Entrance surface dose

Cone-beam computed tomography (CBCT) systems specifically designed and manufactured for dental, maxillofacial imaging (MFI) and otolaryngology (OLR) applications have been commercially available in the United States since 2001 and have been in widespread clinical use since. Until recently, there has been a lack of professional guidance available for medical physicists about how to assess and evaluate the performance of these systems and about the establishment and management of quality control (QC) programs...

A comprehensive search was performed to examine the literature on diagnostic reference levels (DRL) for computed tomography (CT) and radiography examinations that are performed routinely in Jordan. EBSCO, Scopus, and Web of Science were used for the search. The acronym "DRL" and the additional phrase "dose reference levels" were used to search for articles in literature. Seven papers that reported DRL values for radiography and CT scans in Jordan were identified. One study reported DRLs for conventional radiography, two studies reported CT DRLs in pediatrics, and the remaining four studies provided DRL values for adult CT scans...

INTRODUCTION: Imaging of the cervical spine in general radiography is most frequently performed using an anti-scatter grid. The purpose of this study was to investigate the effects of a gridless setting on image quality and radiation dose during digital radiography of the anteroposterior (AP) and lateral (LAT) cervical spine. METHODS: A phantom study was performed with a variety of tube voltages (63-75 kV) with and without an anti-scatter grid. The tube current time product (mAs) and dose area product (DAP) were recorded and used to calculate effective dose (ED) and individual organ dose using PCXMC 2...

In recent years, knowing the risks of stochastic effects of radiation, patient dose in diagnostic radiology is taken in to consideration extensively. Many countries and international organization, including International Commission on Radiological Protection, use quantities such as dose area product, entrance surface dose, etc. in radiological investigations, which serve as a guide for patient dose reduction. The concept of diagnostic reference level (DRL) is used to optimizing the dose of patients undergoing diagnostic radiology examinations...

Effective dose is sometimes used to compare medical radiation exposure to patients and natural radiation for providing explanations about radiation exposure to patients, but its calculation is lengthy and requires dedicated measuring devices. The purpose of this study was to identify the most suitable conversion coefficient for conversion of easily measurable dose to effective dose in posterior-anterior chest radiography, and to evaluate its accuracy by direct measurement. We constructed an examination environment using Monte Carlo simulation, and evaluated the variation in conversion coefficients from incident air kerma (IAK), entrance-surface air kerma (ESAK), and air kerma-area product (KAP) to effective dose when the irradiation field size and radiation quality were changed...

PURPOSE: Dynamic chest radiography (DCR) is a novel imaging technique used to noninvasively evaluate pulmonary perfusion. However, the standard DCR protocol, which is roughly adapted to the patient's body size, occasionally causes over- or underexposure, which could influence clinical evaluation. Therefore, we proposed a refined protocol by increasing the number of patient body mass index (BMI) categories from three to seven groups and verified its usefulness by comparing the image sensitivity indicators (S-values) and entrance surface doses (ESDs) of the conventional protocol with those of our refined protocol...

The diagnostic reference level (DRL) is an effective tool for optimizing protection in medical exposures to patients. However, regarding air kerma at the patient entrance reference point ( K a,r ), one of the DRL quantities for endoscopic retrograde cholangiopancreatography (ERCP), manufacturers use a variety of the International Electrotechnical Commission (IEC) and their own specific definitions of the reference point. The research question for this study was whether K a,r is appropriate as a DRL quantity for ERCP...

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...

The average glandular dose (AGD) is very important in the quality control of mammography. The AGD calculation requires measurements of half-value layer (HVL) and entrance surface air karma (ESAK). The HVL is measured by the Al-attenuation method using a non-energy-dependent ionization dosimeter. As the Al-attenuation method performs measurements using a succession of added filters, it requires lots of X-ray exposure and measurement time. In recent years, measuring instruments that can measure tube voltage, irradiation time, exposure dose, HVL, and other factors, at the same time, using one shot of X-rays have been developed...

BACKGROUND: We aimed to investigate the radiation dose to the eye lens (lens dose) during cerebral angiography and to evaluate the effectiveness of the lens dose reduction protocol for 3-dimensional rotational angiography (3D-RA) in reducing overall lens dose exposure. METHODS: We conducted a randomized, controlled clinical trial at a tertiary hospital with patients undergoing cerebral angiography. The lens dose reduction protocol in 3D-RA involved raising the table to position the patient's eye lens away from the rotation axis...

The purpose was to investigate air-kerma area product (PKA ) and entrance surface air-kerma rate ([Formula: see text]a,e ) on the effect of the shape of automatic dose rate control (ADRC) in the presence of a wedge compensation filter. We compared and evaluated the variability of the X-ray output using a combination of wedge compensation filters and the ADRC. Two ADRC shapes (round and square) and three poly-methyl-methacrylate thicknesses (15, 20, and 25 cm) were used. A wedge compensation filter was inserted 2 cm at a time, up to 6 cm...

Objective
Dose due to the electron streaming effect (ESE) is a significant contribution to out-of-field dose on the Elekta Unity MR-Linac. The aim of this work is to provide a systematic comparison of calculated and measured streaming dose for this system. 
Approach
Beams 1.0 × 1.0 cm2 to 5.0 × 5.0 cm2, gantry 90.0°, 1000 MU, were incident on an in-house phantom. At the beam entrance and exit surfaces of the phantom, ESE was generated in the Y-direction (IEC 61217). EBT3 film, orientated within the X-Z plane and at 14...

BACKGROUND: Mixed electron-photon beam radiation therapy (MBRT) is an emerging technique in which external electron and photon beams are simultaneously optimized into a single treatment plan. MBRT exploits the steep dose falloff and high surface dose of electrons while maintaining target conformity by leveraging the sharp penumbra of photons. PURPOSE: This study investigates the dosimetric benefits of MBRT for soft tissue sarcoma (STS) patients. MATERIAL AND METHODS: A retrospective cohort of 22 STS of the lower extremity treated with conventional photon-based Volumetric Modulated Arc Therapy (VMAT) were replanned with MBRT...

PURPOSE: Optimization studies in digital radiology help to reduce the radiological risk to patients and maximize the benefits associated with their clinical purpose. The aim of this study was to assess the optimization of lateral lumbar spine projection via a combination of exposure parameters adjustments and additional filtration using a sectional anthropomorphic phantom. MATERIALS AND METHODS: We evaluated the effects of peak voltage, tube loading, and low-cost filters made of copper, titanium, brass, and nickel on both the perceived and physical quality of 125 radiographs obtained in a computer 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...

In this study, the effective point of measurement (EPOM) for plane-parallel ionization chambers in clinical high-energy electron beams was determined experimentally. Previous studies have reported that the EPOM of plane-parallel chambers is shifted several tens of millimeters downstream from the inner surface of the entrance window to the cavity. These findings were based on the Monte Carlo (MC) simulation, and few experimental studies have been performed. Thus, additional experimental validations of the reported EPOMs were required...

INTRODUCTION: Hepatic arterial infusion chemotherapy (HAIC) has been popular for treating unresectable hepatocellular carcinoma (HCC). However, there are few reports comparing the transradial approach (TRA) and transfemoral approach (TFA) in HAIC. OBJECTIVE: This study aimed to compare the duration of the hepatic artery catheterization, fluoroscopy time (FT), radiation exposure, safety, and quality of life associated with the procedure in patients undergoing HAIC via TRA and TFA...

Some clinical situations in radiotherapy require electron beams to be incident on curved patient surfaces. This study presents central-axis dose output (cGy/MU) and percent dose versus depth (PDD) data that show the effects of curvature on results computed by the Varian eMC v15.6 algorithm using 6, 9, 12, 16, and 20 MeV electron beams incident on virtual phantoms with curved surfaces. The phantoms were designed to simulate common treatment sites. The dose outputs at the depth of maximum dose (dmax) on the central axis were observed to decrease 0%-14%, and several features of the PDDs for the A10 applicator changed, including up to 12% increased entrance dose...

PURPOSE: The purpose of this study was to evaluate the effect of outside-field-of-view (FOV) lead shielding on the entrance surface dose (ESD) of the breast on an anthropomorphic X-ray phantom for a variety of axial skeleton X-ray examinations. METHODS: Using an anthropomorphic phantom and radiation dosimeter, the ESD of the breast was measured with and without outside-FOV shielding in anterior-posterior (AP) abdomen, AP cervical spine, occipitomental 30° (OM30) facial bones, AP lumbar spine, and lateral lumbar spine radiography...

The emergence of the Halcyon linear accelerator has allowed for increased patient throughput and improved treatment times for common treatment sites in radiation oncology. However, it has been shown that this can lead to increased surface dose in sites like breast cancer compared with treatments on conventional machines with flattened radiation beams. Cherenkov imaging can be used to estimate surface dose by detection of Cherenkov photons emitted in proportion to energy deposition from high energy electrons in tissue...