Journal article
Dynamic rotating-shield brachytherapy
Medical physics (Lancaster), Vol.40(12), pp.121703-n/a
12/2013
DOI: 10.1118/1.4828778
PMCID: PMC3838430
PMID: 24320489
Abstract
Purpose:
To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process.
Methods:
A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing theD
90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and 192Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D
2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α/β = 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively.
Results:
For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci192Ir source, and the average HR-CTV D
90 was 78.9 Gy. In order to match the HR-CTV D
90 of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D
90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively.
Conclusions:
For cervical cancer patients, D-RSBT can boost HR-CTVD
90 over IS + ICBT and S-RSBT without violating the tolerance doses to the bladder, rectum, or sigmoid. The D
90 improvements from D-RSBT depend on the patient, the delivery time budget, and the applicator structure.
Details
- Title: Subtitle
- Dynamic rotating-shield brachytherapy
- Creators
- Yunlong Liu - Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242Ryan T Flynn - Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242Yusung Kim - Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242Wenjun Yang - Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705Xiaodong Wu - Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Medical physics (Lancaster), Vol.40(12), pp.121703-n/a
- DOI
- 10.1118/1.4828778
- PMID
- 24320489
- PMCID
- PMC3838430
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Number of pages
- 11
- Grant note
- CCF-0844765 / NSF K25-CA123112 / NIH
- Language
- English
- Date published
- 12/2013
- Academic Unit
- Electrical and Computer Engineering; Radiation Oncology
- Record Identifier
- 9984047764902771
Metrics
12 Record Views