Sequential evaluation of prostate edema after permanent seed prostate brachytherapy using CT-MRI fusion

Journal Article · Fri Jul 15 04:00:00 EDT 2005 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2004.12.012· OSTI ID:20698602

Taussky, Daniel ^[1]; Austen, Lyn ^[1]; Toi, Ants ^[2]; Yeung, Ivan ^[3]; Williams, Theresa ^[4]; Pearson, Shannon ^[4]; McLean, Michael ^[1]; Pond, Gregory ^[5]; Crook, Juanita ^[1]

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1. Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON (Canada)
2. Department of Medical Imaging, Princess Margaret Hospital, Toronto, ON (Canada)
3. Department of Radiation Physics, Princess Margaret Hospital, Toronto, ON (Canada)
4. Department of Radiation Medicine, Princess Margaret Hospital, Toronto, ON (Canada)
5. Department of Biostatistics, Princess Margaret Hospital, Toronto, ON (Canada)

Purpose: To analyze the extent and time course of prostate edema and its effect on dosimetry after permanent seed prostate brachytherapy. Methods and Materials: Twenty patients scheduled for permanent seed {sup 125}I prostate brachytherapy agreed to a prospective study on postimplant edema. Implants were preplanned using transrectal ultrasonography. Postimplant dosimetry was calculated using computed tomography-magnetic resonance imaging (CT-MRI) fusion on the day of the implant (Day 1) and Days 8 and 30. The prostate was contoured on MRI, and the seeds were located on CT. Factors investigated for an influence on edema were the number of seeds and needles, preimplant prostate volume, transitional zone index (transition zone volume divided by prostate volume), age, and prostate-specific antigen level. Prostate dosimetry was evaluated by the percentage of the prostate volume receiving 100% of the prescribed dose (V{sub 100}) and percentage of prescribed dose received by 90% of the prostate volume (D{sub 90}). Results: Prostate edema was maximal on Day 1, with the median prostate volume 31% greater than preimplant transrectal ultrasound volume (range, 0.93-1.72; p < 0.001) and decreased with time. It was 21% greater than baseline at Day 8 (p = 0.013) and 5% greater on Day 30 (p < 0.001). Three patients still had a prostate volume greater than baseline by Day 30. The extent of edema depended on the transition zone volume (p = 0.016) and the preplan prostate volume (p 0.003). The median V{sub 100} on Day 1 was 93.6% (range, 86.0-98.2%) and was 96.3% (range, 85.7-99.5%) on Day 30 (p = 0.079). Patients with a Day 1 V{sub 100} >93% were less affected by edema resolution, showing a median increase in V{sub 100} of 0.67% on Day 30 compared with 2.77% for patients with a V{sub 100} <93 % on Day 1. Conclusion: Despite the extreme range of postimplant edema, the effect on dosimetry was less than expected. Dose coverage of the prostate was good for all patients during Days 1-30. Our data indicate that postimplant dosimetry on the day of implant is sufficient for patients with good dose coverage (Day 1 V{sub 100} >93%)

• OSTI ID: 20698602
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 62; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ANTIGENS
BRACHYTHERAPY
CARCINOMAS
COMPUTERIZED TOMOGRAPHY
DOSIMETRY
EDEMA
EVALUATION
IODINE 125
NMR IMAGING
PATIENTS
PROSTATE
RADIATION SOURCE IMPLANTS
ULTRASONOGRAPHY