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

Abstract

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.

Lodox/Statscan facilitates the early detection of commonly overlooked extracranial injuries in patients with traumatic brain injury

“…A comparison of radiation dose, cost, and overall sensitivity of the Lodox/Statscan, conventional X-rays, and whole-body CT scans is presented in were 72.0, 9.0, 1.6, and 9.2% of the doses associated with conventional techniques, respectively [14,[22][23][24]. Furthermore, the cost of the brain CT and adjunct single-image Lodox/Statscan study is lower than the sum of the cost for brain CT and multiple X-ray studies [25].…”

“…Although the above facts indicated that torso and extremity injuries were sometimes missed by the Lodox/Statscan, these missed injuries were not life-threatening, and further treatments were not necessary. In addition, Table 5 also showed that the Lodox/Statscan minimized radiation exposure and had a lower cost in terms of medical resources [22][23][24][25].…”

Local reference dose evaluation in conventional radiography examinations in Iran

“…The last 50 years of dosimetry in the United States have shown that the regular use of quality control programs for diagnostic radiology equipment and the establishment of DRLs by the National Evaluation of X‐ray Trends (NEXT) have played vital roles in reducing patient radiation doses (6) . For example, based on NEXT patient average entrance skin dose (ESD) and data such as reference dose levels, a 50%‐70% reduction in average ESD was achieved for the years 1964 to 2004 for chest PA, abdomen AP, and lumbar‐sacral spine AP radiography examinations (6) .…”

“…For example, based on NEXT patient average entrance skin dose (ESD) and data such as reference dose levels, a 50%‐70% reduction in average ESD was achieved for the years 1964 to 2004 for chest PA, abdomen AP, and lumbar‐sacral spine AP radiography examinations (6) . Similar efforts have led to large reductions in patient doses in countries such as the UK.…”

In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

“…6,8 Although ideal and highly desirable, real-time accurate dose estimation for each patient undergoing CT exams is difficult to achieve due to complexities caused by several factors: (1) patient anatomy and tissue composition; 9 (2) the motion of radiation source(s), table, and the patient; (3) tube current and voltage modulation; 10 (4) the limited dose estimation methods. 11 CT dose estimation methods are generally based on Monte Carlo simulations and physical measurements. Computational simulations have great versatility in specifying the entire imaging scenario, and have been validated in terms of high accuracy in describing the physical interactions between radiation and material and in calculating energy deposition.…”