An inventory of patient-image based risk/dose, image quality and body habitus/size metrics for adult abdomino-pelvic CT protocol optimisation.

PURPOSE: Patient-specific protocol optimisation in abdomino-pelvic Computed Tomography (CT) requires measurement of body habitus/size (BH), sensitivity-specificity (surrogates image quality (IQ) metrics) and risk (surrogates often dose quantities) (RD). This work provides an updated inventory of metrics available for each of these three categories of optimisation variables derivable directly from patient measurements or images. We consider objective IQ metrics mostly in the spatial domain (i.e., those related directly to sharpness, contrast, noise quantity/texture and perceived detectability as these are used by radiologists to assess the acceptability or otherwise of patient images in practice). MATERIALS AND METHODS: The search engine used was PubMed with the search period being 2010-2024. The key words used were: 'comput* tomography', 'CT', 'abdom*', 'dose', 'risk', 'SSDE', 'image quality', 'water equivalent diameter', 'size', 'body composition', 'habit*', 'BMI', 'obes*', 'overweight'. Since BH is critical for patient specific optimisation, articles correlating RD vs BH, and IQ vs BH were reviewed. RESULTS: The inventory includes 11 BH, 12 IQ and 6 RD metrics. 25 RD vs BH correlation studies and 9 IQ vs BH correlation studies were identified. 7 articles in the latter group correlated metrics from all three categories concurrently. CONCLUSIONS: Protocol optimisation should be fine-tuned to the level of the individual patient and particular clinical query. This would require a judicious choice of metrics from each of the three categories. It is suggested that, for increased utility in clinical practice, more future optimisation studies be clinical task based and involve the three categories of metrics concurrently.

Evidence-based radiology 5 years on-a single-centre review of image referral appropriateness.

BACKGROUND: The iRefer guidelines provide evidence-based recommendations on imaging and are designed to facilitate appropriate referrals and limit unnecessary radiation exposure. In 2017, a review at this institution assessed the appropriateness of imaging referrals. This study provides an update 5 years later on the referral appropriateness and aims to assess what impact the previous review has had on referral appropriateness. METHODS: A retrospective study of 945 referrals across GPs, ED, and inpatients was audited against the iRefer guidelines with costs and cumulative dose estimates calculated for inappropriate referrals considering salaries of those involved, the average time spent performing and reporting radiographs, and the median effective dose values. RESULTS: Results show a decrease in the volume of requests overall with the relative proportion of inappropriate requests rising significantly. Inappropriate requests for abdominal X-rays from GPs decreased from 72 to 37.5%, whereas inappropriate ED referrals increased from 38 to 46% and inappropriate inpatient requests remained static at 30%. The proportion of inappropriate GP requests for spinal radiographs significantly increased for cervical, thoracic, and lumbar spine radiographs, respectively (18 to 66%; 47 to 72%; 53 to 80%; p-value < 0.001). Inappropriate radiographs represent an increased financial and dose-based burden. CONCLUSION: The volume of radiograph requests reduced after over a 5-year interval; however, the relative proportion of inappropriate requests rose significantly. The iRefer guidelines provide a useful resource to ensure that imaging is used appropriately, effectively, and safely; however, more work is needed to ensure that requests are adhering to these guidelines.

Improving a regional project on diagnostic reference levels for interventional procedures (OPRIPALC) with the support of a dose management system for the protection of patients and staff.

Interventional radiology is a clinical practice with important benefits for patients, but which involves high radiation doses. The optimisation of radiation protection (RP) for paediatric interventional cardiology is a priority for both patients and staff. The use of diagnostic reference levels (DRLs) has been proposed by the International Commission on Radiological Protection to improve RP in imaging procedures. Dose management systems (DMSs) allow the automatic collection of dosimetric, geometric and technical data to assist the optimisation process, with a continuous audit of the procedures, generating alerts to implement corrective actions when necessary. Patient dose indicators may be analysed individually and for different radiation events (fluoroscopy and cine runs). Occupational doses per procedure may be analysed (if electronic dosimeters are available) and linked with patient doses for an integrated approach to RP. Regional optimisation programmes require data collection and processing from several countries to set and periodically update the DRLs. Patient data is anonymised, and each participating hospital has access to their data in a central computer server. Using DMSs may be one of the best ways to support these programs in the collection and analysis of data, raising alerts about high patient and occupational doses and suggesting optimisation actions.

National Diagnostic Reference Levels for Standard Descending Thoracic Endovascular Aortic Repair and Optimisation Strategies.

OBJECTIVE: The International Commission on Radiological Protection has highlighted the large number of medical specialties that use fluoroscopy outside diagnostic imaging departments without radiation protection programmes for patients and staff. Vascular surgery is one of these specialties. Thoracic endovascular aortic repair (TEVAR) is a complicated procedure requiring radiation protection guidance and optimisation. The recent EU Basic Safety Standards Directive requires the use and periodic updating of diagnostic reference levels (DRLs) for interventional procedures. The aim of this study was to determine doses for patients undergoing TEVAR with mobile Xray systems and hybrid rooms (fixed Xray systems) to obtain national DRLs and to suggest optimisation actions. METHODS: This was a retrospective cross sectional study. The Spanish Chapter of Endovascular Surgery conducted a national survey in 11 autonomous communities representing around 77.6% of the Spanish population (47.33 million inhabitants). A total of 266 TEVAR procedures from 17 Spanish centres were analysed, of which 53.0% were performed in hybrid operating rooms. National DRLs were obtained and defined as the third quartile of the median values from the different participating centres. RESULTS: The proposed national DRLs are: for kerma area product (KAP), 113.81 Gy·cm2 for mobile Xray systems and 282.59 Gy·cm2 for hybrid rooms; and for cumulative air kerma (CAK) at the patient entry reference point, 228.38 mGy for mobile systems and 910.64 mGy for hybrid rooms. CONCLUSION: Based on the requirement to know radiation doses for standard endovascular procedures, this study of TEVARs demonstrated that there is an increased factor of 2.48 in DRLs for KAP when the procedure is performed in a hybrid room compared with mobile C-arm systems, and an increased factor of 3.98 in DRLs for CAK when the procedure is performed with hybrid equipment. These results will help to optimise strategies to reduce radiation doses during TEVAR procedures.

Trends in patient dose and compression force for digital (DR) mammography systems over an eleven-year period.

This study evaluated trends in patient dose and compression force for screening digital (DR) mammography systems. The results of five audits (carried out in 2011, 2014, 2018, 2020 and 2022) were compared. For every audit, anonymised screening examinations from each system consisting of the standard craniocaudal (CC) and mediolateral oblique (MLO) views of both breasts were analysed. Exposure parameters were extracted from the Digital Imaging and Communications in Medicine (DICOM) header and the mean glandular dose (MGD) for each image was calculated. Trends in the distribution of MGD, compressed breast thickness, compression force and compression force per radiographer were investigated. The mean MGD per image (and mean compressed breast thickness) was 1.20 mGy (58 mm), 1.53 mGy (59 mm), 1.83 mGy (61 mm), 1.94 mGy (60 mm) and 2.11 mGy (61 mm) for 2011, 2014, 2018, 2020 and 2022 respectively. The mean (and standard deviation) compression force was 114 (32) N, 112 (29) N, 108 (27) N, 104 (24) N and 100 (23) N for 2011, 2014, 2018, 2020 and 2022 respectively. The mean MGD per image has increased over time but remains below internationally established Diagnostic Reference Levels (DRLs). This increase is primarily due to a change in the distribution of the different manufacturers and digital detector technologies, rather than an increase in the dose of the individual systems over time. The mean compression force has decreased over time in response to client feedback surveys. The standard deviation has also reduced, indicating more consistent application of force.

Patient Dose Estimation in Computed Tomography-Guided Biopsy Procedures.

This study establishes typical Diagnostic Reference Levels (DRL) values and assesses patient doses in computed tomography (CT)-guided biopsy procedures. The Effective Dose (ED), Entrance Skin Dose (ESD), and Size-Specific Dose Estimate (SSDE) were calculated using the relevant literature-derived conversion factors. A retrospective analysis of 226 CT-guided biopsies across five categories (Iliac bone, liver, lung, mediastinum, and para-aortic lymph nodes) was conducted. Typical DRL values were computed as median distributions, following guidelines from the International Commission on Radiological Protection (ICRP) Publication 135. DRLs for helical mode CT acquisitions were set at 9.7 mGy for Iliac bone, 8.9 mGy for liver, 8.8 mGy for lung, 7.9 mGy for mediastinal mass, and 9 mGy for para-aortic lymph nodes biopsies. In contrast, DRLs for biopsy acquisitions were 7.3 mGy, 7.7 mGy, 5.6 mGy, 5.6 mGy, and 7.4 mGy, respectively. Median SSDE values varied from 7.6 mGy to 10 mGy for biopsy acquisitions and from 11.3 mGy to 12.6 mGy for helical scans. Median ED values ranged from 1.6 mSv to 5.7 mSv for biopsy scans and from 3.9 mSv to 9.3 mSv for helical scans. The study highlights the significance of using DRLs for optimizing CT-guided biopsy procedures, revealing notable variations in radiation exposure between helical scans covering entire anatomical regions and localized biopsy acquisitions.

Network-targeting combination therapy of leptomeningeal glioblastoma using multiple synthetic lethal strategies: a case report.

Network targeting of disease-specific nodes represents a useful principle for designing combination cancer therapy. In this case of a patient with relapsed leptomeningeal glioblastoma, comprehensive molecular diagnosis led to the identification of a disease network characterized by multiple disease-specific synthetic lethal vulnerabilities involving DNA repair, REDOX homeostasis, and impaired autophagy which suggested a novel network-targeting combination therapy (NTCT). A treatment regimen consisting of lomustine, olaparib, digoxin, metformin, and high dose intravenous ascorbate was employed using the principle of intra-patient dose escalation to deliver the treatment with adequate safety measures to achieve a definitive clinical result.

Feasibility of new patient dose management tool in digital radiography: Using clinical exposure index data of mobile chest radiography in a large university hospital.

The clinical anteroposterior (AP) chest images taken with a mobile radiography system were analyzed in this study to utilize the clinical exposure index (EI) as a patient dose-monitoring tool. The digital imaging and communications in medicine header of 6048 data points exposed under the 90 kVp and 2.5 mAs were extracted using Python for identifying the distribution of clinical EI. Even under the same exposure conditions, the clinical EI distribution was 137.82-4924.38. To determine the cause, the effect of a patient's body shape on EI was confirmed using actual clinical chest AP image data binarized into 0 and 255-pixel values using Python. As a result, the relationship between the direct X-ray area of the chest AP image, the higher the clinical EI, the larger the rate of the direct X-ray area. A conversion equation was also derived to infer entrance surface dose through clinical EI based on the patient thickness. This confirmed the possibility of directly monitoring patient dose through EI without a dosimeter in real-time. Therefore, to use the clinical EI of the mobile radiography system as a patient dose-monitoring tool, the derivation method of clinical EI considers several factors, such as the relationship between patient factors.

A retrospective survey to establish institutional diagnostic reference levels for CT urography examinations based on clinical indications: preliminary results.

Objective. To establish institutional diagnostic reference levels (IDRLs) based on clinical indications (CIs) for three- and four-phase computed tomography urography (CTU).Methods. Volumetric computed tomography dose index (CTDIvol), dose-length product (DLP), patients' demographics, selected CIs like lithiasis, cancer, and other diseases, and protocols' parameters were retrospectively recorded for 198 CTUs conducted on a Toshiba Aquilion Prime 80 scanner. Patients were categorised based on CIs and number of phases. These groups' 75th percentiles of CTDIvoland DLP were proposed as IDRLs. The mean, median and IDRLs were compared with previously published values.Results. For the three-phase protocol, the CTDIvol(mGy) and DLP (mGy.cm) were 22.7/992 for the whole group, 23.4/992 for lithiasis, 22.8/1037 for cancer, and 21.2/981 for other diseases. The corresponding CTDIvol(mGy) and DLP (mGy.cm) values for the four-phase protocol were 28.6/1172, 30.6/1203, 27.3/1077, and 28.7/1252, respectively. A significant difference was found in CTDIvoland DLP between the two protocols, among the phases of three-phase (except cancer) and four-phase protocols (except DLP for other diseases), and in DLP between the second and third phases (except for cancer group). The results are comparable or lower than most studies published in the last decade.Conclusions. The CT technologist must be aware of the critical dose dependence on the scan length and the applied exposure parameters for each phase, according to the patient's clinical background and the corresponding imaging anatomy, which must have been properly targeted by the competent radiologist. When clinically feasible, restricting the number of phases to three instead of four could remarkably reduce the patient's radiation dose. CI-based IDRLs will serve as a baseline for comparison with CTU practice in other hospitals and could contribute to national DRL establishment. The awareness and knowledge of dose levels during CTU will prompt optimisation strategies in CT facilities.

Quantitative Analysis of Image Quality in Low-Dose Computed Tomography Imaging for COVID-19 Patients.

Background: Computed tomography (CT) scan is one of the main tools to diagnose and grade COVID-19 progression. To avoid the side effects of CT imaging, low-dose CT imaging is of crucial importance to reduce population absorbed dose. However, this approach introduces considerable noise levels in CT images. Methods: In this light, we set out to simulate four reduced dose levels (60% dose, 40% dose, 20% dose, and 10% dose) of standard CT imaging using Beer-Lambert's law across 49 patients infected with COVID-19. Then, three denoising filters, namely Gaussian, bilateral, and median, were applied to the different low-dose CT images, the quality of which was assessed prior to and after the application of the various filters via calculation of peak signal-to-noise ratio, root mean square error (RMSE), structural similarity index measure, and relative CT-value bias, separately for the lung tissue and whole body. Results: The quantitative evaluation indicated that 10%-dose CT images have inferior quality (with RMSE = 322.1 ± 104.0 HU and bias = 11.44% ± 4.49% in the lung) even after the application of the denoising filters. The bilateral filter exhibited superior performance to suppress the noise and recover the underlying signals in low-dose CT images compared to the other denoising techniques. The bilateral filter led to RMSE and bias of 100.21 ± 16.47 HU and - 0.21% ± 1.20%, respectively, in the lung regions for 20%-dose CT images compared to the Gaussian filter with RMSE = 103.46 ± 15.70 HU and bias = 1.02% ± 1.68% and median filter with RMSE = 129.60 ± 18.09 HU and bias = -6.15% ± 2.24%. Conclusions: The 20%-dose CT imaging followed by the bilateral filtering introduced a reasonable compromise between image quality and patient dose reduction.

Effect of varying X-ray tube voltage and additional filtration on image quality and patient dose in digital radiography system.

This study investigated the effect of varying x-ray tube voltage and additional filtration thicknesses on radiation dose and image quality in digital radiography system. The polymethylmethacrylate (PMMA) phantoms of different thicknesses simulating both the adult chest and abdomen and the pediatric patient's chest examinations were used. X-ray tube voltage range of 70-125 kVp was used for adult patient chest radiography, 70-100 kVp for adult patient abdominal radiography, and 50-70 kVp for pediatric 1-year-old chest examination. 0.1-0.3 mm Cu and 1.0 mm Al filters were used as additional filters. Patient doses were measured with an ionization chamber, considering the irradiation parameters recommended for radiographic examinations performed in radiology clinics in the EUR 16260 protocol. The Entrance Skin Dose (ESD) was calculated from the air kerma value measured at the entrance surface of the PMMA phantoms. Effective dose values were calculated by employing PCXMC 2.0 program. For image quality evaluations, CDRAD, LCD-4, Beam stop and Huttner test object used together with PMMA phantoms and Alderson RS-330 Lung/Chest phantom were used. Figure of Merit (FOM), which allows quantitative assessment in terms of image quality and patient dose, has been calculated. Based on the calculated FOM values were evaluated at the tube voltages and additional filter thicknesses recommended in the EUR 16260 protocol. Entrance Skin Dose and Inverse Image Quality Figure (IQFinv) value obtained from contrast detail analysis decreased with increasing filter thickness and tube voltage. Decrease in ESD and IQFinv with increasing tube voltage without additional filter was 56% and 21% for adult chest radiography, 69% and 39% for adult abdominal radiography and 34% and 6% for 1-year-old pediatric chest radiography. When calculated FOM values are examined, it can be recommended to use a 0.1 mm Cu filter at 90 kVp and a 0.1 mm Cu + 1.0 mm Al filter at 125 kVp for adult chest radiography. For adult abdominal radiography, 0.2 mm Cu filter at 70 and 80 kVp and 0.1 mm Cu filter at 90 and 100 kVp were found to be appropriate. It was determined that the appropriate additional filter at 70 kVp for 1-year-old chest radiography was 1.0 mm Al+0.1 mm Cu.

Fluoroscopically guided vascular and cardiac transcatheter procedures: a comparison of occupational and patient dose by anatomical region.

X-ray guided procedures are being performed by an increasing variety of medical specialties. Due to improvements in vascular transcatheter therapies, there is an increasing overlap of imaged anatomy between medical specialties. There is concern that non-radiology fluoroscopic operators may not have sufficient training to be well informed of the potential implications of radiation exposure and mitigation strategies to reduce dose. This was a prospective, observational, single center study to compare occupational and patient dose levels when imaging different anatomical regions during fluoroscopically guided cardiac and endovascular procedures. Occupational radiation dose was measured at the level of the temple of 24 cardiologists and 3 vascular surgeons (n = 1369), 32 scrub nurses (n = 1307) and 35 circulating nurses (n = 885). The patient dose was recorded for procedures (n = 1792) performed in three angiography suites. Abdominal imaging during endovascular aneurysm repair (EVAR) procedures was associated with a comparatively high average patient, operator and scrub nurse dose despite additional table-mounted lead shields. Air kerma was relatively high for procedures performed in the chest, and chest + pelvis. Higher dose area product and staff eye dose were recorded during procedures of the chest + pelvis due to the use of digital subtraction angiography to evaluate access route prior to/during transaortic valve implantation. Scrub nurses were exposed to higher average radiation levels than the operator during some procedures. Staff should be cognizant of the potentially higher radiation burden to patients and exposed personnel during EVAR procedures and cardiac procedures using digital subtraction angiography.

Estimation of patient-size dependent imaging dose for stereoscopic/monoscopic real-time kV image guidance in lung and prostate SBRT.

Purpose.The purpose of this work is to quantify the dependence of patient-specific imaging dose on patient-size from ExacTrac stereoscopic/monoscopic real-time tumor monitoring during lung and prostate stereotactic body radiotherapy (SBRT).Approach. Thirty lung and 30 prostate SBRT patients that were treated with volumetric modulated arc therapy (VMAT) were selected and divided into three patient size categories. Imaging doses from all SBRT fractions were calculated retrospectively assuming patients went through real-time tumor monitoring during their actual VMAT treatment times. Treatment times were divided into periods of stereoscopic and monoscopic real-time imaging depending on the imaging view with linac gantry blockage. The computed tomography (CT) images and contours of the planning target volume (PTV) and organs at risk (OARs) were exported from the treatment planning system. Based on the CT data, patient-specific 3D imaging dose distributions were calculated in a validated Monte Carlo model using DOSEXYZnrc. Vendor-recommended imaging protocols (lung: 120-140 kV, 16-25 mAs; prostate: 110-130 kV, 25 mAs) were used for each patient size category. Patient-specific imaging doses received by PTV and OARs were evaluated using dose volume histograms, dose delivered to 50% of organ volume (D50), and 2% of organ volume (D2).Results. Bone and skin received the highest imaging dose. For the lung patients, the highest D2 for bone and skin were 4.30% and 1.98% of the prescription dose respectively. For prostate patients, the highest D2 were 2.53% and 1.35% of the prescription for bone and skin. Additional imaging dose to PTV as a percentage of the prescribed dose was at most 2.42% for lung and 0.29% for prostate patients. T-test results showed statistically significant difference in D2 and D50 between at least two patient size categories for PTVs and all the OARs. Larger patients received more skin dose in both lung and prostate patients. For the internal OARs, larger patients received more dose in lung treatment while the trend was opposite in prostate treatment.Conclusion. Patient-specific imaging dose was quantified for monoscopic/stereoscopic real-time kV image guidance in lung and prostate patients with respect to patient size. Additional skin dose was 1.98% (in lung patients) and 1.35% (in prostate patients) of the prescription which is within 5% recommended value by the AAPM Task Group 180. For internal OARs, larger patients received more dose in lung patients while the trend was the opposite for prostate patients. Patient size was an important factor to determine additional imaging dose.

Discussion on the evaluation of radiation protection of “four-in-one” dental X-ray equipment / 中国辐射卫生

Objective To evaluate the radiation protection of “four-in-one” dental X-ray equipment and to investigate the safety interlock of the equipment by measuring the scattered radiation at the position of the patient during operation. Methods A cone-beam CT dental phantom was used to simulate the patient’s head. The intra-oral and extra-oral components of the “four-in-one” X-ray equipment were installed in a 5 m2 room. The scattered radiation at patient position was measured using a γ/X-ray survey meter, and the effects of intra-oral and extra-oral components were compared. Results For a 5 m2 room, when CBCT was exposed under typical conditions, the dose at the patient's position was 10.70 uSv/h when there was an intra-oral component and 10.60 uSv/h when there was no intraoral component. The intra-oral part did not affect the radiation dose at the patient's position. When the intra-oral component was exposed, the dose rate at the patient's position was 4.05-6.85 uSv/h, and the extra-oral part did not affect the scattered dose of the patient examined with intra-oral components. Conclusion The evaluation of radiation protection of new equipment must comprehensively consider radiation safety and equipment operation safety. The results of this study provide suggestions for clinical radiation protection supervision and evaluation of “four-in-one” dental X-ray equipment.

Optimisation of Radiological Protection in Digital Radiology Techniques for Medical Imaging.

Use of medical imaging continues to increase, making the largest contribution to the exposure of populations from artificial sources of radiation worldwide. The principle of optimisation of protection is that 'the likelihood of incurring exposures, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable (ALARA), taking into account economic and societal factors'. Optimisation for medical imaging involves more than ALARA - it requires keeping individual patient exposures to the minimum necessary to achieve the required medical objectives. In other words, the type, number, and quality of images must be adequate to obtain the information needed for diagnosis or intervention. Dose reductions for imaging or x-ray-image-guided procedures should not be used if they degrade image quality to the point where the images are inadequate for the clinical purpose. The move to digital imaging has provided versatile acquisition, post-processing, and presentation options, and enabled wide and often immediate availability of image information. However, because images are adjusted for optimal viewing, the appearance may not give any indication if the dose is higher than necessary. Nevertheless, digital images provide opportunities for further optimisation, and allow the application of artificial intelligence methods.Optimisation of radiological protection for digital radiology (radiography, fluoroscopy, and computed tomography) involves selection and installation of equipment, design and construction of facilities, choice of optimal equipment settings, day-to-day methods of operation, quality control programmes, and ensuring that all personnel receive proper initial and career-long training. The radiation dose levels that patients receive also have implications for doses to staff. As new imaging equipment incorporates more options to improve performance, it becomes more complex and less easily understood, so operators have to be given more extensive training. Ongoing monitoring, review, and analysis of performance is required that feeds back into the improvement and development of imaging protocols. Several different aspects relating to optimisation of protection that need to be developed are set out in this publication. The first is collaboration between radiologists/other radiological medical practitioners, radiographers/medical radiation technologists, and medical physicists, each of whom have key skills that can only contribute to the process effectively when individuals work together as a core team. The second is appropriate methodology and technology, with the knowledge and expertise required to use each effectively. The third relates to organisational processes which ensure that required tasks, such as equipment performance tests, patient dose surveys, and review of protocols, are carried out. There is wide variation in equipment, funding, and expertise around the world, and the majority of facilities do not have all the tools, professional teams, and expertise to fully embrace all the possibilities for optimisation. Therefore, this publication sets out broad levels for aspects of optimisation that different facilities might achieve, and through which they can progress incrementally: Level D - preliminary; Level C - basic; Level B - intermediate; and Level A - advanced. Guidance from professional societies can be invaluable in helping users to evaluate systems and aid in adoption of best practice. Examples of systems and activities that should be in place to achieve the different levels are set out. Imaging facilities can then evaluate the arrangements they already have, and use this publication to guide decisions about the next actions to be taken in optimising their imaging services.

CTContour: An open-source Python pipeline for automatic contouring and calculation of mean SSDE along the abdomino-pelvic region for CT images; validation on fifteen systems.

PURPOSE: Calculation of the Size Specific Dose Estimate (SSDE) requires accurate delineation of the skin boundary of patient CT slices. The AAPM recommendation for SSDE evaluation at every CT slice is too time intensive for manual contouring, prohibiting real-time or bulk processing; an automated approach is therefore desirable. Previous automated delineation studies either did not fully disclose the steps of the algorithm or did not always manage to fully isolate the patient. The purpose of this study was to develop a validated, freely available, fast, vendor-independent open-source tool to automatically and accurately contour and calculate the SSDE for the abdomino-pelvic region for entire studies in real-time, including flagging of patient-truncated images. METHODS: The Python tool, CTContour, consists of a sequence of morphological steps and scales over multiple cores for speed. Tool validation was achieved on 700 randomly selected slices from abdominal and abdomino-pelvic studies from public datasets. Contouring accuracy was assessed visually by four medical physicists using a 1-5 Likert scale (5 indicating perfect contouring). Mean SSDE values were validated via manual calculation. RESULTS: Contour accuracy validation produced a score of four of five for 98.5 % of the images. A 300 slice exam was contoured and truncation flagged in 6.3 s on a six-core laptop. CONCLUSIONS: The algorithm was accurate even for complex clinical scenarios and when artefacts were present. Fast execution makes it possible to automate the calculation of SSDE in real time. The tool has been published on GitHub under the GNU-GPLv3 license.

SIZE-specific dose estimate for lower-limb CT.

The Computed Tomography Dose Index (CTDI) is an indicator for dose management in computed tomography (CT), but has limited use for patient dosimetry. To evaluate the patient dose, the size-specific dose estimate (SSDE), reported by the American Association of Physics in Medicine task groups 204, 220, and 293, must be calculated by the CTDIvol(z) displayed on the CT console, and the conversion factor f(D(z)) from the effective diameter (DEff) or water equivalent diameter (Dw). However, no reports have verified the appropriateness of using the 320-mm diameter phantom for dose assessment in CT examinations involving the lower limbs. Therefore, we validated a new method for evaluating the SSDE(z) of the lower limbs, using two 160-mm diameter phantoms instead of the 320-mm diameter phantom. The CTDIvol(z) obtained from Monte Carlo (MC) simulation study was reliable because they were almost the same as obtained in a dosimetry study. The conversion factor f (D (zl.l.)) for the lower limbs was evaluated based on the CTDIvol(z) obtained by MC simulation performed using two polymethyl methacrylate cylinder phantoms of 160-mm diameter. The MC simulation was performed by the International Commission on Radiological Protection publication 135 reference adult phantom and was used to evaluate the absorbed dose of the pelvis, thighs, knees, and ankles. The dose showing the greatest difference was the thighs, which was 8.3 mGy (16%) lower than the absorbed dose. Thus, the SSDE (zl.l.) could be estimated from the [Formula: see text] displayed on the CT scanner console.

An approach for the online determination of Entrance Surface Air Kerma (ESAK) from Kerma Area product (PKA) in digital radiology.

We propose determining the entrance surface air kerma (ESAK) from the kerma area product (PKA) in digital radiology. ESAK values were derived from the X-ray tube outputs and patient exposure factors across five X-ray departments. Using linear regression between ESAK and PKA values, the slope and intercept coefficients were determined for each X-ray equipment and procedure. The method was examined using the data collected from patients who underwent chest PA/LAT, abdomen, pelvic AP, and lumbar spine AP/LAT X-ray examinations. The results showed a highly significant correlation between ESAK and PKA values and correlation coefficients, ranging from 0.77 to 1 with P-value < 0.001 in most studies. This method can be employed by incorporating dose data and related parameters into the X-ray device's software, similar to other dose-displayed information. The online determination of ESAK from PKA could help with quality assurance and patient dose management in digital radiology.

Does Dose Matter? Ionizing Radiation Exposure of the Veterinary Patient From Computed Tomography: A Discussion.

Advanced imaging techniques such as computed tomography are commonplace in human medicine and increasingly, are being utilized by the veterinary profession as scanners become more available and affordable. The benefit of computed tomography imaging is the provision of detailed cross-sectional imaging and 3D reconstruction, but this incurs higher doses of ionizing radiation to the patient. This paper reviews risks and effects associated with ionizing radiation, making comparisons to human models, and a hypothetical scenario is discussed using the human risk model for age at time of exposure and increased lifetime risk of cancer with a dog to human year's formula. Various issues are considered with respect to dose reduction, training, equipment and the reported "greater need for guidance and the establishment of best practice" which may lead to future guidance from the International Commission on Radiological Protection.