Abstract
Brachytherapy plays an important role in the definitive treatment of cervical cancers by radiotherapy. In the present study, we investigated whether sliding‐window intensity‐modulated radiation therapy (IMRT) can achieve a pear‐shaped distribution with a similar sharp dose falloff identical to that of brachytherapy. The computed tomography scans of a tandem and ovoid patient were pushed to both a high dose rate (HDR) and an IMRT treatment planning system (TPS) after the rectum, bladder, and left and right femoral heads had been outlined, ensuring identical structures in both planning systems. A conventional plan (7 Gy in 5 fractions, defined as the average dose to the left and right point A) was generated for HDR treatment. The 150%, 125%, 100%, 75%, 50%, and 25% isodose curves were drawn on each slice and then transferred to the IMRT TPS. The 100% isodose envelope from the HDR plan was the target for IMRT planning. A 7‐field IMRT plan using 6‐MV X‐ray beams was generated and compared with the HDR plan using isodose conformity to the target and 125% volume, dose– volume histograms, and integral dose. The resulting isodose distribution demonstrated good agreement between the HDR and IMRT plans in the 100% and 125% isodose range. The dose falloff in the HDR plan was much steeper than that in the IMRT plan, but it also had a substantially higher maximum dose. Integral dose for the target, rectum, and bladder were found to be 6.69 J, 1.07 J, and 1.02 J in the HDR plan; the respective values for IMRT were 3.47 J, 1.79 J, and 1.34 J. Our preliminary results indicate that the HDR dose distribution can be replicated using a standard sliding‐window IMRT dose delivery technique for points lying closer to the three‐dimensional isodose envelope surrounding point A. Differences in radiobiology and patient positioning between the two techniques merit further consideration.PACS: 87.53.Jw
Highlights
Bladder, left and right femur heads, and other structures had been contoured, the computed tomography (CT) scans of a patient with an implanted tandem and ovoid applicator were electronically transferred to a Plato treatment planning system for high dose rate (HDR) planning and to an Eclipse treatment planning system for intensity-modulated radiation therapy (IMRT) planning
The HDR isodose curves could instantly be visualized against the equivalent IMRT plan
The isodose curves in the HDR and IMRT plans were evaluated slice by slice, and for isodose values higher than or equal to 75%, excellent agreement between the plans was observed
Summary
The advent of high dose rate (HDR) afterloading technology reduced the treatment time, enabling outpatient treatment. In developed countries, the incidence of cancer of cervix is comparatively low, and because of early detection, the rate of presentation of advanced-stage lesions requiring radiation and, brachytherapy as treatment modality is even lower. These factors have combined to produce a scenario in which not all treatment centers can provide the brachytherapy option to patients. Delivery of this type of therapy with an intensity-modulated radiation therapy (IMRT) approach has been proposed.[1,2,3,4,5]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
