Brachytherapy Device Research Articles

Brachytherapy next generation: robotic systems

In a field dominated by external beam radiation therapy (EBRT), both the therapeutic and technical possibilities of brachytherapy (BT) are underrated, shadowed by protons and intensity modulated radiotherapy. Decreasing expertise and indications, as well as increasing lack of specific BT training for radiation therapy (RT) residents led to the real need of shortening its learning curve and making it more popular. Developing robotic BT devices can be a way to mitigate the above issues. There are many teams working at custom-made robotic BT platforms to perfect and overcome the limitations of the existing systems. This paper provides a picture of the current state-of-the-art in robotic assisted BT, as it also conveys the author's solution to the problem, a parallel robot that uses CT-guidance.

Outcomes for APBI with strut-based brachytherapy: First 100 accrued patients (5-year median follow-up).

114 Background: The SAVI Collaborative Research Group (SCRG), was created to study the long-term outcomes of women receiving accelerated partial breast irradiation (APBI) using strut-based applicators. The outcomes for the first 100 accrued patients in the study are reported. Methods: Patients for this subset analysis weretaken as the initial 100 treated across all participating sites. Median follow-up of this cohort was 56.3 months at the time of the abstract. Patients were treated with APBI using the strut-based brachytherapy device with conventional dose and fractionation (3.4 Gy x 10 fx, BID). Treatment planning goals for the planning target volume were a V90>90%, V150<50 cc, and V200<20 cc. Patients were followed regularly by their radiation oncologist and outcomes were graded based on the CTCAE v3.0 (common terminology criteria for adverse events, version 3.0). Recurrence (raw and actuarial) rates were also calculated based on the follow up. Cosmesis was graded using the Harvard Scale. Results: 75 patients had invasive disease and 25 had ductal carcinoma in situ. The median age was 60.5 yrs (range 40-85 yrs), with 84% post-menopausal. Median tumor size was 10.0 mm (range 0.7-35 mm) with 92% being estrogen receptor positive. 65% of patients had at least one round of hormone therapy and 7% had chemotherapy. All patients completed APBI as planned with no serious adverse events. All patients met the dosimetric criteria. Good/excellent cosmesis was seen in >94% of subjects at all times of follow up (6-60 months). The 5-yr actuarial rates for TR/MM were 2.2%, 1.5% and 4.2% for all subjects, invasive and DCIS subgroups, respectively. The 5-yr actuarial rates for IBTR were 3.3%, 3.0% and 4.2% for all subjects, invasive and DCIS subgroups, respectively. Conclusions: For these initially treated 100 patients with a median 5 years of follow up, strut-based brachytherapy appears to be a well-tolerated, effective treatment with low rates of toxicities and local control as good as other brachytherapy APBI methods.

Delivery systems for brachytherapy.

Brachytherapy is described as the short distance treatment of cancer with a radioactive isotope placed on, in, or near the lesions or tumor to be treated. The main advantage of brachytherapy compared with external beam radiation (EBR) is the improved localized delivery of dose to the target volume of interest, thus normal tissue irradiation is reduced. The precise and targeted nature of brachytherapy provides a number of key benefits for the effective treatment of cancer such as efficacy, minimized risk of side effects, short treatment times, and cost-effectiveness. Brachytherapy devices have yielded promising results in preclinical and clinical studies. However, brachytherapy can only be used in localized and relatively small tumors. Although the introduction of new delivery devices allows the treatment of more complex tumor sites, with wider range of dose rate for improving treatment efficacy and reduction of side effects, a better understanding about the safety, efficacy, and accuracy of these systems is required, and further development of new techniques is warranted. Therefore, this review focuses on the delivery devices for brachytherapy and their application in prostate, breast, brain, and other tumor sites.

Development of an open source software module for enhanced visualization during MR-guided interstitial gynecologic brachytherapy.

In 2010, gynecologic malignancies were the 4th leading cause of death in U.S. women and for patients with extensive primary or recurrent disease, treatment with interstitial brachytherapy may be an option.However, brachytherapy requires precise insertion of hollow catheters with introducers into the tumor in order to eradicate the cancer. In this study, a software solution to assist interstitial gynecologic brachytherapy has been investigated and the software has been realized as an own module under (3D) Slicer, which is a free open source software platform for (translational) biomedical research. The developed research module allows on-time processing of intra-operative magnetic resonance imaging (iMRI) data over a direct DICOM connection to a MR scanner. Afterwards follows a multi-stage registration of CAD models of the medical brachytherapy devices (template, obturator) to the patient’s MR images, enabling the virtual placement of interstitial needles to assist the physician during the intervention.

Assessment of Dosimetric Changes and Adaptive Replanning for Intraoperatively Placed Brachytherapy Applicators during Accelerated Partial Breast Irradiation

Assessment of Dosimetric Changes and Adaptive Replanning for Intraoperatively Placed Brachytherapy Applicators during Accelerated Partial Breast Irradiation

Brachytherapy in breast cancer: an effective alternative.

Breast conserving surgery (BCS) with following external beam radiation therapy (EBRT) of the conserved breast has become widely accepted in the last decades for the treatment of early invasive breast cancer. The standard technique of EBRT after BCS is to treat the whole breast up to a total dose of 42.5 to 50 Gy. An additional dose is given to treated volume as a boost to a portion of the breast. In the early stage of breast cancer, research has shown that the area requiring radiation treatment to prevent the cancer from local recurrence is the breast tissue that surrounds the area where the initial cancer was removed. Accelerated partial breast irradiation (APBI) is an approach that treats only the lumpectomy bed plus a 1-2 cm margin rather than the whole breast and as a result allows accelerated delivery of the radiation dose in four to five days. There has been a growing interest for APBI and various approaches have been developed under phase I-III clinical studies; these include multicatheter interstitial brachytherapy, balloon catheter brachytherapy, conformal external beam radiation therapy (3D-EBRT) and intra-operative radiation therapy (IORT). Balloon-based brachytherapy approaches include MammoSite, Axxent electronic brachytherapy, Contura, hybrid brachytherapy devices. Another indication for breast brachytherapy is reirradiation of local recurrence after mastectomy. Published results of brachytherapy are very promising. We discuss the current status, indications, and technical aspects of breast cancer brachytherapy.

Abstract P5-14-06: Outcomes in 500 patients from a large, retrospective study of APBI with a strut-based breast brachytherapy applicator

Abstract Purpose/Objectives: The SAVI Collaborative Research Group (SCRG) is a coalition of 14 institutions who have retrospectively compiled a large database of APBI patients treated with a strut-based brachytherapy device (SAVI). This report details the findings of statistical correlations between numerous dosimetric variables and cosmetic outcome. Materials/Methods: The SCRG study enrolled 1005 patients. A subset of patients with complete dosimetry and more than 1 year of follow-up by a radiation oncologist were analyzed for toxicity, cosmesis and recurrence/survival. Dosimetric parameters were tabulated for patients, including: V90, V95, V100, V150, V200, skin spacing (skin-bridge), maximum skin dose, tumor size, PTV-Eval volume and applicator size (model). Toxicity (e.g., telangiectasia, fibrosis, fat necrosis, seroma) were graded by physicians for patients with at least 1 year of follow-up (up to 6 years) using the CTCAE v3 Scale and fat necrosis using a simplified CTCAE scale (Grade 1 asymptomatic but seen on imaging, grade 2 symptomatic without intervention, & grade 3 required intervention). Results: Median follow up in this cohort was 29.2 months (range 2.4 to 72.2 months). Follow up was >2 yr and >3 yr for 323 and 191 subjects, respectively. Overall, in 500 subjects the late toxicity (grade ≥2) rates were less than 5% during follow up: telangiectasia 1.0%, fibrosis 4.1%, seroma 2.9% and fat necrosis 0.6%. Cosmesis was reported at various post-APBI follow-up visits following treatment completion (6, 12, 24, 36, 48 & 60+ months). For the 6 and 12 month intervals, 98% (n = 122) and 97% (n = 262) were reported excellent or good (E/G), respectively. At 24, 36, 48 and 60 month intervals, the E/G rates were 93% (n = 184), 90% (n = 98), 100% (n = 41) and 94% (n = 15), respectively. The raw rates of ipsilateral breast tumor recurrence (IBTR) and TR/MM were 1.6% (n = 8) and 1.2% (n = 6), respectively, in 500 patients with >1 year of follow up. The 1- and 2-year actuarial rates of overall survival and disease-free survival were: 1-year, 99.6% & 99.4%, resp. and 2-year, 99.2% & 96.7%. Conclusions: APBI treatment with the strut-based applicators was well-tolerated, demonstrated low toxicity rates, favorable cosmetic outcomes and excellent local control over the follow-up to date. Patients with challenging breast anatomy were successfully treated with strut-based devices. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-06.

Irradiación parcial acelerada en cáncer de mama: revisión de las diferentes técnicas

Breast conservation therapy is the procedure of choice of early-stage breast cancer. Accelerated partial breast irradiation is an approach that treats only the lumpectomy bed plus a 1-2cm margin, rather than the whole breast. Because of the small volume of irradiation, a higher dose can be delivered, thus reducing the total length of treatment. Growing interest in accelerated partial breast irradiation has prompted the development of phase i-iii clinical studies evaluating distinct techniques within this therapeutic modality; these techniques include multicatheter interstitial brachytherapy, balloon-catheter brachytherapy, conformal external beam radiation therapy, and intraoperative radiation therapy. Balloon-based brachytherapy approaches include MammoSite, Axxent and Contura electronic brachytherapy. Hybrid brachytherapy devices include SAVI and ClearPath. This article reviews the different techniques, identifying the weaknesses and strengths of each approach, and proposes a direction for future research and development. Although further follow-up and mature phase iii data are needed, it seems evident that accelerated partial breast irradiation will play a role in the management of a selected group of patients with early-stage breast cancer.

Outcomes for APBI With Strut-Based Brachytherapy: 101 Patients at 4.5 Years Median Follow-up

The SAVI Collaborative Research Group (SCRG), was created to study the long-term outcomes of women receiving accelerated partial breast irradiation (APBI) using strut-based applicators. The outcomes for the most mature subgroup of this study's patients (n = 101), accrued 3.5 to 6 years ago at 3 institutions, is presented. All patients were treated at least 42 months prior to abstract submission. Median follow-up of this cohort was 54 months. Patients were treated with APBI using the strut-based brachytherapy device with conventional dose and fractionation (3.4 Gy x 10 fx, BID). Treatment planning goals for the planning target volume were a V90 >90%, V150 <50 cc, and V200 <20 cc. Patients were followed regularly and outcome was graded based on the CTCAE v3.0 (common terminology criteria for adverse events, version 3.0). Seventy-one patients had invasive disease and 29 had ductal carcinoma in situ. The median age was 62 years (range, 40-82 years), with 82% post-menopausal. Median tumor size was 12.5 mm (range, 2-35 mm) with 92% being estrogen receptor positive. All patients completed APBI as planned with no serious adverse events. All patients met the dosimetric criteria with median V90 of 96%, V150 of 29 cc and V200 of 14 cc. Late toxicity (grade ≥2) rates were low; hyperpigmentation (0%), telangiectasias (2%), seroma (2%), fat necrosis (0%) and breast asymmetry secondary to radiation effects (3%). Statistically, tumor size had a weak association with fibrosis (21.7 cc vs 12.5 cc, p = 0.049) and surgical breast asymmetry (22 cc vs 12.7 cc, p = 0.089). There were no statistical associations (p < 0.05) between treatment parameters and toxicity, possibly due to the low event rates (≤3%). Local control was excellent with a true recurrence/marginal miss rate of 2% and an ipsilateral/elsewhere recurrence rate of 2%. These data will be updated and presented for 5 year median follow-up in October 2013. For these 101 patients with a median 4.5 years of follow-up (all with >3.5 years), strut-based brachytherapy appears to be a well-tolerated, effective treatment with low rates (<5%) of toxicities. With APBI an acceptable treatment for many women with early-stage breast cancer, strut-based brachytherapy continues on longer follow-up to be versatile, safe and effective.

HDR brachytherapy of rectal cancer using a novel grooved‐shielding applicator design

The aim of this work was to design a novel high-dose rate (HDR) ((192)Ir) brachytherapy applicator for treatment of rectal carcinomas that uses tungsten shielding for possibly improved dosimetric results over commercial brachytherapy applicator(s). A set of 15 single-depth applicators and one dual-depth applicator were designed and simulated using Monte Carlo (MCNPX). All applicators simulated were high-density tungsten alloy cylinders, 16-mm in diameter, and 60-mm long, with longitudinal grooves within which an (192)Ir source can be placed. The single-depth designs varied regarding the number and depth of these grooves, ranging from 8 to 16 and 1-mm to 3-mm, respectively. The dual-depth design had ten channels, each of which had two depths at which the source could be placed. Optimized treatment plans were generated for each design on data from 13 treated patients (36 fractions) with asymmetrical clinical target volumes (CTVs). All results were compared against the clinically treated plans which used intracavitary mold applicator (ICMA), as well as a recently designed, highly automated, and collimated intensity modulation device named dynamic modulated brachytherapy (DMBT) device. All applicator designs outperformed the ICMA in every calculated dosimetric criteria, except the total dwell times (∼30% increase). There were clear, but relative, tradeoffs regarding both the number of channels and the depth of each channel. Overall, the 12-channel, 1-mm depth, and 14-channel 2-mm depth designs had the best results of the simpler designs, sparing the healthy rectal tissues the most while achieving comparable CTV coverage with the dose heterogeneity index and lateral spill doses improving by over 10% and the contralateral healthy rectum dose dropping over 30% compared to ICMA. The ten-channel dual-depth design outperformed each single-depth design, yielding the best coverage and sparing. New grooved tungsten HDR-brachytherapy devices have been designed and simulated. The results of this work attest to the capability of these new, highly anisotropic, intelligently shielded applicators to limit dose to healthy tissues while maintaining a conformal prescription dose to the CTV.

SU-D-108-06: Dosimetry of 108 Strut-Based Accelerated Partial Breast Irradiation (APBI) Treatments With Applicator Distance Less Than 7 Mm From Both the Skin and Ribs

Purpose: To report on the dosimetry of 108 strut-based APBI treatments where the applicators were less than 7 mm from both the skin and the ribs Methods: Data from 108 patients whose applicators were sandwiched between the skin and ribs were analyzed. The patients were divided into three cohorts: those where the applicator was less than 7 mm from the skin and ribs (n=67), those where the distance was less than 5 mm (n=33), and those with less than 3 mm between both the skin and ribs (n=8). Dosimetric parameters analyzed include PTVEVAL volume (cm3), V90 (%), V95 (%), V100 (%), V150 (cm3), V200 (cm3), and the maximum doses to the skin and ribs. Results: Over all three cohorts the PTV_EVAL volumes ranged from 20.5 cm3 to 125.7 cm3 with a median value of 55.5 cm3. In each of the three groups, the V90 averaged between 94% and 95%, the V95 averaged between 90% and 92%, and the V100 averaged between 85% and 87%. The average V150 ranged between 21.8 cm3 and 26.6 cm3, and the average V200 ranged from 10.9 cm3 to 13.1 cm3. Across the three cohorts, the maximum skin dose ranged from 8.4% of the prescription dose to 117% of the prescription dose (median values were between 85% and 87%) and the maximum rib dose fell between 1.8% of the prescription dose and 198% of the prescription dose with the median values falling between 100% and 107%. Conclusion: This study demonstrates the dosimetric versatility of the strut-based brachytherapy device. It has been used in patients where the proximity of the skin and chest wall precludes the use of other types of single-entry brachytherapy devices. It allows for optimized dose coverage of the target while providing dose sparing to the adjacent critical structures. This project was partially funded by Cianna Medical, Inc.

SU-E-T-337: Intensity Modulated Brachytherapy for Rectal Cancer Using A Novel Grooved Shielding Design

Purpose: To create a novel HDR (192‐Ir) brachytherapy applicator for treatment of rectal carcinomas that uses tungsten shielding to make it dosimetrically superior to all commercially available applicators, despite being no larger than them. Methods: A set of 16 new applicators were designed and simulated using Monte Carlo (MCNPX). All designs were made of a 16‐mm diameter, high density tungsten alloy cylinder with inset grooves running along its length for the source to travel along. The designs varied regarding the number and depth of these grooves. Each design was optimized on 36 clinically treated plans (using 8‐channel Intracavitary Mold Applicator (Nucletron)) with asymmetrical CTVs, on in‐house written intensity modulated brachytherapy planning optimization software. Additionally, a 10 channel device with two channels per groove at varying depths was considered. All results were compared against the clinically treated plans. Results: First, all device designs outperformed the Intracavitary Mold Applicator in EVERY metric, except the total dwell times (about 30% increase). There were clear but relative tradeoffs regarding both the number of channels and the depth of each channel. Overall, the 12‐channel, 1‐mm depth design had the best results of the simpler designs, sparing the healthy rectal tissues the most while achieving comparable CTV coverage. All designs significantly outperformed the clinically treated plans using the Intracavitary Mold Applicator. Conclusions: Our extensive simulations and planning showed that our device designs have the ability to conform to the CTV and spare OAR with previously unmatched quality compared to existing commercial brachytherapy devices.

Apport de l’imagerie 3D en curiethérapie : quel type d’imagerie pour quelle localisation ?

The use of image-guided brachytherapy has led to a significant change in application techniques and improvements in treatment planning. Today, 3D imaging has replaced orthogonal radiographs for a large number of treatments, providing a possibility of an optimization adapted to the anatomy of each patient. When properly selected and implemented, this imaging provides accurate 3D information of volumes and brachytherapy device, allowing moving from a dose to points assessment to a dose/volume evaluation. This article describes the contribution of different imaging modalities for the different brachytherapy techniques: gynecological brachytherapy, interstitial brachytherapy (breast, penis, etc.) and prostate brachytherapy. It reminds recommendations for the establishment of protocols of images acquisition and 3D reconstruction of brachytherapy devices (applicators, plastic tubes, needles, etc.).

Low-Kilovoltage, Single-Dose Intraoperative Radiation Therapy for Breast Cancer: Results and Impact on a Multidisciplinary Breast Cancer Program

The Intrabeam (Carl Zeiss) brachytherapy device (IB) is an electronic brachytherapy device that can be used to deliver low energy x-rays (50 kV) to a lumpectomy cavity at the time of lumpectomy for breast cancer. Reported experience with IB for breast cancer in the United States has been extremely limited. Here we describe our experience and analyze the impact of IB on our multidisciplinary breast cancer program. This is a retrospective review of a prospectively collected breast cancer database. Patient characteristics, treatment characteristics, recurrence, and cosmesis were analyzed. Cost data were also analyzed to determine the impact of IB on the breast cancer program. Seventy-eight patients underwent 80 IB treatments in this series between November 2010 and October 2012. Most patients had invasive ductal carcinoma. Mean total operative time for patients receiving lumpectomy, sentinel node biopsy, and IB was 132 minutes (range 79 to 243 minutes). Intrabeam brachytherapy was the only adjuvant radiation required in 81% of patients, and only 15% of patients required additional operation after the index lumpectomy procedure. At 12 months of follow-up, cosmesis was good to excellent in 92% of patients. There have been no local recurrences in patients treated in this series. Intrabeam brachytherapy is associated with considerably lower costs ($1,857) than conventional whole breast radiation therapy ($9,653). Implementation of IB impacts treatment planning and operating room use in a multidisciplinary breast cancer program. The safety profile, ease of administration, and reduced costs of IB favor its more widespread use in selected patients with early-stage breast cancer.

Abstract P4-16-09: Dosimetric feasibility and acute toxicity in a prospective trial of ultra-short course accelerated partial breast irradiation (APBI) using a multi-lumen balloon brachytherapy device

Abstract Background: Shorter courses of APBI with novel fractionation schedules are being investigated; a large randomized trial from Europe has recently shown the safety and efficacy of a single-fraction adjuvant approach (with limited follow-up). We designed a prospective trial to identify and address the potential radiobiological and logistical limitations of single-fraction, intraoperative APBI. Methods: We designed a single-arm, multi-institutional, prospective phase II trial that sequentially treats three cohorts of women (each n=30) with three progressively hypofractionated schedules. Eligible women were age ≥ 50 years with unifocal invasive or in situ tumors ≤ 3.0 cm, excised with negative margins, and with negative lymph nodes and positive hormone-receptors. Using a reference schedule of 60 Gy delivered in 2 Gy fractions, and assuming tumor parameters: a/b = 4 Gy; a = 0.27 Gy-1, and repopulation parameters of: Teff = 26 days; delay time = 0 days, the reference tumor BED is ∼ 86 Gy4. We began with a schedule of 4 fractions of 7 Gy delivered twice-daily using a Contura MLB multi-lumen device. We defined very conservative dosimetric criteria for acceptability: maximum skin and rib dose to not exceed 100% of prescription dose, and V150 and V200 to not exceed 40 cc and 10 cc, respectively. Subsequent schedules are 3 fractions of 8.25 Gy and 2 fractions of 10.25 Gy, both delivered over 2 days. The primary endpoint is to exclude a local failure rate exceeding 10% with the upper limit of a 95% confidence interval. Results: A total of 30 patients have been enrolled at the 7 Gy × 4 fractions dose-level and followed for a minimum of 6 months. The median skin dose as a percent of prescription dose (PD) was 84% (40–100) and the median rib dose was 71% (16–119). 96% of the PTV_eval received a median of 95% of PD (range 85–103). The V150 (range 14–48cc) and V200 (range 0–29cc) criteria were met in all cases. One breast infection occurred and was treated; 2 cases of symptomatic fat necrosis and 2 cases of symptomatic seromas occurred. No acute toxicities greater than CTCAE grade 2 have been observed. Conclusion: Short-course APBI is dosimetrically feasible using the Contura MLB and appears to be tolerable in terms of acute toxicities. Our approach is based on well-defined radiobiological parameters and allows for an abbreviated course of treatment that is guided by full pathological review and the ability to objectively achieve and validate acceptable dosimetric criteria in each case. We have opened enrollment to the next schedule of 8.25 Gy for three fractions. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-16-09.

Dosimetric Feasibility and Acute Toxicity in a Prospective Trial of Ultrashort-Course Accelerated Partial Breast Irradiation (APBI) Using a Multi-Lumen Balloon Brachytherapy Device

Shorter courses of APBI, including single-fraction intraoperative therapy, are under active investigation. We designed a prospective trial to identify and address the potential radiobiological and logistical shortcomings of single-fraction APBI. We designed a single-arm, multi-institutional, prospective phase II trial that sequentially treats 3 cohorts of women (each n=30) with 3 progressively hypofractionated schedules. Eligible women were age ≥50years with unifocal invasive or in situ tumors ≤3.0cm, excised with negative margins, and with negative lymph nodes and positive hormone receptors. We defined strict dosimetric criteria for appropriateness. A total of 30 patients were enrolled at the 7Gy×4 fractions dose-level and followed for 6months. The median skin dose as a percent of prescription dose (PD) was 84% (40-100), and the median rib dose was 71% (16-119). Also, 95% of the PTV_eval received a median of 95% of PD (range 85-103). The V150 (range 14-48cc) and V200 (range 0-29cc) criteria were met in all cases. One breast infection occurred and was treated; 2 cases of symptomatic fat necrosis and 2 cases of symptomatic seromas occurred. Short-course APBI is dosimetrically feasible using the Contura MLB and appears to be tolerable in terms of acute toxicities. Our approach is based on well-defined radiobiological parameters and allows for an abbreviated course of treatment that is guided by full pathological review and the ability to objectively achieve and validate acceptable dosimetric criteria in each case. We have opened enrollment to the next schedule of 8.25Gy for 3 fractions.

Accelerated partial breast irradiation using a strut-based brachytherapy device: A multi-institutional initial report on acute and late toxicity with greater than 24-month follow-up.

149 Background: Accelerated partial breast irradiation (APBI) is commonly used in early-stage breast cancer. The SAVI Collaborative Research Group is a multi-institutional group created to study outcomes in patients who received APBI utilizing strut-based brachytherapy. This analysis reports the acute and late toxicities for patients with greater than 2-year follow-up (F/U) from this study. Methods: 904 APBI patients (ductal carcinoma in situ [n=267] or invasive breast cancer [n=637]), received HDR brachytherapy (34 Gy in 10 fractions) using the SAVI device (Cianna Medical). Patients with dosimetry and documented follow-up were evaluated within 6 weeks of treatment for early adverse events (AEs), and at 1 year, 2 years, and beyond for late AEs. Dosimetric parameters were evaluated with respect to toxicity and will be presented. Results: In 212 patients (median age 62.9 years, range 40-88) all with follow-up greater than 24 months, the median tumor size was 12mm. As of last follow-up (&gt;24 months) cumulative rates of erythema and hyperpigmentation of grade 2 or higher were 1.4% and 0.5%. The incidence of grade 2 or higher telangiectasia, seroma and fat necrosis were 2.8%, 2.8%, and 0.5% respectively. Conclusions: Adverse events for APBI with SAVI are low in incidence, low in grade and compare favorably to other HDR APBI methods.

Microbrachytherapy using holmium-166 acetylacetonate microspheres: A pilot study in a spontaneous cancer animal model

Holmium-166 acetylacetonate microspheres ((166)Ho-AcAc-MS) are proposed as an intratumoral radioablation device. This article presents a pilot study in housecats with unresectable liver cancer. Feasibility and tolerability of intratumoral administrations of (166)Ho-AcAc-MS was investigated. Three cats with unresectable liver tumors of different histotype were included. One cat had hepatocellular carcinoma (HCC), one had cholangiocarcinoma (CC), and one had a malignant epithelial liver tumor (MELT) of unspecified histotype. (166)Ho-AcAc-MS were injected percutaneously under ultrasound guidance into the tumors. Followup consisted of physical examinations and hematologic and biochemical analyses. (166)Ho-AcAc-MS were administered to three liver tumor-bearing cats. The treatment was well tolerated and the clinical condition, that is body weight, alertness, mobility, and coat condition of the animals improved markedly. Most biochemical and hematologic parameters normalized shortly after treatment. Life of all cats was extended and associated with a good quality of life. The HCC cat that received 33-Gy tumor-absorbed dose was euthanized 6 months after the first administration owing to disease progression. The MELT cat received 99-Gy tumor dose and was euthanized 3 months posttreatment owing to bacterial meningitis. The CC cat received 333Gy and succumbed 4 months after the first treatment owing to the formation of a pulmonary embolism. Percutaneous intratumoral injection of radioactive (166)Ho-AcAc-MS is feasible in liver tumor-bearing cats. The findings of this pilot study indicate that (166)Ho-AcAc-MS may constitute safe brachytherapeutic microspheres and warrant studies to confirm the clinical utility of this novel brachytherapy device.

SU-E-T-308: Dosimetry of a New Minimally Invasive Episcleral Brachytherapy Device.

Describe the dosimetry of an episcleral brachytherapy device. The SMD-I device is designed to treat exudative age-related macular degeneration (AMD) and employs a Sr-90/Y-90 source encapsulated in a stainless steel cylinder. The source is welded to a flexible wire allowing it to travel from a shielded vault in the SMD-I handle to the distal end of a curved cannula to deliver a therapeutic dose of radiation through the sclera to the neovascular target in the subchoroidal space. The SMD-I handle and vault are comprised of Ultem, a lightweight radiation tolerant plastic, which shields the surgeon. Dose calculations were performed using the MCNPX radiation transport code. The absolute dose rate was determined using radiochromic film (GAFChromatic© MD-55) at a point in solid water 2.0mm from the source center perpendicular to the cannula. Dose rates at several depths were measured using Kodak EDR2 film in water equivalent phantoms to compare with the absolute dose rate measurement and MCNPX calculations. The surgeon's hand dose received while manipulating the device with the source in the vault was measured using standard TL (thermoluminescence) finger ring dosimeters, TL ChipstratesTM, and calculated with MCNPX. The absolute dose rate 2.0mm from the source center is 0.45 Gy/min/mCi. The EDR2 film results agree with the absolute dose measurement and the MCNPX calculations. The dose rate decreases rapidly with depth so that the dose at the target depth (3mm) is approximately 8 times less than at 1mm depth (sclera). The dose distribution is sensitive to the angle between the cannula and the neovascular plane. Both TL methods yield a maximum dose rate of 6 μSv/min mCi to the surgeon's fingers consistent with the MCNPX calculation. The SMD-I device permits accurate delivery of a therapeutic radiation dose for the treatment of exudative AMD. Russell J. Hamilton is a founder and currently serves on the Scientific Advisory Board of Salutaris Medical Devices, Inc. Wendell Lutz and Thomas Cetas serve on the Scientific Advisory Board of Salutaris Medical Devices, Inc. All authors have received financial support from Salutaris Medical Devices, Inc.

1229 ROBOT-ASSISTED LAPAROSCOPIC INTRAOPERATIVE BRACHYTHERAPY: A PORCINE TRIAL

You have accessJournal of UrologyTechnology & Instruments: Robotics - Malignant Disease & Benign Disease I1 Apr 20121229 ROBOT-ASSISTED LAPAROSCOPIC INTRAOPERATIVE BRACHYTHERAPY: A PORCINE TRIAL Jennifer Yates, Dan Smith, Stephen Musialek, Ravi Munver, Ihor Sawczuk, Samay Jain, and Loren Godfrey Jennifer YatesJennifer Yates Hackensack, NJ More articles by this author , Dan SmithDan Smith Teaneck, NJ More articles by this author , Stephen MusialekStephen Musialek Hackensack, NJ More articles by this author , Ravi MunverRavi Munver Hackensack, NJ More articles by this author , Ihor SawczukIhor Sawczuk Hackensack, NJ More articles by this author , Samay JainSamay Jain Hackensack, NJ More articles by this author , and Loren GodfreyLoren Godfrey Hackensack, NJ More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1519AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Intraoperative brachytherapy using an electronic brachytherapy source is currently utilized for dermatologic and breast malignancies. Patients with advanced urologic disease are often treated with multimodal therapy, including surgical excision and postoperative radiotherapy. Delivery of intraoperative brachytherapy at the time of surgery is limited in part by the radiation source and a means of delivering the brachytherapy in a minimally-invasive fashion. The Xoft electronic brachytherapy device is portable and does not require operative room shielding. A minimally-invasive intraoperative radiotherapy (IORT) technique has been developed which utilizes the robotic platform, the Xoft electronic brachytherapy source, and minimally-invasive applicators. The feasibility of applying this system to a pelvic target in the porcine model was explored. METHODS In-vivo trials were conducted at the David Jurist Research Institute at Hackensack University Medical Center after obtaining IACUC Board approval. A DaVinci standard Robotic Surgical System was used to manipulate minimally-invasive brachytherapy applicators and Axxent electronic brachytherapy catheters (Xoft Inc., Sunnyvale, CA). A porcine pelvic target was identified that served as a surrogate for periprostatic tissue in the human patient. RESULTS Trocars were placed in a fashion similar to a prostatectomy template, with three robotic arms (8 mm trocars) and one 12 mm assistant trocar utilized. Two of the robotic arms were equipped with grasping instruments, and the third robotic arm was equipped with a forceps to manipulate the GafChromic paper. The Axxent electronic brachytherapy applicator was advanced through the 12 mm assistant trocar. While the minimally-invasive applicator was held in position with the robotic instruments, the brachytherapy catheter was used to deliver a prescribed brachytherapy treatment plan to the target. The minimally-invasive applicator could access the targeted site. Optimal stability of the applicator required two robotic arms. On average, five minutes were required to introduce, place, and stabilize the applicator. CONCLUSIONS The minimally invasive IORT system described above can be reproducibly deployed in-vivo. Additional in-vivo studies are needed to further characterize systematic and operator dependent variance and perform quantitative dose analysis. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e497 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jennifer Yates Hackensack, NJ More articles by this author Dan Smith Teaneck, NJ More articles by this author Stephen Musialek Hackensack, NJ More articles by this author Ravi Munver Hackensack, NJ More articles by this author Ihor Sawczuk Hackensack, NJ More articles by this author Samay Jain Hackensack, NJ More articles by this author Loren Godfrey Hackensack, NJ More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...