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Biomedical subjects

Danny Y Song

Publications and source records attributed to Danny Y Song.

5 recordsLinked to original sources
PubMed2005

Stereotactic body radiation therapy of lung tumors: preliminary experience using normal tissue complication probability-based dose limits.

OBJECTIVES: To assess the feasibility and toxicity of stereotactic body radiotherapy (SBRT) for patients with locally advanced or metastatic tumors in lung. METHODS: Twenty-five tumors in 17 patients were treated. All treatments were delivered in 3 daily fractions of 9 to 15 Gy per fraction. Normal tissue complication probability (NTCP) calculations (using the Lyman model) were performed to facilitate dose prescription, and doses were prescribed with a maximum allowable NTCP risk of pneumonitis of up to 20%, not to exceed 15 Gy per fraction. Planning target volumes were designed to allow for respiratory variation in tumor location. RESULTS: The median dose prescribed was 35 Gy (range, 24 to 45 Gy). Twenty-three of 25 tumors remained controlled at median follow-up of 14 months. Four patients experienced grade 1-2 acute toxicity. Late toxicity developed in 2 patients who received treatment to peri-hilar tumors, including one patient in whom bronchial stenosis developed with complete occlusion and lobar atelectasis 6 months after treatment. No patient had grade 3 or 4 radiation pneumonitis. CONCLUSIONS: SBRT prescribed within the confines of NTCP-restricted dosing on this protocol resulted in no radiation pneumonitis. Tissues other than lung parenchyma which are unaccounted for by NTCP may be dose-limiting when performing hypofractionated SBRT in the lung.

Adult↗
PubMed2004

Stereotactic body radiation therapy. Rationale, techniques, applications, and optimization.

Stereotactic body radiation therapy (SBRT) is a rapidly evolving cancer treatment method in which concepts and techniques previously developed for brain tumor radiosurgery are adapted to eradicate tumors elsewhere in the body. The spatial accuracy, conformality, and steep radiation dose gradients of radiosurgery, which have been critical to its success in the treatment of intracranial tumors, are applied in SBRT to treat a variety of extracranial tumors. Early results demonstrate excellent response rates and low toxicity with a variety of hypofractionated dose regimens and localization/immobilization techniques. This article provides an overview of the rationale and results of SBRT for specific indications, descriptions of some methods of treatment delivery, and discussion of potential areas of future investigation.

Brain Neoplasms↗
PubMed2002

Salvage radiotherapy for rising or persistent PSA after radical prostatectomy.

OBJECTIVES: To assess the effectiveness of salvage radiotherapy (RT) for a persistent or rising prostate-specific antigen (PSA) level after radical prostatectomy, and to identify the pretreatment factors that may predict for patients likely to benefit from this treatment. METHODS: Seventy-three consecutive patients were treated during a 10-year period (1989 to 1999) with RT after radical prostatectomy. Twelve patients were excluded from analysis because of either an undetectable PSA level before RT or lack of follow-up data. No patients had clinical or radiographic evidence of distant disease. An undetectable PSA level (less than 0.1 ng/mL) was required to be considered disease free. RESULTS: The median PSA level before RT was 0.8 ng/mL (range 0.1 to 63). The median radiation dose prescribed was 66.6 Gy. The actuarial PSA-free survival rate at 4 years was 39%. Failure was uncommon in patients followed up beyond 4 years. Univariate analysis revealed that a pre-RT PSA level of less than 1.0 ng/mL (P = 0.001), Gleason score less than 8 (P = 0.003), and achievement of an undetectable PSA level after prostatectomy (P = 0.018) were significant predictors of improved disease-free survival. On multivariate analysis, both a pre-RT PSA level of less than 1.0 ng/mL and a Gleason score less than 8 maintained statistical significance. CONCLUSIONS: Salvage RT provides a reasonable chance of intermediate-term disease-free survival in patients with PSA persistence or relapse after radical prostatectomy. Patients with a higher PSA level (greater than 1 ng/mL) and Gleason score of 8 or more are less likely to benefit from this treatment, and improved therapies are needed for this subset of patients. Patients should be referred promptly for salvage RT after detection of relapse.

Analysis of Variance↗