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Biomedical subjects

H M Ferguson

Publications and source records attributed to H M Ferguson.

6 recordsLinked to original sources
PubMed2001

Quality assurance in a Radiation Oncology Unit: the Chart Round experience.

Quality assurance ensures that planned treatments eventuate. Programmes must include feedback loops to promptly correct any shortfall in predetermined standards. In March 1999, a weekly Chart Round was introduced to verify that certain items relevant to quality care were being completed for patients of the Head and Neck Radiotherapy Unit at the Peter MacCallum Cancer Institute. The experience was reviewed after 1 year and it was found that the initiation of Chart Rounds has assisted in raising the level of item completion from 80% to 99% in similar groups of patients treated before and after the initiation of the Chart Round. Initiation of the Chart Round has also provided a useful forum for in-house peer-review, education and effective real-time communication between medical and allied health personnel, all of which has further added to the quality of patient care.

Hospital Units↗
PubMed1998

Tumour dose estimation using automated TLD techniques.

Lithium fluoride (TLD-700) dosimeters were used to measure exit surface absorbed doses in external beam radiotherapy using an automated TLD reader. Delivered tumour absorbed doses were derived from these measurements for head and neck, pelvis and breast treatments. For the head and neck treatments (first fraction only), the mean percentage difference between prescribed and delivered tumour absorbed doses was -0.15 +/- 3.0% (+/- 1 SD), for the pelvic treatments -0.83 +/- 2.8% and for the breast treatments +0.26 +/- 2.9%. The spread of results is approximately +/- 3% (+/- 1 SD). This is comparable with the estimated uncertainty in a single TLD absorbed dose measurement in phantom (+/- 2%; +/- 1 SD). Thus, ICRU recommended tolerances for absorbed dose delivery of +/- 5% may not be unequivocally detectable using this method. An action level of +/- 10% is suggested, allowing investigation of possible gross errors in treatment delivery at an early stage, before the course of treatment has progressed to a point at which absorbed dose compensation is impossible.

Breast Neoplasms↗
PubMed1997

Automated TLD system for tumor dose estimation from exit dose measurements in external beam radiotherapy.

PURPOSE: An automated TLD facility has been commissioned and calibrated, and techniques have been developed for the measurement of exit doses in external beam radiotherapy, to enable the routine estimation of delivered tumor doses. METHODS AND MATERIALS: An automated TLD system, originally intended for use in diagnostic radiology and radiation protection, has been evaluated and configured for the measurement of exit doses in radiotherapy. Linearity, optimum heating cycles and calibration procedures have been determined. At the photon energies used, encapsulated lithium fluoride chips provide insufficient buildup to ensure electronic equilibrium, necessitating calibration to allow for oblique exit surfaces. Expressions are derived to allow the calculation of delivered tumor doses. RESULTS: Under the calibration conditions described, the uncertainty in a single TLD measurement is approximately +/-2% (+/-1 standard deviation). Over the dose range 0.4-1.5 Gy, TL response is linear. The total heating cycle time, including annealing, is 75 s. Measurements of R(exit) (the ratio of exit dose with and without full backscatter), used in the estimation of tumor doses, decreases with field size for small fields and varies only slightly for field sizes greater than 7 x 7 cm. Lack of electronic equilibrium leads to a decrease in R(exit) with increasing exit surface obliquity for all energies considered. Application of the technique to a simulated treatment showed good agreement between estimated and applied tumor doses, when surface obliquity was taken into account. CONCLUSION: This work describes the commissioning and calibration of an automated TLD facility and demonstrates that exit surface measurements using TLD chips used under conditions where electronic equilibrium was not established, have the potential for identifying discrepancies in delivered tumor doses.

Calibration↗