Comparison of implant quality between intraoperatively built custom-linked seeds and loose seeds in permanent prostate brachytherapy using sector analysis

Abstract

We compared the implant quality of intraoperatively built custom-linked (IBCL) seeds with loose seeds in permanent prostate brachytherapy. Between June 2012 and January 2015, 64 consecutive prostate cancer patients underwent brachytherapy with IBCL seeds (n = 32) or loose seeds (n = 32). All the patients were treated with 144 Gy of brachytherapy alone. Brachytherapy was performed using a dynamic dose calculation technique. Computed tomography/magnetic resonance imaging fusion-based dosimetry was performed 1 month after brachytherapy. Post-implant dose–volume histogram (DVH) parameters, prostate sector dosimetry, operation time, seed migration, and toxicities were compared between the IBCL seed group and the loose seed group. A sector analysis tool was used to divide the prostate into six sectors (anterior and posterior sectors at the base, mid-gland, and apex). V100 (95.3% vs 89.7%; P = 0.014) and D90 (169.7 Gy vs 152.6 Gy; P = 0.013) in the anterior base sector were significantly higher in the IBCL seed group than in the loose seed group. The seed migration rate was significantly lower in the IBCL seed group than in the loose seed group (6% vs 66%; P < 0.001). Operation time per seed was significantly longer in the IBCL seed group than in the loose seed group (1.31 min vs 1.13 min; P = 0.003). Other post-implant DVH parameters and toxicities did not differ significantly between the two groups. Our study showed more dose coverage post-operatively in the anterior base prostate sector and less seed migration in IBCL seed implantation compared with loose seed implantation.

Plan reproducibility of intraoperatively custom-built linked seeds compared to loose seeds for prostate brachytherapy

“…To date, many studies compared stranded seeds to loose seeds [ 9 , 13 , 14 , 19 , 20 , 21 ], but few studies have compared the implant quality of linked seeds with that of loose seeds for prostate brachytherapy [ 17 , 22 , 23 , 24 , 25 ]; however, until now, there have been no reports about the plan reproducibility of linked seeds. Generally, intraoperative dosimetry based on ultrasound would not predict biochemical outcome [ 26 ].…”

Dosimetry advantages of intraoperatively built custom-linked seeds compared with loose seeds in permanent prostate brachytherapy

“…This study demonstrated the dosimetric advantages of IBCL over LS for PPB. Several reports comparing DVH parameters between IBCL and LS found that prostate DVH did not differ between the two groups [ 22 , 23 , 24 , 25 ]. However, Jarusevicius et al .…”

“…Several studies have reported the merits of IBCL over LS [ 21 , 22 , 23 , 24 , 25 ]. Jarusevicius et al .…”

“…IBCL is a method that combines seeds and connectors into seed trains of variable length and seed-to-seed spacing [ 21 ]. IBCL has advantages of less seed migration and stability due to intraoperative linking [ 22 , 23 , 24 , 25 ]. This IBCL method may improve the dose volume histogram of the target and organs at risk (OAR) compared with conventional LS.…”

“…In addition, IBCL was also advantageous in intraoperative customization compared with suture-embedded type strand seeds [ 26 ]. However, several studies have reported the advantages and disadvantages of IBCL [ 21 , 22 , 23 , 24 , 25 ]. Although IBCL reduces seed migration by linking seeds to each other, the nature of this feature also prolongs the operation time compared with LS.…”