TY - JOUR
T1 - Dosimetric comparison of rectal-sparing capabilities of rectal balloon vs injectable spacer gel in stereotactic body radiation therapy for prostate cancer
T2 - lessons learned from prospective trials
AU - Jones, Ryan T.
AU - Hassan Rezaeian, Nima
AU - Desai, Neil B
AU - Lotan, Yair
AU - Jia, Xun
AU - Hannan, Raquibul
AU - Kim, D. W.Nathan
AU - Hornberger, Brad
AU - Dubas, Jeffrey
AU - Laine, Aaron M
AU - Zelefsky, Michael J.
AU - Timmerman, Robert
AU - Folkert, Michael R
N1 - Publisher Copyright:
© 2017 American Association of Medical Dosimetrists
PY - 2017/2/4
Y1 - 2017/2/4
N2 - This study aimed to compare the rectal-sparing capabilities of rectal balloons vs absorbable injectable spacer gel in stereotactic body radiation therapy (SBRT) for prostate cancer. Patient samples included in this analysis were obtained from 2 multi-institutional prospective trials of SBRT for prostate cancer using a rectal balloon (n = 36 patients) and injectable spacer gel (n = 36). Treatment prescription dose was 45 Gy in 5 fractions in 42 patients; for equal comparison, the remaining 30 patients were rescaled to 45 Gy from 47.5 Gy prescription (n = 6) and 50 Gy prescription (n = 24). The median prostate volumes and body mass index in the 2 patient samples were not statistically significantly different (p = 0.67 and 0.45, respectively), supporting anatomic similarity between cohorts. The injectable spacer gel achieved dosimetric superiority over the rectal balloon with respect to the maximum dose to the rectum (42.3 vs 46.2 Gy, p < 0.001), dose delivered to 33% of the rectal circumference (28 vs 35.1 Gy, p < 0.001), and absolute volume of rectum receiving 45 Gy (V45Gy), V40Gy, and V30Gy (0.3 vs 1.7 cc, 1 vs 5.4 cc, and 4.1 vs 9.6 cc, respectively; p < 0.001 in all cases). There was no difference between the 2 groups with respect to the V50Gy of the rectum or the dose to 50% of the rectal circumference (p = 0.29 and 0.06, respectively). The V18.3Gy of the bladder was significantly larger with the rectal balloon (19.9 vs 14.5 cc, p = 0.003). In this analysis of patients enrolled on 2 consecutive multi-institutional prospective trials of SBRT for prostate cancer, the injectable spacer gel outperformed the rectal balloon in the majority of the examined and relevant dosimetric rectal-sparing parameters. The rectal balloon did not outperform the injectable spacer gel in any measured rectal dose parameter.
AB - This study aimed to compare the rectal-sparing capabilities of rectal balloons vs absorbable injectable spacer gel in stereotactic body radiation therapy (SBRT) for prostate cancer. Patient samples included in this analysis were obtained from 2 multi-institutional prospective trials of SBRT for prostate cancer using a rectal balloon (n = 36 patients) and injectable spacer gel (n = 36). Treatment prescription dose was 45 Gy in 5 fractions in 42 patients; for equal comparison, the remaining 30 patients were rescaled to 45 Gy from 47.5 Gy prescription (n = 6) and 50 Gy prescription (n = 24). The median prostate volumes and body mass index in the 2 patient samples were not statistically significantly different (p = 0.67 and 0.45, respectively), supporting anatomic similarity between cohorts. The injectable spacer gel achieved dosimetric superiority over the rectal balloon with respect to the maximum dose to the rectum (42.3 vs 46.2 Gy, p < 0.001), dose delivered to 33% of the rectal circumference (28 vs 35.1 Gy, p < 0.001), and absolute volume of rectum receiving 45 Gy (V45Gy), V40Gy, and V30Gy (0.3 vs 1.7 cc, 1 vs 5.4 cc, and 4.1 vs 9.6 cc, respectively; p < 0.001 in all cases). There was no difference between the 2 groups with respect to the V50Gy of the rectum or the dose to 50% of the rectal circumference (p = 0.29 and 0.06, respectively). The V18.3Gy of the bladder was significantly larger with the rectal balloon (19.9 vs 14.5 cc, p = 0.003). In this analysis of patients enrolled on 2 consecutive multi-institutional prospective trials of SBRT for prostate cancer, the injectable spacer gel outperformed the rectal balloon in the majority of the examined and relevant dosimetric rectal-sparing parameters. The rectal balloon did not outperform the injectable spacer gel in any measured rectal dose parameter.
KW - Rectal balloon
KW - Rectal dosimetry
KW - Rectal spacer
KW - Rectal toxicity
KW - Stereotactic body radiation therapy
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U2 - 10.1016/j.meddos.2017.07.002
DO - 10.1016/j.meddos.2017.07.002
M3 - Article
C2 - 28774760
AN - SCOPUS:85026383065
SN - 0958-3947
VL - 42
SP - 341
EP - 347
JO - Medical Dosimetry
JF - Medical Dosimetry
IS - 4
ER -