Biomedical subjects

Adam Dickler

Publications and source records attributed to Adam Dickler.

9 recordsLinked to original sources

PubMed2005

Surface optimization technique for MammoSite breast brachytherapy applicator.

PURPOSE: We present a technique to optimize the dwell times and positions of a high-dose-rate (192)Ir source using the MammoSite breast brachytherapy applicator. The surface optimization method used multiple dwell positions and optimization points to conform the 100% isodose line to the surface of the planning target volume (PTV). METHODS AND MATERIALS: The study population consisted of 20 patients treated using the MammoSite device between October 2002 and February 2004. Treatment was delivered in 10 fractions of 3.4 Gy/fraction, twice daily, with a minimum of 6 h between fractions. The treatment of each patient was planned using three optimization techniques. The dosimetric characteristics of the single-point, six-point, and surface optimization techniques were compared. RESULTS: The surface optimization technique increased the PTV coverage compared with the single- and six-point methods (mean percentage of PTV receiving 100% of the prescription dose was 94%, 85%, and 91%, respectively). The surface method, single-point, and six-point method had a mean dose homogeneity index of 0.62, 0.68, and 0.63 and a mean full width at half maximum value of 189, 190, and 192 cGy/fraction, respectively. CONCLUSION: The surface technique provided greater coverage of the PTV than did the single- and six-point methods. Using the FWHM method, the surface, single-, and six-point techniques resulted in equivalent dose homogeneity.

Brachytherapy↗

PubMed2005

The MammoSite breast brachytherapy applicator: a review of technique and outcomes.

The MammoSite breast brachytherapy device was designed to overcome the potential scheduling problems associated with external beam radiotherapy (EBRT) and the technical difficulties of multi-catheter-based interstitial brachytherapy. The device consists of a silicone balloon connected to a catheter which contains an inflation channel and a port for passage of a high-dose-rate brachytherapy source. The American Brachytherapy Society and American Society of Breast Surgeons have published partial breast irradiation (PBI) patient selection guidelines. The MammoSite applicator has been shown in two dosimetric studies to treat a comparable volume to multicatheter-based interstitial implants. The MammoSite catheter can be placed at the time of lumpectomy or in a separate procedure using ultrasound guidance. Four optimization methods have been described: the single point method, the six prescription point method (RUSH Technique), the University of Southern California Norris Cancer Center Method, and the Surface Optimization Technique. An excellent or good cosmetic outcome has been reported in 80% to 93% of patients at 1 year in most studies. Cosmetic results appear highly related to skin spacing. The MammoSite applicator has been associated with early side effects comparable with traditional breast conserving therapy. A NSABP trial will randomize patients to either whole breast irradiation or PBI consisting of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal radiation.

Brachytherapy↗

PubMed2005

Vaginal lymphatic channel location and its implication for intracavitary brachytherapy radiation treatment.

PURPOSE: In vaginal intracavitary brachytherapy using cylindrical applicators, it is common to prescribe dose to a depth of 0.5 cm to cover the lymphatic channels. However, the actual depth of the lymphatics within the vaginal wall has never been determined. In this study, we examined the depth distribution of lymphatics lying beneath the mucosal surface of the vagina. METHODS AND MATERIALS: Between January 24, 1996 and October 27, 2003, 31 patients underwent full-thickness vaginal biopsy or partial resection for both benign and malignant disease. In addition, in February 2004, vaginal samples from two autopsy specimens were stretched and pinned for formalin fixation and slide production. Forty-five slides of both stretched and nonstretched vaginal tissue were stained with D2-40 monoclonal antibody lymphatic endothelium marker. The percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were calculated for all slides. RESULTS: For the nonstretched samples, the percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were 50.5%, 30.7%, 11.9%, and 6.9%, respectively. For the stretched samples, the percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were 44.0%, 33.8%, 18.8%, and 3.4%, respectively. The differences of lymphatic percentages within and superficial to 1mm (p=0.60), 1-2mm (p=0.85), 2-3mm (p=0.89), and 3-4mm (p=0.99) were not statistically significant between the stretched and nonstretched states. CONCLUSIONS: Our results show that approximately 95% of vaginal lymphatic channels are located within a 3mm depth from the vaginal surface. This suggests that dose prescribed to a depth less than 0.5 cm may be adequate and could permit treatment with less normal tissue toxicity in certain clinical situations.

Adult↗

PubMed2005

Radiochemotherapy in the management of pancreatic cancer--part II: use in adjuvant and locally unresectable settings.

Inherently, treating pancreatic adenocarcinoma with chemotherapy is limited by the marginal sensitivity of this tumor to available drugs and drug combinations. For radiotherapy, a similar therapeutic insensitivity is adversely combined with a compromised ability to escalate biologic dose within relevant target volumes because of an intertwining and surrounding matrix of dose-limiting critical normal organs and tissues. The need for effective adjuvant therapy has been intensified by an increase in the safety, applicability, and availability of surgical resection even though such resections remain largely inadequate for producing long-term disease-free survival. The need for improved treatments for locally unresectable tumors remains self-evident based on limited prognosis and the frequency of this presentation. Studies in both domains have attempted to incorporate technical advances in radiotherapy planning and delivery (3-dimensional conformal, intensity modulation) as well as the systemic promise and radiosensitizing properties of gemcitabine-based approaches. The challenges of clinical research are well reflected by the controversies resulting from available studies and the difficulties in successfully designing and executing future trials.

Adenocarcinoma↗

PubMed2005

The MammoSite breast brachytherapy device: targeted delivery of breast brachytherapy.

The MammoSite breast brachytherapy device was designed to overcome the logistic difficulties presented by external beam radiation therapy and the technical difficulties of multicatheter-based interstitial brachytherapy. The device consists of a silicone balloon connected to a catheter which contains an inflation channel and a port for passage of a high-dose-rate brachytherapy source. The American Brachytherapy Society and American Society of Breast Surgeons have published partial breast irradiation patient selection guidelines. Initial reports have shown a favorable cosmetic outcome in the majority of patients. The MammoSite applicator has also been associated with minimal side effects. The NSABP B-39/RTOG 0413 trial will randomize patients to either whole breast irradiation or partial-breast irradiation consisting of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal radiation. This national randomized trial has the potential to provide a definitive answer regarding the benefits of partial-breast irradiation, and therefore lead to more women undergoing breast conserving therapy.

Brachytherapy↗

PubMed2004

Treatment volume and dose optimization of MammoSite breast brachytherapy applicator.

PURPOSE: Limited information has been reported on the dosimetry achieved with the MammoSite breast brachytherapy applicator. We present our results regarding the volume of treatment and a comparison of a single prescription point, single dwell position optimization technique with a six prescription point, multiple dwell position method. METHODS AND MATERIALS: Between October 14, 2002 and February 28, 2003, 21 patients with early-stage breast cancer were treated using the MammoSite device. The treatment was delivered in 10 fractions of 3.4 Gy/fraction, b.i.d., with a minimum of 6 hours between the daily fractions. CT of the lumpectomy cavity was obtained both with and without the inflated balloon. A planning target volume was constructed using a three-dimensional planning system. A three-dimensional expansion of the balloon surface was performed using the chest wall and skin as limiting structures. The volume of the inflated balloon was removed from this volume, and the volume of tissue treated in each patient was determined. A sequential expansion in 1-mm increments around the empty lumpectomy cavity was performed until the closest equivalent volume to the planning target volume was obtained. The treatment for the patients in this study was planned using both a single prescription point, single dwell position optimization technique and a six-prescription point, multiple dwell position technique. The single prescription point method has been described in a previous publication. The six-prescription point method used six points placed 1 cm from the balloon surface. Four points are in a plane transverse to the balloon axis perpendicular to the axis of the catheter, and two points are placed along the axis of the catheter. The prescription points along the catheter axis are used to compensate for the decreased dose coverage owing to anisotropy dose distribution of the source. The Nucletron HDR Plato Brachytherapy planning system was used to optimize the source positions and dwell times. RESULTS: The volume of breast tissue treated by the MammoSite device was equal to the volume encompassed by a mean 1.6-cm (SD, 0.1) margin around the empty lumpectomy cavity. Compared with the single prescription point optimization method, the six prescription point method provided better dose coverage, with a mean percentage of volume receiving 90% of the prescription dose of 97.2% (SD = 2.1) vs. 89.5% (SD = 4.6) for the single-point method. The mean percentage of volume receiving 100% of the prescription dose was 88.9% (SD = 3.3) for the six-point method vs. 77.6% (SD = 6.1) for the single-point method. However, compared with the single-point method, the six-point optimization method resulted in treatment that was less uniform, with a mean dose homogeneity index of 0.62 (SD =.07) vs. 0.66 (SD =.08) for the single-point method. CONCLUSION: The volume of normal breast tissue treated by the MammoSite device is comparable to other methods of interstitial brachytherapy that treat a 1-2-cm margin of tissue around the excision cavity. The six-prescription point, multiple dwell position method improved dose coverage with a slight decrease in dose homogeneity. The six-point method offers greater reliability of dose coverage compared with the single-point method by providing an increased number of reference points.

Adult↗

PubMed2004

Dose perturbation induced by radiographic contrast inside brachytherapy balloon applicators.

Phantom measurements and Monte Carlo calculations have been performed for the purpose of characterizing the dose perturbation caused by radiographic contrast inside the MammoSite breast brachytherapy applicator. Specifically, the dose perturbation is quantified as a heterogeneity correction factor (HCF) for various balloon radii and contrast concentration levels. The dose perturbation is larger for larger balloon radii and higher contrast concentrations. Based on a validated Monte Carlo simulation, the calculated HCF values are 0.99 for a 2 cm radius balloon and 0.98 for a 3 cm radius balloon at 6% contrast concentration levels, and 0.89 and 0.87 for 2 and 3 cm radius balloons, respectively, at 100% contrast concentrations. For a typical implanted balloon radius of 2.4 cm, the HCF values decrease from 0.99 at 6% contrast concentration to 0.90 at 100% contrast concentration. For balloons implanted in patients at our institution, the mean HCF is 0.99, corresponding to a dose reduction of approximately 1%. The contrast effect results in a systematic reduction in the delivered dose, therefore the minimal amount of radiographic contrast necessary should be used.

Angiography↗

PubMedDate not supplied

A dosimetric comparison of three-dimensional conformal, intensity-modulated radiation therapy, and MammoSite partial-breast irradiation.

PURPOSE: Limited information is available comparing target volume and normal tissue dosimetry with the different techniques of partial breast irradiation (PBI). We present results of a dosimetric comparison of single catheter, balloon-based brachytherapy using the MammoSite catheter (BRT), 3D conformal radiation therapy (3DCRT), and intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: Fifteen patients were treated using the BRT device. With the use of CT scans with balloons in inflated and deflated states, plans were developed for each patient using each of the methods of PBI, for a total of 45 plans. The plans were then compared using the below dosimetric parameters. RESULTS: The mean V100 was 95%, 92%, and 94% for the BRT, 3DCRT, and IMRT techniques, respectively. The mean ipsilateral breast V50 was 29%, 56%, and 46% (p < 0.0001) and the mean ipsilateral lung V30 was 5%, 7%, and 2% (p < 0.001 for IMRT vs. others) for the BRT, 3DCRT, and IMRT methods, respectively. For the 10 patients with left-sided breast tumors, the mean heart V5 was 12%, 4%, and 1% for the BRT, 3DCRT, and IMRT methods, respectively (p < 0.01). CONCLUSIONS: With increasing interest in PBI, our data may help clinicians individualize patient treatment decisions.

Brachytherapy↗

PubMedDate not supplied

Cosmetic outcome and incidence of infection with the MammoSite breast brachytherapy applicator.

We present our results regarding the cosmetic outcome achieved and the rate of infection using the MammoSite breast brachytherapy applicator to treat patients with partial breast irradiation. In addition, factors associated with cosmetic outcome and infection are analyzed. The study population consisted of 30 patients with early stage breast cancer treated using the MammoSite device from October 28, 2002, to February 13, 2004. Cosmetic outcome was analyzed for its association with the following parameters: volume of the balloon, balloon-to-skin distance, maximal skin point dose per fraction, V100 (percent of volume that received 100% of the prescription dose), V150 (percent of volume that received 150% of the prescription dose), and V200 (percent of volume that received 200% of the prescription dose). The occurrence of infection at the time of treatment and during follow-up was also recorded. At a median follow-up of 13 months (range 1-16 months), 53.3% of the patients (16/30) were reported to have an excellent cosmetic outcome and 40.0% (12/30) had a good cosmetic outcome. Excellent cosmetic outcome was associated with a greater mean balloon-to-skin distance compared to those who achieved a good cosmetic outcome (1.5 cm versus 1.2 cm) (p = 0.164). The mean V100, V150, and V200 of those in the excellent cosmetic outcome group were 92.1%, 34.5%, and 7.6% versus 93.0%, 34.7%, and 7.6% in the good cosmetic outcome group (p = 0.642, 0.926, and 0.853), The mean balloon volumes were 47.7 cm3 and 56.9 cm3, respectively (p = 0.063) in the excellent and good outcome groups. The mean maximal skin doses per fraction in the excellent and good outcome groups were 354.8 cGy and 422.3 cGy (p = 0.286), respectively. Infection occurred in 13.3% of the patients (4/30). An excellent or good cosmetic outcome was achieved in 93.3% of patients and infection occurred in 13.3% of patients treated with the MammoSite breast brachytherapy applicator. Excellent cosmetic outcome was associated with a greater balloon-to-skin distance, lower maximal skin dose per fraction, and smaller mean balloon volume; however, the results did not reach statistical significance.

Adult↗