Prostatic Neoplasms: Prestidge BR

Bice WS, Prestidge BR, Kurtzman SM, Beriwal S, Moran BJ, Patel RR, Rivard MJ, Anonymous00014. · Foundation for Medical Physics Research, San Antonio, TX 78216, USA. · Brachytherapy. · Pubmed #18782682 No free full text.

Abstract: PURPOSE: Published clinical information on the safety and efficacy of (131)Cs implants is limited. We provide consensus recommendations for (131)Cs prostate brachytherapy based on experience to date. METHODS AND MATERIALS: The Cesium Advisory Group (CAG) consists of experienced (131)Cs users. Recommendations are based on three clinical trials, one of which has completed accrual and has been published in the peer reviewed literature, and combined CAG experience of more than 1200 (131)Cs implants. RESULTS: We recommend using 1.059cGyh(-1)U(-1) as the dose rate constant for the IsoRay source. The prescription for monotherapy implants is 115Gy and when combined with 45-50Gy external beam it is 85Gy. Suggested individual source strength ranges from 1.6 to 2.2U. The release criterion for (131)Cs implants is 6mRh(-1) at 1m. (131)Cs brachytherapy should be performed differently from (125)I and (103)Pd brachytherapy: source placement is further from the urethra and rectum; the prostate V(150) should be < or =45%; sufficient margins may be obtained while limiting source placement to the capsule or close to the capsule. The increased dose rate may cause degradation of postimplant quantifiers due to edema. However, large variability in the magnitude and rate of resolution of edema make determination of the most representative postoperative imaging time impossible. The CAG recommends postimplant imaging on the day of the implant. Recommended postimplant evaluation goals include prostate D(90) greater than the prescription dose; maintaining D(u)(,30)<140% of the prescription dose and keeping V(r)(,100)<0.5cm(3). CONCLUSION: It was the consensus of the CAG that optimal (131)Cs implants should be performed differently from those performed with (125)I or (103)Pd. Guidelines have been established to allow for safe and effective delivery of (131)Cs prostate brachytherapy.

Beyer GP, Scarantino CW, Prestidge BR, Sadeghi AG, Anscher MS, Miften M, Carrea TB, Sims M, Black RD. · Sicel Technologies, Morrisville, NC 27560, USA. · Int J Radiat Oncol Biol Phys. · Pubmed #17889274 No free full text.

Abstract: PURPOSE: To perform a comparison of the daily measured dose at depth in tissue with the predicted dose values from treatment plans for 29 prostate cancer patients involved in a clinical trial. METHODS AND MATERIALS: Patients from three clinical sites were implanted with one or two dosimeters in or near the prostatic capsule. The implantable device, known as the DVS, is based on a metal-oxide-semiconductor field effect transistor (MOSFET) detector. A portable telemetric readout system couples to the dosimeter antenna (visible on kilovoltage, computed tomography, and ultrasonography) for data transfer. The predicted dose values were determined by the location of the MOSFET on the treatment planning computed tomography scan. Serial computed tomography images were taken every 2 weeks to evaluate any migration of the device. The clinical protocol did not permit alteration of the treatment parameters using the dosimeter readings. For some patients, one of several image-guided radiotherapy (RT) modalities was used for target localization. RESULTS: The evaluation of dose discrepancy showed that in many patients the standard deviation exceeded the previous values obtained for the dosimeter in a phantom. In some patients, the cumulative dose disagreed with the planned dose by > or =5%. The data presented suggest that an implantable dosimeter can help identify dose discrepancies (random or systematic) for patients treated with external beam RT and could be used as a daily treatment verification tool for image-guided RT and adaptive RT. CONCLUSION: The results of our study have shown that knowledge of the dose delivered per fraction can potentially prevent over- or under-dosage to the treatment area and increase the accuracy of RT. The implantable dosimeter could also be used as a localizer for image-guided RT.

Scarantino CW, Prestidge BR, Anscher MS, Ferree CR, Kearns WT, Black RD, Bolick NG, Beyer GP. · Sicel Technologies Inc., Morrisville, NC, USA. · Int J Radiat Oncol Biol Phys. · Pubmed #18793963 No free full text.

Abstract: PURPOSE: Report the results of using a permanently implantable dosimeter in radiation therapy: determine specific adverse events, degree of migration, and acquire dose measurements during treatment to determine difference between expected and measured dose. METHODS AND MATERIALS: The Dose Verification System is a wireless, permanently implantable metal-oxide semiconductor field-effect transistor dosimeter using a bidirectional antenna for power and data transfer. The study cohort includes 36 breast (33 patients received two devices) and 29 prostate (21 patients received two devices) cancer patients. A total of 1,783 and 1,749 daily dose measurements were obtained on breast and prostate patients, respectively. The measurements were compared with the planned expected dose. Biweekly computed tomography scans were obtained to evaluate migration and the National Cancer Institute's Common Toxicity Criteria, version 3, was used to evaluate adverse events. RESULTS: Only Grade I/II adverse events of pain and bleeding were noted. There were only four instances of dosimeter migration of >5 mm from known factors. A deviation of > or =7% in cumulative dose was noted in 7 of 36 (19%) for breast cancer patients. In prostate cancer patients, a > or =7% deviation was noted in 6 of 29 (21%) and 8 of 19 (42%) during initial and boost irradiation, respectively. The two patterns of dose deviation were random and systematic. Some causes for these differences could involve organ movement, patient movement, or treatment plan considerations. CONCLUSIONS: The Dose Verification System was not associated with significant adverse events or migration. The dosimeter can measure dose in situ on a daily basis. The accuracy and utility of the dose verification system complements current image-guided radiation therapy and intensity-modulated radiation therapy techniques.

Frank SJ, Grimm PD, Sylvester JE, Merrick GS, Davis BJ, Zietman A, Moran BJ, Beyer DC, Roach M, Clarke DH, Stock RG, Robert Lee W, Michalski JM, Wallner KE, Hurwitz M, Potters L, Kuban DA, Prestidge BR, Vera R, Hathaway S, Blasko JC. · Department of Radiation Oncology, The University of Texas, M. D. Anderson Cancer Center, Houston, TX 77030, USA. · Brachytherapy. · Pubmed #17284379 No free full text.

Abstract: PURPOSE: This study is aimed at understanding and defining the current patterns of care with respect to prostate brachytherapy for patients with intermediate-risk localized disease in the combined academic and community setting. METHODS AND MATERIALS: A nomogram-based survey was developed at the Seattle Prostate Institute defining the accepted criteria for intermediate-risk prostate cancer. Patients were defined as having intermediate-risk prostate cancer if they met one of the following criteria: prostate-specific antigen (PSA) >10 ng/dL, Gleason score (GS) > or = 7, or cT2b or cT2c disease. Additional potential predictive factors including perineural invasion (PNI), GS 3+4 vs. 4+3, and high-volume disease were included. RESULTS: In the absence of PNI, all of those surveyed would perform monotherapy for intermediate-risk patients, GS 7 (3+4) or PSA 10-20, with cT1c and <30% cores +. Up to 80% would perform monotherapy for patients with cT1c, GS 7 (4+3), and <30% cores +. Eighty to 90% of physicians would perform an implant alone with cT2a and either a PSA of 10-20 or GS of 7 (3+4) and <30% cores +. Fifty to 60% of those surveyed stated that they would treat a patient with cT2b disease, GS 7 (3+4), or PSA 11-20, with less than two-thirds of the biopsy cores positive in the absence of PNI. CONCLUSIONS: This Patterns of Care (POC) study reveals that certain subsets of intermediate-risk localized prostate cancer patients are considered appropriate candidates for an interstitial implant alone.

Bice WS, Prestidge BR, Sarosdy MF. · University of Texas Health Science Center at San Antonio, USA. · Med Phys. · Pubmed #11797961 No free full text.

Abstract: The analysis of treatment plans generated following prostate implants (post plans) is an essential part of the patient's treatment regimen. The results are used to determine the adequacy of the individual implant and, just as importantly, to provide an evaluation of the institution's brachytherapy technique. Compiled post plan results can be used to compare data from different institutions and help determine guidelines that should be established as dosimetric goals. Sector analysis, or spatial dose mapping, is a novel method of analyzing brachytherapy results that has been developed for this purpose. The display of isodose curves provides spatial information pertaining to the dosimetric evaluation of post plans but is an unwieldy tool; ill suited to the creation of general conclusions for comparative efforts. Dose-volume histogram (DVH) analysis is an excellent tool for examining dosimetric results, but the spatial information is lost. Sector analysis bridges the gap between isodose curves and DVH analysis in post plan analysis. To perform sector analysis we divide the gland into three regions in the cranial-caudal direction (base, midgland, and apex) and four regions on each transverse slice (anterior, posterior, left and right). This gives twelve sectors, each identified by its location in the cranial-caudal direction and position on the transverse slice, e.g., posterior midgland. DVH analysis is performed for each region separately and compiled for display. We present an example of the use of this technique wherein we have analyzed a sequential series of 118 implants performed by a single practitioner (BRP) at two institutions over a calendar year. The implants were performed using two different techniques at the two institutions. Sector analysis was used to compare the results of the implants at the two institutions.

Bice WS, Freeman JE, Russell LF, Case GD, Dubois DF, Prete JJ, Prestidge BR. · University of Texas Health Science Center at San Antonio, Texas, USA. · Tech Urol. · Pubmed #10798817 No free full text.

Abstract: PURPOSE: We describe a method of performing salvage prostate brachytherapy on patients whose initial implant was suboptimal. This technique uses an image correlation algorithm only previously used to fuse postimplant magnetic resonance and computed tomographic (CT) images. Here, the initial postimplant CT and the second preimplant volume study are coregistered to plan delivery of the salvage implant. MATERIALS AND METHODS: Two early-stage patients had salvage implants performed with this technique, in which only a limited number of sources were visible on the ultrasound images. The dosimetric results of the first implant were displayed on the preplan generated for the second procedure. The planned total dose then was visualized prior to salvage implant. RESULTS: The implants were performed without complication. Rectum and urethra doses remained acceptable. In each case, the improvement in coverage of the gland was dramatic (V80 coverage improved from 65.2% and 47.3% to 93.1% and 92.2%, respectively), precluding the need for further intervention. CONCLUSIONS: Coregistration of the postimplant CT scan to an ultrasound volume study can be quantifiably and reliably performed. The resulting image set can be used to guide needle placement during a second salvage implant to achieve much improved dosimetric coverage of the gland.

Bice WS, Dubois DF, Prete JJ, Prestidge BR. · University of Texas Health Science Center, San Antonio 78229, USA. · Med Phys. · Pubmed #10505881 No free full text.

Abstract: The use of axial image sets has become widely used to localize interstitial brachytherapy sources. One application of this method of localization is to perform post-implant dosimetry following transperineal interstitial permanent prostate brachytherapy (TIPPB) where the target structure and the source locations are displayed on the same image. The design of an appropriate scanning sequence often results in abutting slices of an intermediate slice width (3, 4, or 5 mm). Because a single source may be imaged on more than one slice, the resultant scans always show many more source locations than actual sources implanted. The physicist is then faced with the tedious task of determining which sources appear on more than one slice and deciding which source locations to eliminate from the data set. We have developed an algorithm, similar to one employed by Roy et al., which automates this process by relaxing the nearest neighbor criterion until the number of sources is reduced to either the number of sources implanted or the number counted on a projection radiograph. This paper details this algorithm and the results of its application to phantom studies, comparing to known source locations, as well as clinical studies, comparing to orthogonal film source localization, on a series of ten patients. Phantom studies demonstrate the superiority of the algorithm over orthogonal film reconstruction, locating 100% of the sources within 5 mm of the actual location as compared to 66% for the paired radiographs. The clinical study findings are commensurate with these results, with 72% of the sources on average located within 5 mm of the corresponding source in the other data set. The positive correlation of the quality of the orthogonal film reconstruction results with the quality of the coregistration results suggests that differences in registration between the two data sets may be due primarily to the uncertainties in the orthogonal film reconstruction.

Prestidge BR, Bice WS. · No affiliation provided · Cancer. · Pubmed #15861416 links to  free full text

This publication has no abstract.

Bice WS, Prestidge BR, Sarosdy MF. · No affiliation provided · Int J Radiat Oncol Biol Phys. · Pubmed #11163528 No free full text.

This publication has no abstract.