Context Cardiac computed tomography (CT) angiography (CCTA) has emerged as a useful diagnostic imaging modality in the assessment of coronary artery disease. However, the potential risks due to exposure to ionizing radiation associated with CCTA have raised concerns. Objectives To estimate the radiation dose of CCTA in routine clinical practice as well as the association of currently available strategies with dose reduction and to identify the independent factors contributing to radiation dose. Design, Setting, and Patients A cross-sectional, international, multicenter, observational study (50 study sites: 21 university hospitals and 29 community hospitals) of estimated radiation dose in 1965 patients undergoing CCTA between February and December 2007. Linear regression analysis was used to identify independent predictors associated with dose. Main Outcome Measure Dose-length product (DLP) of CCTA. Results The median DLP of 1965 CCTA examinations performed at 50 study sites was 885 mGy × cm (interquartile range, 568-1259 mGy × cm), which corresponds to an estimated radiation dose of 12 mSv (or 1.2 x the dose of an abdominal CT study or 600 chest x-rays). A high variability in DLP was observed between study sites (range of median DLPs per site, 331-2146 mGy x cm). Independent factors associated with radiation dose were patient weight (relative effect on DLP, 5%; 95% confidence interval [Cl], 4%-6%), absence of stable sinus rhythm (10%; 95% Cl, 2%-19%), scan length (5%; 95% Cl, 4%-6%), electrocardiographically controlled tube current modulation (-25%; 95% Cl, -23% to -28%; applied in 73% of patients), 100-kV tube voltage (-46%; 95% Cl, -42% to -51 %; applied in 5% of patients), sequential scanning (-78%; 95% Cl, -77% to -79%; applied in 6% of patients), experience in cardiac CT (-1%; 95% Cl, -1 % to 0%), number of CCTAs per month (0%; 95% Cl, 0%-1 %), and type of 64-slice CT system (for highest vs lowest dose system, 97%; 95% Cl, 88%-106%). Algorithms for dose reduction were not associated with deteriorated diagnostic image quality in this observational study. Conclusions Median doses of CCTA differ significantly between study sites and CT systems. Effective strategies to reduce radiation dose are available but some strategies are not frequently used. The comparable diagnostic image quality may support an increased use of dose-saving strategies in adequately selected patients.

Estimated Radiation Dose Associated With Cardiac CT Angiography. Commentary

(1983). Ionizing Radiation: Sources and Biological Effects. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 43, No. 5, pp. 585-586.

Ionizing Radiation: Sources and Biological Effects

Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors.

https://www.mdpi.com/1424-8220/9/5/3491/pdf?view=inline

Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications

Radiation dose from mammographic techniques was determined as a function of surface exposure, beam quality, and depth. Relative exposure vs. depth was measured in tissue-substitute materials by thermoluminescent dosimetry. The f-factors were calculated from elemental compositions of mastectomy specimens. Dose at depth depends on beam quality as well as exposure and tissue composition. Analysis of data from the ACS/NCI Screening Centers shows current average midbreast doses to be 25 times lower (film/screen) and 3 times lower (Xerox) than the 2 rads previously estimated. Quantitative risk indicators other than midbreast dose are also discussed.

Absorbed radiation dose in mammography.

Photon, electron and proton radiations are used extensively for medical purposes in diagnostic and therapeutic procedures. Dosimetry of these radiation sources can be performed with radiochromic films, devices that have the ability to produce a permanent visible colour change upon irradiation. Within the last 10 years, the use of radiochromic films has expanded rapidly in the medical world due to commercial products becoming more readily available, higher sensitivity films and technology advances in imaging which have allowed scientists to use two-dimensional (2D) dosimetry more accurately and inexpensively. Radiochromic film dosimeters are now available in formats, which have accurate dose measurement ranges from less than 1 Gy up to many kGy. A relatively energy independent dose response combined with automatic development of radiochromic film products has made these detectors most useful in medical radiation dosimetry.

/pdf/radiochromic-film-for-medical-radiation-dosimetry-3ivt1gv8ns.pdf

F. W. Spiers

Papers

Physics of Radiology