Radiat Oncol J.  2019 Mar;37(1):43-50. 10.3857/roj.2018.00556.

The use of tissue fiducial markers in improving the accuracy of post-prostatectomy radiotherapy

• Chao M
• Ho H
• Joon DL
• Chan Y
• Spencer S
• Ng M
• Wasiak J
• Lawrentschuk N
• McMillan K
• Sengupta S
• Tan A
• Koufogiannis G
• Cokelek M
• Foroudi F
• Khong TS
• Bolton D

• KMID: 2447551
• DOI: http://doi.org/10.3857/roj.2018.00556

Abstract

PURPOSE
The aim of this retrospective study was to investigate the use of a radiopaque tissue fiducial marker (TFM) in the treatment of prostate cancer patients who undergo post-prostatectomy radiotherapy (PPRT). TFM safety, its role and benefit in quantifying the set-up uncertainties in patients undergoing PPRT image-guided radiotherapy were assessed.
MATERIALS AND METHODS
A total of 45 consecutive PPRT patients underwent transperineal implantation of TFM at the level of vesicourethral anastomosis in the retrovesical tissue prior to intensity-modulated radiotherapy. Prostate bed motion was calculated by measuring the position of the TFM relative to the pelvic bony anatomy on daily cone-beam computed tomography. The stability and visibility of the TFM were assessed in the initial 10 patients.
RESULTS
No postoperative complications were recorded. A total of 3,500 images were analysed. The calculated prostate bed motion for bony landmark matching relative to TFM were 2.25 mm in the left-right, 5.89 mm in the superior-inferior, and 6.59 mm in the anterior-posterior directions. A significant 36% reduction in the mean volume of rectum receiving 70 Gy (rV₇₀) was achieved for a uniform planning target volume (PTV) margin of 7 mm compared with the Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recommended PTV margin of 10 mm.
CONCLUSION
The use of TFM was safe and can potentially eliminate set-up errors associated with bony landmark matching, thereby allowing for tighter PTV margins and a consequent favourable reduction in dose delivered to the bladder and rectum, with potential improvements in toxicities.

Keyword

Fiducial marker; Image-guided radiotherapy; Intensity-modulated radiotherapy; Prostatectomy; Prostate cancer

MeSH Terms

Clothing
Cone-Beam Computed Tomography
Fiducial Markers*
Humans
New Zealand
Postoperative Complications
Prostate
Prostatectomy
Prostatic Neoplasms
Radiation Oncology
Radiotherapy*
Radiotherapy, Image-Guided
Radiotherapy, Intensity-Modulated
Rectum
Retrospective Studies
Urinary Bladder