Biomedical subjects

Nicholas Theocharopoulos

Publications and source records attributed to Nicholas Theocharopoulos.

16 recordsLinked to original sources

PubMed2006

Dosimetric characteristics of a 16-slice computed tomography scanner.

Standard CT dose measurements were performed on a Siemens Sensation 16 scanner. CT dose indices, free-in-air (CTDI(F)) and weighted (CTDI(W)), were measured in all available axial and helical beam collimations of the head and body scanning modes. The effect of tube current, high voltage, rotation time, beam collimation and pitch on the CT doses was investigated. CT doses increased as a power function of high voltage. The kVp exponent n varied with beam collimation from 2.7 to 3.1 for CTDI(W), and from 2.4 to 2.6 for CTDI(F). Automatic change of the focal spot size increased radiation doses up to a factor of 1.18. Measured small-focus CTDI(W) values differed from those displayed at the console from -24 to 14%. Peripheral doses in the head phantom were higher compared to the body phantom by a factor of 1.5 to 2. Central doses are 2.7 to 4.1 times higher. Differences in beam collimation resulted in 50% variation in the CTDI(W) in the body phantom and 60% in the head phantom. In conclusion, our study has confirmed the great impact of technique factors and acquisition parameters on CT doses. The provided comprehensive dosimetric data will facilitate the dose-effective use of the scanner studied.

Computer Simulation↗

PubMed2006

Fluoroscopically assisted surgical treatments of spinal disorders: conceptus radiation doses and risks.

STUDY DESIGN: A series of anterior-posterior and lateral fluoroscopic exposures at 5 spinal levels were performed on anthropomorphic phantoms simulating the 3 trimesters of gestation. OBJECTIVES: To provide normalized data for the determination of conceptus dose specific to gestational stage and treated spinal level. To estimate the conceptus radiation dose and risk associated with typical fluoroscopically guided spinal treatments performed on the pregnant patient. SUMMARY OF BACKGROUND DATA: To our knowledge, there are no available data on conceptus doses and radiogenic risks resulting from fluoroscopically guided spinal surgery of the expectant mother. METHODS: Direct measurement of conceptus doses from simulated fluoroscopic projections involved in orthopedic surgery at different spinal levels for the 3 trimesters of gestation with use of anthropomorphic phantoms and thermoluminescent dosimetry. Estimation of conceptus radiation risks from a typical pedicle screw fixation and kyphoplasty procedure using the experimentally derived data. RESULTS: Conceptus doses from fluoroscopically guided spinal treatments are smaller than 4 mGy during all gestational stages, provided that the conceptus lies outside the primarily irradiated region. The associated risks of fatal cancer during childhood and congenital malformation on its progeny are at least 2 and 1500 times, respectively, lower than the spontaneous incidence rates. When the embryo is primarily irradiated, mean conceptus dose can be as high as 105 mGy from a nonoptimized exposure. At least 35 minutes of fluoroscopy are required for the induction of deterministic effects. CONCLUSIONS: Individual dose assessment is paramount in every pregnancy. Variations in fluoroscopy practices and gestational stage significantly affect fetal doses.

Computer Simulation↗

PubMed2006

Occupational radiation exposure from fluoroscopically guided percutaneous transhepatic biliary procedures.

PURPOSE: The aim of this study was to determine occupational dose levels for projections commonly used in fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent placement procedures. METHODS: Exposure data from 71 consecutive PTB examinations were analyzed to determine average examination parameters for biliary drainage and stent placement procedures. An anthropomorphic phantom was exposed at three projections common in PTB interventions according to the actual geometric parameters recorded in the patient study. Scattered air-kerma dose rates were measured for neck, waist, and gonad levels at various sites in the interventional radiology laboratory. To produce technique- and instrumentation-independent data, dose rate values were converted to dose-area product (DAP)-normalized air-kerma values. In addition, sets of thermoluminescent dosimetry crystals were placed in both hands of the interventional radiologist to monitor doses during all PTB procedures. RESULTS: Isodose maps of DAP-normalized air-kerma doses in the interventional laboratory for projections commonly used in PTB procedures are presented. To facilitate effective dose estimation, normalized dosimetric data at the interventional radiologist's position are presented for left and right access drainage procedures, metallic stent placement only, and drainage and metallic stent placement in one-session procedures with and without under-couch shielding. Doses to the hands of interventional radiologists are presented for left and right transhepatic biliary access and metallic stent placement. CONCLUSIONS: Body level-specific normalized air-kerma distributions from commonly used projections in PTB procedures may be useful to accurately quantify dose, maximum workloads, and possible radiogenic risks delivered to medical personnel working in the interventional radiology laboratory. Normalized dose data presented will enable occupational exposure estimation from other institutions.

Aged↗

PubMed2006

Estimation of effective doses to adult and pediatric patients from multislice computed tomography: A method based on energy imparted.

The purpose of this study is to provide a method and required data for the estimation of effective dose (E) values to adult and pediatric patients from computed tomography (CT) scans of the head, chest abdomen, and pelvis, performed on multi-slice scanners. Mean section radiation dose (dm) to cylindrical water phantoms of varying radius normalized over CT dose index free-in-air (CTDIF) were calculated for the head and body scanning modes of a multislice scanner with use of Monte Carlo techniques. Patients were modeled as equivalent water phantoms and the energy imparted (epsilon) to simulated pediatric and adult patients was calculated on the basis of measured CTDI(F) values. Body region specific energy imparted to effective dose conversion coefficients (E/epsilon) for adult male and female patients were generated from previous data. Effective doses to patients aged newborn to adult were derived for all available helical and axial beam collimations, taking into account age specific patient mass and scanning length. Depending on high voltage, body region, and patient sex, E/epsilon values ranged from 0.008 mSv/mJ for head scans to 0.024 mSv/mJ for chest scans. When scanned with the same technique factors as the adults, pediatric patients absorb as little as 5% of the energy imparted to adults, but corresponding effective dose values are up to a factor of 1.6 higher. On average, pediatric patients absorb 44% less energy per examination but have a 24% higher effective dose, compared with adults. In clinical practice, effective dose values to pediatric patients are 2.5 to 10 times lower than in adults due to the adaptation of tube current. A method is provided for the calculation of effective dose to adult and pediatric patients on the basis of individual patient characteristics such as sex, mass, dimensions, and density of imaged anatomy, and the technical features of modern multislice scanners. It allows the optimum selection of scanning parameters regarding patient doses at CT.

Adult↗

PubMed2005

Fluoroscopically guided implantation of modern cardiac resynchronization devices: radiation burden to the patient and associated risks.

OBJECTIVES: To establish radiation risks for patients undergoing fluoroscopically guided cardiac resynchronization device implantation. BACKGROUND: Cardiac resynchonization therapy (CRT) may be associated with extended fluoroscopic exposure. METHODS: The fluoroscopy time, dose-area product (DAP), exposure parameters, and percentage contribution of the fluoroscopic projections commonly used were recorded in a series of 14 consecutive patients referred for cardiac resynchronization device implantation and compared to corresponding data obtained from a control group of 20 patients who underwent a conventional rhythm device implantation operation. The DAP to peak skin dose, DAP to effective dose, and DAP to gonadal dose conversion factors were determined for biventricular pacing and conventional rhythm device implantation using a humanoid phantom and thermoluminescence dosimetry. RESULTS: The mean total fluoroscopy time and DAP values were 35.2 min and 4,765 cGy cm2, respectively, for biventricular pacing and 8.2 min and 1,106 cGy cm2, respectively, for conventional rhythm device implantation. Patient skin dose from biventricular pacing procedures requiring extended fluoroscopic exposure may exceed threshold dose for the induction of skin effects only if X-ray source-to-skin distance is kept low. The risk values for fatal cancer and severe hereditary disorders, respectively, associated with a typical CRT procedure were 273 per million and 0.2 per million treated patients. CONCLUSIONS: Radiation risks associated with fluoroscopically guided CRT procedures may be considerable. Present data may be used for the estimation of patient radiation risks from CRT procedures performed in other institutions.

Aged↗

PubMed2005

Image-guided reconstruction of femoral fractures: is the staff progeny safe?

The potential of adverse effects to progeny caused by preconceptual and fetal exposure to ionizing radiation is an issue of increasing concern to orthopaedic surgeons and assisting staff. Are these fears justified? How effectively is the embryo or fetus protected, and should pregnant staff alter their duties? In this study, an anthropomorphic phantom was exposed fluoroscopically at two geometries common in surgical reconstruction of proximal femur fractures. Scatter radiation was converted to gonadal dose and embryo or fetal dose with and without use of a protective apron. The genetic risk for the orthopaedic surgeon after 10 years of occupational exposure was estimated to be 16,000 times lower than the natural frequency of heritable disease. The excess risk of childhood cancer associated with the dose accumulated during gestation was at least 600 times lower than the corresponding natural frequency. A properly shielded pregnant orthopaedic surgeon is allowed to do 14 hours of hip fluoroscopy during gestation, whereas 2100 hours of fluoroscopy are required for the induction of gross malformation or mental retardation to the growing embryo or fetus. The supplementary dose constraints for pregnant staff provide adequate protection to the unborn child without affecting regular personnel duties.

Dose-Response Relationship, Radiation↗

PubMed2005

Anticipation of radiation dose to the conceptus from occupational exposure of pregnant staff during fluoroscopically guided electrophysiological procedures.

UNLABELLED: Conceptus dose from occupational exposure. INTRODUCTION: A female employee working in the electrophysiology suite has the right to know potential radiation hazards to the unborn child before she is pregnant or before she decides to formally declare her pregnancy. Moreover, the employer of a declared pregnant worker must evaluate the work situation and ensure that the conceptus dose is kept below the maximum permissible level during the remaining gestation period. The aim of this study was to develop a method for conceptus dose anticipation and determination of maximum workload allowed for the pregnant employee who participates in fluoroscopically guided electrophysiological procedures. METHODS AND RESULTS: A C-arm fluoroscopy system, an anthropomorphic phantom, and a radiation meter were used to obtain scattered air kerma dose rates separately for each of the three fluoroscopic projections typically used in the electrophysiology suite. Air kerma to conceptus dose conversion factors for all trimesters of gestation were calculated using Monte Carlo simulation. A formula is presented for the anticipation of the conceptus dose from occupational exposure of pregnant staff during fluoroscopically guided electrophysiological procedures. Normalized data are provided for conceptus dose estimation from occupational exposure of pregnant staff working in any electrophysiology laboratory. A methodology for estimation of maximum workload allowed for each month of the remaining gestation period of a worker who declared her pregnancy is proposed, which ensures that the regulatory dose limits are not exceeded. CONCLUSION: Data presented may be used for the implementation of a radiation protection program designed for pregnant staff working in an electrophysiological suite.

Electrophysiologic Techniques, Cardiac↗

PubMed2005

Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: a Monte Carlo study.

Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 degrees angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region.

Adolescent↗

PubMed2004

Occupational gonadal and embryo/fetal doses from fluoroscopically assisted surgical treatments of spinal disorders.

STUDY DESIGN: Simulation of lumbar spine fluoroscopy used during surgical treatments of spinal disorders on a humanoid phantom and monitoring of the scattered radiation levels. OBJECTIVES: To assess the potential of adverse effects to progeny due to the preconceptual and embryo/fetal exposure to ionizing radiation resulting from the parental occupational exposure to scattered radiation from lumbar fluoroscopy. SUMMARY OF BACKGROUND DATA: There are no available data on embryo/fetal doses resulting from maternal occupational exposure in the orthopedic theater. Besides, studies on staff gonadal doses from fluoroscopically assisted spine surgery are scarce and their results are not generally applicable. METHODS: Lumbar spine anterior-posterior and lateral fluoroscopy were performed on an anthropomorphic phantom. Scattered radiation within the orthopedic theater was recorded at the staff genitals and waist level. Gonadal, abdominal surface, and embryo/fetal doses normalized to the dose-area-product specific to each projection were calculated. RESULTS: If the annual dose limits of occupational exposure are continuously exhausted for 10 years, the resulting radiogenic risk of congenital malformation in infants born to the orthopedic theater staff will be at least two orders of magnitude lower than the corresponding spontaneous probability. The occupational exposure of the pregnant mother bears a negligible contribution to the risk of hereditary effect on the newborn's progeny compared with the natural incidence rate. CONCLUSIONS: Radiogenic genetic and embryo/fetal risks resulting from occupational exposure due to fluoroscopically assisted surgical treatments of spinal disorders are well within tolerance levels provided that rigorous confinement to all pertinent occupational dose constraints is established.

Dose-Response Relationship, Radiation↗

PubMed2004

Patient exposure and associated radiation risks from fluoroscopically guided vertebroplasty or kyphoplasty.

PURPOSE: To derive normalized data for the estimation of effective, gonadal, and peak skin doses to patients undergoing vertebroplasty or kyphoplasty and to investigate the potential for cancer induction, genetic effects, and radiation-induced skin injury after such procedures. MATERIALS AND METHODS: Dose values normalized over dose-area product were determined for all radiosensitive organs and tissues by using a humanoid phantom and thermoluminescence dosimetry separately for anteroposterior and lateral projections. Measurements were obtained for treatments of the fifth, eighth, and 11th thoracic vertebrae and the first, third, and fifth lumbar vertebrae. Total fluoroscopy time and resultant dose-area product from each fluoroscopic exposure were monitored in 11 consecutive patients (seven women and four men) undergoing kyphoplasty. The age range of these patients was 41-78 years, and the mean age was 58 years. RESULTS: Mean total fluoroscopy time for kyphoplasty was 10.1 minutes +/- 2.2 (standard deviation). Mean effective dose to patients from kyphoplasty was 8.5-12.7 mSv, and mean gonadal dose was 0.04-16.4 mGy, depending on the level of the treated vertebra. Skin injuries after kyphoplasty are improbable if source-to-skin distance is 35 cm or more; however, such injuries may occur if the total fluoroscopy time per projection is extended and/or the source-to-skin distance is less than 35 cm during the procedure. CONCLUSION: Patient radiation exposure and associated risks from vertebroplasty or kyphoplasty may be considerable. Data obtained in the current study may be used to establish patient effective dose, gonadal dose, and entrance skin exposure, as well as associated risks, from these fluoroscopically guided surgical treatments of spinal disorders.

Adult↗

PubMed2004

Estimation of patient dose and associated radiogenic risks from fluoroscopically guided pedicle screw insertion.

STUDY DESIGN: An experimental model for the assessment of patient dose and associated radiogenic risks associated with pedicle screw internal fixation surgical procedures. OBJECTIVES: To provide data for the accurate determination of patient effective dose, gonadal dose, and entrance skin dose from fluoroscopically assisted pedicle screw insertion procedures and to investigate the potential of both stochastic and deterministic radiogenic effects to occur following such procedures. SUMMARY OF BACKGROUND DATA: There is increased concern on radiation exposure of patients undergoing fluoroscopically guided interventional procedures. METHODS: The cumulative screening time and dose area product, for each fluoroscopic projection used, were monitored in 20 patients undergoing pedicle screw internal fixation. The dose absorbed by each radiosensitive organ/tissue was determined from direct measurements obtained using an anthropomorphic phantom appropriately loaded with thermoluminescence dosimeters. RESULTS: An average pedicle screw insertion procedure requires 1.2 minutes and 2.1 minutes of fluoroscopic exposure along anteroposterior and lateral projections, respectively, resulting in a dose area product of 232 cGy cm and 568 cGy cm, correspondingly. Gender-specific normalized data for the determination of effective, gonadal, and entrance skin dose to patients undergoing fluoroscopically guided pedicle screw internal fixation procedures were derived. The effective dose from an average procedure was 1.52 and 1.40 mSv and the gonadal dose 0.67 and 0.12 mGy for female and male patients, respectively. The average radiogenic risks for fatal cancer and genetic defects were 115 and 4 per million of patients treated, respectively. Induction of skin injuries might be induced when fluoroscopy along the lateral projection is highly extended and the source to skin distance is kept low. CONCLUSIONS: Patient dose and radiogenic risks associated with an average pedicle screw internal fixation procedure are tolerable. However, for young patients with complex spinal disorders requiring extended fluoroscopy, radiogenic risks may be considerable. Present data may beused for estimation of effective dose, gonadal dose, and entrance skin exposure and associated radiogenic risks to patients undergoing fluoroscopically guided pedicle screw insertion in any institution.

Adult↗

PubMed2004

Patient effective dose and radiogenic risks from fluoroscopically assisted surgical reconstruction of femoral fractures.

The objectives were to assess patient effective radiation dose from fluoroscopically guided surgical reconstruction of femoral fractures and provide normalized data for the estimation of patient effective dose and risks associated with such procedures performed in any laboratory. The fluoroscopic control required during surgical reconstruction of femoral fractures was classified into two types identified by beam orientation, i.e., posterior-anterior (PA) and lateral crosstable (LC) exposures. The duration and the dose area product (DAP) of each exposure were monitored in 24 patients with femoral fractures. Patient dose per DAP unit and per minute of fluoroscopy were measured at 14 radiosensitive organs/tissues using an anthropomorphic phantom and thermoluminescence dosimetry. The typical effective dose to patients with femoral fracture treated surgically in our institution was 11.6-21.7 microSv. This effective dose is estimated to cause an excess of 1.4 fatal cancers per million patients treated, and an excess of 0.4 hereditary disorders per million of births. Induction of deterministic skin injuries to treated patients is highly improbable at the dose levels found in this study. Patient effective dose and associated risks from a typical fluoroscopically guided surgical fixation of femoral fracture are low. However, they may be significantly elevated if treated patients are young individuals and/or the fluoroscopic exposure is prolonged. The present data may be used to determine effective dose to patients undergoing surgical reconstruction of femoral fracture in any institution.

Adult↗

PubMed2003

Radiogenic risks from hysterosalpingography.

The aim of this study was to determine ovarian dose, effective dose and associated radiogenic risks from hysterosalpingography (HSG), and to provide data for the estimation of radiogenic risks related to HSG studies performed in any laboratory. The fluoroscopy time, number of radiographs taken and entrance surface dose were measured in a series of 78 consecutive patients undergoing HSG as part of their infertility work-up. Organ-dose values per radiograph and per minute of fluoroscopy were separately determined using an anthropomorphic phantom and thermoluminescence dosimetry. The radiogenic risk for deleterious effects on a possible future embryo and the radiogenic risk for cancer induction on the patient undergoing HSG were estimated. The average HSG procedure in our laboratory involves a mean fluoroscopic time of 0.3 min and a mean number of radiographs of 3.2. The dose to female gonads from an average HSG procedure was 2.7 mGy and the patient effective dose was 1.2 mSv. The risk for radiogenic anomalies in a future embryo of the woman undergoing an average HSG procedure and the risk for radiogenic fatal cancer induction in the exposed woman were estimated to be less than 10(-3) of the correspondent nominal risks. Radiation risks from a typical HSG are low, but they may be elevated if fluoroscopic and/or radiographic exposures are prolonged for any reason. Present data allow the estimation of radiogenic risks associated with HSG procedures performed in other laboratories with use of different equipment, screening time and number of radiographs taken.

Abnormalities, Radiation-Induced↗

PubMed2003

Occupational exposure from common fluoroscopic projections used in orthopaedic surgery.

BACKGROUND: Personnel assisting in or performing fluoroscopically guided procedures may be exposed to high doses of radiation. Accurate occupational dosimetric data for the orthopaedic theater staff are of paramount importance for practicing radiation safety. METHODS: Fluoroscopic screening was performed on an anthropomorphic phantom with use of four projections common in image-guided orthopaedic surgery. The simulated projections were categorized, according to the imaged anatomic area and the beam orientation, as (1) hip joint posterior-anterior, (2) hip joint lateral cross-table 45 degrees, (3) lumbar spine anterior-posterior, and (4) lumbar spine lateral 90 degrees. The scattered air kerma rate was measured on a grid surrounding the operating table. For each grid point, the effective dose, eye lens dose, and face skin dose values, normalized over the tube dose area product, were derived. For the effective dose calculations, three radiation protection conditions were considered: (1) with the exposed personnel using no protection measures, (2) with the exposed personnel wearing a 0.5-mm lead-equivalent protective apron, and (3) with the exposed personnel wearing both an apron and a thyroid collar. Maximum permissible workloads for typical hip, spine, and kyphoplasty procedures were derived on the basis of compliance with effective dose, eye lens dose, and skin dose limits. RESULTS: We found that the effective dose, eye lens dose, and face skin dose to an orthopaedic surgeon wearing a 0.5-mm lead-equivalent apron will not exceed the corresponding limits if the dose area product of the fluoroscopically guided procedure is <0.38 Gy m (2). When protective eye goggles are also worn, the maximum permissible dose area product increases to 0.70 Gy m (2), while the additional use of a thyroid shield allows a workload of 1.20 Gy m (2). The effective dose to the orthopaedic surgeon working tableside during a typical hip, spine, kyphoplasty procedure was 5.1, 21, and 250 micro Sv, respectively, when a 0.5-mm lead-equivalent apron alone was used. The additional use of a thyroid shield reduced the effective dose to 2.4, 8.4, and 96 micro Sv per typical hip, spine, and kyphoplasty procedure, respectively. CONCLUSIONS: The levels of occupational exposure vary considerably with the type of fluoroscopically assisted procedure, staff positioning, and the radiation protection measures used. The data presented in the current study will allow for accurate estimation of the occupational dose to orthopaedic theater personnel.

Fluoroscopy↗

PubMed2002

Patient effective radiation dose and associated risk from transmission scans using 153Gd line sources in cardiac spect studies.

The aim of the present study was to determine the contribution of transmission measurements acquisition to total patient effective dose from cardiac SPECT studies. A dual-head L-shaped gamma camera equipped with a transmission scan acquisition system based on two 153Gd line sources was used to simulate transmission measurements acquisition exposure on an anthropomorphic phantom. Thermoluminescence dosimeters were used to directly monitor the dose to 550 measuring points in the phantom. The effective dose and associated risk from transmission scans acquisition were estimated and compared to those associated to the radiopharmaceutical injected. The maximum effective dose from a typical transmission measurements acquisition was 1.3 microSv and 1.9 microSv for male and female patients, respectively. The contribution of the typical transmission scans acquisition to total patient radiation risk from a cardiac SPECT study is less than 10(-3). Thus, radiation exposure may not be considered as a limiting factor for the clinical application of attenuation correction methods based on transmission measurements in cardiac SPECT.

Gadolinium↗

PubMed2002

Comparison of four methods for assessing patient effective dose from radiological examinations.

Three methods of indirect effective dose estimation were reviewed and compared to a direct effective dose determination method. An anthropomorphic phantom and thermoluminescence dosimetry were used to obtain dosimetric data associated with anterior-posterior (AP) abdominal radiography, posterior-anterior (PA) chest radiography, PA head radiography, and AP heart fluoroscopy. Effective dose was determined using: (i) organ specific dose values directly determined by thermoluminescence dosimeters, (ii) data published by National Radiological Protection Board (NRPB) and entrance surface dose (ESD), (iii) NRPB data and dose area product (DAP), (iv) energy imparted derived from DAP. The effective dose values estimated from the Rando phantom measurements were 161, 32.3, and 8.4 microSv/projection for the abdomen, chest, and head radiographs, respectively. Cardiac fluoroscopy yielded an effective dose value of 111 microSv/min. The effective dose values obtained indirectly using NRPB data and DAP were in good agreement with directly assessed values in all simulated exposures (difference <8%). The effective doses using NRPB data and ESD values differed from directly assessed values by less than 15% for the radiographic exposures and 60% for heart fluoroscopy. The energy imparted method yielded 136, 31, and 6.6 microSv/projection for the abdomen, chest, and head radiographs, respectively, and 111 microSv/min for heart fluoroscopy. Indirect patient effective dose determination using the NRPB dosimetric data and the measured value of incident radiation allows for reliable patient effective dose estimates. The use of DAP rather than ESD is recommended because it yields accurate results even for complex radiologic exposures involving fluoroscopy. The value of energy imparted may be used for the accurate determination of patient effective dose, especially when specific organ dose values are not of interest. The calculation of energy imparted with the use of EAP provides a reliable starting point for estimation of effective dose from radiologic examinations for which dosimetric data are not provided by NRPB.

Abdomen↗