Eleven dogs with naturally occurring oral squamous cell carcinomas were treated with photodynamic therapy (PDT) using Photochlor (HPPH) as the photosensitizer. The largest length of the tumours measured in a two-dimensional plane ranged from 0.9 to 6.8 cm. Seven of the tumours invaded underlying bone as determined by radiograph appearance. Photochlor was injected intravenously at a dose of 0.3 mg kg–1. Forty-eight hours later the tumours were treated. Tumours with a surface to base depth of greater than 1 cm were surgically reduced to less than 1 cm. Irradiation with 665 nm light with an energy density of 100 J cm–2was administered. Eight dogs were considered cured with no tumour recurrence for at least 17 months after treatment. Local treatment of oral squamous cell carcinomas with PDT appears to give results similar to those obtained with surgical removal of large portions of the mandible or maxilla. The cosmetic results with PDT are superior to those of radical surgical removal. The new sensitizer, Photochlor, appears effective for oral squamous carcinomas with results similar to those reported for other sensitizers. © 2000 Cancer Research Campaign
Photochlor photodynamic therapy applied after surgery appears to have no advantage over other forms of therapy in regards to preventing recurrence. Delayed wound healing and infections are problematic and make HPPH-PDT an undesirable addition to surgery for the treatment of this tumor type.
A helical tomotherapy machine combines a straight 6 MV linear accelerator mounted on a ring gantry with CT technology for image-guided intensity-modulated radiation therapy (IMRT) treatment. A fan beam created by the collimator and jaws produces a maximum of 40 × 5 cm2 field size at the isocenter. The gantry and hence the fan beam rotates at a constant speed while the couch moves linearly into the gantry bore, thus producing a helical delivery. The beam is modulated by a 64-leaf binary multileaf collimator (MLC), which enables IMRT treatment. The linac can be operated at a lower voltage (3.5 MV) and dose rate to produce megavoltage CT images, which are used for image-guided patient setup. We have installed two such units since 2004 and treated more than 2000 patients. The machine comes “precommissioned” from the manufacturer, and the beam characteristics and IMRT plans on phantom are measured and compared with manufacturer's data after acceptance tests are performed on site. Our experience with commissioning the machines and periodic quality assurance with tolerance limits for optimal performance are described.
Recent advances in imaging modalities within radiation therapy departments have the capability to initiate differing roles for radiation therapists. This has the potential to considerably improve the knowledge base and clinical skills of radiation therapists, while also enhancing the relationship between the allied health and medical professions. In addition, the quality of patient care may be improved while reducing the workload of oncologists. This article aims to discuss possible links between role expansion and image guided radiation therapy (IGRT) and avenues where this may be possible in modern radiotherapy departments. The work focuses on kilovoltage (kV) and megavoltage (MV) imaging modalities and their use in IGRT processes – primarily at treatment delivery. A literature review was conducted and knowledge gathered based on clinical experience at a number of departments across New South Wales and Queensland, Australia with the literature discussed framed by the authors' clinical learning and experiences. It was found that information is available supporting role expansion and IGRT separately; however, there is no direct correlation of information between these two subject areas across the current Australian or international spectra. Role expansion for radiation therapists must be accompanied by a clear definition of redeveloped roles and responsibilities in order to avoid confusion between oncologists and therapists. The authors recommend funding as vital to ensure adequate education and standardised training intra and inter departments. Ultimately, the development of radiation therapists into IGRT specialists may involve exclusively in imaging planning and treatment aspects.
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