Prediction of seed migration after transperineal interstitial prostate brachytherapy with I-125 free seeds

PurposeThe present study was undertaken to determine the incidence and predictors of seed migration after transperineal interstitial prostate brachytherapy using I-125 free seeds.Methods and MaterialsBetween September 2004 and November 2007, 158 patients who underwent transperineal interstitial prostate brachytherapy as monotherapy for clinical T1/T2 carcinoma of the prostate gland were reviewed. Implants had been performed with standard techniques. All 158 patients underwent followup radiographs (orthogonal chest radiographs, a kidney–ureter–bladder radiograph, and a posteroanterior pelvic radiograph) to assess the presence of seed migration at 3 months after transperineal interstitial prostate brachytherapy. Patient characteristics and treatment status were recorded. Univariate and multivariate analyses were performed to identify predictors of seed migration.ResultsSeed migration occurred in 35 of 158 patients (22.2%). Univariate analyses revealed that preoperative prostate volume estimated by transrectal ultrasound, the number of needles, the number of seeds implanted, and the presence or absence of pubic arch interference (PAI) were significantly associated with seed migration. These results indicated that larger prostate glands were more likely to have seed migration. However, the absolute difference in prostate size was not overly impressive (22.4 vs. 26.3 cm³). Multivariate analysis revealed that the number of seeds implanted and the presence or absence of PAI were significant predictors of seed migration.ConclusionThe number of seeds implanted and the presence or absence of PAI provide the most predictive information on seed migration.     

Seed migration after transperineal interstitial prostate brachytherapy with I-125 free seeds: analysis of its incidence and risk factors

Purpose

The purpose of this study was to evaluate the incidence and predictors of seed migration after transperineal interstitial prostate brachytherapy.

Materials and methods

From March 2007 to March 2011, 121 patients with stage T1?CT2 prostate cancer underwent transperineal interstitial prostate brachytherapy. Pre-planning was performed 3?weeks prior to implantation, and the implants were inserted using the standard parallel needle insertion technique. All patients underwent a series of radiographs [chest radiography, kidney?Cureter?Cbladder (KUB) radiography, and a CT scan] to assess whether seed migration had occurred on postoperative days?1 and 30, and 12?months.

Results

Seed migration occurred in 31 (25.6?%) of 121 patients. A total of 51 of 7,883 (0.65?%) implanted seeds migrated. Migration was detected on postoperative day?1 in 16 patients, day?30 in 13 patients and at 12?months in 4 patients (migration occurred at different times in 2 patients). The migrated seeds were found in the lungs, pelvis, heart, mediastinum, kidney, inguinal canal, liver and sacrum. The number of needles was a statistically significant factor in seed migration.

Conclusions

The seeds migrated to many organs. No decrease in the dose administered to the prostate or adverse effects associated with seed migration were noted.     

Fluoroscopy guided transperineal percutaneous permanent 125iodine implantation of prostate cancer

The transperineal percutaneous template permanent iodine interstitial brachytherapy under "C-arm" fluoroscopic guidance is a simple, easily-learned, accurate and rapid procedure which can be performed without subjecting the patient to celiotomy. We have treated 58 patients by the transperineal percutaneous permanent interstitial brachytherapy. The use of transperineal percutaneous technique with C-arm fluoroscopic guidance improves the symmetry and dosimetry of the implant. This results in reduction of the incidence of chronic radiation-induced complications. In the group of 22 patients who underwent brachytherapy without celiotomy and lymphadenectomy and without adjuvant external-beam radiotherapy, there were no major complications.     

Lung tumors: percutaneous implantation of I-125 sources with CT treatment planning

Seven patients with lung tumors underwent percutaneous implantation of iodine-125 sources into the tumor. Needle placement and seed implantation were effected with biplane fluoroscopy and a computer planning model based on computed tomography. No complications were encountered. Five of the seven patients underwent the procedure at the outpatient center and were discharged the same day. Follow-up radiologic evaluations were available for six patients; in all six the examination demonstrated tumor shrinkage, and in four tumor shrinkage was essentially complete.     

Surface treatments of silver rods with enhanced iodide adsorption for I-125 brachytherapy seeds

This study described an effective method to load ¹²⁵I on silver rods for the preparation of a brachytherapy source. We tested various ligands on the silver rod surface to screen the one with the highest adsorption and specific radioactivity. In addition, we investigated the effect of surface etching to increase the adsorption capability followed by the extended surface area. We also found that the use of an oxidant during iodide adsorption can increase the loading significantly. The maximum activity of 137.90 MBq/rod (3.7269 mCi/rod) was achieved on the etched silver rods with phosphate ligand and hydrogen peroxide as an oxidant. In addition, this is 4.5-fold higher than that of the conventional chloride treatment method.     

Radiation safety with use of I-125 seeds for localization of nonpalpable breast lesions

RATIONALE AND OBJECTIVES: To describe radiation safety procedures for limiting exposures during localizing placement of iodine-125 (I-125) seeds in nonpalpable breast lesions. Radiation safety tasks included seed receipt, assay, sterilization, transfer, and placement; surgical localization and retrieval; and extraction of seeds by pathologists. Additional regulatory aspects included institutional review board approval, physician credentialing, off-label use, and governmental licensing. MATERIALS AND METHODS: Titanium seeds were assayed to ensure strength (1.85-5.55 MBq). Radiologists credentialed in mammography placed seeds with an 18-gauge needle under ultrasound or mammographic guidance. Surgeons located seeds with a hand-held, solid-state radiation detector. I-125 seeds were extracted from excised tissue and secured by pathologists. RESULTS: After the investigational phase, state permission was obtained for the institution's Radiation Safety Committee to oversee the clinical application of the procedure. In more than 300 procedures, all seeds and targeted lesions were removed successfully; more than 98% of patients had seeds removed within 24 hours. Mean diameter of excised specimens was about 4 cm, for a maximum dose to residual breast tissue of 2 cGy (approximately that of a two-view mammogram). Badge monitoring showed no loss of seeds and no increase in physician or technologist exposure. Radiation safety precautions facilitated safe handling. CONCLUSION: Clinically, the procedure has been accepted as routine, with standardized steps for safe and secure handling of radioactive seeds. Compared with conventional methods, use of I-125 seeds offers an improved method for localizing before surgical excision and has essentially replaced wire localization in our tertiary-care academic medical center.     

Dosimetry of I-125 seeds implanted on the surface of a cavity

Dosimetry of a new implant technique to treat brain tumors is presented. High grade gliomas or astrocytomas are surgically removed, and radioactive I-125 seeds are implanted on the surface of the cavity. A computational model is presented to determine the number of seeds and the activity of the seeds for a given dose and cavity size.     

Interstitial radiotherapy using I-125 seeds in brain neoplasms of slow development

The opportunity of stereotactic biopsy for the histological diagnosis of brain tumors, the radiobiologic bases, clinical implications and technical possibilities of interstitial radiation therapy are discussed. The results of 9 cases, out of 14 treated to-date over 20 months, with a minimum follow-up of 4 months, are presented.     

The effect of the radial function on I-125 seeds used for permanent prostate implantation.

The purpose of this study was to evaluate the integrity of eight commercially-available low-activity Iodine-125 (125I) seeds for their radial function g(r) and its effect on the dose delivered to the adjacent critical structures when used in permanent prostate implants (PPI). Ten previously treated patients were retrospectively used in this comparison. The Amersham Health Oncura seed was used to peripherally design an isodose distribution with urethral and anterior rectal wall sparing. Plan criteria included minimum coverage of 144 Gy to the planning target volume (PTV), < or = 70% dose to 150% of the PTV volume (V150-PTV), and the quantity of needles < or = 70% of the size of the PTV, in cc. Upon completion of the Oncura plan, the seed type was changed and the activity was adjusted until the V100-PTV for each of the other 7 seed types matched the V100-PTV defined by the Oncura seed. Computed tomography (CT)-based postimplant dosimetry was used to determine the dose to 40% (D40) of the bulb of the penis (in Gy). Dose-volume histograms (DVH) were used to evaluate the differences to V100 (in %) and D40 (in Gy) of the anterior rectal wall and bulb of the penis, and V100 (in %) of the urethra. The data was tabulated. Radioactive 125I sources included in this study were 125I Source 2301 (Best); I-Plant (MedTech), IoGold (Mentor), Oncura (Amersham Health), ProstaSeed (UroCor), SelectSeed (Nucletron), SourceTech (Bard), and Symmetra (UroMed). The sizes of the PTV for the 10 patients ranged from 18.82 cc to 48.99 cc. The Oncura seed was used as the reference seed and all other seed types were normalized to it for data comparison. It was determined that the dose rate constant (Delta) and anisotropy factor (phi) contribute to the activity needed to achieve comparable V100-PTV doses, but a strong dependence on the radial function g(r) was found to effect the doses to the critical structures studied. Values of g(r) at 4 cm were calculated and the IoGold and SourceTech seeds were determined to have the highest g(r) values, with ProstaSeed and SelectSeed having the lowest values. 125I Source 2301 and IoGold required less activity per seed to achieve the same dose to the V100-PTV due to the higher dose rate and anisotrophy constants (Delta.phi). The seed types with silver were less penetrating and resulted in the production of characteristic x-rays that modified the energy spectrum and influenced the radial function. The seeds requiring the lowest activity showed the highest dose to the anterior rectal wall, a posterior adjacent structure; the urethra, an interior structure; and the bulb, an inferior structure. This study was designed to investigate the integrity of eight different commercially-available seed types, and their dependence on the g(r) in seed choice. It was determined that the dose rate constant and anisotropy factor determine the activity needed for implantation but a strong dependence on the radial function was found to effect the doses to the adjacent structures.     

经皮穿刺植入125I粒子治疗恶性肿瘤的临床应用

目的根据内放射源125I粒子的物理特性探讨其治疗原理、治疗计划系统(TPS)的意义、治疗方式及临床疗效.方法18例晚期肿瘤患者采取经皮穿刺植入125I粒子行组织间放疗.结果18例肿瘤患者均未出现任何严重的并发症,生存质量明显提高.2个月后经胸片、CT复查18例患者肿瘤均有不同程度缩小,12例明显缩小,其中5例肿瘤基本消失.结论短期疗效证明,125I粒子组织间放疗对晚期肿瘤效果显著,不良反应小.     

Results of interstitial radiotherapy using I-125 seeds in the treatment of prostatic cancer

30 patients with localized adenocarcinoma of the prostate were treated with pelvic lymphadenectomy and I-125 interstitial implantation from 1980 to 1985 (21/30 T3-tumors and 14/30 with poor differentiation). The mean follow-up is 59.5 months (range 18 to 88 months). The crude, progression-free and local progression-free survival rates (Kaplan-Meier) for all patients are 68%, 61% and 71% respectively. But, the progression-free survival is 39% in patients with G3-tumors after five years and only 25% in patients with T3 G3-tumors after four years. The local progression rate was 33% in patients with T3-tumors. We did not observe any late intestinal side-effects, but 11/30 (37%) patients suffered from later urinary flow problems caused mainly by local tumor progression. Therefore, we regard interstitial implantation with I-125-seeds as an alternative treatment to radical prostatectomy in patients with T1, 2 G1, 2-tumors but as insufficient in patients with T3 G3-tumors.     

Choroidal melanoma: I-125 plaque therapy

An iodine-125 eye plaque was used to treat 58 patients with choroidal melanoma. Patients were followed up for a mean of 48.7 months. Fifty patients had medium-sized lesions (height between 3.1 and 8.0 mm and base diameter less than 16.0 mm), and six patients had large lesions. There were 24 lesions less than 3.0 mm from the optic nerve. The average radiation dose to the apex of the tumor was 8,468 cGy (dose rate, 71 cGy per hour). Initial local disease control was achieved in 50 patients (86.2%). One patient with local treatment failure received another plaque treatment, which controlled disease, so the total disease control rate was 87.9%. Only eight patients died of their disease. Complications were similar to those with other treatment methods, but none of the patients in this study developed optic nerve atrophy.     

Procedures for radioactive I-125 seed implants

Typical safety procedures and guidelines for the use of radioactive I-125 seed implant are presented. Topics covered include: Physical properties, management and planning of I-125, source logging, source transportation, source accounting during and after implant, room monitoring, recording, dosimetry films, nursing procedures, discharge of patient. These guidelines have been found to be of practical value for personnel involved with the implant to ensure compliance with the regulations, but are not necessarily the only procedures that could be utilized.     

Equipment for rapid and reliable perineal implantation of I-125 seeds in prostatic cancer with reduced radiation exposure

The aim of an implantation of iodine seeds into the prostate controlled by ultrasound is reached by means of the equipment presented in this paper. The method, allowing to implant the seeds according to the therapy plan, has been developed above all in order to reduce the radiation exposure to the physicist, the radiotherapist and the surgeon.     

A computer program for I-125 seed implant

A computer program, written in FORTRAN, for I-125 permanent interstitial implants has been developed. After implantation, isocentric radiographs are taken using radiotherapy simulator (Siemens) in order to obtain two X-ray images of seeds on the same film. Honeywell DPS8 computer and Hewlett-Packard 7221A plotter are used for the dose calculation. The program calculates the dose distribution at the plane desired using 100 X 100 matrix.     

Simple, accurate, safe, and cost-effective percutaneous transperineal template technique for permanent 125iodine interstitial brachytherapy of prostate cancer

We present the technique, intraoperative and postoperative complications of percutaneous transperineal template permanent 125iodine interstitial brachytherapy of prostate cancer. The percutaneous transperineal template permanent iodine interstitial brachytherapy under "C-arm" fluoroscopic guidance is a simple, easily-learned, accurate and rapid procedure which can be performed without subjecting the patient to celiotomy. We have treated 58 patients by the transperineal percutaneous permanent interstitial brachytherapy. 33 of 58 patients also had a staging celiotomy just prior to the brachytherapy. In the group of 22 patients undergoing brachytherapy without celiotomy and without adjuvant external-beam pelvic radiotherapy, there were no major complications. Blood transfusions were not required by any patients who underwent percutaneous transperineal permanent iodine interstitial brachytherapy without celiotomy.     

Monte Carlo single-cell dosimetry of I-131, I-125 and I-123 for targeted radioimmunotherapy of B-cell lymphoma

Abstract

Purpose: To study the dosimetric characteristics of a non-internalizing and an internalizing monoclonal antibody (MAb) labeled with ¹³¹I, ¹²⁵I or ¹²³I, which targets a typical lymphoma B-cell. Materials and methods: Using our hybrid Monte Carlo (MC) code which combines detailed- and condensed-history electron track simulation we carry out transport calculations of Auger and beta electrons for different intracellular distributions of radioactivity. Results: Assuming permanent retention of the MAb in cells, ¹²⁵I gave the highest absorbed dose and ¹²³I the highest absorbed dose rate. Under the more realistic scenario of biologic excretion from the cells, ¹²³I resulted in the highest absorbed dose and absorbed dose rate. Conclusion: The present dosimetric analysis shows that biological half-life, subcellular localization, and the proper account of low-energy electrons is critical in assessing the energy deposition inside the targeted cells from the three iodide radioisotopes examined. From a dosimetric point of view and under the present approximations ¹²³I might be superior to the other two radioiodides in the treatment of microscopic disease in B-cell lymphoma patients.     

Effectiveness and security of CT-guided percutaneous implantation of 125I seeds in pancreatic carcinoma

Objective:

To assess the effectiveness and security of CT-guided percutaneous implantation of iodine-125 (¹²⁵I)-labelled seeds in pancreatic carcinoma.

Methods:

A total of 36 patients (25 males and 11 females) with an average age of 57 years (range, 39–84 years) were enrolled and categorized into Stage III (27 cases) and Stage IV (9 cases) of pancreatic cancer. There were 3 tumours in the pancreatic head and 33 tumours in the pancreatic body or tail. The average diameter of the tumours was 37.1 mm (range, 15–65 mm). The implantation of ¹²⁵I seeds was performed by using 18-G needles (length, 150–200 mm) through the anterior, lateral and posterior approaches. Then, ¹²⁵I seeds were loaded and released into the lesions.

Results:

Implantations were performed via the anterior (23 patients), lateral (9 patients) and posterior (4 patients) approaches. During implantation, 3–14 punctures were performed for each patient, and a total of 164 punctures were recorded. Meanwhile, a total of 657 seeds were implanted with an average of 25.27 (range, 12–50) seeds per patient, and the success rate was 100%. The activity of each seed ranged from 0.55 to 0.65 mCi. A main adverse event occurred in one puncture and minor events in seven punctures. No significant relationship between the punctures or adverse events was identified. No serious complication was detected after the implantations during follow-up visits.

Conclusion:

This study suggested that CT-guided percutaneous implantation of ¹²⁵I seeds in a pancreatic carcinoma was relatively safe and effective for treating unresectable pancreatic cancer.

Advances in knowledge:

The CT-guided percutaneous implantation of ¹²⁵I seeds in unresectable pancreatic cancer showed highly successful rates without serious complications.Pancreatic cancer is the sixth most common cause of cancer-related deaths in China and the fourth worldwide.¹ The life quality of a patient with pancreatic cancer is severely influenced, since pancreatic cancer develops rapidly and can lead to abdominal pain, weight loss and jaundice.² Clinically, early pancreatic cancer does not cause obvious symptoms, while the later symptoms are usually non-specific and varied.³ As a result, most patients are diagnosed with mid- and terminal-staged pancreatic cancer that cannot be removed surgically. Although 15–20% of patients are diagnosed at an early stage, only 20–25% of them may survive more than 5 years after a tumour resection.⁴ For all stages of pancreatic cancer, the 5-year relative survival rate is 6%, whereas the 5-year survival rate is approximately 15% for a local tumour.⁵ Local control and distant metastases are the major factors that affect prognoses.⁶ During the past decades, the treatment outcome of locally advanced pancreatic carcinoma has not been improved significantly.⁷Currently, comprehensive therapy (radiotherapy plus chemotherapy) is the most common treatment for locally advanced pancreatic carcinoma.^8,9 Radioactive seeds, interstitial brachytherapy¹⁰ and conformal radiotherapy,⁷ show great curative effects on local control. The implantation methods include intra-operative and ultrasound- and CT-guided implantations.^10–12With the development of modern medical imaging technology, the CT-guided percutaneous implantation technique has been widely applied in clinics.^12,13 Additionally, CT-guided implantation of iodine-125 (¹²⁵I)-labelled seeds shows precision position, minimal invasion and great effectiveness. Also, the slow and continuous release of ¹²⁵I seeds has been radiobiologically advantageous, allowing the repair of non-lethal damage and re-oxygenation of hypoxic areas in normal tissues.⁷ However, the security of percutaneous implantation guided by CT scanning is still contradictory, because the pancreas is surrounded by the liver, stomach, intestines, spleen, kidney and blood vessels.In this present study, we retrospectively analysed 36 cases with unresectable pancreatic carcinoma who underwent CT-guided percutaneous implantation of ¹²⁵I seeds. The security of CT-guided percutaneous implantation of ¹²⁵I seeds in pancreatic carcinoma was assessed, which might provide the basis for individual treatment of CT-guided percutaneous implantation.     

CT引导下经皮125I粒子猪胰腺内植入的实验研究

目的比较^125I粒子和单纯吉西他滨化疗治疗中晚期胰腺癌的作用。方法将46例不能手术切除的中晚期胰腺癌患者分为2组：A组22例（^125I粒子植入组）和B组24例（吉西他滨静脉化疗组）。疗效评价主要指标包括临床受益率、客观肿瘤疗效、安全性和生活质量评估。结果治疗后3个月,有效率A组为45．5％,B组为8．3％。临床受益率A组为47．1％,B组为25．0％。A组无进展生存期中位时间为4个月,B组为3个月。两组毒性反应率和并发症率无差异。结论^125I粒子和吉西他滨在治疗中晚期胰腺癌方面均有一定的缓解率,但^125I粒子比吉西他滨能更好的改善患者的生存质量,提高生存率。     

New approach of ultra-focal brachytherapy for low- and intermediate-risk prostate cancer with custom-linked I-125 seeds: A feasibility study of optimal dose coverage

PurposeTo present the feasibility study of optimal dose coverage in ultra-focal brachytherapy (UFB) with multiparametric MRI for low- and intermediate-risk prostate cancer.Methods and MaterialsUFB provisional dose plans for small target volumes (<7 cc) were calculated on a prostate training phantom to optimize the seeds number and strength. Clinical UFB consisted in a contour-based nonrigid registration (MRI/Ultrasound) to implant a fiducial marker at the location of the tumor focus. Dosimetry was performed with iodine-125 seeds and a prescribed dose of 160 Gy. On CT scans acquired at 1 month, dose coverage of 152 Gy to the ultra-focal gross tumor volume was evaluated. Registrations between magnetic resonance and CT scans were assessed on the first 8 patients with three software solutions: VariSeed, 3D Slicer, and Mirada, and quantitative evaluations of the registrations were performed. Impact of these registrations on the initial dose matrix was performed.ResultsMean differences between simulated dose plans and extrapolated Bard nomogram for UFB volumes were 36.3% (26–56) for the total activity, 18.3% (10–30) for seed strength, and 22.5% (16–38) for number of seeds. Registration method implemented in Mirada performed significantly better than VariSeed and 3D Slicer (p = 0.0117 and p = 0.0357, respectively). For dose plan evaluation between Mirada and VariSeed, D₁₀₀% (Gy) for ultra-focal gross tumor volume had a mean difference of 28.06 Gy, mean values being still above the objective of 152 Gy. D₉₀% for the prostate had a mean difference of 1.17 Gy. For urethra and rectum, dose limits were far below the recommendations.ConclusionsThis UFB study confirmed the possibility to treat with optimal dose coverage target volumes smaller than 7 cc.