Improving positioning in high-dose radiotherapy for prostate cancer: safety and visibility of frequently used gold fiducial markers.
OBJECTIVE
The use of gold fiducial markers (GFMs) for prostate positioning in high-dose radiotherapy is gaining interest. The purpose of this study was to compare five GFMs regarding feasibility of ultrasound-based implantation in the prostate and intraprostatic lesion (IPL); toxicity; visibility on transabdominal ultrasound (TU) and cone-beam CT (CBCT); reliability of automatic, soft tissue, and GFM-based CBCT patient positioning by comparing manual and automatic fusion CBCT.


METHODS
Twenty-five patients were included. Pain and toxicity were scored after implantation and high-dose radiotherapy. Fisher exact test was used to evaluate the correlation of patients' characteristics and prostatitis. Positioning was evaluated on TU and kilovoltage CBCT images. CBCT fusion was performed automatically (Elekta XVI technology, release 3.5.1 b27, based on grey values) and manually on soft tissue and GFMs. Pearson correlation statistics and Bland-Altman evaluation were used. Five GFMs were compared.


RESULTS
Twenty percent of the patients developed prostatitis despite antibiotic prophylaxis. Cigarette smoking was significantly correlated with prostatitis. The visualization of all GFMs on TU was disappointing. Consequently we cannot recommend the use of these GFMs for TU-based prostate positioning. For all GFMs, there was only fair to poor linear correlation between automatic and manual CBCT images, indicating that even when GFMs are used, an operator evaluation is imperative. However, when GFMs were analyzed individually, a moderate to very strong correlation between automatic and manual positioning was found for larger GFMs in all directions.


CONCLUSIONS
The incidence of prostatitis in our series was high. Further research is imperative to define the ideal preparation protocol preimplantation and to select patients. Automatic fusion is more reliable with larger GFMs at the cost of more scatter. The stability of all GFMs was proven.
Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium. valerie.fonteyne@uzgent.be
Valérie
V
Fonteyne
Piet
P
Ost
Geert
G
Villeirs
Willem
W
Oosterlinck
Aline
A
Impens
Werner
W
De Gersem
Carlos
C
De Wagter
Gert
G
De Meerleer
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis / Q000379:methods; D002939:Ciprofloxacin / Q000627:therapeutic use; D054893:Cone-Beam Computed Tomography; D005240:Feasibility Studies; D057918:Fiducial Markers / Q000009:adverse effects; D006046:Gold; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000000981:diagnostic imaging; D010147:Pain Measurement / Q000379:methods; D056888:Patient Positioning / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011472:Prostatitis / Q000209:etiology / Q000517:prevention & control; D019919:Prosthesis Implantation / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012907:Smoking / Q000009:adverse effects; D018084:Ultrasonography, Interventional / Q000379:methods
D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D006046:Gold