Use of the concept of energy imparted in diagnostic radiology

Carlsson, Gudrun Alm; Dance, David R.; Persliden, Jan; Sandborg, Michael

doi:10.1016/s0969-8043(98)00087-6

Cited by 24 publications

(11 citation statements)

References 68 publications

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“…Values of energy imparted can be used as a relative risk indicator when a given body region is irradiated for a fixed body size. 13 One potential use for this parameter is to estimate the relative change in risk as CT technique factors ͑kVp, mAs, T, pitch ratio͒ are changed for a given type of patient examination. Limitations of the energy imparted parameter, however, include the inability to compare radiation risks for patients of differing size, or permit meaningful comparisons to be made when different parts of the body are irradiated ͑e.g., head versus chest͒.…”

Section: Discussionmentioning

confidence: 99%

Effective doses to patients undergoing thoracic computed tomography examinations

Huda¹,

Scalzetti²,

Roskopf³

2000

Medical Physics

132

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The purpose of this study was to investigate how x-ray technique factors and effective doses vary with patient size in chest CT examinations. Technique factors (kVp, mAs, section thickness, and number of sections) were recorded for 44 patients who underwent a routine chest CT examination. Patient weights were recorded together with dimensions and mean Hounsfield unit values obtained from representative axial CT images. The total mass of directly irradiated patient was modeled as a cylinder of water to permit the computation of the mean patient dose and total energy imparted for each chest CT examination. Computed values of energy imparted during the chest CT examination were converted into effective doses taking into account the patient weight. Patient weights ranged from 4.5 to 127 kg, and half the patients in this study were children under 18 years of age. All scans were performed at 120 kVp with a 1 s scan time. The selected tube current showed no correlation with patient weight (r2=0.06), indicating that chest CT examination protocols do not take into account for the size of the patient. Energy imparted increased with increasing patient weight, with values of energy imparted for 10 and 70 kg patients being 85 and 310 mJ, respectively. The effective dose showed an inverse correlation with increasing patient weight, however, with values of effective dose for 10 and 70 kg patients being 9.6 and 5.4 mSv, respectively. Current CT technique factors (kVp/mAs) used to perform chest CT examinations result in relatively high patient doses, which could be reduced by adjusting technique factors based on patient size.

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Section: Discussionmentioning

confidence: 99%

Effective doses to patients undergoing thoracic computed tomography examinations

Huda¹,

Scalzetti²,

Roskopf³

2000

Medical Physics

132

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“…163,164 Energy imparted, also known as the integral dose, is the total energy deposited in a patient undergoing a radiological examination, and has been widely used in conventional x-ray imaging. 165 Energy imparted can also be used in CT dosimetry, 166,167 with the advantage that values of energy imparted for multiple scans can be added together, whereas doses are concentration units ͑energy per unit mass͒ that do not permit this form of simple addition when different parts of the body are irradiated. Other benefits of energy imparted include the ability to intercompare different types of radiological examinations, as well as conversion into effective doses using examination specific conversion coefficients that can be readily scaled to take into account the size of the patient.…”

Section: Va Dosimeters Dose Quantities and Measurement Techniquesmentioning

confidence: 99%

Overview of patient dosimetry in diagnostic radiology in the USA for the past

2008

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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.

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“…For the newly developed CR system, the mean absorbed doses were calculated from the dose measurements for the hip and knee exposures, respectively, for the 8 image pairs. The energy imparted (2) was then determined as the product between the mean absorbed dose and the exposed mass.…”

Section: Materials Methods and Resultsmentioning

confidence: 99%

Orthopaedic Measurements With Computed Radiography

Sanfridsson

2008

Acta Radiologica

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Sanfridsson J.: Orthopaedic measurements with computed radiography. Methodological development, accuracy, and radiation dose with special reference to the weight‐bearing lower extremity and the dislocating patella. Lund 2001. ISBN 87‐16‐16449‐0. The overall aim of this study was to develop and evaluate a measurement system for computed radiography (CR) and Picture Archiving and Communication Systems (PACS), permitting measurements of long distances and angles in and between related images. The developed measurement system, which was based on the QUESTOR Precision Radiography (QPR) system, was applied to the weight‐bearing knee with special reference to the dislocating patella. The QPR system modified for CR fulfilled the criteria for measuring the weight‐bearing knee. The special measuring assistance tools that were developed were important for the implementation of CR and PACS, particularly in workstations programmed for musculoskeletal radiology. The energy imparted to the patient was reduced by 98% at the lowest exposure of the CR‐system, compared with our conventional analogue method, without loss of diagnostic accuracy. The CR technique creates a possibility, to an extent not previously feasible, to differentiate the exposure parametres (and thus minimise the radiation dose to the patient) by carefully considering the purpose of the examination. A radiographic method for measuring the rotation of the femur and the tibia, the Q‐angle, and the patellar translation was developed and applied to healthy volunteers. The introduced patellar variables have yielded new insights into the complex sequence of motions between the femur, tibia, and patella. The patients with a dislocating patella were subdivided into one “clean” group of spontaneous dislocations and one group with various traumas in the history, which thus resulted in two groups with distinct radiographic differences. The Q‐angle was decreased in knees that had suffered dislocations, and the traditional surgical treatment with a further reduction of the Q‐angle must be challenged. The use of clinical measurements of the Q‐angle was not an optimal way to evaluate the mechanical alignment in the patellofemoral joint under physiological conditions. In this study, we have proved that the developed method for CR and PACS is a useful technique for measurements in and between related images, and is superior to the conventional analogue technique (NoteNoteNote).

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Use of the concept of energy imparted in diagnostic radiology

Cited by 24 publications

References 68 publications

Effective doses to patients undergoing thoracic computed tomography examinations

Effective doses to patients undergoing thoracic computed tomography examinations

Overview of patient dosimetry in diagnostic radiology in the USA for the past

Orthopaedic Measurements With Computed Radiography

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