Tomotherapy: implications on daily workload and scheduling patients based on three years' institutional experience.

Helical tomotherapy (HT) was introduced at the Greater Poland Cancer Centre (GPCC) in April 2009. Retrospective analysis included data from the treatments performed for the first 656 patients treated with HT between May 2009 and May 2012 at the GPCC. In order to evaluate the implications on daily workload and scheduling of patients, stepwise regression and time analysis for each component of the overall treatment time, such as positioning, imaging, registration, and irradiation were performed. A detailed analysis included: (1) learning curves and optimized time needed for positioning and registration; (2) relation between irradiation time and parameters used for plan creation; and (3) average time of daily imaging. The irradiation component has the highest influence on the overall treatment time (R = 0.911). The lowest influence was observed for the imaging (R = 0.670). The learning curve for positioning was 7 months while the reduction of the average daily time needed for registration was observed even after two years. The irradiation time strongly depends on the planning parameters. Changing the pitch from 0.215 to 0.287 for pelvic cancer cases decreased the average daily beam-on time per patient by about 2 minutes. Similar changes for head and neck reduced this time by 1.3 minutes. The limitation in the usage of 1 cm field width only for complex cases, lower than 10 cm in the cranio-caudal direction, reduced the beam-on time per patient by 2 minutes. The average overall treatment time decreased from 21.5 minutes per patient in the first year of the HT usage to 13.8 minutes per patient in current practice. Our current practice shows that for a group of patients including mainly those with pelvis and head and neck cancers, the HT treatment takes approximately 15 minutes per patient allowing 40 patients to be treated within 10 hours.

Monitoring of photodynamic therapy results in age-related macular degeneration by means of preferential hyperacuity perimeter.

PURPOSE: To describe changes revealed by Zeiss Preferential Hyperacuity Perimeter (PreView PHP) in age-related macular degeneration (AMD), before and after photodynamic therapy (PDT), and determine usefulness of such monitoring. METHODS: Forty patients (40 eyes) with subfoveolar choroidal neovascularization (CNV) and 20 volunteers with cataract (40 eyes) were examined in a prospective study. Control group was screened for false positive results to evaluate reliability of the test. Subfoveolar CNV was confirmed by fluorescein angiography and optical coherence tomography (OCT). Best-corrected visual acuity (BCVA) and macular visual field in the PHP (area and intensity of distortion) were assessed 1 day before and 1 week and 4 weeks after PDT. RESULTS: Four weeks after PDT there was improvement in PHP results in 20 eyes (50%), stabilization in 15 eyes (37.5%) and progression in 5 eyes (12.5%). At this time there was BCVA improvement in 9 eyes (22.5%), stabilization in 28 eyes (70%), and worsening in 3 eyes (7.5%). 1 week after PDT 30 eyes (75%) presented temporary progression in PHP but only 3 patients (7.5%) presented temporary decrease of visual acuity and progression in OCT. Correlation coefficient of BCVA and PHP results was low during whole study. There was no significant change in control group during observation. 17.5% false positive PHP results were obtained at baseline. In the PDT group no false negative results were noted. CONCLUSIONS: Visual outcome after PDT cannot be predicted with use of PreView PHP. Temporary progression of changes in PHP 1 week after PDT can be expected in most cases.