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Brian J Davis

Publications and source records attributed to Brian J Davis.

At least 19 recordsLinked to original sources
PubMed2006

Combined prostate brachytherapy and short-term androgen deprivation therapy as salvage therapy for locally recurrent prostate cancer after external beam irradiation.

PURPOSE: We describe the treatment outcome in 17 patients who received combined salvage brachytherapy and short-term androgen deprivation therapy for local prostate cancer relapse after prior external beam irradiation. MATERIALS AND METHODS: Median patient age was 68 years. Local relapse after external beam irradiation was confirmed by biopsy. Median prostate specific antigen at local relapse was 4.7 ng/ml. Five of the 17 patients were enrolled in a protocol combining androgen deprivation therapy with brachytherapy and the remaining men were treated off protocol. All patients received neoadjuvant androgen deprivation therapy for a median of 3 months, followed by ultrasound guided brachytherapy using 125I in 9 and 103Pd seeds in 8. Five patients also received adjuvant leuprolide for a median of 6 months. Biochemical failure was defined using the American Society for Therapeutic Radiology and Oncology definition. Toxicity was graded with a modified Radiation Therapy Oncology Group scale. RESULTS: Median followup was 44 months. The actuarial 4-year biochemical control rate was 75%. Three patients died of intercurrent diseases. No prostate cancer mortality or local failure had occurred at last followup. One patient had bone metastasis. No clinical or treatment factor was associated with biochemical control. Grade 3 and 4 genitourinary toxicity developed in 7 (41%) and 1 patients (6%), respectively. Grade 2 and 3 gastrointestinal toxicity occurred in 5 (29%) and 1 patients (6%), respectively. CONCLUSIONS: Our series suggests that salvage brachytherapy and short-term androgen deprivation therapy can achieve biochemical control in select patients with local relapse after prior external beam irradiation. The major side effects are urinary complications, including grade 3 and 4 complications in 41% and 6% of cases, respectively.

Aged↗
PubMed2006

Permanent prostate brachytherapy: pathologic implications as assessed on radical prostatectomy specimens of broadening selection criteria for monotherapy.

OBJECTIVES: To assess the impact of clinical selection criteria on pathologic features among patients treated by radical retropubic prostatectomy and to evaluate the implications of broadening eligibility for permanent prostate brachytherapy monotherapy. METHODS: A consecutive series of 423 patients with prostate cancer, who underwent diagnostic biopsy and subsequent radical retropubic prostatectomy, were selected for this study. Four subgroups were defined using the American Brachytherapy Society selection criteria, including prostate size limits (group 1), no prostate size limits (group 2A), a modified set of criteria (group 2B), and clinical Stage T1-T2 (group 3). The rates of extraprostatic extension, seminal vesicle invasion, and lymph node involvement were compared. RESULTS: Adverse pathologic features at radical retropubic prostatectomy were noted in 8 (9.3%) of 86 patients in group 1, 11 (5.6%) of 195 patients in group 2A, 35 (12.0%) of 292 patients in group 2B, and 90 (21.8%) of 413 patients in group 3. The rates of extraprostatic extension, seminal vesicle invasion, and lymph node involvement appeared comparable among groups 1 (5.8%, 3.5%, and 0.0%, respectively), 2A (3.6%, 2.1%, and 0.0%, respectively), and 2B (6.9%, 3.8%, and 1.4%, respectively), but were greater in group 3 (9.7%, 7.8%, and 4.4%, respectively). CONCLUSIONS: Judicious broadening of the clinical selection criteria may allow a greater number of patients to be eligible for permanent prostate brachytherapy monotherapy by including patients whose risk of having adverse pathologic features is comparable to that of patients currently deemed suitable for permanent prostate brachytherapy monotherapy. Prospective assessment of oncologic outcomes of such an approach is required.

Adult↗
PubMed2006

TRUS-fluoroscopy fusion for intraoperative prostate brachytherapy dosimetry.

A fluoroscopic to TRUS fusion based approach for intraoperative prostate brachytherapy dosimetry was developed. Seed images were identified from multiple fluoroscopic images and reconstructed to determine the three dimensional distribution of the implanted seeds. Seeds identified from the TRUS images were used as fiducials for the registration between fluoroscopic and TRUS images. Dose analysis was then performed based on the fused images. A phantom study was performed to test this approach and a 3 mm registration error was observed. Radiation isodose contours were generated and superimposed on the TRUS images.

Brachytherapy↗
PubMed2005

A preclinical large animal model of adenovirus-mediated expression of the sodium-iodide symporter for radioiodide imaging and therapy of locally recurrent prostate cancer.

The sodium-iodide symporter (NIS) is primarily a thyroid protein, providing for the accumulation of iodide for biosynthesis of thyroid hormones. Native NIS expression has made possible the use of radioactive iodide to image and treat thyroid disease successfully. The current study, using adult male beagle dogs, was carried out in preparation for a Phase I clinical trial of adenovirus-mediated NIS gene (approved symbol SLC5A5) therapy for prostate cancer. Direct intraprostatic injection of virus (Ad5/CMV/NS) was followed by iv injection of 3 mCi 123I and serial image acquisition. The dogs were then given a therapeutic dose of 131I (116 mCi/m2) and observed for 7 days. SPECT/CT fusion imaging revealed clear images of the NIS-transduced prostates. Dosimetry calculations revealed an average absorbed dose to the prostate of 23 +/- 42 cGy/mCi 131I, with acceptably low radiation doses to other organs. This study demonstrated the successful introduction of localized NIS expression in the prostate gland of dogs, with no vector-related toxicity observed. None of the animals experienced any surgical complications, and serum chemistry panels showed no significant change following therapy. The results presented provide further evidence of the safety and efficacy of NIS as a therapeutic gene and support translation of this work into the clinical setting.

Adenoviridae↗
PubMed2005

Urinary fistulas following external radiation or permanent brachytherapy for the treatment of prostate cancer.

PURPOSE: Prostate cancer (PCa) radiotherapy (RT), including brachytherapy, may lead to significant morbidity, including urinary fistulas. If conservative measures fail, urinary and/or fecal diversion is often required. In this study we examined a series of patients with fistulas that developed after pelvic radiation therapy and explored potential predisposing factors and treatment recommendations for refractory fistulas. MATERIALS AND METHODS: Patients were identified who received radiation therapy for PCa between 1977 and 2002, and subsequently had a fistula to the urinary tract. Patients were excluded who had diverticulitis, inflammatory bowel disease, a history of recent radical retropubic prostatectomy (possible iatrogenic etiology) or cancer in the excised fistula. Data were extracted from patient charts, mailed questionnaires and outside records. RESULTS: A total of 51 patients were identified with a history of radiation for PCa who subsequently had a urinary fistula. Of 20 patients meeting inclusion criteria 30% received external beam RT alone, 30% received brachytherapy and 40% received combined external beam RT/brachytherapy. Most fistulas (80%) were from the rectum to the urinary tract with an average diameter of 3.2 cm. Of patients with rectal fistulas 81% had a history of rectal stricture, urethral stricture, rectal biopsy, rectal argon beam therapy or transurethral prostate resection after radiation. All patients with rectourethral fistulas who achieved symptomatic resolution required urinary and fecal diversion. CONCLUSIONS: Conservative treatment is generally ineffective in the management of large urinary fistulas. Surgical intervention offers symptomatic relief and improved quality of life in most patients.

Aged↗
PubMed2005

Examination of dosimetry accuracy as a function of seed detection rate in permanent prostate brachytherapy.

The variation of permanent prostate brachytherapy dosimetry as a function of seed detection rates was investigated for I125 implants with seed activities commonly employed in contemporary practice. Post-implant imaging and radiation dosimetry data from nine patients who underwent PPB served as the basis of this simulation study. One-thousand random configurations of detected seeds were generated for each patient dataset using various seed detection levels from 30% to 99%. Dose parameters, including D90, were computed for each configuration and compared with the actual dosimetry data. A total of 108 000 complete sets of post-PPB dose volume statistics were computed. The results demonstrated that although the average D90 differed from the true value by less than 5% when 70% or more seeds were identified, the D90 of an individual case could deviate up to 13%. The 95% confidence interval (CI) of estimated D90 values differ by less than 5% from the actual value when 95% or more seeds are detected, or approximately a 7 Gy difference in the D90 value for a prescription dose of 144 Gy. Estimated target volume dose parameters tended to decrease with reduced seed detection rates. The most variable dose parameter was the prostate V100 in absolute scale while the urethral V100 was most variable in a relative sense. Based on this comprehensive simulation study, it is suggested that 95% or more seeds need to be localized in order to provide an accurate estimation of dose parameters for contemporary iodine 125 permanent prostate brachytherapy.

Brachytherapy↗
PubMed2004

Prostate volume measurement by transrectal ultrasound and computed tomography before and after permanent prostate brachytherapy.

PURPOSE: To quantify prostate volume (pvol) changes with transrectal ultrasound (TRUS) immediately after permanent prostate brachytherapy (PPB) and to correlate these changes with postimplant computed tomography (CT) volumetrics. To provide data relevant to evaluating the potential of TRUS-based image fusion for intraoperative dosimetry. METHODS AND MATERIALS: Between July 2000 and January 2003, 177 patients underwent (125)I PPB monotherapy at our institution, and 165 patients provided research authorization. A total of 136 patients (82%) completed 4 imaging studies: planning TRUS, intraoperative pre- and postimplant TRUS, and CT. RESULTS: Mean planning TRUS pvol was 38.7 +/- 11.7 cc standard deviation (SD), 95% confidence interval (CI) (36.7, 40.7). Mean intraoperative TRUS pvol preimplant was 37.1 +/- 11.7 cc SD, 95% CI (35.1, 39.0), and postimplant was 44.5 +/- 15.1 cc SD, 95% CI (42.0, 47.1). The mean ratio of postimplant:preimplant intraoperative TRUS pvols was 1.2 +/- 0.2 SD, 95% CI (1.18, 1.24), and the difference in mean values was 7.5 cc (p < 0.0001). CT performed within 1 day revealed a mean pvol of 47.9 +/- 15.7 cc SD, 95% CI (45.2, 50.5). The mean volumetric ratio of CT to postimplant TRUS pvol was 1.13 +/- 0.36, 95% CI (1.07-1.19). CONCLUSIONS: Whereas mean preimplant step-section TRUS pvol measurements are similar, postimplant TRUS and CT measurements have greater variability that depend on initial pvol. CT-based pvol measurements determined a mean of 10.6 hours after implant were more likely to be identical to those of immediate postimplant TRUS in prostates >33 cc. These data are relevant for establishing accuracy in image-fusion based approaches being investigated for real-time intraoperative PPB dosimetry.

Analysis of Variance↗
PubMed2004

Radioactive seed migration to the chest after transperineal interstitial prostate brachytherapy: extraprostatic seed placement correlates with migration.

PURPOSE: To examine the incidence of seed migration detected on chest X-ray and to identify the predictors associated with its occurrence. METHODS AND MATERIALS: Between May 1998 and April 2000, 102 patients underwent permanent prostate brachytherapy at our institution and 100 were eligible for the study. Chest X-rays obtained at follow-up were examined for the number and location of seeds. The patient and treatment variables potentially associated with the occurrence and number of seed migrations were analyzed. RESULTS: One or more seeds were identified on the chest X-rays of 55 (55%) of 100 patients. The mean number of intrathoracic seeds in patients with migration was 2.2 (range, 1-10), and the proportion of seeds that migrated to the thorax was 0.98%. The rate of extraprostatic seeds planned was 43.9%, and postimplant CT identified 37.9% in such a location. The number of seeds planned for extraprostatic placement and below the apex were statistically significant (alpha = 0.05) predictors in univariate logistic analysis. Multivariate analysis revealed the planned number of extraprostatic seeds as the only statistically significant predictor (p = 0.04). CONCLUSION: Extraprostatic placement of loose seeds is associated with an increased likelihood for, and frequency of, seed migration to the thorax. Nonetheless, the small proportion of implanted seeds that migrated (<or=1%) is highly unlikely to have significant dosimetric consequences.

Aged↗
PubMed2004

Selective identification of different brachytherapy sources, ferromagnetic seeds, and fiducials in the prostate using an automated seed sorting algorithm.

PURPOSE: Routine permanent prostate brachytherapy (PPB) includes CT-based postimplant dosimetry (PID). A method of identifying different source types from CT data in the same implant volume is described. METHODS AND MATERIALS: A previously described automatic method for seed localization using CT data is used in this study. Two cases were analyzed: a PPB case with (103)Pd followed by salvage (125)I implantation, both performed at another institution, and a cadaver case where 4 different seed types, including ferromagnetic seeds, and fiducials were implanted. RESULTS: Automatic segregation of different seed types with minimal manual correction is demonstrated using the described localization algorithm. The process is confirmed accurate by comparison of plain film radiographs to CT data and digitally reconstructed radiographs. CONCLUSION: Unique identification of different source types, including PPB seeds, fiducial markers, and ferromagnetic seeds in permanent implants is possible and permits dosimetric analyses that are spatially coincident.

Aged↗
PubMed2004

Prostate brachytherapy seed localization by analysis of multiple projections: identifying and addressing the seed overlap problem.

Intraoperative three-dimensional reconstruction of seed locations during prostate brachytherapy for purposes of immediate computation of radiation dosimetry is an active area of current investigation, including methods which use multiple fluoroscopic projections. A simulation study using seed locations extracted from clinical CT data was performed; the result showed that on average one quarter of the seeds had a projection image overlapping with other seeds. The average percentage of non-overlapping seeds for the prostate implants and seed types investigated was 74.5% with a range of 56.9%-92.9%. The distribution of seeds in different cluster sizes was analyzed as well as the distribution of pixel counts of connected components. A statistical classifier was developed to determine the number of seed images in a self-connected component in the segmented images. The classifier was tested with simulation data, and the error rate was below 2%. A method to determine seed image position is also provided. A modified three-film technique was used to reconstruct 3-D seed locations. The algorithm allows unequal number of seed images for each projection as input while current methods require the same number of seed images detected in all projections. An accuracy analysis based on angular and positional uncertainty was performed. The reconstruction and seed localization algorithms were tested with simulation data, and the mean distance error of the reconstructed results was 0.61 mm. A phantom study was performed to validate the seed localization method. Three false positive seeds, 4.7% of the total, in the reconstruction result were observed in this study.

Algorithms↗
PubMed2003

Technical aspects of daily online positioning of the prostate for three-dimensional conformal radiotherapy using an electronic portal imaging device.

PURPOSE: To develop a real-time electronic portal imaging device (EPID) procedure to identify intraprostatic gold markers and correct daily variations in target position during external beam radiotherapy for prostate cancer. METHODS AND MATERIALS: Pretherapy electronic portal images (EPIs) were acquired with a small portion of the therapeutic 18-MV dose from an orthogonal pair of treatment fields. The position of the intraprostatic gold markers on the EPIs was aligned with that on the simulation digitally reconstructed radiographs. If the initial three-dimensional target displacement (3DI) exceeded 5 mm or rotations exceeded 3 degrees, the beam was realigned before the remainder of the dose was delivered. Field-only EPIs were then acquired for all fields and offline analysis was performed to determine the final 3D target placement (3DF). RESULTS: Twenty patients completed protocol-specified treatment, and all markers were identified on 99.6% of the pretherapy EPIs. Overall, 53% of treatment fractions were realigned. The mean 3DI was 5.6 mm in all patients (range 3.7-9.3), and the mean 3DF was 2.8 mm (range 1.6-4.0), which was statistically significant (p < 0.001). Rotational corrections were made on 15% of treatments. Mean treatment duration was 1.4 min greater for protocol patients than for similar patients in whom localization was not performed. CONCLUSIONS: Frequent field misalignment occurs when external fiducial marks are used for patient alignment. Misalignments can be readily and rapidly identified and corrected with an EPID-based online correction procedure that integrates commercially available equipment and software.

Calibration↗
PubMed2003

Measurement of the ultrasound backscatter signal from three seed types as a function of incidence angle: application to permanent prostate brachytherapy.

PURPOSE: To measure the relative ultrasound backscatter of different seed types as a function of seed orientation and to evaluate the corresponding images of these seeds. METHODS AND MATERIALS: Three seed types were evaluated: OncoSeed (standard), EchoSeed (corrugated), and RAPID Strand(RS). Ultrasound images for angles of incidence varying from 90 degrees (perpendicular) to 20 degrees at 5MHz and 7.5MHz were produced by raster scanning the seeds in a degassed water bath. Seed images were visually inspected and analyzed using the integrated-optical-density (IOD) method. RESULTS: Corrugated seeds appear as contiguous objects over the range of frequencies and orientations examined, whereas standard seeds appear as contiguous objects from 90 degrees to 80 degrees only. The ranges and means of the backscattered IOD ratio of the seeds from 85 degrees to 20 degrees were: (corrugated vs. standard) 1.48 to 3.72 (2.32 +/- 0.62) for 5 MHz and 1.26 to 3.77 (2.19 +/- 0.84) for 7.5 MHz and (corrugated vs. RS) 1.21 to 9.53 (2.98 +/- 2.48) for 5 MHz and 1.008 to 10.86 (2.79 +/- 3.08) for 7.5 MHz. Backscattered signal increase ranged from 1.66 dB to 20.7 dB for the corrugated seed as compared to the other seeds. CONCLUSIONS: Corrugated seeds produce greater backscatter signal and a more readily identifiable seed image over a large range of seed orientation as compared with standard brachytherapy seeds.

Brachytherapy↗
PubMed2003

Radiation exposure to operating room personnel during transperineal interstitial permanent prostate brachytherapy.

PURPOSE: To identify factors associated with radiation exposure (RE) to operating room personnel during transperineal interstitial permanent prostate brachytherapy (TIPPB). METHODS AND MATERIALS: Between May 1998 and December 2000, 155 patients underwent TIPPB with fluoroscopic and ultrasound guidance. Data for each case included: operating room time (OT), anesthesia time (AT), fluoroscopy time (FT), number and type of seed implanted, total seed activity, and resident participation. RESULTS: Personnel RE per case, FT, OT, and AT decreased as case number increased. Whole body badge dose per case decreased from a mean of 0.15+/-0.01 mSv (15+/-1 mrem) in 1998 to 0.074+/-0.011 mSv (7+/-1 mrem) in 2000. Average FT per case decreased from a mean of 17:27 min (range, 10:40-28:23) in 1998 to 12:08 min (range, 6:40-31:00) in 2000. Resident participation was associated with increased FT. Mean whole body and ring badge doses for the treating radiation oncologist were 0.0076 mSv/min (0.76 mrem/min) and 0.05 mSv/min (5.26 mrem/min) of FT, respectively. CONCLUSIONS: FT was the predominant factor that related to RE during TIPPB. Treating radiation oncologists were exposed to less than 20 mSv per 100 cases, significantly less than other fluoroscopically guided procedures. Nonetheless, appropriate radiation exposure precautions during TIPPB should continue.

Body Burden↗
PubMed2003

Adjuvant external radiation therapy following radical prostatectomy for node-negative prostate cancer.

PURPOSE OF REVIEW: The use of adjuvant radiation therapy following prostatectomy is commonplace. The purpose of this review is to summarize completed and ongoing clinical trials and to review recent relevant studies and debates related to this subject. RECENT FINDINGS: The routine use of adjuvant radiation therapy remains a controversial topic. Recent retrospective matched-pair analyses support its use in appropriately selected patients with positive margins, extraprostatic extension or seminal vesicle invasion, but interpretation of these and other data vary. Although the 5-year biochemical recurrence rate using adjuvant radiotherapy may be decreased from approximately 40 to 10% in patients with either positive margins or extraprostatic extension, its effect on cause-specific mortality is unclear. Two prospective randomized trials with cumulative enrollment of over 1400 patients have examined the role of adjuvant radiation therapy compared with observation following prostatectomy: one trial was a National Cancer Institute-sponsored Intergroup study coordinated by the Southwest Oncology Group, and the other was from the European Organization for Research and Treatment of Cancer. Currently, the Radiation Therapy Oncology Group is conducting a three-arm trial, with broadened stratification criteria as compared with previous trials. This ongoing trial examines the use of adjuvant radiotherapy with or without adjuvant androgen deprivation following prostatectomy and also androgen deprivation alone in patients at high risk for disease relapse. SUMMARY: In lieu of data from completed randomized trials, indications for immediate adjuvant radiation therapy following prostatectomy exist and are supported by retrospective data with respect to reducing local and biochemical recurrence rates. However, data demonstrating an overall or cause-specific survival advantage for adjuvant radiotherapy as compared with delayed salvage therapy do not exist.

Humans↗
PubMed2002

Electronic and film portal images: a comparison of landmark visibility and review accuracy.

PURPOSE: To quantitatively compare a scanning liquid ion chamber electronic portal imaging device (SLIC-EPID) and an amorphous silicon flat panel (aSi) EPID with portal film in clinical applications using measures of landmark visibility and treatment review accuracy. METHODS AND MATERIALS: Six radiation oncologists viewed 39 electronic portal images (EPIs) from the SLIC-EPID, 36 EPIs from the aSi-EPID, and portal films of each of these treatment fields. The physicians rated the clarity of anatomic landmarks in the portal images, and the scores were compared between EPID and film. Nine hundred portal image reviews were performed. EPID and film portal images were acquired with known setup errors in either phantom or cadaver treatments. Physicians identified the errors visually in portal films and with computerized analysis for EPID. RESULTS: There were no statistically significant (p < 0.05) differences between film and SLIC-EPID in ratings of landmark clarity. Eleven of 12 landmarks were more visible in aSi-EPID than in film. Translational setup errors were identified with an average accuracy of 2.5 mm in film, compared to 1.5 mm with SLIC-EPID and 1.3 mm with aSi-EPID. CONCLUSIONS: Both EPIDs are clinically viable replacements for film, but aSi-EPID represents a significant advancement in image quality over film.

Movement↗
PubMed2002

The relevance of prostatectomy findings for brachytherapy selection in patients with localized prostate carcinoma.

BACKGROUND: The efficacy of brachytherapy for patients with localized prostate carcinoma depends on adequate radiotherapeutic coverage of the primary tumor and its subclinical extraprostatic extensions. Predictive models based on pretherapy factors may be useful to estimate the likelihood for clinically relevant extraprostatic disease and may be incorporated into selection criteria for this procedure. METHODS: Multivariate logistic regression model building was performed using pretherapy factors in 2905 surgically staged patients with localized prostate carcinoma to estimate the probability of seminal vesicle and/or lymph node involvement. Bootstrap methods were employed to assess the stability of the final model parameters and to determine the sensitivity and specificity of the final model. RESULTS: Clinical tumor classification, biopsy Gleason score groupings, and serum prostate specific antigen (PSA) levels were associated with seminal vesicle and/or pelvic lymph node involvement. These factors were incorporated into a multivariate model that predicted for these adverse histopathologic features. Allowing for up to a 10% likelihood for seminal vesicle and/or pelvic lymph node involvement, patients with tumors classified as T1c-T2a, Gleason scores of 2-6, and PSA < or = 16 ng/mL; or with tumors classified as T1c-T2a, Gleason scores of 7-10, and PSA < or = 4 ng/mL; or with tumors classified as T2b-T2c, Gleason scores of 2-6, and PSA < or = 6 ng/mL would be potential candidates for brachytherapy alone. CONCLUSIONS: The predictive model presented may provide criteria whereby an adequately performed prostate brachytherapy procedure is expected to encompass the intraprostatic and adjacent extraprostatic disease. Prostate brachytherapy alone may be considered in these circumstances, whereas the addition of external beam radiotherapy may be reserved for patients with disease that is apt to extend beyond the brachytherapy target volume.

Brachytherapy↗