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Re: Xray exposure
Kenneth Travis asked:
>Can anyone advise me where I could obtain x-ray exposure information at the
>table top (or at the cassette) that will produce good x-ray results? What I
>am looking for is a table of reference exposures for x-rays of the spine.
>Information should include kVp, beam filtration, patient thickness, and
>exposure at some identifiable distance between the target and the cassette.
A typical set of typical radiographic techniques and calculated entrance
skin exposures (ESE) for a modern radiographic system is shown below. Note
that entrance skin dose = ESE X Backscatter factor (~1.30 for this range of
photon energies).
This information is generally understood to be required by the JCAHO of all
hospitals. Contact your nearest hospital-based certified medical physicist
to confirm this information.
PATIENT RADIOGRAPHIC ENTRANCE SKIN EXPOSURES
Institution: St. Anywhere Medical Center
Room: Room 2
Tube: Siemens Overhead
Date: sometimes
----------------------------------------------------------------------------
MEASURED RADIATION OUTPUT: (@ estimated tube filtration= 2.46 mm Al)
Focal Spot kVp Rad. Output (mR/mAs) Distance (in) HVL(mm Al)
Large 60 2.8 40.0
Large 81 5.4 40.0 2.80
Large 99 8.2 40.0
Small 60 2.8 40.0
Small 81 5.3 40.0
Small 99 8.0 40.0
----------------------------------------------------------------------------
PATIENT
# PROCEDURE ID Spot kVp mAs SID(in) THICK(cm) ESE(mR)
1 Skull, 'Caldwell', Water L 70 32 40 16 178.2
2 Towne's Skull L 70 36 40 18 210.2
3 Lateral Skull L 66 25 40 14 116.8
4 Obl. Mandible L 60 8.0 40 14 30.1
5 Zygomas L 57 8.0 40 14 27.0
6 Submento vertex L 70 40 40 16 222.8
7 Lateral nose L 55 4.0 40 16 13.1
8 Lateral cervical spine S 70 25 72 8 33.1
9 AP cervical spine S 66 16 40 8 65.1
10 Odontoid S 70 20 40 8 92.3
11 Lat soft tissue neck S 66 16 72 8 18.7
12 AP thoracic spine L 70 32 40 18 186.8
13 Lat thoracic spine L 77 80 40 32 827.1
14 Swimmer`s thor. spine S 81 80 40 38 1082.0
15 PA sternum S 60 71 36 24 451.2
16 Lateral sternum S 66 25 40 32 184.0
17 AP Lumbar spine L 70 50 40 20 306.4
18 Lateral Lumbar L 85 56 40 28 637.7
19 Spine: L5-S1 Spot L 96 125 40 32 2050.0
20 Obl. Lumbar Spine L 81 80 40 24 740.5
21 AP Pelvis L 70 50 40 20 306.4
22 AP Hip L 70 40 40 18 233.6
23 Lateral Hip L 70 63 40 19 376.8
24 Lateral Shoot Through L 81 50 45 16 288.4
25 AP Sacrum L 70 50 40 20 306.4
26 AP Coccyx L 70 50 40 20 306.4
27 Lateral Sacrum L 85 100 40 32 1273.5
28 Lateral Coccyx L 70 125 40 32 1053.0
29 KUB L 70 40 40 20 245.1
30 Small Bowel L 109 13 40 20 187.3
31 Gall Bladder prelim L 70 40 40 18 233.6
32 Decubitus Abdomen L 66 32 40 20 172.3
33 Fingers S 52 3.2 40 1 6.7
34 AP Hand S 52 5.0 40 4 11.1
35 Lateral Hand S 52 6.3 40 7 14.9
36 AP Wrist S 52 4.5 40 4 10.0
37 Lateral Wrist S 52 6.3 40 6 14.6
38 AP Elbow S 52 3.6 40 7 8.5
39 AP Forearm S 52 2.5 40 6 5.8
40 AP Shoulder S 66 16 40 12 71.1
Douglas J. Simpkin, Ph.D., DABR
St. Luke's Medical Center
2900 West Oklahoma Avenue
Milwaukee, WI 53215
phone: (414)649-6457
fax: (414)649-5061
email: dsimpkin@execpc.com
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