With the continuing improvement in computer speed, dose distributions can be calculated quickly with confidence. However, the resulting biological effect is known with much less certainty, despite its critical importance when assessing treatment plans. To assess plans accurately, biologically based methods of ranking plans are necessary. Many authors have suggested the use of dose volume histograms with reduction schemes and Niemierko has recently introduced another method based on the cell kill occurring in the tumour. This study presents an investigation into this value and suggests a use in prescribing dose. Equivalent uniform dose (EUD) can obviously be used for assessing treatment plans, although in its current form it is not adequate for assessing normal tissues; however, it can also be used to adjust the prescription dose ensuring all plans deliver the same EUD to the tumour. Once this is performed, plans can more easily be assessed on the effects to the normal tissues. In calculating the EUD another concept is introduced--the equivalent uniform biologically effective dose (EUBED). This value considers the distribution of dose and dose per fraction when comparing plans. Reduced dose per fraction at the edge of the target volume will exacerbate the effect of reduced dose on cell kill. Two methods are suggested for calculating the necessary prescription dose: one using an iterative method and one using the gradient of the EUBED function. A comparison was made for a series of stereotactic cases using different collimator sizes. Interestingly, using this method, although the maximum doses were different, the dose volume histograms (DVHs) for the brainstem were similar in all cases.
To be able to predict the impact of any radiotherapy treatment the physics of radiation interactions and the expected biological effect for any radiotherapy treatment situation (dose, fractionation, modality) must be both understood and modelled. This review considers the current use and accuracy of the linear quadratic model which can be used to consider the variation in tissue response with fraction size. Cell kill following radiation damage results from damage to the DNA which can take a variety of forms. In many cases the linear quadratic model is used to estimate the relative impact for different situations especially clinical studies relating to fraction size. This is mainly undertaken using parameters derived from the linear quadratic model such as biological effective dose and standard effective dose. The model has also been adapted to consider the effect of overall treatment time, repair during treatment (as occurs for brachytherapy treatments) and other situations. There are some concerns over its use, mainly in the small dose ranges (both total low doses and low doses per fraction) where studies have shown its inaccuracy. In other situations however it does appear to provide a reasonable estimate of relative clinical effect. As with all models, however results should never be considered out of clinical context.
A study has been made by questionnaire, personal examination and telephone interview of unilateral upper limb amputees seen at the Prince Henry Hospital, Australia between 1994 and 1997. There were 60 questionnaires posted. Replies were received from 46. Problems were noted in the remaining arm of 23 (50%). The respondents' problems not only consisted of overuse symptoms, but also of an exacerbation of pre-existing arthritis and injury due to trauma to the remaining arm during the accident. Case histories are given in 3 typical cases. Treating professionals are warned about the hazards that one arm amputations present to the remaining arm.
Painful neuromata occurring after upper limb amputation are a significant cause of stump pain and limit the success of prosthetic training and use. There is little information in the literature regarding incidence, consequences or outcomes of painful neuromata subsequent to upper limb amputation. This article reports an analysis of thirty-two consecutive upper limb amputees. Of these 25% had moderate-to-severe stump pain and clinical signs suggestive of neuromata. All patients with neuromata were limited in their ability to use a prosthesis prior to surgery and following failure of conservative measures, were referred for surgical opinion. Six patients have undergone surgical management. The results of surgery, with respect to pain and prosthetic usage, are discussed.
A follow-up study by questionnaire or interview has been made of the 27 respondents of 41 upper limb amputees (66%) treated at the Royal South Sydney Hospital between 1981 and 1990. Prosthetic use of 8 h/day or more was 37% and occasional use was 18.5%. The prosthetic users were more likely to be distal amputees. The reason for the low level of prosthetic use is not known. The majority of non-users discarded prostheses after leaving their rehabilitation programme. Occupational changes were made by 72% of the amputees. The unemployment rate at follow-up was similar to the rest of the community, which is a better outcome than 25 years ago. Activities of daily living had been affected in all patients, but to a lesser extent in prosthetic users. Leisure pursuits were changed in 70% of patients, with these activities being more sedentary and indoor in nature. Of the 18 car drivers, 15 drove automatic cars with modifications. Phantom pain was experienced by 16 of the respondents (59%) and stump pain was experienced by seven. Only 26% used medication or alcohol for the pain. Pain did not affect prosthetic use or functional ability.
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