Browsing Clinical Oncology by Subjects
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Inter-fraction motion and dosimetric consequences during breast intensity-modulated radiotherapy (IMRT).BACKGROUND AND PURPOSE: Intensity-modulated radiotherapy (IMRT) can improve dose homogeneity within the breast planned target volume (PTV), but may be more susceptible to patient/organ motion than standard tangential radiotherapy (RT). We used daily cone-beam CT (CBCT) imaging to assess inter-fraction motion during breast IMRT and its subsequent impact on IMRT and standard RT dose homogeneity. MATERIALS AND METHODS: Ten breast cancer patients selected for IMRT were studied. CBCT images were acquired immediately after daily treatment. Automatic image co-registration was used to determine patient positioning variations. Daily PTV contours were used to calculate PTV variations and daily delivered IMRT and theoretically planned tangential RT dose. RESULTS: Group systematic (and random) setup errors detected by CBCT were 5.7 (3.9)mm laterally, 2.8 (3.5)mm vertically and 2.3 (3.2)mm longitudinally. Rotations >2 degrees in any axis occurred on 53/106 (50%) occasions. Daily PTV volume varied up to 23%. IMRT dose homogeneity was superior at planning and throughout the treatment compared with standard RT (1.8% vs. 15.8% PTV received >105% planned mean dose), despite increased motion sensitivity. CONCLUSIONS: CBCT revealed inadequacies of current patient positioning and verification procedures during breast RT and confirmed improved dose homogeneity using IMRT for the patients studied.
Prophylactic radiotherapy to intervention sites in mesothelioma: a systematic review and survey of UK practice.BACKGROUND AND PURPOSE: Patients with malignant pleural mesothelioma (MPM), who undergo chest instrumentation, may develop seeding at the site of intervention, leading to subcutaneous tumour. This is believed to be reduced by the common practice of prophylactic irradiation to intervention tracts (PIT). However, evidence to support PIT is currently inadequate and contentious. MATERIALS AND METHODS: We carried out a systematic search of published literature for articles relating to the incidence of chest wall intervention tract metastases and the use of PIT in mesothelioma. In addition, a survey of current practice was conducted in 54 UK oncology centres. RESULTS: Fourteen studies revealed an incidence of chest wall intervention tract metastases of 0-48% with a trend toward a higher rate of metastases for more invasive procedures. Three randomised controlled trials (RCTs), two prospective non-randomised studies and five retrospective series met the eligibility criteria to evaluate the role of PIT in MPM. Of the three RCTs, two did not support the use of PIT. None of the RCTs included patients who had received systemic chemotherapy. Of the oncology centres responding to the survey, 75% practiced PIT, and 80% would be interested in a trial to determine the efficacy of PIT. CONCLUSIONS: No consensus has been reached to support the use of PIT. However, most centres in the UK still offer PIT. There was widespread interest in a randomised controlled trial to establish PIT efficacy in the era of effective systemic chemotherapy for malignant pleural mesothelioma.