about 70 percent of the patients.

By accurately locating the sentinel lymph nodes, lymphoscintigraphy allows each relevant node field to be sampled with minimal surgery. If the sentinel lymph node is normal, then the node field is normal and no further nodal surgery is required. If the sentinel node is positive for metastases, then a radical node dissection is performed in that node field.

Once the location of the sentinel nodes has been determined, it is necessary to communicate this information to the surgeon and record it for use in research. The application described elsewhere in this article satisfies both of these requirements.

Using Arcview

An application was developed that allows the physician carrying out the lymphoscintigraphy to record the details of the patient and the results of the investigation. The location of the primary lesion is recorded as a map number and x and y coordinates on that map.

The draining node fields are recorded as codes showing the depth and number of sentinel nodes. For example, 1.5la2 indicates that the left axilla field contains two sentinel nodes at a depth of 1.5 cm. The name and sex of the patient as well as the number of draining channels and the maximum separation between the channels are also recorded. There is provision for noting details of surgery performed immediately or as follow up.

The primary storage of the data is currently in a Filemaker Pro V3 database file. This communicates with ArcView via DDE (in Windows) or Appletalk (on the final target system) and passes a DBF file of the data for display in a report. The script processes the data and prints out a report based on it. This report can be sent to the surgeon and is also stored on the patient's file.

Working With Scripts

Several scripts were developed to produce the reports. The fact that these could be developed on a PC and seamlessly ported for use on a Macintosh highlighted the excellent cross-platform capabilities of ArcView. Much of the inspiration for the code came from Amir H. Razavi (ArcView Devoloper's Guide, OnWord Press, 1995), although it must be said that neither his book nor the ArcView online help are particularly well organized and both leave a great deal to be desired in the area of indexing and cross referencing.

The main script for the application is a list containing the data to be displayed. In particular, they contain the map number, x and y coordinates, node field codes, comments and patient details. The map number is used to retrieve the appropriate image from a list and the image added to a view. The site of the primary lesion is then marked.

Next, the node-field codes are parsed into a list and each element passed to the node-field definition script for display. A dictionary containing a count of the number of times each node field is referenced is established for use by the node-field definition script.

The layout production script follows, and finally the layout is printed and the view and layout removed from the project. If the layout cannot be printed, it is renamed (and not removed) to allow subsequent manual printing. The script returns the name of the layout as an indication to the calling program of the process's success.

Node-Field Definition

The node-field definition script highlights the node-field area on the schematic diagram and labels it with the code, indicating the number of nodes and their depth below the surface. Since nodes exist at different depths and each of the depths is treated as a separate call to this script, the dictionary defined in the main script is used to ensure that the highlight shape is only drawn once and that text is not overwritten. The location and dimension