For standard radiographs, dosimetry is presented in Table 46-5. In pregnancy, the AP-view chest radiograph is the most commonly used study, and fetal exposure is exceptionally small-0.0007 Gy or 70 mrad. With one abdominal radiograph, because the embryo or fetus is directly in the x-ray beam, the dose is higher-O.OO 1 Gy or 100 mrad. he standard intravenous pyelogram may exceed 0.005 Gy or 500 mrad because of several exposures. The one-shot pyelogram described in Chapter 53 (p. 1030) is useful when urolithiasis or other causes of obstruction are unproven by sonography but still suspected. Most "trauma series," such as radiographs of an extremity, skull, or rib series, deliver low doses because of the fetal distance from the target area (Shakerian, 2015).
Dosimetry calculations are much more diicult with these procedures because of variations in the number of radiographs obtained, total fluoroscopy time, and luoroscopy time in which the fetus is in the radiation field. As shown in Table 46-6, the range is variable. he Food and Drug Administration (FDA) limits the exposure rate for conventional fluoroscopy such as barium studies, however, special-purpose systems such as angiography units have the potential for much higher exposure.
Dosea per View Study View (mGy) No. Filmsb Dose (mGy)
TABLE 6-5. Dose to the Uterus for Common Radiologic Procedures
SkuW AP, PA, Lat <0.0001
Chest AP, PN, Latd <0.0001n-0.0008 <0.0005 1.5 0.0002-0.0007
Mammogramd Cc, Lat <0.0003-0.0005 4.0 0.0007 -0.002 Lumbosacral spinee AP, Lat 1.14-2.2 3.4 1.76-3.6 Abdomene AP 1.0 0.8-1n.63 Intravenous pyelograme 3 views 5.5 6.9-14
Hipb (single) AP 0.7-1.4 2.0 1-2
Lat 0.18-0.51 aCalculated for x-ray beams with half-value layers ranging from 2 to 4 mm aluminum equivalent using the methodology of Rosenstein, 1988.
bBased on data and methods reported by Laws, 1978. (Entrance exposure data from Conway, 1989. dEstimates based on compilation of above data.
eBased on NEXT data reported in National Council on Radiation Protection and Measurements, 1989.
AP = anterior-posterior; CC = cranial-caudal; Lat = lateral; PA = posterior-anterior.
TABLE 46-6. Estimated X-Ray Doses to the Uterus/ Embryo from Common Fluoroscopic Procedures
Dose to Fluoroscopic
Cerebral angiographl <0.1
Cardiac angiographyb,( 0.65 223 (± 11n8)
Single-vessel PTCAb,c 0.60 1023 (± 952)
Double-vessel PTCAb,c 0.90 1186 (± 593)
Upper gastrointestinal seriesd 0.56 136 ,e 0.06 192
Barium enemab,f,9 20-40 289-311 aWagner, 1997.
Calculations based on data of Gorson, 1984.
cFinci, 1987.
dSuleiman, 1991n.
eBased on female data from Rowley, 1987.