Magnetic Resonance Imaging-Defined Treatment Margins in Iodine-125 Prostate Brachytherapy

Journal Article · Thu Jul 15 04:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.06.040· OSTI ID:21436075

Crook, Juanita ^[1]; Patil, Nikhilesh ^[1]; Ma, Clement ^[2]; McLean, Michael ^[1]; Borg, Jette ^[3]

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1. Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON (Canada)
2. Department of Biostatistics, Princess Margaret Hospital, Toronto, ON (Canada)
3. Department of Radiation Physics, Princess Margaret Hospital, Toronto, ON (Canada)

Purpose: Low-dose-rate prostate brachytherapy achieves a very high and effective intraprostatic dose. Implant quality parameters concentrate on the dose received by the prostate (D90, V100) but not that received by the periprostatic tissue. We calculated implant quality parameters, D90 and V100, for the magnetic resonance imaging (MRI)-defined prostate plus 2, 3, and 5 mm. Methods and Materials: A total of 131 men with early-stage prostate cancer treated with iodine-125 brachytherapy represent all those treated with brachytherapy monotherapy in our institution in 2005. Postplan assessment was performed at 1 month using magnetic resonance (MR)-computed tomography (CT) fusion. The prostate V100 and D90 were calculated with 2-, 3-, and 5-mm margins. Results were compared with those in 8 patients with biopsy-proven local failure occurring in an experience of more than 1,100 implants. Results: Mean prostate V100 (SD) and D90 (SD) were 95.6% (4.1) and 117.2% (12.7). For prostate plus a 2-mm margin the D90 was 107.9% (14.3) and for a 3-mm margin 96.0 % (14.0). For prostate plus a 5-mm margin, the D90 was only 78.4% (11.0). The 8 patients experiencing local failure, despite adequate implants, had a lower mean V100 of 91.2% (SD, 2.8; p = 0.0008) and D90 of 103.7% (SD, 8.3; p = 0.002) and significantly inferior margin coverage. Conclusions: Satisfactory coverage of a 2-mm and 3-mm periprostatic margin is obtained with the described planning approach. Coverage falls off significantly by 5 mm. The 8 patients who experienced local failure had significantly lower doses than the margin cohort. Although the V100 and D90 would be considered acceptable, the fall-off in margin coverage was observed by 3 mm.

• OSTI ID: 21436075
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 77; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BODY
BRACHYTHERAPY
COMPUTERIZED TOMOGRAPHY
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
IMPLANTS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 125
IODINE ISOTOPES
ISOTOPES
MALE GENITALS
MEDICINE
NEOPLASMS
NMR IMAGING
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANS
PROSTATE
RADIOISOTOPES
RADIOLOGY
RADIOTHERAPY
THERAPY
TOMOGRAPHY