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Background: Accurate dosimetry is crucial in radiotherapy to ensure optimal radiation dose delivery to the tumor while sparing healthy tissues. Traditional dosimetry techniques using homogeneous phantoms may not accurately represent the complex anatomical variations in cervical cancer patients, highlighting the need to compare dosimetry results obtained from different phantom models. Purpose: The aim of this study is to design and evaluate an anthropomorphic heterogeneous female pelvic (AHFP) phantom for radiotherapy quality assurance in cervical cancer treatment. Materials and method: Thirty RapidArc plans designed for cervical cancer patients were exported to both the RW3 homogeneous phantom and the anthropomorphic heterogeneous pelvic phantom. Dose calculations were performed using the anisotropic analytic algorithm (AAA), and the plans were delivered using a linear accelerator (LA). Dose measurements were obtained using a 0.6 cc ion chamber. The percentage (%) variation between planned and measured doses was calculated and analyzed. Additionally, relative dosimetry was performed for various target locations using RapidArc and IMRT treatment techniques. The AHFP phantom demonstrated excellent agreement between measured and expected dose distributions, making it a reliable quality assurance tool in radiotherapy. Results: The results reveal that the percentage variation between planned and measured doses for all RapidArc quality assurance (QA) plans using the AHFP phantom is 10.67% (maximum value), 2.31% (minimum value), and 6.89% (average value), with a standard deviation (SD) of 2.565 (t = 3.21604, p = 0.001063). Also, for the percentage of variation between homogeneous and AHFP phantoms, the t-value is −11.17016 and the p-value is <0.00001. The result is thus significant at p < 0.05. We can see that the outcomes differ significantly due to the influence of heterogeneous media. Also, the average gamma values in RapidArc plans are 0.29, 0.32, and 0.35 (g ≤ 1) and IMRT plans are 0.45, 0.44, and 0.42 (g ≤ 1) for targets 1, 2, and 3, respectively. Conclusion: The AHFP phantom results show more dose variability than homogenous phantom outcomes. Also, the AHFP phantom was found to be suitable for QA evaluation. [ABSTRACT FROM AUTHOR]

The present study was conducted as part of a comprehensive work to establish National Diagnostic Reference Levels (NDRLs) in Sri Lanka for the first time. DRLs can be used as an effective optimization tool for identifying unusually high or low patient doses during X‐ray examinations. This study aims to propose institutional DRLs (IDRLs) by measuring the kerma‐area product (KAP) of adult patients undergoing routine projection X‐ray examinations. The median and the 75th percentile KAP values obtained were compared with that of the single institution KAP values reported from India and Greece. This descriptive cross‐sectional study was conducted in a public hospital in Uva province, Sri Lanka, with 400 adult patients aged 18–87 years and weighing 58 ± 20 kg. The patient‐specific information (age, sex, weight, and height) and corresponding exposure parameters (tube voltage and current‐exposure time product) were obtained. The KAP values were measured, and descriptive statistics were utilized for data analysis. The median KAP values obtained were proposed as IDRLs. The IDRLs in Gy.cm2 were 0.23 for cervical spine anterior–posterior (AP), 0.19 for cervical spine lateral (LAT), 0.10 for chest posterior–anterior (PA), 0.06 for knee joint AP, 0.05 for knee joint LAT, 1.47 for KUB AP, 0.85 for lumbar spine AP, 1.97 for lumbar spine LAT, 0.29 for shoulder joint AP, 0.61 for skull PA, and 0.60 for skull LAT examinations. The maximum to minimum ratio of KAP values ranged from 2.4 for KUB AP to 6.3 for the cervical spine AP examinations. The median and the 75th percentile of most of the examinations were comparable to corresponding KAP values reported by the countries mentioned above, except for the skull PA and LAT examinations. Accordingly, interquartile ranges of exposure parameters are recommended for skull examinations to improve the optimization of patient doses. [ABSTRACT FROM AUTHOR]

Heterogeneity of dose distribution has been shown at different spatial scales in diagnostic nuclear medicine. In cancer treatment using new radiopharmaceuticals with alpha-particle emitters, it has shown an extensive degree of dose heterogeneity affecting both tumour control and toxicity of organs at risk. This review aims to provide an overview of generalized internal dosimetry in nuclear medicine and highlight the need of consideration of the dose heterogeneity within organs at risk. The current methods used for patient dosimetry in radiopharmaceutical therapy are summarized. Bio-distribution and dose heterogeneities of alpha-particle emitting pharmaceutical 223Ra (Xofigo) within bone tissues are presented as an example. In line with the strategical research agendas of the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radiation Dosimetry Group (EURADOS), future research direction of pharmacokinetic modelling and dosimetry in patient radiopharmaceutical therapy are recommended. [ABSTRACT FROM AUTHOR]

Background: Accurate dosimetry is crucial in radiotherapy to ensure optimal radiation dose delivery to the tumor while sparing healthy tissues. Traditional dosimetry techniques using homogeneous phantoms may not accurately represent the complex anatomical variations in cervical cancer patients, highlighting the need to compare dosimetry results obtained from different phantom models. Purpose: The aim of this study is to design and evaluate an anthropomorphic heterogeneous female pelvic (AHFP) phantom for radiotherapy quality assurance in cervical cancer treatment. Materials and method: Thirty RapidArc plans designed for cervical cancer patients were exported to both the RW3 homogeneous phantom and the anthropomorphic heterogeneous pelvic phantom. Dose calculations were performed using the anisotropic analytic algorithm (AAA), and the plans were delivered using a linear accelerator (LA). Dose measurements were obtained using a 0.6 cc ion chamber. The percentage (%) variation between planned and measured doses was calculated and analyzed. Additionally, relative dosimetry was performed for various target locations using RapidArc and IMRT treatment techniques. The AHFP phantom demonstrated excellent agreement between measured and expected dose distributions, making it a reliable quality assurance tool in radiotherapy. Results: The results reveal that the percentage variation between planned and measured doses for all RapidArc quality assurance (QA) plans using the AHFP phantom is 10.67% (maximum value), 2.31% (minimum value), and 6.89% (average value), with a standard deviation (SD) of 2.565 (t = 3.21604, p = 0.001063). Also, for the percentage of variation between homogeneous and AHFP phantoms, the t-value is −11.17016 and the p-value is p < 0.05. We can see that the outcomes differ significantly due to the influence of heterogeneous media. Also, the average gamma values in RapidArc plans are 0.29, 0.32, and 0.35 (g ≤ 1) and IMRT plans are 0.45, 0.44, and 0.42 (g ≤ 1) for targets 1, 2, and 3, respectively. Conclusion: The AHFP phantom results show more dose variability than homogenous phantom outcomes. Also, the AHFP phantom was found to be suitable for QA evaluation.

• Critical analysis of available Skin Dose Calculation (SDC) software tools. • Patient radiation protection in relation to skin dose in interventional cardiology. • Review of SDC capabilities to display dose distribution. In interventional cardiology, patients may be exposed to high doses to the skin resulting in skin burns following single or multiple procedures. Reviewing and analysing available software (online or offline) may help medical physicists assessing the maximum skin dose to the patient together with the dose distribution during (or after) these procedures. Capabilities and accuracy of available software were analysed through an extensive bibliography search and contacts with both vendor and authors. Their markedly differed among developers. In total, 22 software were identified and reviewed according to their algorithms and their capabilities. Special attention was dedicated to their main features and limitations of interest for the intended clinical use. While the accuracy of the 12 software products validated with measurements on phantoms was acceptable (within ± 25%), the agreement was poor for the two products validated on patients (within ± 43% and ± 76%, respectively). In addition, no software has been validated on angiographic units from all manufacturers, though several software developers claimed vendor-independent transportability. Only one software allows for multiple procedures dose calculation. Large differences among vendors made it clear that work remains to be done before an accurate and reliable skin dose mapping is available for all patients. [ABSTRACT FROM AUTHOR]

• Effective dose (E) provides a measure of potential risk in terms of health detriment. • E is calculated as a risk-weighted average of organ doses. • E is applied to a reference person, but patient-specific calculations can be done. • E is useful as a guide in making everyday decisions about patient imaging. • E should be derived using the most up-to-date phantoms and weighting factors. Effective dose (E) has been developed by the International Commission on Radiological Protection (ICRP) as a dose quantity with a link to risks of health detriment, mainly cancer. It is based on reference phantoms representing average individuals, but this is often forgotten in its application to medical exposures, for which its use sometimes goes beyond the intended purpose. There has been much debate about issues involved in the use of E in medicine and ICRP is preparing a publication with more information on this application. This article aims to describe the development of E and explain how it should be used in medicine. It discusses some of the issues that arise when E is applied to medical exposures and provides information on how its use might evolve in the future. The article concludes with responses to some frequently asked questions about uses of E that are in line with the forthcoming ICRP publication. The main use of E in medicine is in meaningful comparison of doses from different types of procedure not possible with measurable dose quantities. However, it can be used, with appropriate care, as a measure of possible cancer risks. When considering E to individual patients, it is important to note that the dose received will differ from that assessed for reference phantoms, and the risk per Sv is likely to be greater on average in children and less in older adults. Newer techniques allow the calculation of patient-specific E which should be distinguished from the reference quantity. [ABSTRACT FROM AUTHOR]

Abstract The positron emission tomography (PET)/computed tomography (CT) technique generates high doses in patients because two radiodiagnostic modalities are used in a single examination. In this study, the absorbed and effective doses generated by CT scans and by the incorporation of radiopharmaceutical solution were evaluated in 19 organs. It was found that 78.2% of the effective dose in PET/CT examinations comes from the CT scan. With an activity of 3.33 MBq/kg−1, 18F-FDG contributes 21.8% of the final effective dose. Highlights • The positron emission tomography/computed tomography (CT) technique generates high effective doses in patients. • The doses generated in the examination were evaluated in 19 organs. • The CT absorbed dose was evaluated with radiochromic film in the Alderson phantom. • The [18F]fluorodeoxyglucose effective dose was calculated with the model proposed in International Commission on Radiological Protection publication 106. [ABSTRACT FROM AUTHOR]

Abstract Patient effective doses and the associated radiation risks arising from particular computed tomography (CT) imaging procedures are assessed. The objectives of this research are to measure radiation doses for patients and to quantify the radiogenic risks from CT brain and chest procedures. Patient data were collected from five calibrated CT modality machines in Saudi Arabia. The results are from a study of a total of 60 patients examined during CT procedures using the calibrated CT units. For CT brain and chest, the mean patient effective doses were 1.9 mSv (with a range of 0.6–2.5 mSv) and 7.4 mSv (with a range of 0.5–34.8 mSv) respectively. The radiogenic risk to patients ranged from between 10−5 and 10−4 per procedure. With 65% of the CT procedure cases diagnosed as normal, this prompts re-evaluation of the referral criteria. The establishment of diagnostic reference levels (DRL) and implementation of radiation dose optimisation measures would further help reduce doses to optimal values. Highlights • Radiation dose survey for patients undergoing CT brain and chest examinations in Saudi Arabia. • Breast dose found to be high in CT chest examination, clear justification criteria being crucial. • Wide discrepancy between patient doses underlines need for establishing dose reference levels. • Dose delivered to patients found to be greater than reported in previous studies. [ABSTRACT FROM AUTHOR]

• Use of EBT-3 for dosimetry in diagnostic radiology. • Two different film calibration methods in CT. • Experimental and computational CT organ dose estimation. This 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. Gafchromic® 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. At 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%. The 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. [ABSTRACT FROM AUTHOR]

Patient dose monitoring for different radiographic procedures has been used as a parameter to evaluate the performance of radiology services; skin entrance absorbed dose values for each type of examination were internationally established and recommended aiming patient protection. In this work, a methodology for dose evaluation was applied to three diagnostic services: one with a conventional film and two with digital computerized radiography processing techniques. The x-ray beam parameters were selected and “doses” (specifically the entrance surface and incident air kerma) were evaluated based on images approved in European criteria during postero-anterior (PA) and lateral (LAT) incidences. Data were collected from 200 patients related to 200 PA and 100 LAT incidences. Results showed that doses distributions in the three diagnostic services were very different; the best relation between dose and image quality was found in the institution with the chemical film processing. This work contributed for disseminating the radiation protection culture by emphasizing the need of a continuous dose reduction without losing the quality of the diagnostic image. [ABSTRACT FROM AUTHOR]

Objectives: A national retrospective survey on patient doses was performed by the French Society of Medical physicists to assess reference levels (RLs) in interventional radiology as required by the European Directive 2013/59/Euratom.Methods: Fifteen interventional procedures in neuroradiology, vascular radiology and osteoarticular procedures were analysed. Kerma area product (KAP), fluoroscopy time (FT), reference air kerma and number of images were recorded for 10 to 30 patients per procedure. RLs were calculated as the 3rd quartiles of the distributions.Results: Results on 4600 procedures from 36 departments confirmed the large variability in patient dose for the same procedure. RLs were proposed for the four dosimetric estimators and the 15 procedures. RLs in terms of KAP and FT were 90 Gm.cm2 and 11 mins for cerebral angiography, 35 Gy.cm2 and 16 mins for biliary drainage, 75 Gy.cm2 and 6 mins for lower limbs arteriography and 70 Gy.cm2 and 11 mins for vertebroplasty. For these four procedures, RLs were defined according to the complexity of the procedure. For all the procedures, the results were lower than most of those already published.Conclusions: This study reports RLs in interventional radiology based on a national survey. Continual evolution of practices and technologies requires regular updates of RLs.Key Points: • Delivered dose in interventional radiology depends on procedure, practice and patient. • National RLs are proposed for 15 interventional procedures. • Reference levels (RLs) are useful to benchmark practices and optimize protocols. • RLs are proposed for kerma area product, air kerma, fluoroscopy time and number of images. • RLs should be adapted to the procedure complexity and updated regularly. [ABSTRACT FROM AUTHOR]

Purpose For antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female/male gonad dose. Methods High sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures. A dose profile was also generated using Unfors Mult-O-Meter 401 along the long axis of the phantom. Results A decrease in dose from the central ray toward the anode was noted, with a marked increase toward the cathode. A significant reduction in dose was received by the testes with feet towards the anode compared with feet towards cathode (P˂0.001). No difference was seen for ovarian dose (P˃0.05). kVp, mAs and SID all have an effect on male and female gonad dose. Conclusion For male pelvis imaging, placing feet towards the anode can be used as a simple dose reduction method. [ABSTRACT FROM AUTHOR]

Computed tomography is widely used for planar imaging. Previous studies showed that CR systems involve higher patient radiation doses compared to digital systems. Therefore, assessing the patient's dose and CR system performance is necessary to ensure that patients received minimal dose with the highest possible image quality. The study was performed at three medical diagnostic centers in Sudan: Medical Corps Hospital (MCH), Advance Diagnostic Center (ADC), and Advance Medical Center (AMC). The following tools were used in this study: Tape measure, Adhesive tape, 1.5 mm copper filtration (>10 × 10 cm), TO 20 threshold contrast test object, Resolution test object (e.g., Huttner 18), MI geometry test object or lead ruler, Contact mish, Piranha (semiconductor detector), Small lead or copper block (∼5 × 5 cm), and Steel ruler, to do a different type of tests (Dark Noise, Erasure cycle efficiency, Sensitivity Index calibration, Sensitivity Index consistency, Uniformity, Scaling errors, Blurring, Limiting spatial Resolution, Threshold, and Laser beam Function. Entrance surface air kerma (ESAK (mGy) was calculated from patient exposure parameters using DosCal software for three imaging modalities. A total of 199 patients were examined (112 chest X rays, 77 lumbar spine). The mean and standard deviation (sd) for patients ESAK (mGy) were 2.56 ± 0.1 mGy and 1.6 mGy for the Anteroposterior (AP) and lateral projections for the lumbar spine, respectively. The mean and sd for the patient's chest doses were 0.1 ± 0.01 for the chest X-ray procedures. The three medical diagnostic centers' CR system performance was evaluated and found that all of the three centers have good CR system functions. All the centers satisfy all the criteria of acceptable visual tests. CR's image quality and sensitivity were evaluated, and the CR image is good because it has good contrast and resolution. All the CR system available in the medical centers and upgraded from old X-ray systems to new systems, has been found to work well. The patient's doses were comparable for the chest X-ray procedures, while patients' doses from the lumbar spine showed variation up to 2 folds due to the variation in patients' weight and X-ray machine setting. Patients dose optimization is recommended to ensure the patients received a minimal dose while obtaining the diagnostic findings. • Computed radiography system performance were evaluated at three hospitals in Sudan. • Patients ESAK (mGy) was quantified for chest X rays and lumber spine procedures. • CR systems performance was acceptable and within the predefined limits. • The ESAK (mGy) was lower compared to previous published studies. [ABSTRACT FROM AUTHOR]

The aims of this study were to measure the patients’ entrance surface air kerma doses (ESAK), effective doses and to compare practices between different hospitals in Sudan. ESAK were measured for patient using calibrated thermo luminance dosimeters (TLDs, GR200A). Effective doses were estimated using National radiological Protection Board (NRPB) software. This study was conducted in five radiological departments: Two Teaching Hospitals (A and D), two private hospitals (B and C) and one University Hospital (E). The mean ESAK was 20.1 mGy, 28.9 mGy, 13.6 mGy, 17.5 mGy, 35.7 mGy for hospitals A, B, C, D, and E, respectively. The mean effective dose was 2.4 mSv, 3.5 mSv, 1.6 mSv, 2.1 mSv and 4.3 mSv in the same order. The study showed wide variations in the ESDs with three of the hospitals having values above the internationally reported values. [ABSTRACT FROM AUTHOR]

Quality assurance for planned radiation exposure situations (e.g. Digital Radiography, Computed Tomography or Radio Fluoroscopic studies) requires the application of examination-specific scans protocols. These are tailored to patient age or size, body region and clinical indication for ensuring that the dose applied to each patient is as low as reasonably achievable for the clinical purpose of the image acquisition (ALARA principle). The European legal framework - 2013/59/EURATOM - points that health authorities will be more pervasive on inspecting the dosimetry applied to patients. This paper discusses these legal alterations and presents an interoperable distributed system for dose monitoring, which is compliant with legal procedures and the IHE Radiation Exposure Monitoring profile (REM). The system combines the most representative stakeholders affected and directly interested in the patient radiological protection: patients, radiologists, practitioners, health authorities, and ethics committee. The system is capable of gathering, in real-time, dose information applied to the patient and storing it in a regional or national wide dose registry. The paper addresses which information should such systems hold and which should be accessed, from each stakeholder perspective. Furthermore, the system may detect irregular dose patterns, which could indicate dose abuses, and signal those findings to the appropriate stakeholders. [ABSTRACT FROM AUTHOR]

Patient-specific internal dosimetry with a high accuracy is one of the most significant issues in the field of nuclear medicine. In recent investigations, there has been a dramatic alter in the different methods for computing the correct organ doses from the injected radioactivity. Monte Carlo simulations have yielded highly accurate results for voxel-based dosimetry techniques. This paper aims to present a precise methodology based on full Monte Carlo simulations, and time-activity curve estimation using three individual scans over 90 min. In this study, a dataset of patients who were injected with F-Fluor-2-D-Glucose, F18-FDG (10 normal cases, 60 ± 8.2 kg, injected activity, 370 ± 10 MBq), was acquired in 3 different time sequences (20, 60, 90 min post-injection). First, the GATE Monte Carlo results were validated using experimental measurements. Subsequently, the Monte Carlo code was considered for S-value calculations. The CT and PET images were used to obtain attenuation maps and activity distribution inside the patients' phantom, respectively. The CT and PET images were registered using an image processing software to achieve the same matrix and pixel sizes. Regions of interest, such as the kidneys, spleen, bladder, lung, pancreas, liver, stomach, and heart wall, were identified on CT images. The segmented ROIs of the CT images were reconstructed and the voxelized phantom and voxelized source of each patient at specific time intervals were generated. The time activity curves (TACs) were obtained based on PET images. The results of the F18-FDG dose distribution in patient-specific phantoms indicate that the bladder, lung, heart, and liver absorbed more activity than other organs, as expected from the PET images. Close agreement was observed between the results obtained in this study and those of previous investigations that used biokinetic models. The dose per activity values was reported within 0.02–0.06 mGy/MBq for most organs with simulation uncertainty less than 7%. There is ample room for further progress in the clinical use of the Monte Carlo method and the improvement of the phantom-based model. • Estimate internal patient dose related to GATE Monte Carlo method. • The procedure of the mentioned method is validated with experimental and simulation steps. • TAC was performed based on static time sequences. • The results of TAC estimation were compared with the biokinetic curves of previous studies. • This study surveyed the internal dosimetry procedure based on patient data. [ABSTRACT FROM AUTHOR]

Cr-doped (Gd X Y 1 − X ) 3 Al 5 O 12 ( X = 0, 0.25, 0.50) crystals prepared by the micro-pulling down method were investigated to develop a infra-red scintillator for implantable patient dosimeter in radiation therapy. In order to evaluate their optical and scintillation performance, the following properties were measured: (i) transmittance between ultra-violet and near-infra red region, (ii) photoluminescence spectra under Xe-lamp excitation, and (iii) X-ray excited radio-luminescence spectra. Cr:Y 3 Al 5 O 12 and Cr:(Gd 0.25 Y 0.75 ) 3 Al 5 O 12 crystals showed increased transmittance of 80%, while Cr:(Gd 0.50 Y 0.50 ) 3 Al 5 O 12 had a lower transmittance of 40% due to its polycrystalline structure. In addition, all the Cr:(Gd X Y 1− X ) 3 Al 5 O 12 crystals showed sharp scintillation luminescence peaks ascribed to Cr 3+ d–d transitions. Therefore, these results suggested that Cr:Y 3 Al 5 O 12 and Cr:(Gd 0.25 Y 0.75 ) 3 Al 5 O 12 crystals can be candidate materials for the dosimeter use. [ABSTRACT FROM AUTHOR]

The objectives of this study were to estimate patient dose in some common diagnostic X-ray examinations. Radiation doses were estimated for 307 patients in six public hospitals comprising 7 X-ray units in Wad-madani, Sudan. Entrance surface air kerma (ESAK) was estimated in a three step protocol: First, X-ray unit output Y(d) was measured at a distance, d for different peak tube voltages and tube loadings (mAs). Next, incident air kerma (K) was calculated from Y(d) using inverse square law combined with patient exposure factors. ESAK was calculated from K using backscatter factor, B. Mean ESAK values are comparable to those reported in other countries and are below reference dose levels. The estimated mean ESAK values are: 0.3, 2.2, 2.2, 2.9, 2.8, 3.1, and 7.5 mGy for chest PA, Skull AP/PA, Skull LAT, Abdomen, Pelvis AP, Lumbar Spine AP and Lumbar Spine LAT examinations, respectively. The results are used for dose optimization, and to propose local diagnostic reference levels. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To quantify ionizing radiation exposure to patients during interventional procedures and establish national diagnostic reference levels (NDRLs) for clinical radiation exposure management. Methods: The cumulative reference point air kerma, kerma area product, fluoroscopy time and other operational parameters were monitored for 50 children and 261 adult patient procedures in five catheterization medical laboratories in Kenya. To estimate the risk associated with the exposure, effective doses were derived from the kerma area product using conversion factors from Monte Carlo models. Results: About 3% of the measured cumulative reference point air kerma for the interventional procedures approached the threshold dose limit with the potential to cause deterministic effects such as skin injuries. In interventional cardiology, the results obtained for both children and adults indicated 33% were below the diagnostic reference levels (DRLs). In adult interventional radiology, 29% for cumulative reference point air kerma, and 43% for kerma area product and fluoroscopy time respectively were below the diagnostic reference levels. NDRLs were proposed for routine use in the procedures considered and for the non-existent DRLs situations in paediatric interventional cardiology. Conclusion: The measured patient doses were above the DRLs available in the literature indicating a need for radiation optimization through, continuous monitoring and recording of patient dose. To promote radiation safety, facilities performing interventional procedures need to establish a radiation monitoring notification threshold for possible deterministic effects, in addition to the use of the newly established national diagnostic reference levels, as a quality assurance measure. [Copyright &y& Elsevier]

The facilities now available on linear accelerators for external beam radiotherapy enable radiation fields to be conformed to the shapes of tumours with a high level of precision. However, in order for the treatment delivered to take advantage of this, the patient must be positioned on the couch with the same degree of accuracy. Kilovoltage cone beam computed tomography systems are now incorporated into radiotherapy linear accelerators to allow imaging to be performed at the time of treatment, and image-guided radiation therapy is now standard in most radiotherapy departments throughout the world. However, because doses from imaging are much lower than therapy doses, less effort has been put into optimising radiological protection of imaging protocols. Standard imaging protocols supplied by the equipment vendor are often used with little adaptation to the stature of individual patients, and exposure factors and field sizes are frequently larger than necessary. In this study, the impact of using standard protocols for imaging anatomical phantoms of varying size from a library of 193 adult phantoms has been evaluated. Monte Carlo simulations were used to calculate doses for organs and tissues for each phantom, and results combined in terms of size-specific effective dose (SED). Values of SED from pelvic scans ranged from 11 mSv to 22 mSv for male phantoms and 8 mSv to 18 mSv for female phantoms, and for chest scans from 3.8 mSv to 7.6 mSv for male phantoms and 4.6 mSv to 9.5 mSv for female phantoms. Analysis of the results showed that if the same exposure parameters and field sizes are used, a person who is 5 cm shorter will receive a size SED that is 3%-10% greater, while a person who is 10 kg lighter will receive a dose that is 10%-14% greater compared with the average size., (Creative Commons Attribution license.)

Objectives: A national study on patient dose values in interventional radiology and cardiology was performed in order to assess current practice in Bulgaria, to estimate the typical patient doses and to propose reference levels for the most common procedures. Methods: Fifteen units and more than 1,000 cases were included. Average values of the measured parameters for three procedures-coronary angiography (CA), combined procedure (CA + PCI) and lower limb arteriography (LLA)-were compared with data published in the literature. Results: Substantial variations were observed in equipment and procedure protocols used. This resulted in variations in patient dose: air-kerma area product ranges were 4-339, 6-1,003 and 0.2-288 Gy cm for CA, CA + PCI and LLA respectively. Reference levels for air kerma-area product were proposed: 40 Gy cm for CA, 140 Gy cm for CA + PCI and 45 Gy cm for LLA. Auxiliary reference intervals were proposed for other dose-related parameters: fluoroscopy time, number of images and entrance surface air kerma rate in fluoroscopy and cine mode. Conclusions: There is an apparent necessity for improvement in the classification of peripheral procedures and for standardisation of the protocols applied. It is important that patient doses are routinely recorded and compared with reference levels. Key Points: • Patient doses in interventional radiology are high and vary greatly • Better standardisation of procedures and techniques is needed to improve practice • Dose reference levels for most common procedures are proposed [ABSTRACT FROM AUTHOR]

Abstract: Less invasive imaging-guided vascular interventions with fluoroscopy and digital subtraction angiography have recently become widespread and have been successfully used for treating various diseases. However, interventional fluoroscopy procedures may present deterministic and stochastic radiation risks. The International Commission on Radiological Protection (ICRP) and the Food and Drug Administration have requested identifying procedures that may involve patient doses greater than the recommended thresholds. In this study, radiochromic dosimetric media, known as self-developing films, and measurement-based Monte Carlo simulations were used to establish an interventional radiology dosing system for individual patients undergoing interventional transcatheter arterial embolization. The peak skin dose, evaluated from the entrance surface dose distribution, was 21% less than the cumulated dose reported from the console. A 3D dose map incorporated into CT images was established. The organ doses and effective doses for individual patients were evaluated using this dosing system. This system could be applied very well to other fluoroscopic or interventional procedures for patient dose management. [Copyright &y& Elsevier]

Abstract: Dosimetric studies in patients submitted to diagnostic radiology examinations have been done in Brazil with the aim of contributing to a radiation protection culture. In this work, a typical chest examination condition was simulated and absorbed doses in selected organs were measured with thermoluminescent dosimeters in a Rando-Alderson anthropomorphic phantom. Doses were also calculated with PCXMC® and CALDose_X Monte Carlo based softwares. In most cases, organ absorbed doses calculated by Caldose_X agreed up to 50% with values from the reliable experimental procedure based on TL dosimeters in the Rando-Alderson phantom. PCXMC® calculations showed large differences in organ absorbed doses that could not be explained. Lack of agreement among doses obtained with the three adopted methodologies could be attributed to the differences between their phantoms in terms size, weight and location of organs as well as poor representation of human anatomy. If a large survey of dose assessment in patients submitted to chest X-ray examinations is intended to be done, the results of this work should be considered. [Copyright &y& Elsevier]

Abstract: Dosimetry studies are of increasing interest in diagnostic high-dose applications such as computed tomography especially for examinations of children. A routine CT scan protocol for paediatric head and neck imaging was investigated at a new multi-detector CT scanner using LiF:Mg,Cu,P thermoluminescence dosemeters (TLDs) and a 0.125 cm3 thimble ionization chamber. Calibrations of the detectors in terms of absorbed dose to water were carried out at the Dosimetry Laboratory Seibersdorf in standard radiation fields. The dosimetry method was validated in the spiral CT X-ray field by comparing TLD and ionization chamber measurement results in cylindrical PMMA phantoms. Absorbed dose results were within stated uncertainties. An anthropomorphic phantom representing a child of about 5 years was loaded with TLD chips at various organ and tissue positions in the head and neck region as well as at some critical organ locations. Organ dose values were calculated from TLD based average absorbed dose with about 5% total uncertainty, e.g. 22 mGy (eyes), 21 mGy (thyroid), 19 mGy (brain), 3.4 mGy (thymus), and 0.03 mGy (testes). For comparison purposes an effective dose of 1.9 mSv was estimated for the investigated paediatric CT examination based on ICRP-103 age-independent tissue-weighting factors. [Copyright &y& Elsevier]

Purpose: There is interest in developing linac-MR systems for MRI-guided radiation therapy. To date, the designs for such linac-MR devices have been restricted to a transverse geometry where the static magnetic field is oriented perpendicular to the direction of the incident photon beam. This work extends possibilities in this field by proposing and examining by Monte Carlo simulations, a probable longitudinal configuration where the magnetic field is oriented in the same direction as the photon beam. Methods: The EGSnrc Monte Carlo (MC) radiation transport codes with algorithms implemented to account for the magnetic field deflection of charged particles were used to compare dose distributions for linac-MR systems in transverse and longitudinal geometries. Specifically, the responses to a 6 MV pencil photon beam incident on water and lung slabs were investigated for 1.5 and 3.0 T magnetic fields. Further a five field lung plan was simulated in the longitudinal and transverse geometries across a range of magnetic field strengths from 0.2 through 3.0 T. Results: In a longitudinal geometry, the magnetic field is shown to restrict the radial spread of secondary electrons to a small degree in water, but significantly in low density tissues such as lung in contrast to the lateral shift in dose distribution seen in the transverse geometry. These effects extend to the patient case, where the longitudinal configuration demonstrated dose distributions more tightly confined to the primary photon fields, which increased dose to the planning target volume (PTV), bettered dose homogeneity within a heterogeneous (in density) PTV, and reduced the tissue interface effects associated with the transverse geometry. Conclusions: Dosimetry issues observed in a transverse linac-MR geometry such as changes to the depth dose distribution and tissue interface effects were significantly reduced or eliminated in a longitudinal geometry on a representative lung plan. Further, an increase in dose to the PTV, resulting from the magnetic field confining electrons to the forward direction, shows potential for a reduction in dose to the surrounding tissues. [ABSTRACT FROM AUTHOR]

The positron emitters (18F-Sodium Fluoride (NaF)) and X-rays used in Positron emission tomography (PET) combined with computed tomography (PET/CT) imaging have a high radiation dose, which results in a high patient dose. The present research intends to determine the radiation dose and risks associated with PET/CT- 18F-Sodium fluoride examinations in patients. The 18F–NaF PET/CT was used to investigate the doses of 86 patients. Patient exposure parameters and ImPACT software were used to calculate mean effective doses. The administered activity of 185 MBq (5.0 mCi) per procedure has a mean and range based on the patient's BMI (BMI). The range of patient effective doses per procedure was found to be 4–10 mSv, with a radiation risk of 1 × 10−5 per procedure. Patient doses are determined by the patient's size, scanner type, imaging protocol, and reconstruction method. For further dose reduction, proper justification and radiation dose optimization is required. • Effective doses were estimated for patients undergoing PET/CT procedures. • CT contributed 66.7% to patient cumulative effective doses (mSv) while (18F–NaF, PET) contributed 33.3%. • Patients dose optimization is recommended during PET/CT examinations. [ABSTRACT FROM AUTHOR]

This review covers the role of medical physics in addressing issues directly related to patient dosimetry in radiography, fluoroscopy, mammography, and CT. The sections on radiography and fluoroscopy radiation doses review the changes that have occurred during the last 50 to 60 years. A number of technological improvements have contributed to both a significant reduction in patient and staff radiation doses and improvements to the image quality during this period of time. There has been a transition from film-screen radiography with hand dip film processing to electronic digital imaging utilizing CR and DR. Similarly, fluoroscopy has progressed by directly viewing image intensifiers in darkened rooms to modern flat panel image receptor systems utilizing pulsed radiation, automated variable filtration, and digitally processed images. Mammography is one of the most highly optimized imaging procedures performed, because it is a repetitive screening procedure that results in annual radiation exposure. Mammography is also the only imaging procedure in the United States in which the radiation dose is regulated by the federal government. Consequently, many medical physicists have studied the dosimetry associated with screen-film and digital mammography. In this review, a brief history of mammography dose assessment by medical physicists is discussed. CT was introduced into clinical practice in the early 1970s, and has grown into one of the most important modalities available for diagnostic imaging. CT dose quantities and measurement techniques are described, and values of radiation dose for different types of scanner are presented. Organ and effective doses to adult patients are surveyed from the earliest single slice scanners, to the latest versions that include up to two x-ray tubes and can incorporate as many as 256 detector channels. An overview is provided of doses received by pediatric patients undergoing CT examinations, as well as methods, and results, of studies performed to assess the radiation absorbed by the conceptus of pregnant patients. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to determine the entrance surface air kerma (ESAK), effective dose (E), and organ radiation dose to patients during hysterosalpingography performed in three major hospitals in Taif city, KSA [King Abdul Aziz Hospital (A), King Faisal Hospital (B), and a private hospital (C)]. The study involved 100 female patients (22–44 years of age) for approximately 6 months. Dosecalc software was used to determine the ESAKs. This software needs to record the exposure factors and X-ray tube output (OP), as well as the backscatter factor (BSF). The mean ESAK was 21.7 mGy for all hospitals and 20, 28, and 17 mGy for hospitals A, B, and C, respectively. There were wide ranges in the ESAKs among the hospitals in the current and previous studies. The mean organ radiation dose estimated for the urinary bladder, gonads, bone marrow, and colon was 0.87, 1.7, 2.6, and 1.7 mSv, respectively. The average ESAK results for all patients was higher than most previous studies. Due to the exposure factors, filtration, and skill of the operator, the dose values varied. Additionally, organs (e.g., ovaries and bone marrow) reported high doses, which increased the probability of cancer and hereditary effects, and necessitate radiation dose optimization. The results indicated the need to standardize the technology and introduce the diagnostic reference level throughout hospitals. • Hysterosalpingography deliver patients with radiation risk. • Hysterosalpingography irradiated patients at youth period in gonad radiosensitive organs. • The mean ESAK was 21.7 mGy for all hospitals and were 20, 28, and 17 mGy for each hospital understudy. • Reduction dose technique is best practice for optimization. [ABSTRACT FROM AUTHOR]

A novel geometry has been proposed for a hybrid magnetic resonance imaging (MRI)-linac system in which a 6 MV linac is mounted on the open end of a biplanar, low field (0.2 T) MRI magnet on a single gantry that is free to rotate around the patient. This geometry creates a scenario in which the magnetic field vector remains fixed with respect to the incident photon beam, but moves with respect to the patient as the gantry rotates. Other proposed geometries are characterized by a radiation source rotating about a fixed cylindrical magnet where the magnetic field vector remains fixed with respect to the patient. In this investigation we simulate the inherent dose distribution patterns within the two MRI-radiation source geometries using PENELOPE and EGSnrc Monte Carlo radiation transport codes with algorithms implemented to account for the magnetic field deflection of charged particles. Simulations are performed in phantoms and for clinically realistic situations. The novel geometry results in a net Lorentz force that remains fixed with respect to the patient (in the cranial-caudal direction) and results in a cumulative influence on dose distribution for a multiple beam treatment scenario. For a case where patient anatomy is reasonably homogeneous (brain plan), differences in dose compared to a conventional (no magnetic field) case are minimal for the novel geometry. In the case of a lung plan where the inhomogeneous patient anatomy allows for the magnetic field to have significant influence on charged particle transport, larger differences occur in a predictable manner. For a system using a fixed cylindrical geometry and higher magnetic field (1.5 T), differences from the case without a magnetic field are significantly greater. [ABSTRACT FROM AUTHOR]

Abstract: A survey of pediatric radiological examinations was carried out in a reference pediatric hospital of the city of São Paulo, in order to investigate the doses to children undergoing conventional X-ray examinations. The results showed that the majority of pediatric patients are below 4 years, and that about 80% of the examinations correspond to chest projections. Doses to typical radiological examinations were measured in vivo with thermoluminescent dosimeters (LiF: Mg, Ti and LiF: Mg, Cu, P) attached to the skin of the children to determine entrance surface dose (ESD). Also homogeneous phantoms were used to obtain ESD to younger children, because the technique uses a so small kVp that the dosimeters would produce an artifact image in the patient radiograph. Four kinds of pediatric examinations were investigated: three conventional examinations (chest, skull and abdomen) and a fluoroscopic procedure (barium swallow). Relevant information about kVp and mAs values used in the examinations was collected, and we discuss how these parameters can affect the ESD. The ESD values measured in this work are compared to reference levels published by the European Commission for pediatric patients. The results obtained (third-quartile of the ESD distribution) for chest AP examinations in three age groups were: 0.056mGy (2–4 years old); 0.068mGy (5–9 years old); 0.069mGy (10–15 years old). All of them are below the European reference level (0.100mGy). ESD values measured to the older age group in skull and abdomen AP radiographs (mean values 3.44 and 1.20mGy, respectively) are above the European reference levels (1.5mGy to skull and 1.0mGy to abdomen). ESD values measured in the barium swallow examination reached 10mGy in skin regions corresponding to thyroid and esophagus. It was noticed during this survey that some technicians use, improperly, X-ray fluoroscopy in conventional examinations to help them in positioning the patient. The results presented here are a preliminary survey of doses in pediatric radiological examinations and they show that it is necessary to investigate the technical parameters to perform the radiographs, to introduce practices to control pediatric patient''s doses and to improve the personnel training to perform a pediatric examination. [Copyright &y& Elsevier]