Donor Medical Record

Student guide · Page 5 of 8

Read the CT

Scrolling slices, switching planes, windowing, and measuring. Labelling is in development, and nothing you draw is saved.

Reading your donor's CTWalkthrough video coming before the first lab session.

Every donor has a full CT, roughly skull to knees, around 1,700 slices at 1 mm. That is a diagnostic-quality study. You are looking at the same images a radiologist would.

Label structures on the CT is the first of the session’s three tasks. This page is how the viewer works, so that when you go looking at the region you are about to open you are not fighting the tool.

Scrolling

Drag, scroll, or swipe through the stack. On the lab iPad, one-finger drag moves through slices.

Switching planes

This is the part that trips people up: you change plane by choosing a different series, not by pressing a button.

Each donor’s study contains three stacks:

  • the original axial series,
  • the coronal reformat, whose series name starts with COR and ends (derived),
  • the sagittal reformat, named the same way with SAG.

Pick the one you want from the study’s series list. The coronal and sagittal stacks were rebuilt from the axial data. That is possible because the original slices are nearly cubic, about 1 mm in every direction.

The series names are wrong. Every stack is labeled something like Lumbar Spine axial_3.0 ST, left over from the CT intake setup. The images cover far more than the lumbar spine.

Windowing

Adjust the window to change what the image shows you. Bone and soft tissue live at very different densities, and a window that makes the skeleton crisp will flatten the viscera into grey mush. If you cannot see something, change the window before you conclude it is not there.

Labeling and measuring (in development)

The viewer has length, angle, ellipse, and text-label tools. The text-label tool is how you tag a structure on the slice where you found it, and the length and ellipse tools are how you size it.

You need a mouse or a trackpad for these. On the lab iPad a one-finger drag scrolls the stack. That is deliberate, so you can scrub slices with a finger, but it means a finger cannot draw. Use a laptop, or an iPad with a mouse attached, when you want to measure something.

Nothing you draw is saved. Anything you draw or type on the image lives in your browser session and disappears when you close the viewer. Labelling that persists to the record is still in development.

Read the number off the screen and type it into the finding, along with the plane and the image number. Mass 4.7 × 3.1 cm, axial image 842 is a durable record.

The same goes for a label. Tagging a structure on the slice is how you show you found it at the table, but it only survives the session if you name the structure, the plane, and the image number in what you file.

Correlate with the dissection

The reason imaging comes before the dissection is that the CT shows you the intact relationship. Once a region is dissected, that relationship is gone. Look at the region you are about to open, not just the region you already opened.