Microscopic gold particle-based fiducial markers for proton therapy of prostate cancer.
OBJECTIVE
We examined the feasibility of using fiducial markers composed of microscopic gold particles and human-compatible polymers as a means to overcome current problems with conventional macroscopic gold fiducial markers, such as dose reduction and artifact generation, in proton therapy for prostate cancer.


METHODS
We examined two types of gold particle fiducial marker interactions: that with diagnostic X-rays and with a therapeutic proton beam. That is, we qualitatively and quantitatively compared the radiographic visibility of conventional gold and gold particle fiducial markers and the CT artifacts and dose reduction associated with their use.


RESULTS
The gold particle fiducials could be easily distinguished from high-density structures, such as the pelvic bone, in diagnostic X-rays but were nearly transparent to a proton beam. The proton dose distribution was distorted <5% by the gold particle fiducials with a 4.9% normalized gold density; this was the case even in the worst configuration (i.e., parallel alignment with a single-direction proton beam). In addition, CT artifacts were dramatically reduced for the gold particle mixture.


CONCLUSIONS
Mixtures of microscopic gold particles and human-compatible polymers have excellent potential as fiducial markers for proton therapy for prostate cancer. These include good radiographic visibility, low distortion of the depth-dose distribution, and few CT artifacts.
Lim
Young Kyung
YK
Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi, Korea.
Kwak
Jungwon
J
Kim
Dong Wook
DW
Shin
Dongho
D
Yoon
Myonggeun
M
Park
Soah
S
Kim
Jin Sung
JS
Ahn
Sung Hwan
SH
Shin
Jungwook
J
Lee
Se Byeong
SB
Park
Sung Yong
SY
Pyo
Hong Ryeol
HR
Kim
Dae Yong
DY
Cho
Kwan Ho
KH
D016477:Artifacts; D005240:Feasibility Studies; D006046:Gold / Q000737:chemistry*; D006801:Humans; D008297:Male; D010316:Particle Size; D019047:Phantoms, Imaging; D011108:Polymers; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D019736:Prostheses and Implants; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D012542:Scattering, Radiation; D014057:Tomography, X-Ray Computed
D011108:Polymers; D006046:Gold