Stranded seed displacement, migration, and loss after permanent prostate brachytherapy as estimated by Day 0 fluoroscopy and 4-month postimplant pelvic x-ray

Dosimetric outcomes of preoperative treatment planning with intraoperative optimization using stranded seeds in prostate brachytherapy

This study aimed to evaluate the quality of low-dose-rate (LDR) prostate brachytherapy (BT) based on treatment-related dosimetric outcomes. Data of 100 patients treated using LDR BT with stranded seeds from November 2012 to November 2017 were collected. The prescription dose for the prostate was 145 Gy. The dose constraints for the preoperative plan were: V100% ≥ 95%, V150% ≤ 60%, V200% ≤ 20% for the prostate; V100% for rectum, ≤ 1 cc; and V200 Gy for urethra, 0.0 cc. Intraoperative real-time dose calculation and postoperative dose distribution analysis on days 0 and 30 were performed. Median dosimetric outcomes on days 0 and 30 respective were: V100% 92.28% and 92.23%, V200% 18.63% and 25.02%, and D90% 150.88 Gy and 151.46 Gy for the prostate; V100% for the rectum, 0.11 cc and 0.22 cc; and V200 Gy for the urethra, 0.00 cc and 0.00 cc, respectively. Twenty patients underwent additional seed implantation to compensate for insufficient dose coverage of the prostate. No loss or substantial migration of seeds or severe toxicity was reported. With stranded seed implantation and intraoperative optimization, appropriate dose delivery to the prostate without excessive dose to the organs at risk could be achieved.

Contamination Resulting From a Broken 125I Seed During a Brachytherapy Procedure

ABSTRACT

Brachytherapy programs within radiation therapy departments are subject to stringent radiation safety requirements in order to ensure the safety of the staff and patients. Training programs often include brachytherapy-specific radiation safety training modules that address the specific risks associated with radioactive sources, emergency procedures, and regulatory requirements specific to the use of radioisotopes. Unlike other uses of radioactive materials, brachytherapy uses sealed sources and therefore under routine operations does not encounter radioactive contaminants. This article presents an unusual clinical situation in which an 125I brachytherapy seed was damaged during routine clinical workflow, resulting in radioactive contamination within the clinical environment. Decisions made at the time of the incident resulted in contamination that spread beyond the initial location. The incident highlighted a shortcoming of the radiation safety program in preparing staff for the possibility of having to deal with unsealed radioactivity. Brachytherapy programs would be strengthened by including training specific to radioactive contamination in their emergency training to equip staff to respond to unexpected damage to the sealed sources.

A review on permanent implants for prostate brachytherapy with comparison between stranded and loose seeds

A systematic literature review to validate the conclusions with regard to stranded seeds versus loose seeds. Published data for this review were identified by searching the PubMed databases. PD90, PV100, PV150, UD30, and RV100 acquired during the perioperative period and the postoperative period were analyzed by meta-analysis. Based on these studies, in addition to the reduction of migration and displacement, stranded seeds had some dosimetric advantages, especially in dose homogeneity and coverage of target area due to its connection characteristics. We also noticed implanted seeds usually excessive both in stranded seeds group and loose seed group. Intraoperatively built custom links will prolong operation time, with the proficiency of technology, the prolonged time gradually decreases.

Self-Expanding Anchors for Stabilizing Percutaneously Implanted Microdevices in Biological Tissues

Percutaneously implanted miniaturized devices such as fiducial markers, miniaturized sensors, and drug delivery devices have an important and expanding role in diagnosing and treating a variety of diseases. However, there is a need to develop and evaluate anchoring methods to ensure that these microdevices remain secure without dislodgement, as even minimal migration within tissues could result in loss of microdevice functionality or clinical complications. Here we describe two anchoring methods made from biocompatible materials: (1) a self-expanding nitinol mesh anchor and (2) self-expanding hydrogel particles contained within pliable netting. We integrate these anchors into existing drug-screening microdevices and experimentally measure forces required to dislodge them from varying tissues. We report similar dislodgement forces of 738 ± 37, 707 ± 40, 688 ± 29, and 520 ± 28 mN for nitinol-anchored microdevices, and 735 ± 98, 702 ± 46, 457 ± 47, and 459 ± 39 mN for hydrogel-anchored microdevices in liver, kidney, fat, and muscle tissues, respectively—significantly higher compared with 13 ± 2, 15 ± 3, 15 ± 2, and 15 ± 3 mN for non-anchored microdevices (p < 0.001 in all tissues). The anchoring methods increased resistance to dislodgement by a factor of 30–50× in all tissues, did not increase the required needle gauge for insertion, and were compatible with percutaneous implantation and removal. These results indicate that anchoring significantly improves microdevice stability and should reduce migration risk in a variety of biological tissues.

Relationship between radiation doses and erectile function deterioration in patients with localized prostate cancer treated with permanent prostate brachytherapy

OBJECTIVES

To investigate the relationship between radiation doses in prostate brachytherapy and deterioration of erectile function in patients with localized prostate cancer.

METHODS

A longitudinal survey study was carried out among 261 prostate cancer patients who received prostate brachytherapy. A total of 48 patients were potent at baseline and they did not receive any supplemental therapy preoperatively. Dosimetry parameters of the whole prostate gland, prostate apex, urethra and rectum were collected using the VariSeed 8.0 treatment planning system (Varian Medical Systems, Palo Alto, CA, USA). We carried out a logistic regression analysis to clarify the relationship between radiation doses and erectile function deterioration, which was assessed using the International Index of Erectile Function-15 questionnaire.

RESULTS

The median patient age was 66 years (range 53-70 years) with a median follow-up time of 44 months (36-71 months). The mean total International Index of Erectile Function-15 score decreased from 49.9 at baseline to 34.7 after 12 months (P < 0.001), but gradually plateaued within 36 months. Erectile function deterioration was noted in 32 (66.7%) patients 36 months after prostate brachytherapy. In an analysis of risk factors for erectile function deterioration after prostate brachytherapy, age ≥70 years (P = 0.029), prostate V100 ≥95% (P = 0.024), apex V100 ≥95% (P = 0.024), apex V150 ≥70% (P = 0.009) and apex D90 ≥150 Gy (P = 0.011) correlated with erectile function deterioration. A multivariate analysis identified an age of ≥70 years (odds ratio 7.91, P = 0.024) and apex V150 ≥70% (odds ratio 7.75, P = 0.007) as independent risk factors for erectile function deterioration after prostate brachytherapy.

CONCLUSIONS

An excessive radiation dose, particularly to the prostate apex area, and an advanced age might have a negative impact on the preservation of potency after prostate brachytherapy.

Reducing seed migration to near zero with stranded-seed implants: Comparison of seed migration rates to the chest in 1000 permanent prostate brachytherapy patients undergoing implants with loose or stranded seeds

PURPOSE

Pulmonary seed emboli to the chest may occur after permanent prostate brachytherapy (PPB). The purpose of this study is to analyze factors associated with seed migration to the chest in a large series of PPB patients from a single institution undergoing implant with either loose seeds (LS), mixed loose and stranded seeds (MS), or exclusively stranded seeds in an absorbable vicryl suture (VS).

METHODS AND MATERIALS

Between May 1998 and July 2015, a total of 1000 consecutive PPB patients with postoperative diagnostic chest x-rays at 4 months after implant were analyzed for seed migration. Patients were grouped based on seed implant technique: LS = 391 (39.1%), MS = 43 (4.3%), or VS = 566 (56.6%). Univariate and multivariate analysis were performed using Cox proportional hazards regression models to determine predictors of seed migration.

RESULTS

Overall, 18.8% of patients experienced seed migration to the chest. The incidence of seed migration per patient was 45.5%, 11.6%, and 0.9% (p < 0.0001), for patients receiving LS, MS, or VS PPB, respectively. The right and left lower lobes were the most frequent sites of pulmonary seed migration. On multivariable analysis, planimetry volume (p = 0.0002; HR = 0.7 per 10 cc [0.6-0.8]), number of seeds implanted (p < 0.0001, HR = 2.4 per 25 seeds [1.7-3.4]), LS implant (p < 0.0001, HR = 15.9 [5.9-42.1]), and MS implant (p = 0.001, HR = 7.9 [2.3-28.1]) were associated with seed migration to the chest.

CONCLUSIONS

In this large series, significantly higher rates of seed migration to the chest are observed in implants using any LS with observed hazard ratios of 15.9 and 7.9 for LS and MS respectively, as compared with implants using solely stranded seeds.

Low dose rate prostate brachytherapy

Low dose rate (LDR) prostate brachytherapy is an evidence based radiation technique with excellent oncologic outcomes. By utilizing direct image guidance for radioactive source placement, LDR brachytherapy provides superior radiation dose escalation and conformality compared to external beam radiation therapy (EBRT). With this level of precision, late grade 3 or 4 genitourinary or gastrointestinal toxicity rates are typically between 1% and 4%. Furthermore, when performed as a same day surgical procedure, this technique provides a cost effective and convenient strategy. A large body of literature with robust follow-up has led multiple expert consensus groups to endorse the use of LDR brachytherapy as an appropriate management option for all risk groups of non-metastatic prostate cancer. LDR brachytherapy is often effective when delivered as a monotherapy, although for some patients with intermediate or high-risk disease, optimal outcome are achieved in combination with supplemental EBRT and/or androgen deprivation therapy (ADT). In addition to reviewing technical aspects and reported clinical outcomes of LDR prostate brachytherapy, this article will focus on the considerations related to appropriate patient selection and other aspects of its use in the treatment of prostate cancer.

Performance of a palladium-103 line source for prostate brachytherapy implants: A Phase I trial

PURPOSE

To evaluate the use of a polymer-encapsulated palladium-103 (¹⁰³ Pd) source with a unique linear radioactive distribution in prostate brachytherapy. This feasibility study assessed dosimetry, ease and efficiency of use, and side effects. The number of needles required for adequate coverage was the primary end point.

METHODS AND MATERIALS

CivaString ¹⁰³ Pd Model CS10 implants were preplanned for 25 patients. CivaStrings were custom manufactured according to plan. CivaStrings were implanted with 18 gauge needles. Post-implant dosimetry was performed at 3-6 weeks.

RESULTS

Monotherapy (125 Gy) was prescribed for 11 implants. External beam radiation with CivaString boost (100 Gy) was prescribed for 14 implants. The mean time to implant the sources was 23.5 min. The number of planned needles and prostate sizes ranged from 14 to 25 and 21-101 cm₃, respectively. 70% of implants in prostates less than 50 cm₃ required ≤17 needles. Planned source strength ranged from 2.8 U/cm to 3.9 U/cm. Total source strength averaged 216 U (130-323 U) for monotherapy and 154 U (92.4-245 U) for boost. Nomograms were generated at both prescription dose levels.

CONCLUSIONS

The linear ¹⁰³Pd source provides good dose coverage to the prostate. Prostate volume changes were minimal suggesting minimal swelling using the CivaString device.