A new method for CT dose estimation by determining patient water equivalent diameter from localizer radiographs: Geometric transformation and calibration methods using readily available phantoms.

PURPOSE: Water equivalent diameter (Dw) reflects patient's attenuation and is a sound descriptor of patient size, and is used to determine size-specific dose estimator from a CT examination. Calculating Dw from CT localizer radiographs makes it possible to utilize Dw before actual scans and minimizes truncation errors due to limited reconstructed fields of view. One obstacle preventing the user community from implementing this useful tool is the necessity to calibrate localizer pixel values so as to represent water equivalent attenuation. We report a practical method to ease this calibration process. METHODS: Dw is calculated from water equivalent area (Aw) which is deduced from the average localizer pixel value (LPV) of the line(s) in the localizer radiograph that correspond(s) to the axial image. The calibration process is conducted to establish the relationship between Aw and LPV. Localizer and axial images were acquired from phantoms of different total attenuation. We developed a program that automates the geometrical association between axial images and localizer lines and manages the measurements of Dw and average pixel values. We tested the calibration method on three CT scanners: a GE CT750HD, a Siemens Definition AS, and a Toshiba Acquilion Prime80, for both posterior-anterior (PA) and lateral (LAT) localizer directions (for all CTs) and with different localizer filters (for the Toshiba CT). RESULTS: The computer program was able to correctly perform the geometrical association between corresponding axial images and localizer lines. Linear relationships between Aw and LPV were observed (with R2 all greater than 0.998) on all tested conditions, regardless of the direction and image filters used on the localizer radiographs. When comparing LAT and PA directions with the same image filter and for the same scanner, the slope values were close (maximum difference of 0.02 mm), and the intercept values showed larger deviations (maximum difference of 2.8 mm). Water equivalent diameter estimation on phantoms and patients demonstrated high accuracy of the calibration: percentage difference between Dw from axial images and localizers was below 2%. With five clinical chest examinations and five abdominal-pelvic examinations of varying patient sizes, the maximum percentage difference was approximately 5%. CONCLUSIONS: Our study showed that Aw and LPV are highly correlated, providing enough evidence to allow for the Dw determination once the experimental calibration process is established.

Repetitive stress symptoms in radiology: prevalence and response to ergonomic interventions.

PURPOSE: To determine the prevalence of repetitive stress symptoms among radiologists working in a archiving and communication systems (PACS) environment and to assess their responses to ergonomic interventions. METHODS: A survey instrument was designed in conjunction with occupational health specialists and administered to 107 faculty members, fellows, and residents working in a PACS-based radiology department. Data gathered included the number of hours per day working at a personal computer or PACS monitor, the presence of repetitive stress symptoms, and prior diagnosis of repetitive stress syndrome. Additionally, respondents who had received ergonomic chairs, ergonomic workstations, or ergonomic training were asked to rank the impact of these interventions on the severity of repetitive stress symptoms using a 7-point, Likert-type scale ranging from -3 ("markedly worse") to 3 ("markedly better"). RESULTS: A total of 73 responses were received (a 68% response rate) from 33 faculty members and 40 trainees (residents and fellows). A majority of respondents (68%) reported working more than 8 hours per day at a personal computer or PACS monitor (55% of faculty members, 80% of trainees). Repetitive stress symptoms were reported by 58% of respondents (52% of faculty members, 63% of trainees), and prior diagnoses of repetitive stress syndrome were reported by 38% (39% of faculty members, 38% of trainees). Improvements in repetitive stress symptoms (scale ratings of 1 to 3) were reported by 70% of respondents who received ergonomic chairs (n = 54), 80% who received ergonomic workstations (n = 55), and 80% who underwent ergonomic training (n = 20). CONCLUSION: Repetitive stress symptoms are highly prevalent among radiologists working in a PACS-based environment but are responsive to ergonomic interventions. Radiology departments should implement ergonomic initiatives to reduce the risk for repetitive stress injuries.

Shareware program for nuclear medicine and PET/CT PACS display and processing.

OBJECTIVE: Many of the functions necessary for imaging and analyzing nuclear medicine studies are not available on radiology PACS. Over the past 20 years, we have developed a user-friendly, easily installed software package for nuclear medicine study analysis, display, Web access, and database storage and an integrated display for fused PET/CT. We are making this software available as free shareware that can be used without a license on any PC. The software package was developed as a cooperative effort between house and attending staff and our nuclear medicine programmer. Particular emphasis was put on making functions intuitive and user friendly. CONCLUSION: A shareware nuclear medicine PACS software package including a display for fused PET/CT studies has been developed, extensively clinically tested, and is freely available on the Internet.

Use of personal digital assistants in diagnostic radiology resident education.

RATIONALE AND OBJECTIVES: Personal digital assistants (PDAs) are gaining widespread use in the medical community. We introduced a PDA-based mobile system that provides departmental and educational information with a seamless connection to the intranet. The objective of this study is to determine the impact a PDA has on educational resources (learning or data reference) brought to work and used at home by a radiology resident based on user surveys. MATERIALS AND METHODS: Survey was performed on 32 radiology residents in our department before and 6 months after the release of the PDA-based system. We assessed the changes in (1) sources of learning at home and at work, and in (2) data reference. The second survey also evaluated the usefulness of each component of the system. RESULTS: After the release of the PDA-based mobile system, the use of "digital books and references" as data references and educational resources that were brought to work every day significantly increased (P = .016, P < .0001, respectively). "Traditional books and references" remained the "most useful source in learning radiology"; however, "digital books and references" increased as the residents' first choice from 0% to 16% within 6 months of introducing the package (P = .125). CONCLUSION: The introduction of a PDA-based system consisting of educational and departmental information had a statistically significant impact in increasing the use of digitized information in radiology resident education.

A mobile solution: PDA-based platform for radiology information management.

OBJECTIVE: We describe how our radiology department set up, integrated, and deployed a personal digital assistant-based mobile platform to deliver updated critical departmental and educational material to our residents. CONCLUSION: We have implemented and described a robust mobile solution that maintains a seamless connection with the departmental intranet. Resident feedback regarding the use of the mobile solution program has confirmed our belief that using this mobile technology is a feasible and clinically practical alternative for accessing time-sensitive and educational materials. Furthermore, our description can help others deploy such digital products and facilitate the transition to soft copy that is already occurring in radiology education.