As most occupational and environmental exposures to ionizing radiation are at low dose rates or in small dose fractions, risk estimation requires that the effects of the temporal distribution of dose are taken into account. Previous in vitro studies of oncogenic transformation, as well as in vivo studies of carcinogenesis induced by high-LET radiation, yielded controversial results concerning the presence of an inverse dose-rate effect. The present study tested the influence of one scheme of dose fractionation of monoenergetic neutrons on neoplastic transformation of C3H 10T1/2 cells. Neutrons of 0.5, 1.0 and 6.0 MeV were used. Cells were exposed to doses of 0.25 and 0.5 Gy, given acutely or in five fractions at 2-h intervals. The acute and fractionated irradiations with each energy were done on the same day. No significant difference between the two irradiation modes was found for both cell inactivation and neoplastic transformation at all energies. These results are in agreement with our data for fractionated fission-spectrum neutrons from the RSV-TAPIRO reactor.
Journal Article Delft Conference Proceedings Editorial 2008: safety and efficacy for new techniques and imaging using new equipment to support European legislation Get access K. Faulkner, K. Faulkner Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Zoetelief, J. Zoetelief Search for other works by this author on: Oxford Academic PubMed Google Scholar F.W. Schultz, F.W. Schultz Search for other works by this author on: Oxford Academic PubMed Google Scholar R. Guest R. Guest Search for other works by this author on: Oxford Academic PubMed Google Scholar Radiation Protection Dosimetry, Volume 129, Issue 1-3, March-April 2008, Pages 1–2, https://doi.org/10.1093/rpd/ncn164 Published: 13 June 2008
The measurement protocol for the 1990 CEC sponsored intercomparison is described and the results have been analysed. The majority of participants achieved good results, within 10% deviation of the correct value. Differences in performance can be linked to how each national centre organised the intercomparison and to national arrangements for similar measurements, particularly legislative requirements. Furthermore, certain types of instruments tended to perform well, particularly those with a flat energy response for the X ray qualities used. Participants who used instruments dedicated to mammographic and diagnostic X ray qualities, tended to obtain the best results. The greatest scope for improvement in the accuracy of measurements is in mammography, and this is related to the use of dedicated mammographic chambers.
Physics and instrumentation are often taught during separate courses in nuclear medicine training. The present book is intended by the authors for use by physicians, technologists and scientists trained to become specialists in nuclear medicine. It is also intended to be used by physicians, scientists and engineers in related fields. Although there have been substantial changes in nuclear medicine, the goal of the book remains the same as for the first edition in 1980, i.e. to provide an introductory text for courses as mentioned above, covering the physics and instrumentation of nuclear medicine. The fourth edition includes recent advances, particularly in single-photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging. A new chapter is included on hybrid imaging techniques, combining functional and physiological imaging capabilities of SPECT and PET with anatomical information obtained by computed tomography (CT) or magnetic resonance imaging (MRI). An introduction to CT scanning is...
For broad antero-posterior beams of monoenergetic (0.1-10 MeV) electrons organ doses per unit fluence were computed through Monte Carlo simulation in a reference male and female adult and a 7 year old girl. Effective doses (E) per unit fluence were calculated for the three phantoms and for an average adult. E increases from about 8 x 10-14 to about 1.2 x 10-10 Svcm2 with increasing electron energy. Uncertainties were (often much) better than 6% for the adults, and 18% for the child. E as calculated for the average adult may be used for both males and females as under- or overestimations stay within 25% from E for the average adult. The child's radiation risk is underestimated for electron energies in the range of 0.6 to 3 MeV. This underestimation up to a factor of about 20 is unacceptable for radiological protection purposes. The present results were compared with literature data on operational quantities associated with radiation hazard from weakly penetrating radiation. Neither directional nor personal dose equivalent appears to be a realistic quantity in this case. Both would yield an unnecessarily large safety factor for radiological protection.
Micturating cystourethrography (MCU) examinations of paediatric patients in a major Dutch children's hospital (JKZ) were evaluated to generate quantitative information on effective dose (E). A standard examination involves three radiographs plus fluoroscopy. Observed total dose-area product (DAP) for 84 children increased, on average, with increasing age class from 0.2 to 2.2 Gy cm2. In 11 cases, separate DAP per view was measured; enabling determination, per view, of organ (CF) and effective (CE) dose conversion factors, i.e. dose per unit of DAP. Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied for newborn, 1 year, 5 year, 10 year and 15-year-old patients, and interpolated for other ages. CE per view decreases with increasing age class, yielding about a factor of 10 difference between the extremes of the range. Female values are usually some 20-30% above male ones. CE for one of the views appeared to be representative for the complete examination and was used to estimate total E for each patient. Averaged per age class, E remains approximately constant at 0.3-0.4 mSv, although a tendency to increase with increasing age exists, for females in particular. Within an age class, individual patients may differ in E by a factor of two up to six. Stomach, lower large intestine, bladder wall, liver and ovaries receive relatively high doses. Compared with published data and DAP measured in a few other Dutch hospitals, the radiation burden of MCU is low at the JKZ. This indicates a good degree of optimization with respect to radiation protection (e.g. modern equipment, increased tube voltage, fast film-screen combination).
Journal Article Quality control of equipment used in digital and interventional radiology Get access J. Zoetelief, J. Zoetelief *Corresponding author: j.zoetelief@iri.tudelft.nl Search for other works by this author on: Oxford Academic PubMed Google Scholar R. T. M. van Soldt, R. T. M. van Soldt Search for other works by this author on: Oxford Academic PubMed Google Scholar I. I. Suliman, I. I. Suliman Search for other works by this author on: Oxford Academic PubMed Google Scholar J. T. M. Jansen, J. T. M. Jansen Search for other works by this author on: Oxford Academic PubMed Google Scholar H. Bosmans H. Bosmans Search for other works by this author on: Oxford Academic PubMed Google Scholar Radiation Protection Dosimetry, Volume 117, Issue 1-3, December 2005, Pages 277–282, https://doi.org/10.1093/rpd/nci739 Published: 03 February 2006
A lack of suitable dosimetric quantities for application in diagnostic radiology is noted by Dr Moores. It is concluded by Dr Moores that it is not possible to adhere to the basic principles of the International Commission on Radiation Units and Measurements (ICRU) regarding patient dosimetry in diagnostic radiology due to the extremely wide variety of quantities and units employed. The conclusion of the ICRU on similar observations, however, was that there is a need for harmonization of quantities and terminology for dosimetry in diagnostic and interventional radiology and they established a Report Committee with the aim of formulating an ICRU report on 'dosimetric procedures in diagnostic radiology'. The report produced by this committee entitled 'Patient dosimetry for x rays used in medical imaging' was accepted for publication in December 2005 and is currently at press, and may serve to improve the current situation with regard to patient dose measurement in diagnostic and interventional radiology.
