This Article Figures Only Full Text Full Text (PDF) CME Activity All Versions of this Article: jnmt.106.037846v1 35/4/213    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Goldman, L. W. Search for Related Content PubMed PubMed Citation Articles by Goldman, L. W.

Principles of CT: Radiation Dose and Image Quality^*

Department of Radiation Therapy and Medical Physics, Hartford Hospital, Hartford, Connecticut

Correspondence: For correspondence or reprints contact: Lee W. Goldman, Department of Radiation Therapy and Medical Physics, Hartford Hospital, 80 Seymour St., Hartford, CT, 06102. E-mail: lgoldma{at}harthosp.org

ABSTRACT

This article discusses CT radiation dose, the measurement of CT dose, and CT image quality. The most commonly used dose descriptor is CT dose index, which represents the dose to a location (e.g., depth) in a scanned volume from a complete series of slices. A weighted average of the CT dose index measured at the center and periphery of dose phantoms provides a convenient single-number estimate of patient dose for a procedure, and this value (or a related indicator that includes the scanned length) is often displayed on the operator's console. CT image quality, as in most imaging, is described in terms of contrast, spatial resolution, image noise, and artifacts. A strength of CT is its ability to visualize structures of low contrast in a subject, a task that is limited primarily by noise and is therefore closely associated with radiation dose: The higher the dose contributing to the image, the less apparent is image noise and the easier it is to perceive low-contrast structures. Spatial resolution is ultimately limited by sampling, but both image noise and resolution are strongly affected by the reconstruction filter. As a result, diagnostically acceptable image quality at acceptable doses of radiation requires appropriately designed clinical protocols, including appropriate kilovolt peaks, amperages, slice thicknesses, and reconstruction filters.

Key Words: PET/CT; quality assurance; radiation safety; CT; CT technology; computed tomography

This article has been cited by other articles:

				C. von Falck, M. Galanski, and H.-o. Shin Informatics in Radiology: Sliding-Thin-Slab Averaging for Improved Depiction of Low-Contrast Lesions with Radiation Dose Savings at Thin-Section CT RadioGraphics, January 12, 2010; (2010) rg.302096007v1. [Abstract] [Full Text]

				L. W. Goldman Principles of CT: Multislice CT J. Nucl. Med. Technol., June 1, 2008; 36(2): 57 - 68. [Abstract] [Full Text] [PDF]