Towards Safer Radiotherapy

Staff should be provided with some or all of the following:
• Clear documentation of the treatment position with any specific immobilisation
requirements
• Skin marks outlining the relevant tattoo and field borders
• Clinical photographs of the proposed set-up
• Digitally reconstructed radiographs of the field
• Computer-generated images showing the projected field
• References from surface landmarks, so the location of tattoos can be checked
• Description of tattoos from previous treatments and a clear indication of their relative
position to new tattoos.
If a small shift from a previous tattoo is required, the use of asymmetric fields might be
preferable to daily shifts.
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Recommendation
Each radiotherapy centre should have a clear protocol outlining the steps to be taken to
ensure correct patient set-up.
5.10.2 Treatment unit verification
In most cases, record and verify (R&V) systems include features which allow for the
automatic loading of the machine settings for each patient and for the automatic positioning
of the treatment machine. Overall, such systems contribute to the avoidance of errors but
care has to be taken to avoid the introduction errors by incorrect loading of verification
data. 78,79
Clear protocols should exist for the use of R&V systems in assisting treatment set-up. The
source documentation should be used by operators to confirm the patient set-up and the
beam parameters set on the linear accelerator. This is a particularly challenging situation as
operators understandably expect the equipment to perform accurately. Verification should
be performed using active rather than passive procedures to reduce the risk of involuntary
automaticity. 74
Prior to turning on the treatment beam, the key parameters of monitor units, beam energy
and beam modification should be verified and confirmed by both operators using the source
documentation. This process should be performed using active verification procedures.
An explicit protocol should be in place specifying accountability when undertaking a
treatment exposure and detailing the responsibilities of each signatory when energising the
beam. This should emphasise that active witnessing means that both operators are
accountable.
There are occasions when it is necessary to either record or change machine parameters;
for example, couch position on the LinAc. There are risks associated with this task. Protocols
should exist detailing the procedures and the responsibilities of each operator and action
levels defined within departmental protocols when further action such as resimulation or
Towards Safer Radiotherapy