Reference Books and Articles on Diagnostic X Ray and CT

I am trying to search some kind of reference values for dose to some organs following radiographic film exams. I would like to get the dose to the organ as a function of the entrance skin exposure, for example. I am concerned with the dose for a chest exam (posterior-anterior) at 150 kVp. I am more interested in the dose to lung, breast, and bone marrow.

We continue to use handbooks available through the Food and Drug Administration. Search on CDRH Organ Dose handbooks. The handbook for this question is FDA 89-8031 Handbook of Selected Tissue Doses for Projections Common in Diagnostic Radiology. We use 14" x 17" fields at 72" and at 120 kVp. We also have our tubes filtered generally at 3.0 mm Al. If I look that up in the table, I find that the dose to the lung is 0.13 mGy, breast is 0.02 mGy, and bone marrow is about 0.03 mGy.

Charts A.3a-c in NCRP Report No. 68 (pages 58-63) contain information on gonadal doses in children from radiographic exposures. I am trying to locate a comparable chart for adults. Would you be able to tell me which report this chart is in? I'm told it does exist, just not where it is located. I appreciate any help in this matter.

Tables providing gonadal doses for adults for typical medical exams can be found in the following book: J.G. Keriakes and M. Rosenstein; CRC Handbook of Radiation Doses in Nuclear Medicine and Diagnostic X-Rays; CRC Press, Inc.; Boca Raton, FL; 1980.

I am a student learning about medical radiation diagnosis. I would very much appreciate if someone can tell me where I can find a report about radiation diagnostic dose or a report of x-ray dose, nuclear medicine dose, CT dose.

There is a book that should provide the information that you need on x-ray and nuclear medicine doses. It is J.G. Keriakes and M. Rosenstein; CRC Handbook of Radiation Doses in Nuclear Medicine and Diagnostic X-Ray, CRC Press, Inc., Boca Raton, FL.

I plan to conduct a study on the radiation doses that pediatric patients receive from computerized tomography (CT) fluoroscopy exams; however, there doesn't seem to be a definitive way to calculate effective dose for this modality. Do you have any suggestions?
An article was recently published giving a general approach to CT dosimetry in children (Huda et al. 1997). To use this method, the following steps need to be followed:
  1. Estimate the equivalent size of the patient being scanned in terms of an equivalent cylinder of water based on the CT image data.
  2. Assume that the scan is being performed on a GE CT/i CT scanner, and use your kV and mA(s) values. In determining the effective kV, mAs, and slice thickness, average the actual techniques in a way that will provide an accurate value of energy imparted. That is, 2 x 5 mm sections that overlap are equivalent to 1 x 10 mm, since the energy imparted remains the same even if the local doses don't. It needs to be kept in mind that the effective dose is a measure of the stochastic risk, which is directly related to energy imparted.
  3. Determine the mean section dose based on the data presented in Figure 1 and Table 5 by using equation 5 (Huda et al. 1997).
  4. Determine the energy imparted, and convert this into an effective dose using a patient size dependent effective dose per unit energy imparted coefficient using Equation (5).
  5. Scale this to your specific CT scanner using the ratio of your CTDI to those of the CT/i CTDI as listed in Table 8.

Huda W, Atherton JV, Ware DE, Cumming WA. An approach for the estimation of effective radiation dose at CT in pediatric patients. Radiology 203(2):417–22; 1997.

Can you direct me to a seminal paper addressing workloads in CT facilities?
In Table 2, Comparison of Workload Values for a Diagnostic Facility, of "Diagnostic X-Ray Shielding Design - New Data and Concepts" by Benjamin Archer, the workload per patient for a Computed Tomography (CT) room is 205 mAmin per patient. For a workload of 64 patients per week the total workload is given as 13,000 mAmin per week. In Table 3, Proposed Values for Workloads (Not Final), the workload in a CT room is given as 200 mAmin per patient. For an average facility with 60 patients per week, the workload is 12,000 mAmin per week. For a busy facility with 100 patients per week, the workload is 20,000 mAmin per week.

Frey GD, Sprawls P, eds. The expanding role of medical physics in diagnostic imaging. Proceedings of the 1997 American Association of Physicists in Medicine Summer School. (AAPM Monograph Series Number 23). American Association of Physicists in Medicine; June 1997.

Do you know of any websites that will tell me when x rays started to be used in medical procedures and when there were technological advances in x-ray procedures?

Following are a number of websites that will give you information on medical x rays:

You might also find the Radiation Information Network website useful.

What is a reference to determine the method (formula) for calculation of leakage and scattered radiation for radiography x-ray units?

There are a variety of formulae that may be used for calculation of various parameters for diagnostic x-ray imaging units. Typically, leakage radiation limits are fixed by regulation or standard to a value that limits the dose received by the portion of the patient's body outside the useful beam. In the United States, the National Council on Radiation Protection and Measurements recommends that the leakage radiation be limited to 100 mR in one hour at one meter from the target (source of radiation). This limit is specified as an integrated value to account for the workloads allowed on various tubes. NCRP Report Number 102 discusses some of these standards.

A standard reference in the field of medical physics has been The Physics of Radiology by Johns and Cunningham, available from Amazon. Other groups have used the text by E. Christensen et al., An Introduction to the Physics of Diagnostic Radiology.

Can x rays be generated by electrons accelerated by a 30kV voltage? How about 40kV? If so, where do I find information on shielding, doses, etc.? If not, at which voltage do x-rays begin to be generated?

According to graphs presented in numerous textbooks (Bushberg et al. 1994), x rays can be produced with any potential voltage across the x-ray tube. However, due to the space charge effect, the relationship "between the filament current and the tube current" is not linear below about 40 kVp. The use of compensation circuits with the filament current will produce the desired tube current at these low operating voltages. Although x rays are produced at very low voltages, most of the low-energy x rays are absorbed by the x-ray tube housing, filtration, etc. The useful x-ray production is then demonstrated by a curve starting at zero intensity at some kVp, increasing to a maximum intensity at approximately 1/3 of the maximum x-ray energy and then decreasing to zero intensity at the maximum energy. X-ray tubes that operate at such low kVp are typical of mammography units in diagnostic radiology (Eichholz and Shonka 1993). Shielding for x rays of this low energy usually consists of two sheets of commercially available drywall, with one sheet on each side of the wall. If the source is an industrial unit and is mounted inside a cabinet, the shielding of the cabinet alone may be sufficient.

References used in this answer that may be of interest to you:

  • Bushberg JT, Seibert JA, Leidholdt Jr. EM, Boone JM. The essential physics of medical imaging. Lippincott, Williams & Wilkins: NY; Chapters 4 and 9; 1994.
  • Eichholz GG, Shonka JJ, eds. Hospital health physics. In: Proceedings of the 1993 Health Physics Society Summer School. Richland, WA: Research Enterprises; 1993: 85-86.
Are there any statistics or data on the consequences of long-term exposure to various forms of radiation to staff repeatedly exposed to scatter radiation during their careers?
Yes, there have been studies conducted involving radiologists, x-ray technicians, etc. None of these studies show that there are long-term health effects from occupational exposure. You may wish to review the following publications for more detailed information: National Research Council BEIR VII Report and a report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).
Ask the Experts is posting information using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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