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Purpose: To evaluate the radiation doses delivered during volumetric helical perfusion CT of the thorax, abdomen or pelvis.Materials and Methods: The dose-length product (DLP) and CT dose index (CTDIvol) were recorded and effective dose (E) determined for patients undergoing CT (4D adaptive spiral) for tumour evaluation. Image noise and contrast to noise (CNR) at peak enhancement were also assessed for quality.Results: Forty two consecutive examinations were included: thorax (16), abdomen (10), pelvis (16). Z-axis coverage ranged from 11.4 to 15.7 cm. Mean DLP was 1288.8 mGy.cm (range: 648 to 2456 mGy.cm). Mean CTDIvol was 96.2 mGy (range: 32.3 to 169.4 mGy). Mean effective dose was 19.6 mSv (range: 12.3 mSv to 36.7 mSv). In comparison mean DLP and effective dose was 885.2 mGy.cm (range: 504 to 1633 mGy.cm) and 13.3 mSV (range: 7.8 to 24.5 mSv) respectively for the standard staging CT thorax, abdomen and pelvis. Mean tumour CNR at peak enhancement was 1.87.Conclusion: The radiation dose imposed by perfusion CT was on average 1.5 times that of a CT thorax, abdomen and pelvis. The dose is not insubstantial, and must be balanced by the potential clinical utility of additional physiologic data. Further efforts towards dose reduction should be encouraged. [ABSTRACT FROM AUTHOR]

Background and Purpose: This study outlines the measured doses for three concomitant imaging modalities used in radiotherapy., Material and Methods: Doses were measured using thermo luminescent dosemeters within pelvis and thorax anthropomorphic phantoms for the Varian On Board Imager (OBI), Elekta X-ray Volume Imager (XVI) and Tomotherapy HiArt II systems. Organ sites were selected to include those organs which would be irradiated by the treatment beam during the therapy exposure., Results: Doses for kilovoltage imaging systems are comparable within the pelvis phantom at 20-30 mGy. Thorax phantom doses are lower, especially where user specified protocols are used at 5-10 mGy. Tomotherapy doses are typically less than 10 mGy for both phantoms., Conclusions: Concomitant imaging dose is a small fraction of the therapy dose, however, for a high fraction technique, the imaging dose can become comparable to the therapy dose outside primary target volume. Recommendations for optimisation of imaging in radiotherapy are presented., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Background: Heart transplant recipients are frequently exposed to ionizing radiation from various imaging and cardiac procedures. However, radiation exposure carries various risks, including cancer. In this retrospective study, we calculated the mean cumulative radiation exposure during a 10-year period and the subsequent cancer risk after heart transplantation., Methods: The study included all patients who underwent heart transplantation from August 1998 to July 2008 at our center. We identified all plain X-ray images, computed tomography, nuclear medicine procedures, and cardiac procedures (endomyocardial biopsies, right and left heart catheterization, and coronary angiograms) each patient underwent during the follow-up period. Radiation doses from cardiac procedures were the recorded exposures, and we used reference values for plain X-ray imaging and nuclear medicine procedures., Results: The mean radiation dose was 84 mSv during the 10-year period, and cardiac procedures represented the largest radiation dose at 43.6 mSv (52%). The 10-year cumulative dose represented an additional 1 in 290 new cancers in the healthy population. Encouragingly, there was a decreasing trend of radiation exposure during the study period, with a mean decrease of 4.3 mSv per year., Conclusion: Heart transplant patients are exposed to a 3.5 times greater dose of radiation per year compared with radiation from medical imaging in general population. The lifetime increase in cancer risk estimated from population studies was small. Although, there was a decreasing trend of radiation exposure during the study period, further reductions in radiation doses may be possible by the use of alternative imaging and non-imaging investigations., (Copyright © 2011 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Purpose: To prospectively determine if gammaH2AX (phosphorylated form of H2AX histone variant)-based visualization and quantification of DNA damage induced in peripheral blood mononuclear cells (PBMCs) can be used to estimate the radiation dose received by adult patients who undergo multidetector computed tomography (CT)., Materials and Methods: After institutional review board approval and written informed patient consent were obtained, eight women and five men (mean age, 63.8 years) who would be undergoing chest-abdominal-pelvic CT or chest CT only were recruited. Venous blood samples obtained before scanning were exposed to different radiation doses in vitro and incubated for 5-30 minutes to obtain reference values of gammaH2AX focus yield. Additional blood samples were taken 5-30 minutes after CT. Leukocytes were isolated, fixed, and stained for gammaH2AX expression. The gammaH2AX focus yields were determined with fluorescence microscopy, and the radiation doses delivered during CT were estimated by comparing post-CT focus yields with in vitro pre-CT focus yields. These CT radiation doses were compared with doses calculated by using phantom dosimetry and Monte Carlo data sets. Data were analyzed by using linear regression, the dispersion index test, and the contaminated Poisson method., Results: Compared with the gammaH2AX focus yields in blood samples taken before CT (0.06 focus per cell+/-0.01 [mean+/-standard error of mean]), the yields in blood samples taken 5 minutes after chest-abdominal-pelvic CT (0.52 focus per cell+/-0.02) were 8-10-fold higher and corresponded to a mean radiation dose of 16.4 mGy (95% confidence interval: 15.1, 17.7). The mean yield of 0.24 focus per cell+/-0.04 in one patient after chest CT corresponded to a mean radiation dose of 6.3 mGy+/-1.4. In comparison, phantom dosimetry-calculated total blood doses were 13.85 mGy with whole-body CT and 5.16 mGy with chest CT., Conclusion: gammaH2AX focus yield in blood cells may be a useful quantitative biomarker of human low-level radiation exposure., (Copyright (c) RSNA, 2007.)

Unlabelled: ABSTRACT RATIONALE, AIMS AND OBJECTIVES: Against the background of a general rise in the incidence of breast cancer temporal variations appear in different age groups, including changes attributable to the introduction of breast screening. This paper attempts to distinguish the influence of breast screening and to examine any underlying patterns., Methods: The incidence data published by the Office of National Statistics for England and Wales have been examined using the method of least squares regression. These data have been subjected to major revision: a new system was introduced in 1971. That year, therefore, has been taken as the starting point for the analyses. Regression lines were fitted from 1971, 1984 and 1988 (when breast screening was started). Results Between 1971 and 1984 breast cancer incidence was unchanged in women under 50 years. In all other age groups and time periods the incidence has risen throughout 1971-1999. The rate of increase remained constant for women over 64 but changed in 1984 for all women under 65 years. The rate of increase is rising exponentially with age since 1984 in the women under 65. The superimposed increases due to screening have been separated from the underlying rates., Conclusions: In the period surveyed there appears to have been a change in the rates of increase in incidence of breast cancer in women under 65 that dates from 1984. This change can be separated from the spurious increase due to breast screening. The rates in women over 64 have remained constant.

It has been suggested that alteration of the distribution of histological grades, that has been found in screening programmes, is evidence for progression in histological grade with increasing size. A predictive model, that was based upon estimated growth data from an unselected series of 98 new primary breast cancers, is used to estimate the proportions of tumors that would be diagnosed according to limiting screen diagnostic and clinical diagnostic sizes after particular screening intervals; windows of opportunity are created. The results show that the limitations imposed by time and size criteria alter the distribution of growth rates of tumours that may appear in the windows. Small screen diagnostic sizes and short screening intervals allow only the most rapidly growing tumours to reach large sizes. This produces an apparent association of grade 3 tumours with large size. Interval cancers are also likely to be more rapidly growing while the more slowly growing tumours will be diagnosed at the subsequent screen to produce a spurious association of slowly growing grade 1 tumours with small size. We conclude that the evidence from screening does not support the thesis of progression of histological grade with the ageing of the tumour, since the changes that have been observed are predictable from a simple model based upon patterns of tumour growth rates and the relationships between growth rate and histology.