Anais do IHC'2001 - Departamento de Informática e Estatística - UFSC

Anais do IHC’2001 - IV Workshop sobre Fatores Humanos em Sistemas Computacionais 297
Structuring the Space of Interaction Practices in the
Segmentation of Medical Images: a First Discussion
Sílvia D. Olabarriaga and Marcelo S. Pimenta
Instituto de Informática – Universidade Federal do Rio Grande do Sul (UFRGS)
Caixa Postal 15.064 – 91.501-970 – Porto Alegre – RS – Brazil
{silvia,mpimenta}@inf.ufrgs.Br
Abstract. This paper presents a first discussion on how to structure the space of
interaction practices in the segmentation of medical images. We first present an
example of application to set a scenario for discussion. Next we summarize some
of the interactive aspects related to image segmentation methods. Finally we
present some initial ideas about how to improve the design of ISMs with HCI
methodology.
1. Introduction
Segmentation is a step in the analysis of digital images where the object of interest is
isolated from the background [Gonzalez and Woods (1993)]. Segmentation supports
several analysis tasks such as quantification, inspection and retrieval; in all cases,
automatic processing is desirable, but sometimes unattainable due to limitations imposed
by image acquisition, abnormalities in the scene, or both. Interactive segmentation methods
(ISMs) are adopted in applications with a high demand for accurate results, when the
volume of images is reasonable, and when the image dimensionality admits human
manipulation.
As a general rule, the goal of ISMs is to combine a human operator and a computer
(also named computational part) to obtain an accurate delineation of the object of interest
in an efficient manner. The underlying assumption is that the user knows the correct
delineation and, as such, he/she could guide the computational part to determine it
efficiently. This is the case of many applications, in particular in the medical field, where
clinical practice and research impose several demands on reliability of results obtained with
or by computational tools.
In this short paper we start a discussion on how to structure the space of interaction
practices in the segmentation of medical images. We first present an example of application
to set a scenario for discussion. Next we present a review of aspects related to interactive
segmentation methods. Finally we present some initial ideas about how to improve the
design of ISMs with HCI methodology.
2. A simple example of interactive segmentation in medical imaging
As an example of interactive segmentation procedures, consider the following scenario: a
pregnant woman is submitted to ultrasound (US) to check the baby's development, which is
roughly assessed by the diameter of the baby's head. The doctor manipulates the US probe
on the belly, trying to get the best view of the head on the screen, such that its diameter can
be most reliably estimated. The image is “frozen” when the doctor is satisfied and then