Faculty Bibliography

It has been suggested that the combination of intravascular brachytherapy and coronary stent implantation may result in further reduction of restenosis after percutaneous balloon angioplasty. The use of an angioplasty balloon filled with a 188Re liquid beta source for intravascular brachytherapy provides the advantages of accurate source positioning and uniform dose distribution to the coronary vessel wall. The effect of source edge and stent on the dose distribution of the target tissue may be clinically important. In BANG gels, the absorbed radiation produces free-radical chain polymerisation of acrylic monomers that are initially dissolved in the gel. The number of polymer particles is proportional to the absorbed dose. In this study, 3D dose distributions are presented for 188Re balloons, with and without stents, using a prototype He-Ne laser CT scanner and the proprietary BANG polymer gel dosemeters

Conventional B-mode ultrasound is the standard means of imaging the prostate for guiding prostate biopsies and planning brachytherapy of prostate cancer. Yet B-mode images do not allow adequate visualization of cancerous lesions of the prostate. Ultrasonic tissue-typing imaging based on spectrum analysis of radiofrequency echo signals has shown promise for overcoming the limitations of B-mode imaging for visualizing prostate tumors. Tissue typing based on radiofrequency spectrum analysis uses nonlinear methods, such as neural networks, to classify tissue by using spectral-parameter and clinical-variable values. Two- and three-dimensional images based on these methods show potential for improving the guidance of prostate biopsies and the targeting of radiotherapy of prostate cancer. Two-dimensional images have been imported into instrumentation for real-time biopsy guidance and into commercial dose-planning software for brachytherapy planning. Three-dimensional renderings seem to be capable of depicting locations and volumes of cancer foci

PURPOSE: A subgroup of prostate cancer patients who have experienced biochemical relapse after radical retropubic prostatectomy (RRP) can benefit from radiation therapy to the prostate fossa. These patients demonstrate biochemical relapse secondary to local failure in the absence of distant failure. In order to define this subgroup, we investigated the impact of pathological and biochemical variables and pre-radiation therapy biopsy of the prostate fossa on biochemical disease-free survival (bNED) and initial prostate-specific antigen response. METHODS: Sixty-two patients with localized prostate cancer who had biochemical relapse after RRP were treated with post-RRP radiation therapy localized to the prostate fossa (median dose, 6120 cGy) and were subsequently followed up for a median time of 47 months. Cox regression analyses and Kaplan-Meier estimates for bNED were used to identify prognostic variables. The Fisher's exact test was used to test the interaction of initial prostate-specific antigen response with identified prognostic variables. RESULTS: Cox regression analysis of bNED as a function of pathological and biochemical parameters showed that only Gleason's score was a significant predictor of bNED. On univariate analysis, seminal vesicle involvement was also found to be a significant predictor. Prostate fossa biopsy result was not significantly related to bNED. Because of the overall high rates of biochemical failure, we wished to identify a high-risk subgroup that did not have local relapse as a component of biochemical relapse after RRP. We assessed initial biochemical response following radiation therapy as a surrogate for local relapse. A complete biochemical response was observed in 50% of patients, and a partial biochemical response was observed in an additional 34%, yielding an overall biochemical response rate of 84%. When stratified by Gleason's score, seminal vesicle, pre-radiation therapy prostate-specific antigen, and biopsy result, response rates greater than 50% were seen for all subgroups. CONCLUSIONS: Gleason's score and seminal vesicle involvement predicted bNED after post-RRP radiation therapy in our cohort. Overall biochemical response rates were high in all subgroups, suggesting that all subgroups demonstrated a high likelihood of residual local disease as a component of failure. Pre-radiation therapy biopsy was predictive of neither bNED nor overall biochemical response

Conventional B-mode ultrasound currently is the standard means of imaging the prostate for guiding prostate biopsies and planning brachytherapy to treat prostate cancer. Yet B-mode images do not adequately display cancerous lesions of the prostate. Ultrasonic tissue-type imaging based on spectrum analysis of radiofrequency (rf) echo signals has shown promise for overcoming the limitations of B-mode imaging for visualizing prostate tumors. This method of tissue-type imaging utilizes nonlinear classifiers, such as neural networks, to classify tissue based on values of spectral parameter and clinical variables. Two- and three-dimensional images based on these methods demonstrate potential for guiding prostate biopsies and targeting radiotherapy of prostate cancer. Two-dimensional images are being generated in real time in ultrasound scanners used for real-time biopsy guidance and have been incorporated into commercial dosimetry software used for brachytherapy planning. Three-dimensional renderings show promise for depicting locations and volumes of cancer foci for disease evaluation to assist staging and treatment planning, and potentially for registration or fusion with CT images for targeting external-beam radiotherapy

Conventional B-mode ultrasound is the standard means of imaging the prostate for guiding prostate biopsies and planning radiotherapy (i.e., brachytherapy and external-beam radiation) of prostate cancer (CaP). Yet B-mode images essentially do not allow visualization of cancerous lesions of the prostate. Ultrasonic tissue-typing imaging based on spectrum analysis of radiofrequency (RF) echo signals has shown promise for overcoming the limitations of B-mode imaging in distinguishing cancerous from common forms of non-cancerous prostate tissue. Such tissue typing utilizes non-linear methods, such as nearest-neighbor and neural-network techniques, to classify tissues based on spectral-parameter and clinical-variable values. Our research seeks to develop imaging techniques based on these methods for the purpose of improving the guidance of prostate biopsies and the targeting of brachytherapy and external-beam radiotherapy of prostate cancer. Images based on these methods have been imported into real-time instrumentation for biopsy guidance and into commercial dose-planning software for real-time brachytherapy. Three-dimensional renderings show locations and volumes of cancer foci. These methods offer exciting possibilities for effective low-cost depiction of prostate cancer in real-time and off-line images. Real-time imaging showing cancerous regions of the prostate can be of value in directing biopsies, determining whether biopsy is warranted, assisting in clinical staging, targeting brachytherapy, planning conformal external-beam radiation procedures, and monitoring treatment