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John J Feldmeier

Publications and source records attributed to John J Feldmeier.

5 recordsLinked to original sources
PubMed2004

Cost-effectiveness analysis of the treatment for intermediate risk endometrial cancer: postoperative brachytherapy vs. observation.

OBJECTIVE: To compare the survival, morbidity, and cost of treating women with intermediate risk endometrial cancer with postoperative vaginal cuff brachytherapy versus observation followed by treatment for vaginal recurrence. METHODS: A cost-effectiveness analysis was performed comparing two treatment strategies for intermediate risk endometrial cancer (Stage IC, IG3, II-tumors limited to the uterus with greater than 50% myometrial invasion or poor differentiation or cervical metastasis). All patients undergo hysterectomy, oophorectomy, and lymphadenectomy: strategy 1-postoperative vaginal cuff brachytherapy, strategy 2-observation. Strategy 2 patients who develop vaginal recurrence undergo diagnostic work-up followed by teletherapy and brachytherapy. All six principles of cost-effectiveness analysis were employed. Importantly, actual payer costs were evaluated, not charges. RESULTS: Although the treatment for vaginal cuff recurrence is expensive, since only 8% of patients develop a vaginal recurrence, there was a 31% decreased cost by not treating patients with postoperative low-dose rate brachytherapy (strategy 2). Also, although the complication rate for teletherapy is greater than brachytherapy, since only 8% of patients develop a vaginal recurrence and require teletherapy, projected complication rates for the two strategies are similar. Survival would be decreased 3% by withholding postoperative brachytherapy (strategy 2). With postoperative high-dose rate brachytherapy (strategy 1), the cost per life saved would be 38,764 US dollars. CONCLUSION: Using a cost-effectiveness analysis, we have shown that withholding postoperative brachytherapy for patients with intermediate risk endometrial cancer results in a 31% decrease in cost, has a similar radiation complication rate, and results in a 3% decrease in survival.

Algorithms↗
PubMed2003

Prophylactic hyperbaric oxygen treatment and rat spinal cord re-irradiation.

Normal tissue injury may lead to severe, life threatening, late side effects after therapeutic use of irradiation. Neurological complications caused by radiation of the spinal cord are ascribed to progressive, irreversible damage to the vasculature. Hyperbaric oxygen (HBO) is known to induce angiogenesis in irradiated tissue and has been proven to reduce late radiation injury in several normal tissues when applied during the latent period before complications become manifest. In the present study: (1). the prophylactic potential of HBO; (2). optimal timing of HBO therapy after spinal cord irradiation, i.e. during the latent period; and (3). effect of HBO on the re-irradiation tolerance of the spinal cord were investigated. The rat cervical spinal cord was locally X-ray irradiated with ten fractions of 6.5 Gy in 11 days. Five treatment groups (n=10) included: irradiation alone and irradiation followed by 30 HBO treatments (100% oxygen at 240 kPa for 90 min) during latency, with HBO starting either immediately, 5, 10 or 15 weeks after the primary irradiation course. One year after the primary treatment, the same spinal cord volume was re-irradiated with 20 Gy single dose. During life span, the animals were observed on the incidence of myelitis and the duration of the latent period. The actuarial analysis revealed no significant difference in neurological complications free survival between the irradiation alone and the irradiation+HBO treatment groups. A tendency towards radiosensitization was found in the group in which the primary irradiation course was immediately followed by the HBO treatment course. The data show that HBO applied during the latent period of progressively developing irradiation damage to the spinal cord does not increase the re-irradiation tolerance of this tissue.

Animals↗
PubMed2003

Dosimetric characteristics of a linear array of gamma or beta-emitting seeds in intravascular irradiation: Monte Carlo studies for the AAPM TG-43/60 formalism.

In principle, the AAPM TG-43/60 formalism for intravascular brachytherapy (IVBT) dosimetry of catheter-based sources is fully valid with a single seed of cylindrical symmetry and in the region comparable to or larger than the mean-free path of emitting radiation. However, for the geometry of a linear array of seeds within the few millimeter range of interest in IVBT, the suitability of the AAPM TG-43/60 formalism has not been fully addressed yet. We have meticulously investigated the dosimetric characteristics of catheter-based gamma (192Ir) and beta (90Sr/Y) sources using Monte Carlo methods before applying the AAPM TG-43/60 formalism. The dosimetric perturbation due to radiation interactions with neighboring seeds is at most 2% over the entire region of interest for the 192Ir source, while it increases to about 5% for the 90Sr/Y source. As the transaxial distance (y) increases beyond 3 mm, the sum of the dose contributions from neighboring seeds exceeds the dose contribution from the center seed for both sources. However, it continues to increase with the increasing y for 192Ir but is saturated beyond y = 5 mm for 9Sr/Y. Even within a few millimeters from the seeds, the dose from the low-energy betas of 192Ir is still less than 1% of the total dose. The radial dose and anisotropy functions are reformulated in reduced cylindrical coordinate with the reference point at y = 2 mm. The dose rate constant of 192Ir and the dose rate of 90Sr/Y at the reference point showed a fairly good agreement (within +/- 2%) with earlier studies and the NIST-traceable value, respectively. We conclude that the dosimetric perturbation caused by close proximity of neighboring seeds is nearly negligible so that the AAPM TG-43/60 formalism can be applied to a linear array of seeds.

Alpha Particles↗