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Author Al-Qaisieh, Bashar ♦ Mason, Josh ♦ Bownes, Peter ♦ Henry, Ann ♦ Dickinson, Louise ♦ Ahmed, Hashim U. ♦ Emberton, Mark ♦ Langley, Stephen
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIOLOGY AND NUCLEAR MEDICINE ♦ BIOPSY ♦ BRACHYTHERAPY ♦ COMPUTERIZED SIMULATION ♦ DOSE RATES ♦ DOSIMETRY ♦ HAZARDS ♦ LIMITING VALUES ♦ MONTE CARLO METHOD ♦ NMR IMAGING ♦ PATIENTS ♦ PLANNING ♦ POSITIONING ♦ PROSTATE ♦ RADIATION DOSES ♦ RADIATION SOURCE IMPLANTS ♦ RECTUM ♦ SIDE EFFECTS ♦ URINARY TRACT
Abstract Purpose: Focal brachytherapy targeted to an individual lesion(s) within the prostate may reduce side effects experienced with whole-gland brachytherapy. The outcomes of a consensus meeting on focal prostate brachytherapy were used to investigate optimal dosimetry of focal low-dose-rate (LDR) prostate brachytherapy targeted using multiparametric magnetic resonance imaging (mp-MRI) and transperineal template prostate mapping (TPM) biopsy, including the effects of random and systematic seed displacements and interseed attenuation (ISA). Methods and Materials: Nine patients were selected according to clinical characteristics and concordance of TPM and mp-MRI. Retrospectively, 3 treatment plans were analyzed for each case: whole-gland (WG), hemi-gland (hemi), and ultra-focal (UF) plans, with 145-Gy prescription dose and identical dose constraints for each plan. Plan robustness to seed displacement and ISA were assessed using Monte Carlo simulations. Results: WG plans used a mean 28 needles and 81 seeds, hemi plans used 17 needles and 56 seeds, and UF plans used 12 needles and 25 seeds. Mean D90 (minimum dose received by 90% of the target) and V100 (percentage of the target that receives 100% dose) values were 181.3 Gy and 99.8% for the prostate in WG plans, 195.7 Gy and 97.8% for the hemi-prostate in hemi plans, and 218.3 Gy and 99.8% for the focal target in UF plans. Mean urethra D10 was 205.9 Gy, 191.4 Gy, and 92.4 Gy in WG, hemi, and UF plans, respectively. Mean rectum D2 cm{sup 3} was 107.5 Gy, 77.0 Gy, and 42.7 Gy in WG, hemi, and UF plans, respectively. Focal plans were more sensitive to seed displacement errors: random shifts with a standard deviation of 4 mm reduced mean target D90 by 14.0%, 20.5%, and 32.0% for WG, hemi, and UF plans, respectively. ISA has a similar impact on dose-volume histogram parameters for all plan types. Conclusions: Treatment planning for focal LDR brachytherapy is feasible. Dose constraints are easily met with a notable reduction to organs at risk. Treating smaller targets makes seed positioning more critical.
ISSN 03603016
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-07-15
Publisher Place United States
Journal International Journal of Radiation Oncology, Biology and Physics
Volume Number 92
Issue Number 4


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