Rx: laughter.
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Adaptation, Psychological↗
Biomedical subjects
P McGhee
Publications and source records attributed to P McGhee.
The Siemens virtual wedge.
A Siemens Virtual Wedge has recently been installed and commissioned at the Northeastern Ontario Regional Cancer Centre. Measurements reported below show that 1) Virtual Wedge factors are within 1.5% of 1; 2) percentage depth doses down to 15 cm for open and virtually wedged fields are identical to within 0.7%; 3) relative cross beam profiles for 60 degrees virtual and physical wedges are very similar except at the toe end where a 5% difference in relative dose has been observed and 4) the peripheral dose from the 60 degrees Virtual Wedge is about half of that from the 60 degrees physical wedge. A clinical protocol requiring combined open and 60 degrees wedged fields has been developed and validated. This protocol, which does not impair the utility of the Virtual Wedge, facilitates the use of on-line portal imaging and significantly reduces the effort required to commission the system.
Humans↗
Anthropomorphic phantom measurements for the validation of a treatment planning system.
A series of eight irradiations of an anthropomorphic phantom has been performed as part of a programme of treatment planning system (TPS) validation. The "treatment' configurations used represent a realistic cross section of those carried out routinely in a radiotherapy centre. The dose distributions within the phantom were determined using 75 LiF TLD chips per irradiation and the measured dose distributions were compared with calculations performed on a TPS for three ranges of dose gradient. The accuracy of the technique per measurement point is estimated to be 3% in dose (low dose gradient) and 3 mm in position (high dose gradient). The measurement and data analysis techniques used permit evaluation of a TPS against recently recommended criteria of acceptability although it is noted that is is not possible to isolate TPS performance from factors depending on, for example, open beam data fitting and treatment set up accuracy.
Anthropometry↗
An efficient approach to routine TL dosimetry.
A new labour-saving protocol for clinical dosimetric measurements based on the thermoluminescence (TL) of lithium fluoride is presented. The accuracy of dose measurements resulting from the application of this protocol is examined with particular emphasis on the linearity, reproducibility, and fading of TL response. It is shown that the technique described here is capable of yielding an accuracy of +/- 5% at the 95% confidence level for doses in excess of 1cGy. This study establishes that adoption of the protocol can result in significant savings in labour whilst maintaining a level of accuracy that is adequate for clinical dosimetry.
Reproducibility of Results↗