Related Experiment Videos
Design and implementation of a system for treating paediatric patients with stereotactically-guided conformal
E J Adams1, B L Suter, A P Warrington
1Joint Department of Physics, The Royal Marsden NHS Trust, Downs Road, Sutton, Surrey SM2 5PT, UK.
Insights
New lightweight immobilization devices were developed for pediatric patients undergoing stereotactically-guided conformal radiotherapy (SCRT). These systems ensure accurate treatment delivery while prioritizing patient comfort and minimizing toxicity for children with brain tumors.
Area of Science:
- Radiation Oncology
- Pediatric Neuro-oncology
- Medical Physics
Background:
- Stereotactically-guided conformal radiotherapy (SCRT) enables precise radiation delivery to localized brain tumors.
- Minimizing treatment toxicity is crucial for pediatric patients with favorable long-term prognoses.
- Existing adult immobilization systems are unsuitable for children due to weight and anesthesia requirements.
Purpose of the Study:
- To design and implement novel immobilization devices for pediatric patients undergoing SCRT.
- To ensure systems are well-tolerated, comfortable, and facilitate treatment of childhood malignancies.
- To enable SCRT delivery for pediatric patients requiring general anesthesia.
Main Methods:
- Development of a lightweight immobilization frame and a shell-based alternative for anesthesia.
- Implementation of patient familiarization procedures to enhance cooperation and comfort.
- Assessment of frame impact on radiation transmission and surface dose, and system reproducibility using electronic portal imaging.
Main Results:
- Both frame (0.6 kg) and shell systems are in clinical use and well-tolerated.
- The frame offers high beam direction availability with acceptable transmission (92-96%) and surface dose characteristics.
- High reproducibility was achieved, with mean 3D errors <3.4mm for the frame and mean 2D random error of 1.5+/-0.2mm for the shell.
Conclusions:
- Two effective, well-tolerated immobilization devices for fractionated SCRT in pediatric patients have been developed.
- The lightweight frame provides broad beam access, while the shell system accommodates general anesthesia.
- These systems ensure reproducible immobilization, complementing high-precision radiotherapy delivery in children.
Background And Purpose:
Stereotactically-guided conformal radiotherapy (SCRT) allows the delivery of highly conformal dose distributions to localised brain tumours. This is of particular importance for children, whose often excellent long-term prognosis should be accompanied by low toxicity. The commercial immobilisation system in use at our hospital for adults was felt to be too heavy for children, and precluded the use of anaesthesia, which is sometimes required for paediatric patients. This paper therefore describes the design and implementation of a system for treating children with SCRT. This system needed to be well tolerated by patients, with good access for treating typical childhood malignancies.
Materials And Methods:
A lightweight frame was developed for immobilisation, with a shell-based alternative for patients requiring general anaesthetic. Procedures were set up to introduce the patients to the frame system in order to maximise patient co-operation and comfort. Film measurements were made to assess the impact of the frame on transmission and surface dose. The reproducibility of the systems was assessed using electronic portal images.
Results:
Both frame and shell systems are in clinical use. The frame weighs 0.6 kg and is well tolerated. It has a transmission of 92-96%, and fields which pass through it deliver surface doses of 58-82% of the dose at d(max), compared to 18% when no frame is present. However, the frame is constructed to maximise the availability of unobstructed beam directions. Reproducibility measurements for the frame showed a mean random error of 1.0+/-0.2mm in two dimensions (2D) and 1.4+/-0.7 mm in 3D. The mean systematic error in 3D was 2.2mm, and 90% of all overall 3D errors were less than 3.4mm. For the shell system, the mean 2D random error was 1.5+/-0.2mm.
Conclusions:
Two well-tolerated immobilisation devices have been developed for fractionated SCRT treatment of paediatric patients. A lightweight frame system gives a wide range of possible unobstructed beam directions, although beams that intersect the frame are not precluded, provided that output corrections are applied. A shell system allows the use of general anaesthesia. Both systems give reproducible immobilisation to complement the high-precision treatment delivery.