Radiotherapy treatment planning: Benefits of CT-MR image registration and fusion in tumor volume delineation

Abstract

This study shows that registration and image fusion allows precise target localization in terms of GTV and CTV and local disease control.

Proton range shift analysis on brain pseudo-CT generated from T1 and T2 MR

“…For CT scans a LightSpeed QX/i scanner (GE Healthcare, Chicago, IL, USA) was used, with the patient positioned for radiotherapy planning. Voxel size ranged from 0.49 Â 0.49 Â 2.5 mm 3 to 0.67 Â 0.67 Â 2.5 mm 3 . CT and MR sequences were acquired on different days, with an interval between 10 and 20 days.…”

“…To utilize the MR information for target definition, the MR is registered to the planning CT, but the registration process itself introduces systematic errors [2]. Hybrid MR/CT tomography scanners could minimize registration uncertainties [3], but the equipment is expensive and not widely available.…”

What are the current and future requirements for magnetic resonance imaging interpretation skills in radiotherapy? A critical review

“…The prevalence of these sites is explained by the superior soft-tissue visualisation offered by CT–MR fusion. This significantly enhances localisation of intracranial, 4 , 9 HN 2 and prostate tumours 10 …”

“…The need for precise determination of target volumes in RT planning arises from the consequences of a geographical miss of a tumour. Intracranial lesions are particularly well delineated on MRI 4 due to the increased contrast between white and grey matter 2 . However, data obtained by CT is still currently required for treatment planning as it provides the electron density for dose calculation 14 .…”

“…It is unsurprising, therefore, that an increasing number of studies report attempts to integrate both imaging modalities and, in many cases, substitute CT with MRI. 3,4 Emerging research in RT suggests a valuable role of MRI in image-guided radiotherapy (IGRT). IGRT optimises the precision and accuracy of dose delivery by decreasing positioning uncertainty, shrinking margins and thus reducing radiation dose to normal tissue.…”