TY - JOUR
T1 - MRI-assisted radiosurgery
T2 - A quality assurance nomogram for palladium-103 and iodine-125 prostate brachytherapy
AU - Hanania, Alexander N.
AU - Kudchadker, Rajat J.
AU - Bruno, Teresa L.
AU - Tang, Chad
AU - Anscher, Mitchell S.
AU - Frank, Steven J.
N1 - Publisher Copyright:
© 2020 American Brachytherapy Society
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Purpose: We sought to develop an activity nomogram for magnetic resonance (MR)–planned permanent seed prostate brachytherapy to improve quality assurance through a secondary dosimetric check. Methods and Materials: Patients undergoing MRI-assisted radiosurgery (MARS), whereby MRI is used for preoperative planning and postimplant dosimetry, were reviewed from May 2016 to September 2018. Planned activity (U) was fitted by MR-prostate volume (cc) via simple linear regression. Resulting monotherapy nomograms were compared with institutional nomograms from an ultrasound-planned cohort. Dosimetric coverage and external urinary sphincter (EUS) dose were also assessed for MR-planned patients. Results: We identified 183 patients treated with MARS: 146 patients received palladium-103 (103Pd; 102 monotherapy and 44 boost), and 37 received iodine-125 (125I) monotherapy. Median prostate volume was 28 cc (interquartile range: 22–35). Lines of best fit for implant activity were U = 4.344 × (vol) + 54.13 (R2: 95%) for 103Pd monotherapy, U = 3.202 (vol) + 39.72 (R2: 96%) for 103Pd boost and U = 0.684 (vol) + 13.38 (R2: 96%) for 125I monotherapy. Compared with ultrasound, MR-planned nomograms had lower activity per volume (p < 0.05) for both 103Pd monotherapy (∼6%) and 125I monotherapy (∼11%), given a median size (30 cc) prostate. Across all MARS implants, postimplant dosimetry revealed a median V100% of 94% (interquartile range: 92–96%). Median EUS V125 was <1 cc for all patients, regardless of isotope. Conclusions: We developed a quality assurance nomogram for MR-planned prostate brachytherapy. When compared with ultrasound-planned, MR-planned monotherapy resulted in a lower activity-to-volume ratio while maintaining dosimetric coverage, likely secondary to EUS-sparing and reduced planning target margins.
AB - Purpose: We sought to develop an activity nomogram for magnetic resonance (MR)–planned permanent seed prostate brachytherapy to improve quality assurance through a secondary dosimetric check. Methods and Materials: Patients undergoing MRI-assisted radiosurgery (MARS), whereby MRI is used for preoperative planning and postimplant dosimetry, were reviewed from May 2016 to September 2018. Planned activity (U) was fitted by MR-prostate volume (cc) via simple linear regression. Resulting monotherapy nomograms were compared with institutional nomograms from an ultrasound-planned cohort. Dosimetric coverage and external urinary sphincter (EUS) dose were also assessed for MR-planned patients. Results: We identified 183 patients treated with MARS: 146 patients received palladium-103 (103Pd; 102 monotherapy and 44 boost), and 37 received iodine-125 (125I) monotherapy. Median prostate volume was 28 cc (interquartile range: 22–35). Lines of best fit for implant activity were U = 4.344 × (vol) + 54.13 (R2: 95%) for 103Pd monotherapy, U = 3.202 (vol) + 39.72 (R2: 96%) for 103Pd boost and U = 0.684 (vol) + 13.38 (R2: 96%) for 125I monotherapy. Compared with ultrasound, MR-planned nomograms had lower activity per volume (p < 0.05) for both 103Pd monotherapy (∼6%) and 125I monotherapy (∼11%), given a median size (30 cc) prostate. Across all MARS implants, postimplant dosimetry revealed a median V100% of 94% (interquartile range: 92–96%). Median EUS V125 was <1 cc for all patients, regardless of isotope. Conclusions: We developed a quality assurance nomogram for MR-planned prostate brachytherapy. When compared with ultrasound-planned, MR-planned monotherapy resulted in a lower activity-to-volume ratio while maintaining dosimetric coverage, likely secondary to EUS-sparing and reduced planning target margins.
KW - Brachytherapy
KW - Iodine
KW - Magnetic resonance (MR)
KW - Nomogram
KW - Palladium
KW - Prostate
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UR - http://www.scopus.com/inward/citedby.url?scp=85076243927&partnerID=8YFLogxK
U2 - 10.1016/j.brachy.2019.10.002
DO - 10.1016/j.brachy.2019.10.002
M3 - Article
C2 - 31812590
AN - SCOPUS:85076243927
SN - 1538-4721
VL - 19
SP - 38
EP - 42
JO - Brachytherapy
JF - Brachytherapy
IS - 1
ER -