Purpose/ObjectivesTo explore the feasibility of using a 50 kV electronic source for delivery of brachytherapy treatment in cervical cancer.Materials/MethodsTwo patients have been treated using the electronic source, with instruments provided by the manufacturer (tandem and colpostats). Both patients received 45 Gy to the pelvis at 1.8 Gy per fraction with weekly cisplatinum at 40 mg/m2. A parametrial boost was then given to 50.4 Gy for the first patient and to 54 Gy for the second. After 36 Gy, both patients were implanted under general anesthesia and dilation of the cervical os to sufficient width in order to permit tandem insertion under ultrasound guidance with a cervical stopper attached to the tandem at the distance from the tip of the tandem to correspond the sounded depth of the uterus. Brachytherapy was performed weekly while external beam treatment was still occurring and then twice weekly to complete treatment within 8 weeks. Colpostat covers were chosen to provide maximum lateral displacement of the vaginal mucosa. CT-based three dimensional planning with non-contrast images was utilized after fixation of the instruments and packing of the vagina to push the bladder and rectum as far away as possible. Dose was prescribed to point A using 5.5 Gy per fraction for one patient and 6 Gy per fraction for the second patient (who had a larger tumor with initial clinical stage IIIB disease). Five fractions were performed for each patient.ResultsThe implantation procedure, treatment planning, treatment delivery and post-anesthesia recovery took over 6 hours in the first insertion attempt, but the total required time had dropped to approximately 3 hours once all staff became familiar with the instruments and software. There were no observed complications from treatment and both patients tolerated anesthesia and brachytherapy well. Mean dose to point A was 5.57 Gy for patient 1 and 5.68 Gy for patient 2. Corresponding doses for points B and H were 1.26 Gy and 1.28 Gy; and 4.59 Gy and 5.68 Gy, respectively. Mean dose to the bladder was 1.37 Gy for patient 1 and 1.61 Gy for patient 2. The dose (D5) received by 5% of bladder volume was 3.64 Gy for patient 1 and 4.49 Gy for patient 2. Mean rectum doses were 1.97 Gy and 1.13 Gy and rectum D5 was 2.37 Gy and 2.95 Gy for patients 1 and 2, respectively.ConclusionsTo our knowledge, this represents the first report of electronic-source brachytherapy for cervical cancer and was accomplished with acceptable dosimetry and clinical tolerability.
Thompson, J,
Feasibility of Cervical Brachytherapy with a Novel 50 kV Electronic Brachytherapy Source. Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL.
http://archive.rsna.org/2014/14041332.html
