Biomedical subjects

J C Pacheco

Publications and source records attributed to J C Pacheco.

10 recordsLinked to original sources

PubMed1991

Effectiveness of genetic counselling. Retinoblastoma.

The authors studied 32 families with 36 RB patients. Among them 24 were sporadic cases; four had recurrence of RB; two had RB plus bone tumour in relatives and two were RB propositi. Two evaluations with an interval from four to 13 years were made. In the first the recurrence risk was informed as high or low. The patients' decisions were evaluated at the second consultation. The authors considered that counselling was negative in more than 50% of cases. For normal parents, prognosis of RB was severe, whereas for RB patients it was mild.

Adolescent↗

PubMed1985

Protocol variations and their influence on the final outcome: critical review of the split-course base of tongue study of the RTOG.

A critical review of the protocol variations in an RTOG prospective randomized multi-institutional clinical trial has been conducted. The objective of the review was to identify variables that might have affected the results of the study. Compliance with general guidelines and specific technical treatment parameters of the Split-Course Radiation Therapy Protocol for Carcinoma of the Base of the Tongue (RTOG #71-02) was analyzed. A +/- 5% variation of the time-dose-fractionation factors, using the NSD and TDF formulae and their respective protocol ratios (ratio between actual case NSD and TDF level and what the protocol recommended), has been defined as fully acceptable. Seventy-two percent of the 141 study cases were within this category. Minor variation has been defined as one resulting in a +/- 6% to +/- 15% deviation from the study values (15.3% of cases). Major and unacceptable variation was a deviation of +/- 16% or more from the research plan (12.7% of cases). After identifying the different variations and correlating them with the clinical results, we conclude that these deviations did not affect the final results to a significant or identifiable degree.

Clinical Trials as Topic↗

PubMed1980

Isocentric dosimetry with 8 MV X-rays.

Tumor-maximum ratios and back-scatter factors were measured for 8 MV x-rays. The measured TMR's are found to conform to the empirical expression TMR(t) = K(t) At m(t). Hence, log-log plots of TMR vs. area at various depths in water, yield straight lines from which values of TMRo (for 0 x 0 cm2 field) are obtained by extrapolation. From these values, scatter-phantom ratios are also derived.

Dose-Response Relationship, Radiation↗

PubMed1976