ESTRO 36 Abstract Book

S108

ESTRO 36 2017

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medical physicists built a document management system

that follows the patient process from university clinics to

the Skandion Clinic. It contains all guiding and supporting

documents, procedures and instructions. An essential

experience acquired was that it is very important to write

the required documents on so many procedures,

guidelines and instructions as much as possible before the

first patient treatment. Thus it was found that once the

clinic was up and running with patient treatments, it was

much easier to revise an existing procedure that to get

time to write entirely new ones.

Acceptance and measurement, education and training.

It was decided early on that the RTT/nurses would work in

team with the medical physicists on measurement and

acceptance of IBA's equipment so there was at least one

RTT/nurse during the daytime. Then we continued during

the first half of the year with a medical physicist and a

RTT/nurse to work together on the morning checks. The

clinical training included the IBA Web training from UPenn

in Philadelphia as well as study visits for two weeks in the

proton clinic in Philadelphia. To this the IBA on site clinical

training at the Skandion Clinic was added. We were given

training on all new systems including trolley transport, CT

scanning, journal system, fire and safety, CPR, etc.

Another valuable experience was gathered from end-to-

end testing, when a mock patient went through all phases

of the process from each university clinic to the Skandion

Clinic and back.

An empty House to a functioning clinic.

RTT/nurses had responsibility for equipping the premises

with all that may be needed in order to start up a

functioning clinic. This included practically everything

from staff clothing to consumables and medicines, the

toys for the children and even the special requirements of

the anesthesia personnel.

In summary, it has been hard work, frustrating at times,

but extremely educational and stimulating most of the

time, and above all a fun time to start up a clinic.

SP-0217 Workflow in a proton therapy department –

real difference from photon therapy?

F. Fellin

Ospedale Santa Chiara di Trento, U.O. Protonterapia,

Trento, Italy

In Europe, there was a significantly increase in proton

therapy (PT) facilities in the last few years. In PT,

Radiation Therapy Technologists (RTTs) have a key role

throughout the patient’s therapeutic course, such as in

photon therapy. The physical characteristics of protons

are an advantage for saving the organs at risk (OARs)

and/or for increasing the dose to the target, but they

imply some important criticalities during the patient

workflow. Pencil Beam Scanning (PBS) is the most

advanced technique for PT but this is the proton technique

with more criticality. RTTs, should know these critical

issues and be aware of the impact that they have in the

patient workflow and in their working activities.

RTTs are involved in several steps of the patient workflow

in PT; in general, they are the same as in photon therapy:

simulation CT, diagnostic imaging, treatment planning,

delivery of therapy. However, in each single step, there

are important differences compared to photon therapy.

Starting from the simulation, the main differences relate

to the choice of the immobilization devices, both for their

purchase that for each specific patient, and the definition

with tatoo of the treatment isocenter that, especially with

PBS, it can be defined directly during the acquisition of

simulation CT. In addition, since the dose delivery is very

accurate, the definition of target volumes and OARs must

be very strict. For this reason, the PT facilities are usually

equipped with MR and PET-CT systems; RTTs must be able

to use this equipment and to acquire the necessary

images.

In the treatment planning step, the Medical Dosimetrists

(MDs) work with the Medical Physicists in the plans

optimization; they will use all the experience to get the

best plan for each patient. In addition to all the attention

that MDs must have during treatment planning, which are

common in photon therapy, in PT there are other

situations in which they must be careful. For example, it

is very important to set the correct direction of the fields

based on the tissues that the beams must pass through

before reaching the target and it is recommended to avoid

that all fields have the distal fall-off in the same area (in

particular near OARs); it is important to limit the use of

the range shifter and to select the most appropriate

irradiation technique based on the specific case (SFO,

MFO); MDs must know and evaluate all possible

uncertainties (range, RBE, …); they must adopt robust

optimization techniques and field specific PTV.

Even for the delivery of therapy sessions, there are some

important differences between photon and proton

therapy. First, the equipment is quite different: RTTs

must know in detail the PT equipment operation. Proton

therapy equipment is much larger and more complex

compared to photon therapy system. In PT, the patient

setup is checked every day; generally, RTTs use flat panels

with x-ray tubes system (for 2D images) or CBCT (for 3D

images). In some facilities, a CT on-rails is installed in the

treatment room and RTTs use this one for monitoring the

patient position before the therapy. The advantage of CT

on-rails is that, in principle, you can use the daily images

for checking the dose distribution every day. In PT, tattoos

performed during the simulation CT are important

especially in the first treatment session. They are used to

align the patient and move manually the treatment couch

on the isocenter, for defined the setup position.

Afterwards, RTTs capture the couch coordinate for setup

position and, during subsequent sessions, the table will be

aligned automatically. In all sessions except the first one,

tattoos are important only in treatments with

immobilization devices that are not perfectly indexed on

the couch, e.g. in the case of treatments in pelvic area.

RTTs must be very careful during the proton dose delivery

with PBS. There isn’t a proper ratio between dose and

monitor units delivered; the number of monitor units

depend on the field size: the greater the size of the target,

the greater the number of MU and the beam-on time.

Given the precision of proton dose delivery, small

anatomical changes can lead to important variations of

dose distribution in the patient. For this reason, RTTs must

observe and communicate any anatomical variations that

they see during the patient setup. In this way, it is possible

to perform any dosimetrical checks in the course of

therapy. In these cases, it is very useful to have a CT on-

rails. In PT, RTTs will have to acquire a weekly control CT

for treatments of areas prone to anatomical changes. It

will be used by Physicists or MDs to perform dose

assessments during the treatment and, if necessary, they

will organize a replanning.

These are some of the most significant differences

observed in proton therapy compared to photon therapy;

they change the work of RTTs in patient workflow. PT is

an advanced, complex and precise radiation therapy

technique and it requires very high skills for RTTs.

Symposium with Proffered Papers: Combining tumour

and normal tissue models

SP-0218 Novel approaches in the study of bladder

cancer

A. Kiltie

Oxford, United Kingdom,

Patients with muscle-invasive bladder cancer can be

treated by removal of their bladder (cystectomy) or by

bladder preserving strategies, which include the use of