Ruedi F. Thoeni, MD •¿ Robert G. Gould, ScD
Enteroclysis and Small Bowel Series: Comparison of Radiation Dose and Examination Time' Respective radiation doses and total examination and fluoroscopy times were compared for 50 patients; 25 underwent enteroclysis and 25 un derwent small bowel series with (n =
17)
and
without
(n
8) an
exami
nation of the upper gastrointestinal
(CI) tract. For enteroclysis, the mean skin entry radiation dose (12.3 rad [123 mGy]) and mean fluoroscopy
time(18.4 minutes) werealmost1'/@
times greater than those for the small bowel series with examina tion of the upper GI tract (8.4 rad [84 mGy]; 11.4 minutes) and almost three times greater than those for the small bowel series without up per GI examination (4.6 rad [46 mGyJ 6.3 minutes). However, the mean total examination completion time for enteroclysis (31.2 minutes) was almost half that of the small bowel series without upper GI ex amination (57.5 minutes) and almost four times shorter than that of the small bowel series with upper GI examination (114 minutes). The higher radiation dose of enterocly sis should be considered along with the short examination time, the age and clinical condition of the patient, and the reported higher accuracy when deciding on the appropriate radiographic examination of the small bowel. Index terms:
Enteroclysis, 74.1272 •¿ Intes
tines, 74.1271, 74.1272 •¿ Radiations, exposure to patients and personnel •¿ Radiations, measure ment
Radiology 1991; 178:659-662
E NTEROCLYSIShas been used ex tensively in Europe and its use in the United States has markedly in creased
over the past few years (1-6).
While many studies have demon strated the high accuracy of this tech nique (1,2,7—11), advocates of the conventional per-oral small bowel series have cited very high radiation exposure, longer room and radiolo gist time, and higher costs as serious factors against its consideration as the primary or preferred method of investigating small bowel disease (12). In many institutions, the most commonly used radiographic small bowel examination is the per-oral small bowel series. In many in stances, the examination of the small bowel is combined with an evalua tion of the upper gastrointestinal (GI) tract despite the disadvantages of mixing various types of barium and focusing primarily on the esophagus, stomach, and duodenum (rendering the small bowel examination almost an afterthought). We included this combined approach in our series be cause it is used frequently. We con ducted our study to compare respec tive radiation doses and total exami nation
completion
and fluoroscopy
times in patients undergoing
entero
clysis and in those undergoing
small
bowel series with and without (dedi cated small bowel series) an examina tion of the upper CI tract. AND METHODS
The patients in our study were the first 54 referred Twenty-nine
to our department patients
for any of
underwent
clysis and 25 underwent
@
and very poor cooperation
by
the other). The average age of the pa tients who underwent enteroclysis (11 women and 14 men) was 48 years (range, 26-85 years). The average age of the pa tients
who underwent
per-oral
small
bowel series (17 women and eight men)
was 49 years (range, 23-77 years). Indica lions and diagnoses
were similar
in both
groups. Among the 25 patients who un derwent enteroclysis,
six had Crohn dis
ease, three had adhesions, five had small bowel obstruction (two with neoplasm and one each with Kaposi sarcoma, isch emia, and scarring), and 11 had normal findings. Among the 25 patients who un derwent per-oral small bowel examina tion, eight
had Crohn
disease,
four had
adhesions, one each had ischemia, radia tion changes, and diverticula, and 10 had normal findings.
A biphasic enteroclysis technique was used and a Maglinte catheter (Cook, Bloo mington,
md) was placed
through
one of
the nostrils and maneuvered into the jeju num beyond the Treitz ligament (13-15). Before
placement
of the tube, 20 mg of
metoclopramide (Reglan; Quad Pharma ceuticals, Indianapolis)
was orally admin
istered. Oropharyngeal anesthesia was routinely used. The ease of intubation was graded in each case as very easy (no special maneuvers necessary), easy (one special maneuver necessary), difficult (several maneuvers needed), and ex tremely difficult (several maneuvers and reintubation needed). Initially, 400-500 mL of 50% wt/vol barium (Entrobar; La fayette Pharmacal, Lafayette, md) were administered, followed by 1100-1200 mL of methylcellulose (Entrocel; Lafayette Pharmacal). Multiple spot radiographs
were obtained during the single- and MATERIALS
three types of small bowel examinations. ‘¿Fromthe Department of Radiology, the University of California, San Francisco, 505 Parnassus Aye, San Francisco, CA 94143-0628. From the 1989 RSNA scientific assembly. Re ceived July 19, 1990; revision requested Sep tember 6; revision received September 19; ac
one patient
entero
a small bowel se
ries, 17 with and eight without an exami nation of the upper GI tract. Four patients who underwent
enteroclysis
were exclud
ed from our study: two because some of the dosimeters were lost and unavailable
cepted October 15. Address reprint requests to
for reading and two because the examina
R.F.T. RSNA, 1991
tions were unusually difficult and incom plete (due to high doses of morphine in
double-contrast
phase; then two overhead
radiographs (one with the patient prone and one with the patient in a prone-an gled position) were obtained. The per-oral small bowel examination was performed with use of 600-800 mL of 70% wt/vol barium (Barosperse; Lafayette
Pharmacal). Multiple spot radiographs
were obtained immediately after adminis tration of the barium and at 10-minute in tervals for the first half hour. Thereafter,
Abbreviation:
CI = gastrointestinal.
659
serial overhead radiographs and spot ra diographs were obtained at 30-minute in
tervals for 2 hours and then hourly if needed. Spot radiographs of the entire small bowel sion.
were
obtained
with
In all patients, the total examination, flu oroscopy, and intubation times were re corded. Total examination time was deter mined as the time the radiologist entered
the fluoroscopy room until the approval of all spot and overhead radiographs by the radiologist. For each group, a mean value and standard deviation was deter
compres
For the small bowel series with an up per CI examination, a biphasic examina tion of the upper CI tract was initially performed with use of high-density 250% wt/vol barium (E-Z-HD; E-Z-Em, West bury, NY) followed by 70% wt/vol ban um as described
previously
(16). After
spot radiographs and three overhead ra diographs were obtained for the upper CI tract examination, an additional 500 mL of Barosperse (Lafayette Pharmacal) was administered and multiple spot and serial overhead radiographs were obtained in a manner similar to that for the dedicated small bowel series.
Prior to the studies, five lithium fluo ride thermoluminescent
dosimeters
(Ra
diation Detection Company, Sunnyvale, Calif) were wrapped in small clear plastic envelopes
and taped
to the patients'
backs
with transparent tape. The location of the five dosimeters is shown in Figure 1. At the end of the study, the dosimeters were removed and read by the supplier. The calibration of the dosimeter readings was based on exposure of controls to cesium 137, and the reported
exposure
2•
was cor
rected for dosimeter response to photons of 30—40keV effective energy (half-value layer
= 3 mm aluminum).
The precision
of these dosimeter readings was ±10%. Exposures were converted to dose values by using
a roentgen-to-rad
conversion
factor of 0.9. The five dose measurements were then averaged, and this average val ue was used for statistical comparisons between
study
4
groups.
For each study, the number of conven tional
spot and overhead
radiographs
was
counted (posteroanterior views of entire abdomen for enteroclysis and small bow el series; posteroanterior views of entire abdomen and right anterior oblique and right lateral view of stomach for small bowel series with upper CI examination).
a.
b.
Figure 1. (a) Plain radiograph of the abdomen with five metal markers (arrows) shows the locations of the five dosimeters that were taped to the back of the patient during all three small bowel studies. (b) Schematic drawing of dosimeter locations.
mean sIan entry dose (rdo)
70
U enteroclysis
60
30
a small bowel serieswithUGI
50
. enteroclysas
U dedicated small bowel series
D smallbowelseneswithUGI 25
0 ctentcated smallbowelsenes
%
40 30
20
20 10 0 0-4 k@cataonof dosameters
2.
4.1 -8
8.1 -12
12.1 -16
16.1 -20
20.1 -24
24.1 -28
28.1 -32
>32.1
rad
3.
Figures2, 3. (2) Meanskin entry doses (in rads)for the five dosimeterlocationsareshown for the three small bowel examinations.(3) Skin entry dose values for all dosimeter locations for the three examinations. simeter readings for that study. UGI upper CI examination.
660 •¿ Radiology
Skin entry dose values are expressed
as the percentage
of total do
March 1991
mined for skin entry radiation dose and fluoroscopy, intubation, and total exami nation completion times. Intubation time
was defined as the time from start of tube placement (including time for patient preparation, such as numbing of back of throat and nasal mucosa) to start of ban urn administration. Differences between study groups were tested for significance by using a two-tailed Student t test.
The use of five dosimetems for each patient allowed us to determine an
average skin entry dose in the area where the x-ray beam entered the pa tient. Because the x-ray beam is panned and the patient moved in nearly all fluomoscopic procedures, no one dosimeter (and, thus, no one skin location) was within the prima ry beam for the entire exposure time.
Our study showed that the average
± 10 and
44 minutes
± 14, respective
ly) and to the fact that the radiation doses were calculated instead of mea sured. While minimizing exposure to ion
izing radiation
is important
in any
radiographic examination, particular ly in examinations of patients of childbearing age, other factors also
need to be considered
(eg, overall ex
clysis consistently produced higher skin entry dose levels in all dosime tem locations, while dedicated small
amination and radiologist's time, pa tient's condition, and accuracy of tests). For enteroclysis, fluoroscopy time and the time the radiologist spent with the patient was the long est, but the total examination com pletion time of this procedure was the shortest of all three tests (Table). The longer examination completion times of dedicated small bowel series and small bowel series with upper CI
patients who underwent dedicated small bowel series. An average of 18 spot and six overhead madiographs
bowel series consistently produced the lowest dose levels. Figure 3
examination has serious implications for logistics in a busy radiology de
shows
were obtained
duced more dosimeter
pamtment. We conducted survey with radiologists
RESULTS Among the intubations in the 25 patients who underwent enterocly sis, four were considered difficult, 14 easy, and seven very easy. An aver
age of 14 spot and two overhead
ma
diographs were obtained for each pa tient who underwent enteroclysis. An average of 12 spot and four over
head radiographs
derwent
were obtained
for
for patients who un
small bowel
series with up
skin entry radiation dose for entemo clysis was 1‘¿/2 times greater than that for per-oral small bowel series with upper CI examination and almost
three times greater than that for the dedicated
per-oral
small bowel
series
(Table). Figure 2 shows that entemo
that enteroclysis
the higher
also pro
readings in
manges than per-oral
small
per GI examination (seven spot and three overhead radiographs for the
bowel series did. Radiation doses for
upper GI series). The respective mean values for skin entry radiation dose, fluomoscopy time, and total examina tion time are listed in the Table. The
were mostly due to radiation deliv emed during intubation. The dosime
mean intubation
time was 8.4 mm
utes ±7.4. Figure 2 is a histogram of the mean skin entry dose values of
each of the five dosimeter locations for each of the three procedures. Fig ure 3 is a histogram of individual do simetem readings for each of the pro cedures. Dose ranges are expressed as
a percentage
of all dosimeter
read
ings for that study method. Each step represents a 4-mad (40-mGy) range.
The skin entry dose values and fluo roscopy and total examination times for entemoclysis were significantly different from those for either dedi
cated small bowel series or small bowel series with upper GI examina tion at the 95% confidence limit. DISCUSSION In our series, all three small bowel examinations were meticulously per formed, and many spot madiographs were obtained ing the entire
documented number
with compression dur examination. This is
by the similar mean
of total madiogmaphs
obtained
for the three small bowel examina tions. We found that the 25 patients who underwent
enteroclysis
were
representative of an average group; most intubations were easy, but some were time-consuming and difficult. The intubation time was a major con tributor to overall fluomoscopy time.
Volume 178 •¿ Number 3
enteroclysis
in locations
1 through
3
tem in location 3 received radiation during manipulation of the tube through the stomach, during place ment of the tube beyond the Tmeitz ligament, and during fluomoscopy and spot view evaluation of the jeju num in the single- and double-con trast phase. These factors lead to the high mean radiation dose at that po sition. The overall high mean madia tion dose of enteroclysis was caused by the fact that intubation and evalu ation of small bowel loops was per formed only with fluoroscopic guid ance. In the per-oral small bowel Se ries, only intermittent fluoroscopy was performed, and the higher madia tion dose of the small bowel series with upper GI examination was due
to the upper CI series as shown by the increased fluomoscopy time and total number of spot and overhead radiogmaphs. To our knowledge, no comparative study in the literature has directly measured radiation dose during small bowel series. Our doses were much lower for entemoclysis and ded
icated per-oral small bowel series than those reported by Ott et al (12) (50 R ±25 [12.9 mC/kg ±6.45] for enteroclysis and 9 R ±5 [2.3 mC/kg ±1.3] for dedicated per-oral small bowel series). The high doses for re
a telephone from several
major institutions known for their expertise in gastrointestinal radiogra phy. This survey showed that our fluoroscopy times fall within the av
erage mange for conventional small bowel studies. For most enteroclysis procedures, the patient may leave the radiology department after 30 mm utes; for per-oral small bowel series, the patient must stay in the fluoros copy suite over an extended period of time and may be brought back to the fluoroscopy room several times.
Perfect timing of performing
fol
low-up overhead radiography and obtaining repeat spot views can be a problem for per-oral small bowel studies. This is not a problem with enteroclysis because the radiologist is present until the study is completed. While the actual time the radiologist spends with the patient is increased for enteroclysis, the diagnostic bene fit of distending all small bowel loops, observing progression of the barium and methylcellulose, and, thus, highlighting any abnormality far outweigh this disadvantage. Fur themmome, the short examination completion time is particularly bene ficial to the disabled or seriously ill patient whose condition does not permit a prolonged stay in the radiol ogy department.
The higher radiation slight
discomfort
placement
dose and the
related
to tube
(12) can be justified in
most instances
by the reported
emaccuracy of enteroclysis
high
for many
ported entemoclysis in the study by Ott et al may be due in part to the much longer intubation and exami
small bowel abnormalities (1,2,7,9— 11). For practical purposes, enterocly sis is definitely not indicated in a
nation
young patient with a low suspicion
completion
times (21 minutes
Radiology •¿ 661
for abnormality, especially in view of the relatively high radiation dose de livemed to a patient of childbearing age. However, the short examination time of entemoclysis should be a seri ous consideration
when
deciding
for
References 1.
2.
3.
4.
per
oral small bowel study. The results of our study clearly make an impact on the selection of a small bowel exami nation in the clinical setting. In se lecting the appropriate examination for any patient with a suspected small bowel abnormality, it is impor tant to carefully consider the indica tion for study (6,17), the age and con dition of the patient, the degree of suspicion of disease, and the mele
662 •¿ Radiology
findings
possible treatment, together with the high radiation dose, short examina tion time, and reported higher accu racy of enteroclysis. •¿
on
the appropriate examination for any patient who is seriously ill, and for whom a long stay in the radiology department would be stressful and difficult. In summary, our study shows that skin entry dose and fluomoscopy time arealmostthreetimesgreaterforen teroclysis than for dedicated per-oral smallbowel series. The total exami nation completion time of enterocly sis is half that of the dedicated
vance of radiographic
5.
6.
7.
8.
Ekberg 0. Crohn's disease of the small bowel examined by double-contrast tech nique: a comparison with oral technique. Castrointest Radio! 1977; 1:355—359. Vallance R. An evaluation of the small bowel enema based on an analysis of 350 consecutive examinations. Clin Radio! 1980; 31:227—232. Nolan DJ, Marks CC. The barium infu sion in small intestinal obstruction. Clin Radio! 1981; 32:651—655. Keddie N, Watson-Baker R, Saran M. The value of the small-bowel enema to the genera! surgeon. BrJ Surg 1982; 69:611612. Taverne PP. van der Jagt EC. Small-bow el radiography: a prospective comparative study of three techniques in 200 patients. Fortschr Rontgenstr 1985; 143:293—297. Maglinte DDT, Lappas JC, Kelvin FM, Rex D, Chernish SM. Small bowel radiogra phy: how, when, and why? Radiology 1987; 163:297-305. Sanders DE, Ho CS. The small bowel en ema: experience with 150 examinations. AJR 1976; 127:743-751. Herlinger H. A modified technique for the double-contrast small bowel enema. Castrointest Radio! 1978; 3:201-207.
9.
Curian L, Jendrezejewski J, Katon R, Si!bao M, Cope R, Melnyk C. Sma!! bowel enema: an underutilized method of small bowel examination. Dig Dis Sci 1982; 237:1101—1108. 10. Khaleghian R. The small bowel enema in the management of small bowel obstruc tion. Australas Radio! 1983; 27:154—159. 11. Herlinger H, Maglinte DDT. Jejunal fold separation in adult celiac disease: rele vance of enteroclysis. Radiology 1986; 158:605—611. 12. Ott DJ, Chen YM, Celfand DW, Van Swearingen F, Munitz HA. Detailed per oral small bowel examination vs. entero clysis. II. Expenditures and radiation ex posure. Radiology 1985; 155:29-34. 13. Miller RE, Selink JL. Enteroclysis: the small bowel enema: how to succeed and how to fail. Gastrointest Radio! 1979; 4:269-283. 14. Maglinte DOT, Lappas JC, Chernish SM, Sellink JL. Intubation routes for entero clysis. Radiology 1986; 158:553—554. 15. Thoeni RF. Enteroclysis: focus on tech nique. Perspect Radio! 1989; 2:71—89. 16. Montagne JP, Moss AA, Margulis AR. Double-blind study of single- and double contrast upper gastrointestinal examina tions using endoscopy as a control. AJR 1978; 130:1041-1045. 17. Thoeni RF. Radiography of the small bowel and enteroclysis: a perspective. In vest Radio! 1987; 22:930—936.
March 1991
Enteroclysis and Small Bowel Series: Comparison of Radiation Dose and Examination Time' Respective radiation doses and total examination and fluoroscopy times were compared for 50 patients; 25 underwent enteroclysis and 25 un derwent small bowel series with (n =
17)
and
without
(n
8) an
exami
nation of the upper gastrointestinal
(CI) tract. For enteroclysis, the mean skin entry radiation dose (12.3 rad [123 mGy]) and mean fluoroscopy
time(18.4 minutes) werealmost1'/@
times greater than those for the small bowel series with examina tion of the upper GI tract (8.4 rad [84 mGy]; 11.4 minutes) and almost three times greater than those for the small bowel series without up per GI examination (4.6 rad [46 mGyJ 6.3 minutes). However, the mean total examination completion time for enteroclysis (31.2 minutes) was almost half that of the small bowel series without upper GI ex amination (57.5 minutes) and almost four times shorter than that of the small bowel series with upper GI examination (114 minutes). The higher radiation dose of enterocly sis should be considered along with the short examination time, the age and clinical condition of the patient, and the reported higher accuracy when deciding on the appropriate radiographic examination of the small bowel. Index terms:
Enteroclysis, 74.1272 •¿ Intes
tines, 74.1271, 74.1272 •¿ Radiations, exposure to patients and personnel •¿ Radiations, measure ment
Radiology 1991; 178:659-662
E NTEROCLYSIShas been used ex tensively in Europe and its use in the United States has markedly in creased
over the past few years (1-6).
While many studies have demon strated the high accuracy of this tech nique (1,2,7—11), advocates of the conventional per-oral small bowel series have cited very high radiation exposure, longer room and radiolo gist time, and higher costs as serious factors against its consideration as the primary or preferred method of investigating small bowel disease (12). In many institutions, the most commonly used radiographic small bowel examination is the per-oral small bowel series. In many in stances, the examination of the small bowel is combined with an evalua tion of the upper gastrointestinal (GI) tract despite the disadvantages of mixing various types of barium and focusing primarily on the esophagus, stomach, and duodenum (rendering the small bowel examination almost an afterthought). We included this combined approach in our series be cause it is used frequently. We con ducted our study to compare respec tive radiation doses and total exami nation
completion
and fluoroscopy
times in patients undergoing
entero
clysis and in those undergoing
small
bowel series with and without (dedi cated small bowel series) an examina tion of the upper CI tract. AND METHODS
The patients in our study were the first 54 referred Twenty-nine
to our department patients
for any of
underwent
clysis and 25 underwent
@
and very poor cooperation
by
the other). The average age of the pa tients who underwent enteroclysis (11 women and 14 men) was 48 years (range, 26-85 years). The average age of the pa tients
who underwent
per-oral
small
bowel series (17 women and eight men)
was 49 years (range, 23-77 years). Indica lions and diagnoses
were similar
in both
groups. Among the 25 patients who un derwent enteroclysis,
six had Crohn dis
ease, three had adhesions, five had small bowel obstruction (two with neoplasm and one each with Kaposi sarcoma, isch emia, and scarring), and 11 had normal findings. Among the 25 patients who un derwent per-oral small bowel examina tion, eight
had Crohn
disease,
four had
adhesions, one each had ischemia, radia tion changes, and diverticula, and 10 had normal findings.
A biphasic enteroclysis technique was used and a Maglinte catheter (Cook, Bloo mington,
md) was placed
through
one of
the nostrils and maneuvered into the jeju num beyond the Treitz ligament (13-15). Before
placement
of the tube, 20 mg of
metoclopramide (Reglan; Quad Pharma ceuticals, Indianapolis)
was orally admin
istered. Oropharyngeal anesthesia was routinely used. The ease of intubation was graded in each case as very easy (no special maneuvers necessary), easy (one special maneuver necessary), difficult (several maneuvers needed), and ex tremely difficult (several maneuvers and reintubation needed). Initially, 400-500 mL of 50% wt/vol barium (Entrobar; La fayette Pharmacal, Lafayette, md) were administered, followed by 1100-1200 mL of methylcellulose (Entrocel; Lafayette Pharmacal). Multiple spot radiographs
were obtained during the single- and MATERIALS
three types of small bowel examinations. ‘¿Fromthe Department of Radiology, the University of California, San Francisco, 505 Parnassus Aye, San Francisco, CA 94143-0628. From the 1989 RSNA scientific assembly. Re ceived July 19, 1990; revision requested Sep tember 6; revision received September 19; ac
one patient
entero
a small bowel se
ries, 17 with and eight without an exami nation of the upper GI tract. Four patients who underwent
enteroclysis
were exclud
ed from our study: two because some of the dosimeters were lost and unavailable
cepted October 15. Address reprint requests to
for reading and two because the examina
R.F.T. RSNA, 1991
tions were unusually difficult and incom plete (due to high doses of morphine in
double-contrast
phase; then two overhead
radiographs (one with the patient prone and one with the patient in a prone-an gled position) were obtained. The per-oral small bowel examination was performed with use of 600-800 mL of 70% wt/vol barium (Barosperse; Lafayette
Pharmacal). Multiple spot radiographs
were obtained immediately after adminis tration of the barium and at 10-minute in tervals for the first half hour. Thereafter,
Abbreviation:
CI = gastrointestinal.
659
serial overhead radiographs and spot ra diographs were obtained at 30-minute in
tervals for 2 hours and then hourly if needed. Spot radiographs of the entire small bowel sion.
were
obtained
with
In all patients, the total examination, flu oroscopy, and intubation times were re corded. Total examination time was deter mined as the time the radiologist entered
the fluoroscopy room until the approval of all spot and overhead radiographs by the radiologist. For each group, a mean value and standard deviation was deter
compres
For the small bowel series with an up per CI examination, a biphasic examina tion of the upper CI tract was initially performed with use of high-density 250% wt/vol barium (E-Z-HD; E-Z-Em, West bury, NY) followed by 70% wt/vol ban um as described
previously
(16). After
spot radiographs and three overhead ra diographs were obtained for the upper CI tract examination, an additional 500 mL of Barosperse (Lafayette Pharmacal) was administered and multiple spot and serial overhead radiographs were obtained in a manner similar to that for the dedicated small bowel series.
Prior to the studies, five lithium fluo ride thermoluminescent
dosimeters
(Ra
diation Detection Company, Sunnyvale, Calif) were wrapped in small clear plastic envelopes
and taped
to the patients'
backs
with transparent tape. The location of the five dosimeters is shown in Figure 1. At the end of the study, the dosimeters were removed and read by the supplier. The calibration of the dosimeter readings was based on exposure of controls to cesium 137, and the reported
exposure
2•
was cor
rected for dosimeter response to photons of 30—40keV effective energy (half-value layer
= 3 mm aluminum).
The precision
of these dosimeter readings was ±10%. Exposures were converted to dose values by using
a roentgen-to-rad
conversion
factor of 0.9. The five dose measurements were then averaged, and this average val ue was used for statistical comparisons between
study
4
groups.
For each study, the number of conven tional
spot and overhead
radiographs
was
counted (posteroanterior views of entire abdomen for enteroclysis and small bow el series; posteroanterior views of entire abdomen and right anterior oblique and right lateral view of stomach for small bowel series with upper CI examination).
a.
b.
Figure 1. (a) Plain radiograph of the abdomen with five metal markers (arrows) shows the locations of the five dosimeters that were taped to the back of the patient during all three small bowel studies. (b) Schematic drawing of dosimeter locations.
mean sIan entry dose (rdo)
70
U enteroclysis
60
30
a small bowel serieswithUGI
50
. enteroclysas
U dedicated small bowel series
D smallbowelseneswithUGI 25
0 ctentcated smallbowelsenes
%
40 30
20
20 10 0 0-4 k@cataonof dosameters
2.
4.1 -8
8.1 -12
12.1 -16
16.1 -20
20.1 -24
24.1 -28
28.1 -32
>32.1
rad
3.
Figures2, 3. (2) Meanskin entry doses (in rads)for the five dosimeterlocationsareshown for the three small bowel examinations.(3) Skin entry dose values for all dosimeter locations for the three examinations. simeter readings for that study. UGI upper CI examination.
660 •¿ Radiology
Skin entry dose values are expressed
as the percentage
of total do
March 1991
mined for skin entry radiation dose and fluoroscopy, intubation, and total exami nation completion times. Intubation time
was defined as the time from start of tube placement (including time for patient preparation, such as numbing of back of throat and nasal mucosa) to start of ban urn administration. Differences between study groups were tested for significance by using a two-tailed Student t test.
The use of five dosimetems for each patient allowed us to determine an
average skin entry dose in the area where the x-ray beam entered the pa tient. Because the x-ray beam is panned and the patient moved in nearly all fluomoscopic procedures, no one dosimeter (and, thus, no one skin location) was within the prima ry beam for the entire exposure time.
Our study showed that the average
± 10 and
44 minutes
± 14, respective
ly) and to the fact that the radiation doses were calculated instead of mea sured. While minimizing exposure to ion
izing radiation
is important
in any
radiographic examination, particular ly in examinations of patients of childbearing age, other factors also
need to be considered
(eg, overall ex
clysis consistently produced higher skin entry dose levels in all dosime tem locations, while dedicated small
amination and radiologist's time, pa tient's condition, and accuracy of tests). For enteroclysis, fluoroscopy time and the time the radiologist spent with the patient was the long est, but the total examination com pletion time of this procedure was the shortest of all three tests (Table). The longer examination completion times of dedicated small bowel series and small bowel series with upper CI
patients who underwent dedicated small bowel series. An average of 18 spot and six overhead madiographs
bowel series consistently produced the lowest dose levels. Figure 3
examination has serious implications for logistics in a busy radiology de
shows
were obtained
duced more dosimeter
pamtment. We conducted survey with radiologists
RESULTS Among the intubations in the 25 patients who underwent enterocly sis, four were considered difficult, 14 easy, and seven very easy. An aver
age of 14 spot and two overhead
ma
diographs were obtained for each pa tient who underwent enteroclysis. An average of 12 spot and four over
head radiographs
derwent
were obtained
for
for patients who un
small bowel
series with up
skin entry radiation dose for entemo clysis was 1‘¿/2 times greater than that for per-oral small bowel series with upper CI examination and almost
three times greater than that for the dedicated
per-oral
small bowel
series
(Table). Figure 2 shows that entemo
that enteroclysis
the higher
also pro
readings in
manges than per-oral
small
per GI examination (seven spot and three overhead radiographs for the
bowel series did. Radiation doses for
upper GI series). The respective mean values for skin entry radiation dose, fluomoscopy time, and total examina tion time are listed in the Table. The
were mostly due to radiation deliv emed during intubation. The dosime
mean intubation
time was 8.4 mm
utes ±7.4. Figure 2 is a histogram of the mean skin entry dose values of
each of the five dosimeter locations for each of the three procedures. Fig ure 3 is a histogram of individual do simetem readings for each of the pro cedures. Dose ranges are expressed as
a percentage
of all dosimeter
read
ings for that study method. Each step represents a 4-mad (40-mGy) range.
The skin entry dose values and fluo roscopy and total examination times for entemoclysis were significantly different from those for either dedi
cated small bowel series or small bowel series with upper GI examina tion at the 95% confidence limit. DISCUSSION In our series, all three small bowel examinations were meticulously per formed, and many spot madiographs were obtained ing the entire
documented number
with compression dur examination. This is
by the similar mean
of total madiogmaphs
obtained
for the three small bowel examina tions. We found that the 25 patients who underwent
enteroclysis
were
representative of an average group; most intubations were easy, but some were time-consuming and difficult. The intubation time was a major con tributor to overall fluomoscopy time.
Volume 178 •¿ Number 3
enteroclysis
in locations
1 through
3
tem in location 3 received radiation during manipulation of the tube through the stomach, during place ment of the tube beyond the Tmeitz ligament, and during fluomoscopy and spot view evaluation of the jeju num in the single- and double-con trast phase. These factors lead to the high mean radiation dose at that po sition. The overall high mean madia tion dose of enteroclysis was caused by the fact that intubation and evalu ation of small bowel loops was per formed only with fluoroscopic guid ance. In the per-oral small bowel Se ries, only intermittent fluoroscopy was performed, and the higher madia tion dose of the small bowel series with upper GI examination was due
to the upper CI series as shown by the increased fluomoscopy time and total number of spot and overhead radiogmaphs. To our knowledge, no comparative study in the literature has directly measured radiation dose during small bowel series. Our doses were much lower for entemoclysis and ded
icated per-oral small bowel series than those reported by Ott et al (12) (50 R ±25 [12.9 mC/kg ±6.45] for enteroclysis and 9 R ±5 [2.3 mC/kg ±1.3] for dedicated per-oral small bowel series). The high doses for re
a telephone from several
major institutions known for their expertise in gastrointestinal radiogra phy. This survey showed that our fluoroscopy times fall within the av
erage mange for conventional small bowel studies. For most enteroclysis procedures, the patient may leave the radiology department after 30 mm utes; for per-oral small bowel series, the patient must stay in the fluoros copy suite over an extended period of time and may be brought back to the fluoroscopy room several times.
Perfect timing of performing
fol
low-up overhead radiography and obtaining repeat spot views can be a problem for per-oral small bowel studies. This is not a problem with enteroclysis because the radiologist is present until the study is completed. While the actual time the radiologist spends with the patient is increased for enteroclysis, the diagnostic bene fit of distending all small bowel loops, observing progression of the barium and methylcellulose, and, thus, highlighting any abnormality far outweigh this disadvantage. Fur themmome, the short examination completion time is particularly bene ficial to the disabled or seriously ill patient whose condition does not permit a prolonged stay in the radiol ogy department.
The higher radiation slight
discomfort
placement
dose and the
related
to tube
(12) can be justified in
most instances
by the reported
emaccuracy of enteroclysis
high
for many
ported entemoclysis in the study by Ott et al may be due in part to the much longer intubation and exami
small bowel abnormalities (1,2,7,9— 11). For practical purposes, enterocly sis is definitely not indicated in a
nation
young patient with a low suspicion
completion
times (21 minutes
Radiology •¿ 661
for abnormality, especially in view of the relatively high radiation dose de livemed to a patient of childbearing age. However, the short examination time of entemoclysis should be a seri ous consideration
when
deciding
for
References 1.
2.
3.
4.
per
oral small bowel study. The results of our study clearly make an impact on the selection of a small bowel exami nation in the clinical setting. In se lecting the appropriate examination for any patient with a suspected small bowel abnormality, it is impor tant to carefully consider the indica tion for study (6,17), the age and con dition of the patient, the degree of suspicion of disease, and the mele
662 •¿ Radiology
findings
possible treatment, together with the high radiation dose, short examina tion time, and reported higher accu racy of enteroclysis. •¿
on
the appropriate examination for any patient who is seriously ill, and for whom a long stay in the radiology department would be stressful and difficult. In summary, our study shows that skin entry dose and fluomoscopy time arealmostthreetimesgreaterforen teroclysis than for dedicated per-oral smallbowel series. The total exami nation completion time of enterocly sis is half that of the dedicated
vance of radiographic
5.
6.
7.
8.
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Curian L, Jendrezejewski J, Katon R, Si!bao M, Cope R, Melnyk C. Sma!! bowel enema: an underutilized method of small bowel examination. Dig Dis Sci 1982; 237:1101—1108. 10. Khaleghian R. The small bowel enema in the management of small bowel obstruc tion. Australas Radio! 1983; 27:154—159. 11. Herlinger H, Maglinte DDT. Jejunal fold separation in adult celiac disease: rele vance of enteroclysis. Radiology 1986; 158:605—611. 12. Ott DJ, Chen YM, Celfand DW, Van Swearingen F, Munitz HA. Detailed per oral small bowel examination vs. entero clysis. II. Expenditures and radiation ex posure. Radiology 1985; 155:29-34. 13. Miller RE, Selink JL. Enteroclysis: the small bowel enema: how to succeed and how to fail. Gastrointest Radio! 1979; 4:269-283. 14. Maglinte DOT, Lappas JC, Chernish SM, Sellink JL. Intubation routes for entero clysis. Radiology 1986; 158:553—554. 15. Thoeni RF. Enteroclysis: focus on tech nique. Perspect Radio! 1989; 2:71—89. 16. Montagne JP, Moss AA, Margulis AR. Double-blind study of single- and double contrast upper gastrointestinal examina tions using endoscopy as a control. AJR 1978; 130:1041-1045. 17. Thoeni RF. Radiography of the small bowel and enteroclysis: a perspective. In vest Radio! 1987; 22:930—936.
March 1991
