Standards Development

Scope

This International Standard is applicable to radiation shielding design and evaluation work for medical proton accelerators with nominal energies of the beam ranging from 70 MeV to 250 MeV, with subsystem such as beamlines, energy selection system (for cyclotron) and nozzle components. The radiation protection requirements and recommendations given in this international standard cover the aspects relating to regulations, shielding design goals and other design criteria, role of the manufacturers, of the radiation protection officer or qualified expert and interactions between stakeholders, source terms and radiations around a proton accelerator, shielding for accelerators and its subsystems (including shielding materials and transmission values, calculations for various room configurations, duct impact on radiation protection), the radiological monitoring (measurements) and area control. 

Purpose

Proton therapy is of technological advancement, as the therapeutic dose is delivered at a prescribed depth (known as the Bragg Peak) in patient. The maximum proton energy in therapy can be up to about 250 MeV, to allow reasonable treatment depth. With such high energy, the strong secondary radiation is produced whenever the proton beam loss or deposition in the patient occurs. A typical large proton therapy centre is quite a complex accelerator system that consists of an injector, a cyclotron or a synchrotron to accelerate the proton, a high-energy beam transport line, several treatment rooms with nozzles. Around the entire accelerator system, meters-thick barriers (concrete walls) are used to attenuate the high energy secondary radiation. Meanwhile, multiple stakeholders, including the equipment vendor, the construction contractor, and the administration, are generally involved in the construction of a proton therapy centre. In principle, the radiation shielding is a one of the key issues to a proton therapy centre, in the perspective of capital and time consumed. The goal of shielding is to attenuate secondary radiation to levels that are within regulatory or design limits for individual exposure, which should be done at a reasonable cost and without compromising the use of the proton accelerator. With the rising number of PT centres built worldwide, the purpose of this proposal is to establish an international standard that:

1. Specify the requirement and recommendations for shielding design and evaluation of medical proton accelerators. Help to accent the role of stakeholders and their interactions with regard to radiation shielding, Therefore, promote the construction and operation.

2. Clarify the source terms and radiation fields around a proton accelerator and the correlated subsystem, standardize the analytical method for radiation attenuation and the radiological monitoring (measurements). Act as a fair technical reference, internationally. The radiological protection issues are involved with the development of proton therapy. Theoretical methods for radiation shielding are developed, benchmarked and published in literatures and technical reports of organisations (IAEA TRS No. 283, NCRP Report 144). Some national standards (GBZ/T 201.5, DIN 6875-20) are also in active, in recent years.

According to the above reasons, the conditions for the developing an international and dedicate standard " Radiological protection – Medical proton accelerators – Requirement and recommendations for shielding design and evaluation" are now in place. 

Proton therapy is of technological advancement, as the therapeutic dose is delivered at a prescribed depth (known as the Bragg Peak) in patient. The maximum proton energy in therapy can be up to about 250 MeV, to allow reasonable treatment depth. With such high energy, the strong secondary radiation is produced whenever the proton beam loss or deposition in the patient occurs. A typical large proton therapy centre is quite a complex accelerator system that consists of an injector, a cyclotron or a synchrotron to accelerate the proton, a high-energy beam transport line, several treatment rooms with nozzles. Around the entire accelerator system, meters-thick barriers (concrete walls) are used to attenuate the high energy secondary radiation. Meanwhile, multiple stakeholders, including the equipment vendor, the construction contractor, and the administration, are generally involved in the construction of a proton therapy centre. In principle, the radiation shielding is a one of the key issues to a proton therapy centre, in the perspective of capital and time consumed.

The goal of shielding is to attenuate secondary radiation to levels that are within regulatory or design limits for individual exposure, which should be done at a reasonable cost and without compromising the use of the proton accelerator.

With the rising number of PT centres built worldwide, the purpose of this proposal is to establish an international standard that:

1. Specify the requirement and recommendations for shielding design and evaluation of medical proton accelerators. Help to accent the role of stakeholders and their interactions with regard to radiation shielding, Therefore, promote the construction and operation.

2. Clarify the source terms and radiation fields around a proton accelerator and the correlated subsystem, standardize the analytical method for radiation attenuation and the radiological monitoring (measurements). Act as a fair technical reference, internationally.

The radiological protection issues are involved with the development of proton therapy. Theoretical methods for radiation shielding are developed, benchmarked and published in literatures and technical reports of organisations (IAEA TRS No. 283, NCRP Report 144). Some national standards (GBZ/T 201.5, DIN 6875-20) are also in active, in recent years.

According to the above reasons, the conditions for the developing an international and dedicate standard " Radiological protection – Medical proton accelerators – Requirement and recommendations for shielding design and evaluation" are now in place.