INFOCUS

INFOCUS - 3D Human Body Shape Measurement In Radiotherapy:

INFOCUS (BMH4950567: Jan 1996 - Jan 1999)

("Information Technology in Conformal Radiotherapy")

Funded by the European Commission as part of the BIOMED II initiative of the European IVth Research Framework.

INFOCUS European Consortium:

Liverpool John Moores University, Liverpool. U.K. (Coordinator)

The Christie Hospital, Manchester. U.K.
Otto Von-Guericke University, Magdeburg. Germany.
Universite Claude Bernard, LYON1, Lyon. France.
SINTEF, Trondheim. Norway.
Elekta Oncology Systems, Crawley, U.K.

Radiotherapy is a well established technique for the treatment of a wide range of cancers. The basic principle of the method is to administer a lethal dose of ionising raditation to the site of the cancer cells with a minimum of damage to the surrounding healthy tissue. Treatments are fractional (the radiation dose is not delivered all at once – the dose is split up into a number of fractions) and typically delivered over a number of weeks.

Using Conformal Radiotherapy it is possible to shape the cross-sectional profile of the radiation beams delivered by a Linear Accelerator. This allows the 3D dose-volume to be tailored to match the exact geometry of the patient's tumour site. By accurately targetting the disease site the overall dosage delivered may be increased and the morbidity (collateral damage to healthy tissues) is reduced.

However, the customisation of the radiation dose-volume to the exact shape of the tumour site does mean that any patient movement becomes of critical importance. This means that there are two major problems that must be resolved within Conformal Radiotherapy.

Precise and repeatable positioning of the patient set-up

Accurate monitoring of patient movement during treatment

Current radiotherapy techniques assume a static patient. The subject is positioned with respect to the isocentre of the radiotherapy machine prior to the start of therapy, and it is assumed that this position is maintained throughout the delivery of the treatment. This is not consistent with the reality of a moving, living patient. The therapeutic course usually requires the patient to undergo several short doses of radiation repeated over a number of weeks in order to allow periodic recovery of healthy tissue. This makes exact repositioning of the patient for each individual treatment a crucial task.

At JMU research is focused on the problems presented by the motion of the 3D external body surface of the patient. The system used to achieve this employs an optical sensor based on interferometric fringe projection, which is used in conjunction with high-speed fringe analysis techniques. This allows repeatable patient set-up and monitoring.

“The principal objective of INFOCUS was to provide health professionals working in radiotherapy new tools for the planning, delivery and post-treatment assessment of radiotherapy in an environment where patient movement is taken into account. The ability to precisely position a patient and to be able to monitor patient movement during treatment is seen by the INFOCUS team as an essential development in creating truly conformal radiotherapy.”

Typical Radiotherapy Treatment Room (Left) and View Underneath Beam Exit Portal Head Showing Multi-leaf Collimator MLC (Right) enabling Conformal Therapy