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Equipment selection

Introduction

Radiotherapy equipment selection and specification will be part of planning for radiotherapy services. A service is established, maintained and upgraded taking into consideration national needs for radiotherapy services and available resources. Radiotherapy equipment is commonly procured through a tender process. The tender document needs to include a detailed technical specification of the equipment required. It is the responsibility of the clinically qualified medical physicists to prepare the specification in consultation with other radiotherapy health professionals.

Important Principles

Radiotherapy equipment include external beam treatment units (linear accelerators, Cobalt 60 machines etc. including in-room patient imaging systems), mould room equipment, immobilisation and stabilisation equipment, dosimetry and quality control equipment, conventional and CT simulators, treatment planning software and hardware, oncology information systems including R&V software, and brachytherapy treatment units and patient imaging systems.

The range of functionality of a modern treatment planning system (TPS) is rather diverse, including modules for virtual simulation, image registration, automatic segmentation, with links to R&V and oncology information systems, and including 3D photon and electron beam algorithms and inverse planning modules. A specification for a TPS needs to carefully consider all these components of TPS capability in line with the department’s needs.

The R&V and oncology information system needs to be compatible with the department’s linear accelerators and TPS. It is advisable to choose the R&V from the same manufacturer as the department’s linear accelerators to simplify maintenance and upgrading. Optional functionality of the oncology information system in image review, scheduling, and electronic patient records needs to be considered in light of the department’s needs.

For selection and specification of a CT simulator, consideration needs to be given to the CT gantry bore size, a flat carbon-fibre couch top with appropriate indexing, and an external laser system consisting of movable or fixed lasers which intersect at a plane set back from the gantry isocentre.

A mould room could include a manual or automated hot wire cutter, low melting point alloy blocks, consumable supplies of foam blocks, an alloy dispenser, a fume cupboard, lead sheets, bolus material (wax and gel), a water bath, consumable supplies of immobilisation thermoplastics, and a vacuum compressor for vacuum bags.

Introduction to References

The IAEA publication 1296 contains basic technical specifications for linear accelerators, Cobalt 60 machines, orthovoltage units, conventional simulators, and brachytherapy equipment. Van Dyk’s textbook includes a description or specification of immobilisation equipment (Chapter 3), a CT simulator (Chapter 5), a TPS (Chapter 8) and dosimetry equipment (Chapter 19).