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Fiducial markers implanted during prostate brachytherapy for guiding conformal external beam radiation therapy
- Source :
- Technology in cancer researchtreatment. 3(4)
- Publication Year :
- 2004
-
Abstract
- Prostate movement imposes limits on safe dose-escalation with external beam radiation therapy. If the precise daily location of the prostate is known, dose escalation becomes more feasible. We have developed an approach to dose escalation using a combination of prostate brachytherapy followed by external beam radiation therapy in which fiducial markers are placed along with125 I seeds during transperineal interstitial permanent prostate brachytherapy. These markers serve to verify daily prostate location during the subsequent external beam radiotherapy. Prior to implementing this approach, preliminary studies were performed to test visibility of the markers. Three different125 I seed models, as well as gold and silver marker seeds were placed within tissue-equivalent phantoms. Images were obtained with conventional x-rays (75–85 kV) and 6 MV photons from a linear accelerator. All125 I seed models were clearly visible on conventional x-rays but none were seen with 6 MV photons. The gold markers were visible with both energies. The silver markers were visible with conventional x-rays and 6 MV x-rays, but not as clearly as the gold seeds at 6 MV. Subsequently, conventional x-rays, CT scans, and 6 MV port films were obtained in 29 patients in whom fiducial gold marker seeds were implanted into the prostate during125 I prostate brachytherapy. To address the possibility of “seed migration” within the prostate, CT scans were repeated 5 weeks apart in 14 patients and relative positions of the gold seeds were evaluated. The repeated CT scans showed no change in intraprostatic gold marker location, suggesting minimal migration. The gold seeds were visible with conventional x-rays, CT, and 6 MV port films in all patients. During the course of external beam radiation therapy, the gold markers were visible on routine 6 MV port films and were seen in different locations from film to film suggesting prostate motion. Mean daily displacement was 4–5 mm in the anterior-posterior, and 4–5 mm in superior-inferior dimensions. Left-right displacement appeared less, averaging 2–3 mm. We conclude that implantation of gold marker seeds during prostate brachytherapy represents an easily implemented and practical means of prostate localization during subsequent image-guided external beam radiotherapy. With such markers, conformality of the external beam component can be confidently improved without expensive new equipment.
- Subjects :
- Male
Cancer Research
medicine.medical_specialty
Silver
medicine.medical_treatment
External beam radiation
Brachytherapy
Linear particle accelerator
03 medical and health sciences
Prostate cancer
0302 clinical medicine
Prostate
medicine
Image Processing, Computer-Assisted
Humans
External beam radiotherapy
Photons
Gold Radioisotopes
business.industry
Radiotherapy Planning, Computer-Assisted
X-Rays
Prostatic Neoplasms
Radiotherapy Dosage
Prostheses and Implants
medicine.disease
Radiographic Image Enhancement
medicine.anatomical_structure
Oncology
030220 oncology & carcinogenesis
Radiology
Radiotherapy, Conformal
business
Nuclear medicine
Fiducial marker
Prostate brachytherapy
Subjects
Details
- ISSN :
- 15330346
- Volume :
- 3
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Technology in cancer researchtreatment
- Accession number :
- edsair.doi.dedup.....fa65309f8a146f29ed2e1d19f680e947