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R Paul Symonds

Publications and source records attributed to R Paul Symonds.

5 recordsLinked to original sources
PubMed2026

Technical note: reconstructing dose distributions from manually planned electron boosts in breast radiotherapy.

PURPOSE: In breast radiotherapy, delivery of manually-calculated electron boosts limits retrospective dose-response analyses as dose distribution is unavailable. This work evaluates the feasibility of reconstructing dose distributions from manually planned electron boosts in breast-conserving radiotherapy. METHODS: Only 72 out of 198 breast cancer patients had complete stored dose distributions from sequential electron boosts in the REQUITE study. Arbitrary data from 70/72 patients were used to develop and validate dose reconstruction method. Twenty patients were used to determine optimal parameters for Monte-Carlo-based (MC) electron dose reconstruction on RayStation (v.11B-R), considering CT-calibration curve, MC-history number, andcalculation grid resolution. Remaining 50 patients were used to quantify dose reconstruction accuracy. The similarity between reconstructed and stored dose was evaluated using 3D-gamma index and dosimetric parameters extracted from breast and tumour bed contours. Dose difference location was evaluated using dose-location histogram. RESULTS: Calculation grid resolution significantly impacted electron dose distribution (p&#xa0;<&#xa0;0.01), where the finest grid (0.15&#xa0;cm) showed highest similarity to stored doses. CT-calibration curve and MC-history number had a negligible influence on dose reconstruction. Dosimetric difference between reconstructed and stored doses was&#xa0;<&#xa0;1&#xa0;Gy for breast and tumour bed. Reconstructed dose was achieved&#xa0;>&#xa0;90% gamma passing rate in the validation set. However, around 2.5&#xa0;Gy dose differences were observed at the skin and tissue interface regions. CONCLUSIONS: Retrospective electron boost dose reconstruction is feasible with acceptable accuracy, and could increase data completeness in large cohort studies. Caution is advised when assessing dose near tissue interface and further validation is needed outside the REQUITE dataset.

Electrons↗
PubMed2003

Antimicrobial therapy to prevent or treat oral mucositis.

Oral mucositis represents a significant source of morbidity after chemotherapy and radiation therapy. Since infection may have an important role in the pathophysiology of oral mucositis, several antimicrobial agents have been investigated for their efficacy in preventing and treating this disease. We sought to establish the weight of evidence for antimicrobial treatment and identified 31 prospectively designed clinical trials of which 13 reported some benefit and 15 did not. No clear pattern was identified regarding patient type, cancer treatment, or type of antimicrobial agent used, and inconsistent assessment of oral mucositis made comparison of outcomes difficult. Newer drugs, such as the topical antimicrobial peptide iseganan HCl initially showed promise in reducing mucositis and the related oral pain but the results of a phase 3 trial were disappointing and the line of enquiry was abandoned altogether. Hence, there is a need to better understand the role of the microflora in the cause of oral mucositis if an antimicrobial agent for prevention and treatment of this disease is to be developed.

Anti-Infective Agents↗
PubMed2003

Improving and predicting radiosensitivity in muscle invasive bladder cancer.

PURPOSE: Muscle invasive bladder cancer is a common urological malignancy with a relatively poor prognosis and 5-year survival rates ranging from 20% to 90%. We review methods of improving the outcome of this condition, with particular emphasis on the principal bladder preserving treatment modality of radiation therapy. MATERIALS AND METHODS: We performed a literature search using MEDLINE and the ISI Web of Science using the keywords radiotherapy, radiosensitization and bladder neoplasia to ascertain the current status of radiation therapy and radiosensitizing agents in the treatment of muscle invasive bladder cancer. RESULTS: Several methods aimed at improving outcome following radiation therapy for muscle invasive bladder cancer are described. These methods range from modifications in the application of radiation therapy to use of conventional radiosensitizing agents, such as accelerated radiotherapy with carbon dioxide, oxygen and nicotinamide, and finally to use of more novel agents that interact with oncogenic products. The use of assays that predict tumor sensitivity on an individual basis represents an additional potential method to improve prognosis following radiation therapy. CONCLUSIONS: The ability to predict tumor radiosensitivity and the subsequent implementation of radiosensitizing techniques are likely to improve the results of treatment centered on radiation therapy, suggesting that bladder sparing approaches will remain a treatment option for muscle invasive bladder cancer.

Carcinoma, Transitional Cell↗