New Hampshire Code of Administrative Rules
He - Department of Health and Human Services
Subtitle He-P - Former Division of Public Health Services
Chapter He-P 4000 - NEW HAMPSHIRE RULES FOR THE CONTROL OF RADIATION
Part He-P 4047 - USE OF RADIATION MACHINES: THERAPEUTIC RADIATION MACHINES
Section He-P 4047.03 - Definitions

(a) "Absorbed dose (D) " means the mean energy imparted by ionizing radiation to matter, and is determined as the quotient of dE by dm, where dE is the mean energy imparted by ionizing radiation to matter of mass dm, and is expressed in the SI unit of joule per kilogram and the special name "gray" (Gy) .

(b) "Absorbed dose rate" means absorbed dose per unit time for radiation machines with timers, or dose monitor unit per unit time for linear accelerators.

(c) "Air kerma (K) " means the kinetic energy released in air by ionizing radiation, and is determined as the quotient of dE by dM, where dE is the sum of the initial kinetic energies of all the charged ionizing particles liberated by uncharged ionizing particles in air of mass dM, and is expressed in the SI unit of joule per kilogram, and the special name the "gray" (Gy) .

(d) "Beam scattering foil" means a thin piece of material placed in the beam to scatter a beam of electrons in order to provide a more uniform electron distribution in the useful beam.

(e) "Bent beam linear accelerator" means a linear accelerator geometry in which the accelerated electron beam must change direction by passing through a bending magnet.

(f) "Conventional Simulator" means any x-ray system designed to produce the geometric conditions of the radiation therapy equipment.

(g) "Dose monitor unit (DMU) " means a unit response from the beam monitoring system from which the absorbed dose can be calculated.

(h) "Dosimetrist" means a person who generates and calculates radiation dose distributions under the direction of a medical physicist and a radiation oncologist.

(i) "Electronic brachytherapy" means a method of radiation therapy where an electrically generated source of ionizing radiation is placed in or near the tumor or target tissue to deliver therapeutic radiation dosage.

(j) "Electronic brachytherapy device" means the system used to produce and deliver therapeutic radiation including the x-ray tube, the control mechanism, the cooling system and the power Source.

(k) "Electronic brachytherapy source" means the x-ray tube component used in an electronic brachytherapy device.

(l) "External beam radiation therapy" means therapeutic irradiation in which the source of radiation is at a distance from the body.

(m) "Field-flattening filter" means a filter used to homogenize the absorbed dose rate over the radiation field.

(n) "Gantry" means that part of a radiation therapy system supporting and allowing movements of the radiation head about a center of rotation.

(o) "High energy external beam therapy" means photons and electrons with energies greater than equal to one MV or one MeV.

(p) "Intensity Modulated Radiation Therapy (IMRT) " means radiation therapy that uses non-uniform radiation beam intensities which have been determined by various computer based and automated optimization techniques.

(q) "Interruption of irradiation" means the stopping of irradiation with the possibility of continuing irradiation without resetting of operating conditions at the control panel.

(r) "Kilovolt (kV) " or "kilo electron volt (keV) " means the energy equal to that acquired by a particle with one electron charge in passing through a potential difference of one thousand volts in a vacuum.

(s) "Megavolt (MV) " or "mega electron volt (MeV) " means the energy equal to that acquired by a particle with one electron charge in passing through a potential difference of one million volts in a vacuum.

(t) "Misadministration" means the administration of an external beam radiation therapy dose:

(u) "Mobile Electronic Brachytherapy Service" means transportation of an electronic brachytherapy device to provide electronic brachytherapy at an address that is not the address of record.

(v) "Monitor unit (MU) " means "dose monitor unit" as defined in He-P 4047.03(g) .

(w) "Moving beam radiation therapy" means radiation therapy with any planned displacement of radiation field or patient relative to each other, or with any planned change of absorbed dose distribution.

(x) "Nominal treatment distance" means:

(y) "Periodic quality assurance check" means a procedure which is performed to ensure that a previous calibration continues to be valid.

(z) "Phantom" means an object behaving in essentially the same manner as tissue, with respect to absorption or scattering of the ionizing radiation in question.

(aa) "Practical range of electrons" means a classical electron range where the only remaining contribution to dose is from bremsstrahlung x-rays.

(ab) "Prescribed dose" means the total dose and dose per fraction as documented in the written directive.

(ac) "Primary dose monitoring system" means a system which will monitor the useful beam during irradiation and which will terminate irradiation when a pre-selected number of dose monitor units have been delivered.

(ad) "Radiation field" means "useful beam" as defined in He-P 4041(dq) .

(ae) "Radiation head" means the structure from which the useful beam emerges.

(af) "Radiation Therapy Physicist" means an individual qualified in accordance with He-P 4047.

(ag) "Recordable event" means the administration of an external beam radiation therapy dose when the calculated weekly administered dose differs by 15 percent or more from the weekly prescribed dose.

(ah) "Redundant beam monitoring system" means a combination of 2 dose monitoring systems in which each system is designed to terminate irradiation in accordance with a pre-selected number of dose monitor units.

(ai) "Scattered primary radiation" means that scattered radiation which has been deviated in direction only by materials irradiated by the useful beam.

(aj) "Secondary dose monitoring system" means a system which will terminate irradiation in the event of failure of the primary dose monitoring system.

(ak) "Shadow tray" means a device attached to the radiation head to support auxiliary beam blocking material.

(al) "Simulator" or "radiation therapy simulation system" means an x-ray system intended for localizing the volume to be exposed during radiation therapy and reproducing the position and size of the therapeutic irradiation field.

(am) "Source-skin distance (SSD) " means "target-skin distance" as defined in He-P 4047.03(ap) .

(an) "Stationary beam radiation therapy" means radiation therapy without displacement of one or more mechanical axes relative to the patient during irradiation.

(ao) "Target" means that part of an x-ray tube or accelerator onto which is directed a beam of accelerated particles to produce ionizing radiation or other particles.

(ap) "Target-skin distance (TSD) " means the distance measured along the beam axis from the center of the front surface of the x-ray target and/or electron virtual source to the surface of the irradiated object or patient.

(aq) "Therapeutic radiation machine" means x-ray or electron producing equipment designed and used for external beam radiation therapy. For the purpose of these regulations, devices used to administer electronic brachytherapy shall also be considered therapeutic machines.

(ar) "Virtual Simulator" means a computed tomography (CT) unit used in conjunction with relevant software which recreates the treatment machine; and that allows import manipulation, display and storage of images from CT and/or other imaging modalities.

(as) "Virtual source" means a point from which radiation appears to originate.

(at) "Written directive" means an order in writing for a specific patient, dated and signed by an authorized user prior to the administration of radiation which contains the total dose, dose per fraction, treatment site, and overall treatment period.