Integrated Brachytherapy Unit – Offering Improved Delivery of Radiation Therapy
By Mahta Mirzaei, MS
The Comprehensive Cancer Center at Wake Forest University Baptist Medical Center recently opened an Integrated Brachytherapy Unit (IBU) – one of only five such units in North America.
The IBU concept integrates all aspects of brachytherapy (radiation source in contact with the tumor) treatment. Patient preparation, applicator insertion, imaging, treatment planning, delivery and verification are now all possible in a single shielded room -- offering real-time savings while implant quality is improved. This ensures that there are virtually no limitations for any brachytherapy procedure.
The integrated procedure with the IBU ensures a stable, conformal geometry for the complete process and drastically reduces the overall treatment time for each patient. So, not only is there better and more control over the entire procedure, but the patient throughput is improved drastically.
Features:
· Rotating system enables unobstructed X-ray imaging from all possible directions without moving the patient. This is particularly important for patients with lung and esophageal cancers who can not lay flat on their back.
· Selection of different viewing angles improves reconstruction and treatment planning accuracy.
· Image data, position and angles of rotation are digitally transferred straight into PLATO treatment planning software for 3D reconstruction purposes which could eliminate any manual reconstruction errors.
· Fully counterbalanced L- and C- arms Motorized Treatment table including X,Y,Z directions for a complete 3-D view
· Quick synchronization with PLATO for up to date dose distribution
Benefits:
· Fluoroscopy from all directions.
· Improved planning accuracy.
· Reduced risk of applicator displacement.
· Verification of source position at any time.
· More comfort for patient.
· Better use of hospital floor space.
· Intraoperative brachytherapy.
· Time saving.
· Improved implant quality
The Integrated Brachytherapy Unit utilizes High Dose Rate Brachytherapy (HDR). The HDR system uses a single, tiny (1mm x 3mm) highly radioactive source of Iridium-192 that is laser-welded to the end of a thin, flexible stainless steel cable.
The source is housed in a device called an afterloader. The computer-guided after loader directs the source into the treatment catheters or applicator that has been placed in the patient by the brachytherapy radiation oncologists.
The source travels through each catheter in 5mm steps, called “dwell” positions. The distribution of radiation and dose is determined by the dwell positions the source stops at and the length of time it dwells there. This ability to vary the dwell times is like having an unlimited choice of source strengths. This level of dose control is possible only with HDR.
A major advantage of HDR is that we know what the final doses will be before any radiation treatment is given. Because the patient and implant position is the same as when the treatment plan was devised, the doses are accurate.
Because of the high radioactivity of the Iridium-192 source, the treatment time is minutes so there is little opportunity for the implant to move and deposit radiation dose where it wasn’t intended. HDR dose accuracy is measured in millimeters.
The afterloader controls the radiation source, so radiation exposure to physicians, hospital staff and family members is eliminated. After the HDR treatment, the source retracts into the afterloader. The patient is no longer radioactive which is why HDR brachytherapy implants are called temporary implants.
HDR brachytherapy treatment courses can be from one to ten treatments, depending on the type of cancer being treated. There are many factors that the physician considers in determining the radiation dose and how many treatments an implant should receive. Currently at Wake Forest Baptist, HDR is used for treatment of various cancers including prostate, breast, lung, cervical and nasopharynx.