Brachytherapy is the use of radioactive isotopes to treat malignancies or benign conditions by means of a radioactive source placed close to or into the tumor or treatment site. Brachytherapy alone or combined with external beam therapy plays an important role in the management and treatment of patients with cancer. Such treatment can be given as interstitial, intracavitary, or intraluminal therapy. High-dose-rate (HDR) brachytherapy uses highly active isotopes, including iridium-192 and cobalt-60, at dose rates of 20 or more cGy per minute at a designated point. HDR brachytherapy is indicated for treatment of malignancies where the treatment site can be well defined and is accessible to applicators to hold the sources. This guideline does not apply to intravascular brachytherapy.
The use of brachytherapy requires detailed attention to personnel, equipment, patient and personnel safety, and continuing staff education.
Process of Brachytherapy
The use of HDR brachytherapy is a complex process involving trained personnel who must work in concert to carry out a variety of interrelated activities. Communication among brachytherapy team members and well-defined procedures are essential for accurate and safe treatment.
- Clinical Evaluation
The initial evaluation of the patient includes history, physical examination, review of pertinent diagnostic studies and reports, and communication with the referring physician and other physicians involved in the patient's care. The extent of the tumor must be determined and recorded for staging; this will facilitate treatment decisions, determine the prognosis of the patient, and enable a comparison of treatment results.
- Establishing Treatment Goals
The goal of treatment (curative, palliative, or to establish local tumor control) should be documented as clearly as possible. Treatment options and their relative merits and risks should be discussed with the patient. Integration of brachytherapy with external beam therapy should be defined. A summary of the evaluation should be communicated to the referring physician.
- Informed Consent
Informed consent must be obtained and documented.
- Applicator Insertion
Oncologic practice, including brachytherapy, commonly requires the interaction of multiple specialists. The choice and placement of after-loading applicators and loading and unloading of radioactive sources are the responsibility of the radiation oncologist.
Each type of brachytherapy procedure has its own set of unique characteristics. The brachytherapy team should operate according to an established system of procedural steps that have been developed by the radiation oncologist and brachytherapy team members. This systematic approach to applicator or source insertion should include a description of preimplantation steps, sedation or anesthesia procedures, the specific applicators used, and the insertion techniques. Standard orders or care guidelines may enhance the systematic approach to the insertion process.
- Treatment Planning
HDR brachytherapy is administered according to the written, signed, and dated prescription of the radiation oncologist. Before treatment, the final prescription must designate the treatment site, the isotope, the number of source positions, the planned dose, the dose per fraction, the number of fractions, and the time interval between HDR fractions. Applicator geometry and isotope dwell positions are defined with localization images or computed tomography (CT) scans, as is the location of the normal dose-limiting structures, as delineated by urinary bladder catheter bulb, rectal marker/contrast, or retractor or vaginal packing. Computerized dosimetry is performed by the medical physicist or his/her designee and approved by the radiation oncologist before the treatment proceeds. Independent verification of brachytherapy parameters (by another person or another method) is done pretreatment (see Patient and Personnel Safety section, below). Optimization techniques to shape the dose distribution are widely available but should be used carefully to avoid undetected hot and cold spots.
- Treatment Delivery
Prior to each delivery session, the medical physicist or radiation oncologist should verify the proper connection of each applicator to the planned delivery channel. The medical physicist should verify all treatment parameters at the HDR console prior to treatment, including the correspondence between planned source strength and after-loader source strength with appropriate corrections for decay and source changes.
HDR treatment is delivered by remote after-loading of high-activity sources. Radiation safety considerations are essential for HDR procedures. The radiation oncologist and the medical physicist must be in the immediate vicinity at all times while HDR brachytherapy is being administered, and the patient and functioning of equipment must be continuously monitored by video or audio means and/or direct observation. Treatment delivery must be subject to detailed scrutiny as described in the Patient and Personnel Safety section (see below). At the end of each treatment, the patient and the room must be surveyed to ensure that the source has been retracted into the after-loading device.
- Treatment Summary
At the conclusion of the course of treatment, a written summary of the treatment delivery parameters should be generated, including the total dose of brachytherapy and the total dose of external beam therapy if given, treatment technique, treatment volume, acute side effects, clinical course, and patient disposition.
- Follow-up Evaluation
Patients treated with HDR brachytherapy should be evaluated at regular intervals by the radiation oncologist for response and early and late effects on normal tissues.
Qualifications of Personnel
The HDR brachytherapy team includes the physician(s), medical physicist, dosimetrist, radiation therapist, nurse, and radiation safety officer. HDR brachytherapy requires extensive interaction between all members of the team. Because treatment is given with such a highly active source over a short duration, the consequences of error and possible misadministration are potentially increased with HDR brachytherapy. Communication among team members and well-defined procedures for performing HDR brachytherapy are essential for accurate and safe treatment. Qualifications of the brachytherapy team include the credentials listed below:
- Radiation Oncologist
Satisfactory completion of an Accreditation Council for Graduate Medical Education (ACGME) approved residency program in radiation oncology.
or
Certification in Radiology by the American Board of Radiology of a physician who confines his/her professional practice to radiation oncology. Alternatively, certification in Radiation Oncology or Therapeutic Radiology by the American Board of Radiology, the American Osteopathic Board of Radiology, the Royal College of Physicians and Surgeons of Canada, or Le College des Medecins du Quebec, may be considered proof of adequate physician qualifications.
- Qualified Medical Physicist
A Qualified Medical Physicist is an individual who is competent to practice independently in one or more of the subfields in medical physics. The American College of Radiology considers that certification and continuing education in the appropriate subfield(s) demonstrate that an individual is competent to practice one or more of the subfields in medical physics, and to be a Qualified Medical Physicist. The ACR recommends that the individual be certified in the appropriate subfield(s) by the American Board of Radiology (ABR).
The appropriate subfields of medical physics for this guideline are Therapeutic Radiological Physics and Radiological Physics.
The continuing education of a Qualified Medical Physicist should be in accordance with the ACR Practice Guideline for Continuing Medical Education (CME).
- Radiation Therapist
Must fulfill state licensing requirements and should have American Registry of Radiologic Technologists (ARRT) certification in radiation therapy.
- Medical Dosimetrist
Certification by the Medical Dosimetrist Certification Board is recommended.
- Nurse
State licensure as a registered nurse or practical nurse is recommended.
Equipment
HDR brachytherapy treatment is delivered with computerized, remotely after-loaded devices that contain a specific radioactive source. Equipment manufacturers offer applicators for interstitial, intracavitary, and intraluminal treatment that are used with the treatment units. An applicator replacement schedule should be implemented to avoid damage caused by excessive use. Computerized treatment planning is accomplished with specialized hardware and software compatible with the respective HDR brachytherapy system being used.
Periodic scheduled preventive maintenance is essential. The medical physicist supervising the quality improvement program is responsible for documenting the maintenance and repair of manual equipment, remote after-loading units, and applicators. (See the ACR Technical Standard for the Performance of Brachytherapy Physics: Remotely Loaded HDR Sources.)
Patient and Personnel Safety
Patient protection measures include those related to medical safety and radiation protection.
- Patient protection measures should include:
- A radiation exposure-monitoring program, as required by the Nuclear Regulatory Commission (NRC) or appropriate state agencies.
- Annual training of staff in emergency procedures in case of equipment malfunction.
- Charting systems for prescription, definition and delivery of treatment parameters, and recording and summation of HDR brachytherapy and external beam therapy treatment.
- A physics program for ensuring accurate dose delivery to the patient.
- A system for the radiation oncologist and medical physicist to verify independently (by another person or another method) all brachytherapy parameters to be used in each procedure (source, isotope and activity, dose rate, total dose, treatment duration, etc.) prior to institution of HDR brachytherapy.
- Personnel safety measures should include:
- A radiation exposure-monitoring program, as required by the Nuclear Regulatory Commission or appropriate state agencies.
- Routine leak testing of all sealed sources, as required by regulatory agencies.
- Appropriate safety equipment for use of sealed sources.
Educational Program
Continuing medical education programs should include radiation oncologists, medical physicists, dosimetrists, nurses, and radiation therapy staff. Radiation safety programs should also include hospital-based personnel who will be involved with brachytherapy patients. Educational programs initially and for retraining must cover the following:
- The safe operation, including emergency procedures, of HDR applicators and HDR remote after-loading equipment and sources as appropriate to the individual's responsibilities.
- Treatment techniques and new developments in radiation oncology and brachytherapy.
The program should be in accordance with the ACR Practice Guideline for Continuing Medical Education (CME).
Documentation
Reporting should be in accordance with the ACR Practice Guideline for Communication: Radiation Oncology.
Quality Control and Improvement, Safety, Infection Control, and Patient Education Concerns
See the "Description of the Implementation Strategy" field, below.
