Multi-atlas and unsupervised learning approach to perirectal space segmentation in CT images

Soumya Ghose, James W. Denham, Martin A. Ebert, Angel Kennedy, Jhimli Mitra, Jason A. Dowling

Research output: Contribution to journalShort Survey/Scientific Reportpeer-review

2 Citations (Scopus)


Perirectal space segmentation in computed tomography images aids in quantifying radiation dose received by healthy tissues and toxicity during the course of radiation therapy treatment of the prostate. Radiation dose normalised by tissue volume facilitates predicting outcomes or possible harmful side effects of radiation therapy treatment. Manual segmentation of the perirectal space is time consuming and challenging in the presence of inter-patient anatomical variability and may suffer from inter- and intra-observer variabilities. However automatic or semi-automatic segmentation of the perirectal space in CT images is a challenging task due to inter patient anatomical variability, contrast variability and imaging artifacts. In the model presented here, a volume of interest is obtained in a multi-atlas based segmentation approach. Un-supervised learning in the volume of interest with a Gaussian-mixture-modeling based clustering approach is adopted to achieve a soft segmentation of the perirectal space. Probabilities from soft clustering are further refined by rigid registration of the multi-atlas mask in a probabilistic domain. A maximum a posteriori approach is adopted to achieve a binary segmentation from the refined probabilities. A mean volume similarity value of 97% and a mean surface difference of 3.06 ± 0.51 mm is achieved in a leave-one-patient-out validation framework with a subset of a clinical trial dataset. Qualitative results show a good approximation of the perirectal space volume compared to the ground truth.

Original languageEnglish
Pages (from-to)933-941
Number of pages9
JournalAustralasian Physical and Engineering Sciences in Medicine
Issue number4
Publication statusPublished - 1 Dec 2016
Externally publishedYes


Dive into the research topics of 'Multi-atlas and unsupervised learning approach to perirectal space segmentation in CT images'. Together they form a unique fingerprint.

Cite this