Direction Modulated Brachytherapy for Treatment of Cervical Cancer. II: Comparative Planning Study With Intracavitary and Intracavitary-Interstitial Techniques.
To perform a comprehensive comparative planning study evaluating the utility of the proposed direction modulated brachytherapy (DMBT) tandem applicator against standard applicators, in the setting of image guided adaptive brachytherapy of cervical cancer.



A detailed conceptual article was published in 2014. The proposed DMBT tandem applicator has 6 peripheral grooves of 1.3-mm width, along a 5.4-mm-thick nonmagnetic tungsten alloy rod of density 18.0 g/cm(3), capable of generating directional dose profiles. We performed a comparative planning study with 45 cervical cancer patients enrolled consecutively in the prospective observational EMBRACE study. In all patients, MRI-based planning was performed while utilizing various tandem-ring (27 patients) and tandem-ring-needles (18 patients) applicators, in accordance with the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology recommendations. For unbiased comparisons, all cases were replanned with an in-house-developed inverse optimization code while enforcing a uniform set of constraints that are reflective of the clinical practice. All plans were normalized to the same high-risk clinical target volume D90 values achieved in the original clinical plans.



In general, if the standard tandem was replaced with the DMBT tandem while maintaining all other planning conditions the same, there was consistent improvement in the plan quality. For example, among the 18 tandem-ring-needles cases, the average D2cm(3) reductions achieved were -2.48% ± 11.03%, -4.45% ± 5.24%, and -5.66% ± 6.43% for the bladder, rectum, and sigmoid, respectively. An opportunity may also exist in avoiding use of needles altogether for when the total number of needles required is small (approximately 2 to 3 needles or less), if DMBT tandem is used.



Integrating the novel DMBT tandem onto both intracavitary and intracavitary-interstitial applicator assembly enabled consistent improvement in the sparing of the OARs, over a standard "single-channel" tandem, though individual variations in benefit were considerable. Although at an early stage of development, the DMBT concept design is demonstrated to be useful and pragmatic for potential clinical translation.
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, University of California, San Francisco, San Francisco, California; Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California.
Dae Yup
DY
Han
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
Habib
H
Safigholi
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
Abraam
A
Soliman
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
Ananth
A
Ravi
Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
Eric
E
Leung
Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
Daniel J
DJ
Scanderbeg
Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California.
Zhaowei
Z
Liu
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
Amir
A
Owrangi
Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada. Electronic address: william.song@sunnybrook.ca.
William Y
WY
Song
D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008875:Middle Aged; D019919:Prosthesis Implantation / Q000295:instrumentation* / Q000379:methods; D011868:Radioisotopes / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy*
D011868:Radioisotopes