Users Manual Part 1

IBA | vi | Clinical User’s Guide
Volume 1 - Treatment Session
Contra-indications and Precautions
There have been numerous reports published indicating that radiotherapy increased
risks of both acute and late toxicities in cancer patients with Collagen Vascular
Diseases (CVDs).
1,2,3,4,5
Most clinicians would likely consider CVDs such as systemic lupus erythematosus,
dermatomyositis, scleroderma, rheumatic arthritis and mixed connective tissue
disease absolute or relative contraindications to radiotherapy.
6
Although there are
also studies suggesting that the increased risk in toxicity was not statistically
significant
7, 8 , 9
the outcomes from cancer patients with CVDs can be varied and
therefore great caution should be taken when treating with radiation therapy.
Another contraindication to receiving radiation therapy is the presence of genetic
abnormalities in DNA repair enzymes, such as in the case of Ataxia-Telangiectasia
and its related polymorphisms. These mutations place patients at higher risk for
acute side effects during radiation treatment.
10
Protons, like photons, are an ionizing radiation with a low Linear Energy Transfer
(LET). The Relative Biological Effectiveness (RBE) of 1.1 has been adopted in current
clinical practice, assuming that protons and photons have similar and predictable
effect on both tumor and normal tissues. However, increased experimental and
clinical evidences have indicated that RBE can vary.
11,12,13
RBE variations may lead
to the creation of suboptimal proton treatment plans with lower than expected effect
in the tumor and higher than expected effect in normal tissue.
14
Extra caution should
be taken when applying proton therapy for patients with diseases that are reported
as high-risk to photon-based radiotherapy.
Proton therapy is used to treat a wide range of conditions. To mitigate errors in
treatment delivery and minimize operating risks, it is imperative to have quality
assurance measures in place and follow guidelines and protocols in practice. Proton
therapy is subject to the same safety guidelines and requirements in terms of risk
management as those existing for photon-based radiotherapy.
When performing the benefit-risk ratio analysis of the therapy the medical
professionals need to take caution with the following conditions that may increase
the risks:
 Pregnancy
 Active and passive implants and devices
 Combination of Chemotherapy and Immunotherapy that may increase the
sensibility to radiation
Proton therapy treatments using Proteus 235 system should only be delivered by
radiation oncologists, medical physicists, dosimetrists and other related medical staff
who have received adequate proton therapy training. Following the instructions for
use, the radiation oncologist performs analysis on the risk/ benefit for the patient
before delivering the treatment, taking into account all the side effects and risks
resulting from the exposure to ionizing radiation. The radiation oncologist also
defines the different volumes and dose constraints that the treatment needs to