A new fiducial marker for Image-guided radiotherapy of prostate cancer: Clinical experience

MR‐CT registration using a Ni‐Ti prostate stent in image‐guided radiotherapy of prostate cancer

“…This approach was used in Fei et al 35 using manually defined landmarks on the pelvic bones. This comparison could be problematic if the manual defined landmarks do not include landmarks within the prostate, e.g., using fiducial markers as the prostate stent in Carl et al 4 Others have used a full circle analysis using multiple scans from the same patient, where an accurate and consistent registration would result in identity matrix as a result of the last registration without the need for a gold standard registration.…”

“…A number of studies 2, 3 have compared MR and CT for prostate contouring, where the mean prostate volume was 1.35 and 1.4 times larger in CT compared to MR, respectively. Nevertheless, prostate contouring using CT may still lead to geometrical misses at the cranial border of the prostate 4 . Steenbakkers et al 5 calculated and compared radiation doses delivered to the rectal wall and the penis bulb using planning target volumes generated from MR and CT.…”

“…A newly developed removable thermoexpandable Ni-Ti prostate stent as the fiducial marker is used in the planning of image-guided radiotherapy. 4 The stent has some advantages over the other fiducial markers described in Refs. 4 and 20 including: a noninvasive insertion procedure using locally urethral anesthesia and that it as a contrast to other fiducials is removable which means less artifacts in postradiotherapy MR scanning.…”

“…The prostate stent has previous been used to perform MR-CT registration of the prostate using manually defined landmarks in both MR and CT presented in Ref. 4. Three landmarks were defined on the prostate stent, one at the cranial, middle and caudal end of the stent.…”

“…Another two anatomical landmarks where defined, one anterior and one lateral to the prostate but as close to the prostate surface as possible. 4 In the present study, the physical appearance of the prostate stent is used to enable a local registration as the stent will appear as a common structure in MR and CT.…”