Biomedical subjects

Michael Gillin

Publications and source records attributed to Michael Gillin.

6 recordsLinked to original sources

PubMed2006

Results of a phase II trial of transrectal ultrasound-guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate (radiation therapy oncology group 98-05).

PURPOSE: To evaluate the effectiveness of transrectal ultrasound-guided permanent radioactive (125)I implantation of the prostate for organ-confined adenocarcinoma of the prostate compared with historical data of prostatectomy and external beam radiotherapy within a cooperative group setting. METHODS AND MATERIALS: Patients accrued to this study had histologically confirmed, locally confined, adenocarcinoma of the prostate with clinical Stage T1b, T1c, or T2a, no nodal or metastatic disease, prostate-specific antigen level of < or =10 ng/mL, and Gleason score of < or =6. All patients underwent transrectal ultrasound-guided radioactive (125)I permanent seed implantation into the prostate. The prescribed dose was 145 Gy to the prostate planning target volume. RESULTS: A total of 27 institutions accrued a total of 101 patients to this protocol, with no institution accruing >8 patients. Six patients were ineligible, leaving 95 properly entered as eligible in the study. The median follow-up was 5.3 years (range, 0.4-6.5 years). At 5 years, 5 patients had local failure, 1 had evidence of distant failure, and 6 (6%) had biochemical failure. The overall survival rate at 5 years was 96.7%. At last follow-up, no patient had died of prostate cancer or related toxicities. Eight patients had a maximal acute toxicity level of 3, and no patient had Grade 4 or 5 acute toxicity. During follow-up, 2 patients had maximal Grade 3 toxicity, both related to bladder issues, and no patient experienced Grade 4 or 5 toxicity. CONCLUSION: The results of this clinical protocol (a multi-institutional trial of brachytherapy for localized adenocarcinoma of the prostate) have demonstrated that this type of trial can be successfully completed through the Radiation Therapy Oncology Group. Biochemical disease-free survival was comparable with other brachytherapy published series and with the results after surgery and external beam radiotherapy.

Adenocarcinoma↗

PubMed2006

A phase II trial of accelerated radiotherapy using weekly stereotactic conformal boost for supratentorial glioblastoma multiforme: RTOG 0023.

PURPOSE: This phase II trial was performed to assess the feasibility, toxicity, and efficacy of dose-intense accelerated radiation therapy using weekly fractionated stereotactic radiotherapy (FSRT) boost for patients with glioblastoma multiforme (GBM). METHODS AND MATERIALS: Patients with histologically confirmed GBM with postoperative enhancing tumor plus tumor cavity diameter <60 mm were enrolled. A 50-Gy dose of standard radiation therapy (RT) was given in daily 2-Gy fractions. In addition, patients received four FSRT treatments, once weekly, during Weeks 3 to 6. FSRT dosing of either 5 Gy or 7 Gy per fraction was given for a cumulative dose of 70 or 78 Gy in 29 (25 standard RT + 4 FSRT) treatments over 6 weeks. After the RT course, carmustine (BCNU) at 80 mg/m(2) was given for 3 days, every 8 weeks, for 6 cycles. RESULTS: A total of 76 patients were analyzed. Toxicity included: 3 Grade 4 chemotherapy, 3 acute Grade 4 radiotherapy, and 1 Grade 3 late. The median survival time was 12.5 months. No survival difference is seen when compared with the RTOG historical database. Patients with gross total resection (41%) had a median survival time of 16.6 months vs. 12.0 months for historic controls with gross total resection (p = 0.14). CONCLUSION: This first, multi-institutional FSRT boost trial for GBM was feasible and well tolerated. There is no significant survival benefit using this dose-intense RT regimen. Subset analysis revealed a trend toward improved outcome for GTR patients suggesting that patients with minimal disease burden may benefit from this form of accelerated RT.

Adult↗

PubMed2005

A phase II study of external beam radiotherapy combined with permanent source brachytherapy for intermediate-risk, clinically localized adenocarcinoma of the prostate: preliminary results of RTOG P-0019.

PURPOSE: To estimate the rate of acute and late Grade 3-5 genitourinary and gastrointestinal toxicity after treatment with external beam radiotherapy and permanent source brachytherapy in a multi-institutional, cooperative group setting. METHODS AND MATERIALS: All patients were treated with external beam radiotherapy (45 Gy in 25 fractions), followed 2-6 weeks later by an interstitial implant using 125I to deliver an additional 108 Gy. Late genitourinary toxicity was graded according to the Common Toxicity Criteria Version 2.0, and the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late radiation morbidity scoring system was used for all other toxicity. RESULTS: A total of 138 patients from 28 institutions were entered on this study. Acute toxicity information was available in 131 patients, and 127 patients were analyzable for late toxicity. Acute Grade 3 toxicity was documented in 10 of 131 patients (7.6%). No Grade 4 or 5 acute toxicity has been observed. The 18-month month estimate of late Grade 3 genitourinary and gastrointestinal toxicity was 3.3% (95% confidence interval, 0.1-6.5). No late Grade 4 or 5 toxicity has been observed. CONCLUSIONS: The acute and late morbidity observed in this multi-institutional, cooperative group study is consistent with previous reports from single institutions with significant prostate brachytherapy experience.

Adenocarcinoma↗

PubMed2005

Effectiveness of noncoplanar IMRT planning using a parallelized multiresolution beam angle optimization method for paranasal sinus carcinoma.

PURPOSE: To determine the effectiveness of noncoplanar beam configurations and the benefit of plans using fewer but optimally placed beams designed by a parallelized multiple-resolution beam angle optimization (PMBAO) approach. METHODS AND MATERIALS: The PMBAO approach uses a combination of coplanar and noncoplanar beam configurations for intensity-modulated radiation therapy (IMRT) treatment planning of paranasal sinus cancers. A smaller number of beams (e.g. 3) are first used to explore the solution space to determine the best and worst beam directions. The results of this exploration are then used as a starting point for determining an optimum beam orientation configuration with more beams (e.g. 5). This process is parallelized using a message passing interface, which greatly reduces the overall computation time for routine clinical practice. To test this approach, treatment for 10 patients with paranasal sinus cancer was planned using a total of 5 beams from a pool of 46 possible beam angles. The PMBAO treatment plans were also compared with IMRT plans designed using 9 equally spaced coplanar beams, which is the standard approach in our clinic. Plans with these two different beam configurations were compared with respect to dose conformity, dose heterogeneity, dose-volume histograms, and doses to organs at risk (i.e., eyes, optic nerve, optic chiasm, and brain). RESULTS: The noncoplanar beam configuration was superior in most paranasal sinus carcinoma cases. The target dose homogeneity was better using a PMBAO 5-beam configuration. However, the dose conformity using PMBAO was not improved and was case dependent. Compared with the 9-beam configuration, the PMBAO configuration significantly reduced the mean dose to the eyes and optic nerves and the maximum dose to the contralateral optical path (e.g. the contralateral eye and optic nerve). The maximum dose to the ipsilateral eye and optic nerve was also lower using the PMBAO configuration than using the 9-beam configuration, although this difference was not significant. The mean doses to the optic chiasm and brain are marginally lower using the PMBAO configuration than using 9-beam configuration. The maximum doses to the optic chiasm and brain are the same with the PMBAO configuration and the 9-beam configuration. CONCLUSION: Parallelized multiple-resolution beam angle optimization with an optimized noncoplanar beam configuration is an effective and practical approach for IMRT treatment planning. Five-beam treatment plans optimized using the PMBAO are at least equivalent to, and overall better than, the plans using 9 equally spaced coplanar beams.

Humans↗

PubMed2002

Posttreatment visual acuity in patients treated with episcleral plaque therapy for choroidal melanomas: dose and dose rate effects.

PURPOSE: To determine the relationship between the long-term visual function and the dose and dose rates delivered to critical ocular structures in patients with choroidal melanoma treated with 125I episcleral plaque radiotherapy. MATERIALS AND METHODS: From 1987 to 1994, 63 patients underwent 125I episcleral plaque (Collaborative Ocular Melanoma Study [COMS] design) application for the treatment of choroidal melanoma. The mean tumor height was 4.5 mm (range 1.7-8.3). Doses and dose rates at the tumor apex, macula, and optic disc were calculated. Forty-three records were scored to assess whether a decrease in visual acuity of >2 lines on a standard Snellen eye chart had occurred. Patient age and the presence of hypertension or diabetes were noted. Statistical analysis was performed to assess both the rate at which visual decline had occurred and the presence of significant factors that had contributed to this decline. RESULTS: With a median follow-up of 36 months, the 3-year actuarial survival rate was 93.6%. The 3-year actuarial local control rate was 86.9%. The median time to visual loss after therapy was 18.7 months. The 3-year actuarial rate of visual preservation was 40.5%. Multivariate analysis demonstrated higher macula dose rates (p = 0.003) to forecast visual decline. Macula dose rates of 111 +/- 11.1 cGy/h were associated with a 50% risk of significant visual loss. CONCLUSION: Patients in our series treated with 125I plaque brachytherapy for choroidal melanoma experienced favorable tumor control, but with a measurable incidence of visual decline. Higher dose rates to the macula correlated strongly with poorer posttreatment visual outcome. This information may be valuable in selecting the optimal dose rates to treat choroidal melanomas and to predict the risk of visual decline.

Adult↗

PubMed2002

Clinical implementation of AAPM TG61 protocol for kilovoltage x-ray beam dosimetry.

Historically, there have been a variety of dosimetry protocols used for kilovoltage x-ray therapy beams with a set of conversion factors and correction factors taken from different references. Corresponding to the continued installation and use of kilovoltage machines, the American Association of Physicists in Medicine (AAPM) presented a unified protocol developed by Task Group 61 (TG61). TG61 determines the absorbed dose to water with an ionization chamber calibrated in air in terms of air kerma (Nk). TG61 presents both an in-air method and an in-phantom method. In this work we only examine the TG61 in-air method. Our traditional dosimetry procedure, which is based upon NCRP Report 69 and on material found in standard medical physics texts, has been compared to the TG61. A variety of kilovoltage beam energies were examined with a set of various field sizes and source to surface distances. TG61 published updated data for the mass absorption coefficient ratios, backscatter factors, and the average energy per ion pair factor. The following conclusions have been reached: (1) Our traditional procedures and the TG61 protocol for in-air measurements are equivalent. (2) The conversion and correction factors used in TG61 are different by up to 4.5% compared to the old factors that we have used. (3) The application of the TG61 factors can result in up to 5% differences in the determination of the absorbed dose.

Air↗