[Intl_DxMedPhys] Dynamic CT Myelogram Protocol - What's a reasonable DLP?

[Eric Gingold]

Hi Tyler,

At my institution, they do CT myelograms as part of an interventional procedure called epidural blood patch, which is used to repair CSF leaks in the spinal cord.  Apparently it's remarkably effective at eliminating severe headaches caused by these CSF leaks.  These are the highest DLP procedures we have, commonly over 5000 mGycm, sometimes hitting 7000-8000 because of repeated long helical scans interspersed with lower dose CT fluoro axial scans.  It's likely that you are looking at the same thing.  I've observed some of these and spoke to the neuroradiologist who does them.  He understands that the DLP is high but assured me that the benefit to the patient is extremely high.

Eric
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From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu> on behalf of Tyler Fisher via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Sent: Friday, February 13, 2026 4:43:13 PM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: [Intl_DxMedPhys] Dynamic CT Myelogram Protocol - What's a reasonable DLP?


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Hi Everyone, A site that I recently began consulting for has a new physician who wants to perform Dynamic CT Myelograms.   The goal of the procedure is to look for CSF leaks in the spine.   The protocol that the physician provided and put on the
Hi Everyone,
A site that I recently began consulting for has a new physician who wants to perform Dynamic CT Myelograms.  The goal of the procedure is to look for CSF leaks in the spine.  The protocol that the physician provided and put on the scanner, simplified, is below:

  1.  Patient in Right lateral decubitus position.
  2.  Prep the skin and advance a 22 gauge spinal needle under serial CT guidance.
  3.  Inject 10 mL of Omnipaque-300.
  4.  Perform 3 continuous passes from sacrum to skull base, then skull base to sacrum, and then sacrum to skull base.
  5.  Rotate the patient to left lateral decubitus and do another single pass from sacrum to skull base.

The acquisition parameters for the 4 passes is 140 kVp, 250 mA, 0.625 mm slices.  They're using a GE Revolution scanner.

This protocol was loaded and they did a patient.  The total exam DLP was 7,871.89 mGy-cm.  The techs promptly freaked out and have since refused to perform the procedure.

So, for the group, what is a reasonable DLP limit for a case like this?  Are any of your sites doing this procedure and what doses are you seeing?  140 kVp seems like the wrong kVp for optimizing iodine contrast - what kVp are you using for the passes?

Thanks in advance for the wisdom I'm sure someone has out there.

Tyler Fisher



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