readily available in the Geant4 Monte Carlo package) was modified by increasing the prostate volume to 35 cm3. The permanent seeds were constructed with an outer cylindrical dimension of 4.5 mm (length) × 0.8 mm (diameter). The effects of various activity per seed (0.5, 0.6 and 0.8 mCi), number of seeds (62, 78, 94 and 110 seeds) and radionuclides, i.e. Palladium-103 (103Pd), 125I and Cesium-131 (131Cs), towards the absorbed dose to the OARs (i.e. rectum, urinary bladder and both testicles) were investigated. In this study, prostate dose of up to 237 Gy was simulated, which resulted in 11 Gy dose to rectum, 7 Gy to urinary bladder and 4 Gy to each testicle. The doses were considered as reasonable, given the low dose rate nature of the treatment, allowing tissue repair for the OARs. Optimal seeds arrangement was found to consist of 78 or fewer seeds, as it resulted in the lowest dose to the OARs. For similar prostate dose, 103Pd resulted in the lowest dose to the OARs, followed by 125I and 131Cs. Permanent seed brachytherapy allows high dose to be delivered to the prostate, while ensuring minimal dose to the OARs.

Evaluation of organ doses following high dose rate (HDR) brachytherapy of breast cancer: a Geant4 Monte Carlo simulation study

This study aimed to evaluate the absorbed doses received by the organs at risk (OARs) following Iridium-192 (192Ir) high dose rate (HDR) brachytherapy of the left breast. The MIRD5 adult female anthropomorphic phantom, readily available in the Geant4 Monte Carlo package was used. However, the left breast was modified from 195 to 145 cm3, to represent a breast following lumpectomy. Left breast was chosen due to its higher cancer occurrence than the right breast. The HDR sources were constructed with an outer cylindrical dimension of 4.5 mm (length) × 0.9 mm (diameter). Various influencing parameters were studied, i.e. catheter arrangement (single versus dual plane), source inter-dwell distances (5 versus 10 mm), and different radionuclides, i.e. Cobalt-60 (60Co) and 192Ir, by delivering a total treatment dose of 32 Gy to the left breast. Absorbed doses to the OARs (e.g. left lung, heart, right breast, spleen, etc.) were then evaluated. A maximum left lung dose of 1.5 Gy was recorded, while doses to the other OARs were all below 1 Gy. The treatment using dual plane catheter arrangement contributed to a slightly higher dose to the OARs, despite equal dose to the breast. There was no dose difference between different inter-dwell distances used in this study. 60Co resulted in a slightly higher left lung dose than that of 192Ir, while the results were the opposite for the other OARs. HDR brachytherapy allows high dose to be delivered to the breast within a short period of time, with minimal absorbed doses to the OARs.

Monte carlo study of organ doses and related risk for cancer in Tanzania from scattered photons in cervical radiation treatment involving Co-60 source

PurposeThe present work aimed to evaluate organ doses and related risk for cancer from external beam radiation treatment (EBRT) and high-dose-rate (HDR) brachytherapy (BT) involving Co-60 source for patients with cervical carcinoma in Tanzania based on Monte Carlo methods and to evaluate the secondary cancer risks in their lifetime. MethodsEBRT and HDR-BR were modelled by using the MCNPX Monte Carlo (MC) code. The MC simulations were performed by using validated models and isocentric irradiation of an adult female computational phantom. The organ doses and cancer risks estimates were obtained. ResultsThe highest absorbed doses of 6.98 × 10−2 and 5.74 × 10−2 Sv/Gy were recorded in the bladder for BT and EBRT. The higher risk was found for colon at 1.06 × 10−3 in the HDR-BT and 9.75 × 10−5 in the EBRT per 100,000 population at exposure age of 35 years than in the other organs. The risk magnitude decreased with increasing age at exposure. In general, the secondary cancer risks in all sites considered from EBRT and HDR-BR for cervical cancer patient were lower than the baseline risks. ConclusionsThe chances of developing secondary cancer take years following radiation therapy are extremely low, but the results of present study can support to establish a future database on secondary cancer risks involving radiation therapy in patients with cervical cancer by using HDR-BR and EBRT with Co-60 source in Tanzania and other developing countries.

EP-1683 Monte Carlo evaluation of organ doses from a proton gantry-mounted CBCT system

EP-1683 Monte Carlo evaluation of organ doses from a proton gantry-mounted CBCT system

PO-0914 Patient specific organ dose evaluation in cone beam CT

PO-0914 Patient specific organ dose evaluation in cone beam CT

Organ doses evaluation for chest computed tomography procedures with TL dosimeters: Comparison with Monte Carlo simulations.

PurposeTo evaluate organ doses in routine and low‐dose chest computed tomography (CT) protocols using an experimental methodology. To compare experimental results with results obtained by the National Cancer Institute dosimetry system for CT (NCICT) organ dose calculator. To address the differences on organ dose measurements using tube current modulation (TCM) and fixed tube current protocols.MethodsAn experimental approach to evaluate organ doses in pediatric and adult anthropomorphic phantoms using thermoluminescent dosimeters (TLDs) was employed in this study. Several analyses were performed in order to establish the best way to achieve the main results in this investigation. The protocols used in this study were selected after an analysis of patient data collected from the Institute of Radiology of the School of Medicine of the University of São Paulo (InRad). The image quality was evaluated by a radiologist from this institution. Six chest adult protocols and four chest pediatric protocols were evaluated. Lung doses were evaluated for the adult phantom and lung and thyroid doses were evaluated for the pediatric phantom. The irradiations were performed using both a GE and a Philips CT scanner. Finally, organ doses measured with dosimeters were compared with Monte Carlo simulations performed with NCICT.ResultsAfter analyzing the data collected from all CT examinations performed during a period of 3 yr, the authors identified that adult and pediatric chest CT are among the most applied protocol in patients in that clinical institution, demonstrating the relevance on evaluating organ doses due to these examinations. With regards to the scan parameters adopted, the authors identified that using 80 kV instead of 120 kV for a pediatric chest routine CT, with TCM in both situations, can lead up to a 28.7% decrease on the absorbed dose. Moreover, in comparison to the standard adult protocol, which is performed with fixed mAs, TCM, and ultra low‐dose protocols resulted in dose reductions of up to 35.0% and 90.0%, respectively. Finally, the percent differences found between experimental and Monte Carlo simulated organ doses were within a 20% interval.ConclusionsThe results obtained in this study measured the impact on the absorbed dose in routine chest CT by changing several scan parameters while the image quality could be potentially preserved.