ESR News November 2015

How to estimate embryo/foetal dose from diagnostic and interventional x-ray procedures

John Damilakis,  Professor of Medical Physics

A substantial increase in the use of radiological procedures for pregnant patients has been observed in developed countries over recent decades (1), while accidental medical exposure of pregnant patients during the first post-conception weeks may occasionally lead to unnecessary pregnancy terminations. Besides, the remarkable increase in the use of fluoroscopically guided interventional procedures has induced apprehension and concerns regarding the occupational exposure of pregnant employees involved in these procedures (2). In either case, the expectant mother has the right to know the level of radiation burden to the embryo from in-utero exposure. Therefore, determination of embryo or foetal radiation dose to pregnant patients undergoing radiological procedures and pregnant workers involved in fluoroscopically guided interventional procedures is of paramount importance.

Several methods have been developed to estimate conceptus dose from diagnostic and interventional x-ray procedures performed on patients. A method for estimating embryo/foetal dose resulting from abdominal radiographic examinations for all trimesters of gestation has been published (3). The data provided in this study also allow the estimation of conceptus dose from abdominal fluoroscopic procedures. Another study presents formulas and data for estimating the dose to the unborn child from cardiac ablation procedures (4). Methods for the estimation of conceptus dose from multi-detector CT examinations have also been published recently (5-7).

Conceptus radiation doses and risks from imaging with ionizing radiation (abbreviation: CONCERT) is a research project which has been set up to perform original research for optimal clinical management of pregnant patients needing radiologic procedures. Information about this project can be found at https://concert.med.uoc.gr. The main task of the project was to produce dose data and develop conceptus dose estimation methods for the main imaging procedures performed on pregnant patients. Another objective was to generate dose data that may be used for the implementation of a radiation protection programme designed for pregnant employees working in imaging departments, interventional laboratories and electrophysiological suites. The CONCERT research team has developed the CODE [COnceptus Dose Estimation] software package. CΟDE is a web-based application developed at the department of Medical Physics of the University of Crete, which provides estimation of

  1. conceptus radiation absorbed dose and radiogenic childhood cancer risk from radiological procedures performed on pregnant patients and
  2. conceptus radiation absorbed dose from occupational exposure of pregnant employees involved in fluoroscopically-guided interventional procedures.

Specifically, CODE ‘radiography’, ‘fluoroscopy’, and ‘CT’ modules provide estimates for the conceptus absorbed dose and radiogenic risk for childhood cancer associated with radiographic projections, diagnostic fluoroscopy and fluoroscopically guided procedures and CT examinations respectively performed on the pregnant patient. The theoretical radiogenic risk for childhood cancer associated with in-utero exposure is estimated using a risk coefficient of 1.2 x 10 per Gy as recommended by the International Commission on Radiological Protection (ICRP) report 90 (8). Furthermore, CODE ‘occupational module’ provides prospective or retrospective estimates of absorbed dose to the embryo or foetus of a pregnant employee involved in fluoroscopically guided interventional procedures. CODE has very recently been uploaded to CONCERT’s website and is freely available at https://concert.med.uoc.gr.

References

  1. Lazarus et al, Utilization of imaging in pregnant patients: 10-year review of 5270 examinations in 3285 patients, Radiology 251:517-24, 2009
  2. Dauer LT et al, Occupational radiation protection of pregnant or potentially pregnant workers in IR: a joint guideline of the Society of Interventional radiology and the Cardiovascular and Interventional Radiological Society of Europe. J Vasc Interv Radiol 26:171-81, 2015
  3. Damilakis J et al, Normalized conceptus doses for abdominal radiographic examinations calculated using a Monte Carlo technique. Medical Physics 29:2641-2648, 2002
  4. Damilakis J et al, Conceptus radiation dose and risk from cardiac catheter ablation procedures. Circulation 104:893-897, 2001
  5. Damilakis et al, A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation. Medical Physics 37:6411-20, 2010
  6. Damilakis et al, Radiation dose to the conceptus from multidetector CT during early gestation: a method that allows for variations in maternal body size and conceptus position. Radiology 257:483-9, 2010
  7. Goldberg-Stein SA et al, Radiation dose management: part 2, estimating fetal radiation risk from CT during pregnancy, AJR 198:W352-6, 2012
  8. Biological effects after prenatal irradiation (embryo and fetus). ICRP publication 90. In Ann. ICRP 2003; 33(1-2)