scholarly journals Hydrogel Spacer Reduces Rectal Dose during Proton Therapy for Prostate Cancer: A Dosimetric Analysis

2019 ◽  
Vol 5 (4) ◽  
pp. 23-31 ◽  
Author(s):  
Praveen Polamraju ◽  
Alexander F. Bagley ◽  
Tyler Williamson ◽  
X. Ronald Zhu ◽  
Steven J. Frank
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Rectal Wall ◽  
Anterior Rectal Wall ◽  
Linear Regression Models ◽  
Intensity Modulated Proton Therapy ◽  
Rectal Dose ◽  
Before And After ◽  
Biodegradable Hydrogel ◽  
Dosimetric Analysis

Abstract Purpose: Proton therapy for prostate cancer may reduce bowel dose and risk of bowel symptoms relative to photon-based methods. Here, we determined the effect of using a biodegradable, injectable hydrogel spacer on rectal dose on plans for treating prostate cancer with intensity-modulated proton therapy (IMPT) or passive scattering proton therapy (PSPT). Materials and Methods: Pairs of IMPT and PSPT plans for 9 patients were created from fused computed tomography/magnetic resonance imaging scans obtained before and after spacer injection. Calculated values of rectal V40, V60, V70, V80, and maximum dose (Dmax) were compared with Wilcoxon signed rank tests. Displacements at the base (BP), midgland (MP), and apex (AP) of the prostate relative to the anterior rectal wall with the spacer in place were averaged for each patient and correlated with V70 by using linear regression models. Results: The presence of a spacer reduced all dosimetric parameters for both PSPT and IMPT, with the greatest difference in V70, which was 81.1% lower for PSPT-with-spacer than for IMPT-without-spacer. Median displacements at BP, MP, and AP were 12 mm (range 7-19), 2 mm (range 0-4), and 1 mm (range 0-5) without the spacer and 19 mm (range 12-23), 10 mm (range 8-16), and 7 mm (range 2-12) with the spacer. Modest linear trends were noted between rectal V70 and displacement for IMPT-with-spacer and PSPT-with-spacer. When displacement was ≥8 mm, V70 was ≤5.1% for IMPT-with-spacer and PSPT-with-spacer. Conclusion: Use of biodegradable hydrogel spacers for prostate cancer treatment provides a significant reduction of radiation dose to the rectum with proton therapy. Significant reductions in rectal dose occurred in both PSPT and IMPT plans, with the greatest reduction for IMPT-with-spacer relative to PSPT alone. Prospective studies are ongoing to assess the clinical impact of reducing rectal dose with hydrogel spacers.

scholarly journals Preliminary analysis of prostate positional displacement using hydrogel spacer during the course of proton therapy for prostate cancer

2020 ◽  
Author(s):  
Hiroki Sato ◽  
Takahiro Kato ◽  
Tomoaki Motoyanagi ◽  
Kimihiro Takemasa ◽  
Yuki Narita ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Rectal Dose ◽  
Prostate Motion ◽  
Significant Difference ◽  
Risk Prostate Cancer ◽  
Bony Anatomy ◽  
Study Population ◽  
Planning Ct ◽  
Anterior Posterior

Abstract In recent years, a novel technique has been employed to maintain a distance between the prostate and the rectum by transperineally injecting a hydrogel spacer (HS). However, the effect of HS on the prostate positional displacement is poorly understood, despite its stability with HS in place. In this study, we investigated the effect of HS insertion on the interfraction prostate motion during the course of proton therapy (PT) for Japanese prostate cancer patients. The study population consisted of 22 cases of intermediate-risk prostate cancer with 11 cases with HS insertion and 11 cases without HS insertion. The irradiation position and preparation were similar for both groups. To test for reproducibility, regular confirmation computed tomography (RCCT) was done four times during the treatment period, and five times overall [including treatment planning CT (TPCT)] in each patient. Considering the prostate position of the TPCT as the reference, the change in the center of gravity of the prostate relative to the bony anatomy in the RCCTs of each patient was determined in the left–right (LR), superior–inferior (SI) and anterior–posterior (AP) directions. As a result, no significant difference was observed across the groups in the LR and SI directions. Conversely, a significant difference was observed in the AP direction (P < 0.05). The proportion of the 3D vector length ≤5 mm was 95% in the inserted group, but 55% in the non-inserted group. Therefore, HS is not only effective in reducing rectal dose, but may also contribute to the positional reproducibility of the prostate.

scholarly journals Early Clinical Outcomes of Intensity Modulated Radiation Therapy/Intensity Modulated Proton Therapy Combination in Comparison with Intensity Modulated Radiation Therapy Alone in Oropharynx Cancer Patients

Cancers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1549
Author(s):  
Han Gyul Yoon ◽  
Yong Chan Ahn ◽  
Dongryul Oh ◽  
Jae Myoung Noh ◽  
Seung Gyu Park ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Proton Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Combination Group ◽  
Intensity Modulated Proton Therapy ◽  
Oropharynx Cancer ◽  
Intensity Modulated ◽  
Before And After ◽  
Grade 3 ◽  
Early Clinical Outcomes

Purpose: To report the early clinical outcomes of combining intensity-modulated radiation therapy (IMRT) and intensity-modulated proton therapy (IMPT) in comparison with IMRT alone in treating oropharynx cancer (OPC) patients. Materials and Methods: The medical records of 148 OPC patients who underwent definitive radiotherapy (RT) with concurrent systemic therapy, from January 2016 till December 2019 at Samsung Medical Center, were retrospectively reviewed. During the 5.5 weeks’ RT course, the initial 16 (or 18) fractions were delivered by IMRT in all patients, and the subsequent 12 (or 10) fractions were either by IMRT in 81 patients (IMRT only) or by IMPT in 67 (IMRT/IMPT combination), respectively, based on comparison of adaptive re-plan profiles and availability of equipment. Propensity-score matching (PSM) was done on 76 patients (38 from each group) for comparative analyses. Results: With the median follow-up of 24.7 months, there was no significant difference in overall survival and progression free survival between groups, both before and after PSM. Before PSM, the IMRT/IMPT combination group experienced grade ≥ 3 acute toxicities less frequently: mucositis in 37.0% and 13.4% (p < 0.001); and analgesic quantification algorithm (AQA) in 37.0% and 19.4% (p = 0.019), respectively. The same trends were observed after PSM: mucositis in 39.5% and 15.8% (p = 0.021); and AQA in 47.4% and 21.1% (p = 0.016), respectively. In multivariate logistic regression, grade ≥ 3 mucositis was significantly less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.027 and 0.024, respectively). AQA score ≥ 3 was also less frequent in the IMRT/IMPT combination group, both before and after PSM (p = 0.085 and 0.018, respectively). Conclusions: In treating the OPC patients, with comparable early oncologic outcomes, more favorable acute toxicity profiles were achieved following IMRT/IMPT combination than IMRT alone.

SU-E-T-403: Intensity Modulated Proton Therapy Plans with Multiple Fields for Prostate Cancer

2013 ◽  
Vol 40 (6Part17) ◽  
pp. 297-297
Author(s):  
S Dhanesar ◽  
N Sahoo ◽  
M Kerr ◽  
M Taylor ◽  
P Summers ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated

The impact of varying rectal contours on rectal dose in prostate cancer patients treated with hypofractionated radiation

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 15598-15598
Author(s):  
B. B. Joshua ◽  
S. Faria ◽  
H. Patrocinio ◽  
F. DeBlois ◽  
M. Duclos ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Radiation Treatment ◽  
Rectal Wall ◽  
Organs At Risk ◽  
Anal Verge ◽  
Rectal Toxicity ◽  
Rectal Dose ◽  
Organ At Risk ◽  
Definition Of

15598 Background: In curative radiation treatment of prostate cancer,the advent of 3DCRT has made a reduction in the incidence of normal tissue toxicities while optimizing tumor control. To optimize 3DCRT, the ICRU has published standard definitions of target volumes and organs at risk such that the tumor can receive the optimal dose with as little as possible dose to the organs at risk. However, the definition of the rectum as an organ at risk in radiation treatment of the prostate varies widely among institutions and so does the report of toxicities. We studied the effect of varying rectal contouring on rectal dose obtained from DVHs in a homogenous group of prostate cancer patients treated with hypo fractionationed radiation. Methods: 71 patients with favorable risk prostate cancer treated with a total of 66Gy in 3Gy/day fractionation.18 MV photons in a 5-field technique was used. None of the patients received hormonal therapy. Their treatment plans were archived and the rectum was re-contoured by a single investigator. 4 different contours were drawn to compare the rectal dose: i) the whole rectum from the anal verge to the recto sigmoid junction (WR); ii) the rectum from 1cm below the PTV to 1cm above (RPTV); iii) the rectal wall (i.e. the inner and outer rectal wall) from the anal verge to the recto sigmoid junction (RW); iv) the rectal wall from 1cm below the PTV to 1cm above (RWPTV) Results: There were significant differences in the median volume, minimum, mean rectal doses and dose to 50% of the volume, (p=0.0001). The whole rectum (WR) is having the lowest and the rectal wall with 1cm above and below the PTV (RWPTV) having the highest in all the parameters. The only parameter not significantly different among the 4 contours is the maximum rectal dose. Conclusion: the varied rectal contouring across different institutions is a possible reason for the broadly different reports of rectal toxicity after prostate irradiation. Our results suggest significant differences in rectal doses with varied contouring. Contouring the rectal wall only and limiting the volume to 1cm above and below the PTV confers the highest mean rectal dose. Comparison of rectal toxicity between institutions can only be meaningful if a consensual volume definition of the organ at risk is agreed upon. No significant financial relationships to disclose.

Assessment of daily dose accumulation for robustly optimized intensity modulated proton therapy treatment of prostate cancer

2021 ◽  
Vol 81 ◽  
pp. 77-85
Author(s):  
Yihang Xu ◽  
Tejan Diwanji ◽  
Nellie Brovold ◽  
Michael Butkus ◽  
Kyle R. Padgett ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Dose Accumulation ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Daily Dose ◽  
Therapy Treatment
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