scholarly journals Are simple verbal instructions sufficient to ensure that bladder volume does not deteriorate prostate position reproducibility during spot scanning proton therapy?

BJR|Open ◽  
2021 ◽  
Author(s):  
Kentaro Nishioka ◽  
Kento Gotoh ◽  
Takayuki Hashimoto ◽  
Takashige Abe ◽  
Takahiro Osawa ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Bladder Volume ◽  
Fiducial Markers ◽  
Image Guided ◽  
Verbal Instructions ◽  
Spot Scanning ◽  
Prostate Motion ◽  
Rectal Volume ◽  
The Mean

Objectives: The purpose of this study is to investigate whether verbal instructions are sufficient for bladder volume (BV) control not to deteriorate prostate position reproducibility in image-guided spot scanning proton therapy (SSPT) for localized prostate cancer. Methods: A total of 268 treatment sessions in 12 consecutive prostate cancer patients who were treated with image-guided SSPT with fiducial markers were retrospectively analyzed. In addition to strict rectal volume control procedures, simple verbal instructions to void urine one hour before the treatment were used here. The BV was measured by a Bladder Scan just before the treatment and the prostate motion was measured by intraprostatic fiducial markers and two sets of X-ray fluoroscopy images. The correlation between the BV change and prostate motion was assessed by linear mixed-effects models and systematic and random errors according to the reproducibility of the BV. Results: The mean absolute BV change during treatment was from −98.7 to 86.3 ml (median 7.1 ml). The mean absolute prostate motion of the patients in the left-right direction was −1.46 to 1.85 mm, in the cranial-caudal direction it was −6.10 to 3.65 mm, and in the anteroposterior direction −1.90 to 5.23 mm. There was no significant relationship between the BV change and prostate motion during SSPT. The early and late genitourinary and gastrointestinal toxicity was minimal with a minimum follow-up of 4.57 years. Conclusions: Simple verbal instructions about urination was suggested to be sufficient to control the BV not to impact on the prostate motion and clinical outcomes in image-guided SSPT. Careful attention to BV change is still needed when the seminal vesicle is to be treated. Advances in knowledge: Our data demonstrated that there was no apparent relationship between BV changes and prostate position reproducibility and simple verbal instruction about urination could be sufficient for image-guided SSPT.

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 Clinical Implementation of Proton Therapy Using Pencil-Beam Scanning Delivery Combined With Static Apertures

2021 ◽  
Vol 11 ◽  
Author(s):  
Christian Bäumer ◽  
Sandija Plaude ◽  
Dalia Ahmad Khalil ◽  
Dirk Geismar ◽  
Paul-Heinz Kramer ◽  
...  
Keyword(s):  
At Risk ◽  
Proton Therapy ◽  
Target Volume ◽  
Delivery Mode ◽  
Pencil Beam ◽  
Clinical Implementation ◽  
Beam Scanning ◽  
Pencil Beam Scanning ◽  
Spot Scanning ◽  
The Mean

Proton therapy makes use of the favorable depth-dose distribution with its characteristic Bragg peak to spare normal tissue distal of the target volume. A steep dose gradient would be desired in lateral dimensions, too. The widespread spot scanning delivery technique is based, however, on pencil-beams with in-air spot full-widths-at-half-maximum of typically 1 cm or more. This hampers the sparing of organs-at-risk if small-scale structures adjacent to the target volume are concerned. The trimming of spot scanning fields with collimating apertures constitutes a simple measure to increase the transversal dose gradient. The current study describes the clinical implementation of brass apertures in conjunction with the pencil-beam scanning delivery mode at a horizontal, clinical treatment head based on commercial hardware and software components. Furthermore, clinical cases, which comprised craniopharyngiomas, re-irradiations and ocular tumors, were evaluated. The dosimetric benefits of 31 treatment plans using apertures were compared to the corresponding plans without aperture. Furthermore, an overview of the radiation protection aspects is given. Regarding the results, robust optimization considering range and setup uncertainties was combined with apertures. The treatment plan optimizations followed a single-field uniform dose or a restricted multi-field optimization approach. Robustness evaluation was expanded to account for possible deviations of the center of the pencil-beam delivery and the mechanical center of the aperture holder. Supplementary apertures improved the conformity index on average by 15.3%. The volume of the dose gradient surrounding the PTV (evaluated between 80 and 20% dose levels) was decreased on average by 17.6%. The mean dose of the hippocampi could be reduced on average by 2.9 GyRBE. In particular cases the apertures facilitated a sparing of an organ-at-risk, e.g. the eye lens or the brainstem. For six craniopharyngioma cases the inclusion of apertures led to a reduction of the mean dose of 1.5 GyRBE (13%) for the brain and 3.1 GyRBE (16%) for the hippocampi.

scholarly journals Strategies to evaluate the impact of rectal volume on prostate motion during three-dimensional conformal radiotherapy for prostate cancer

2016 ◽  
Vol 49 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Ana Paula Diniz Fortuna Poli ◽  
Rodrigo Souza Dias ◽  
Adelmo José Giordani ◽  
Helena Regina Comodo Segreto ◽  
Roberto Araujo Segreto
Keyword(s):  
Prostate Cancer ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Prostate Motion ◽  
Rectal Volume ◽  
Three Dimensional Conformal Radiotherapy ◽  
Interfraction Motion ◽  
The Impact ◽  
Anterior Posterior ◽  
3D Crt

Abstract Objective: To evaluate the rectal volume influence on prostate motion during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. Materials and Methods: Fifty-one patients with prostate cancer underwent a series of three computed tomography scans including an initial planning scan and two subsequent scans during 3D-CRT. The organs of interest were outlined. The prostate contour was compared with the initial CT images considering the anterior, posterior, superior, inferior and lateral edges of the organ. Variations in the anterior limits and volume of the rectum were assessed and correlated with prostate motion in the anteroposterior direction. Results: The maximum range of prostate motion was observed in the superoinferior direction, followed by the anteroposterior direction. A significant correlation was observed between prostate motion and rectal volume variation ( p = 0.037). A baseline rectal volume superior to 70 cm3 had a significant influence on the prostate motion in the anteroposterior direction ( p = 0.045). Conclusion: The present study showed a significant interfraction motion of the prostate during 3D-CRT with greatest variations in the superoinferior and anteroposterior directions, and that a large rectal volume influences the prostate motion with a cutoff value of 70 cm3. Therefore, the treatment of patients with a rectal volume > 70 cm3 should be re-planned with appropriate rectal preparation.

Ten-Year Outcomes From Three Prospective Clinical Trials Of Image-Guided Proton Therapy In Prostate Cancer

2020 ◽  
Vol 108 (3) ◽  
pp. e916-e917
Author(s):  
N.P. Mendenhall ◽  
C.M. Bryant ◽  
B.S. Hoppe ◽  
R.C. Nichols ◽  
W.M. Mendenhall ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trials ◽  
Proton Therapy ◽  
Image Guided

SU-E-T-496: Influence of the Intrafraction Patient Repositioning On Spot Scanning Proton Therapy for Prostate Cancer

2015 ◽  
Vol 42 (6Part20) ◽  
pp. 3449-3449
Author(s):  
◽  
Y Fujii ◽  
T Matsuura ◽  
S Takao ◽  
Y Matsuzaki ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Spot Scanning

A treatment planning comparison of proton therapy and intensity-modulated radiotherapy (IMRT) for prostate cancer using the normal tissue complication probability (NTCP).

2016 ◽  
Vol 34 (2_suppl) ◽  
pp. 153-153
Author(s):  
Benjamin Walker Fischer-Valuck ◽  
Lindsey Olsen ◽  
Thomas Mazur ◽  
Michael Altman ◽  
Beth Bottani ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Normal Tissue ◽  
Normal Tissue Complication Probability ◽  
Phase Iii ◽  
High Dose ◽  
Rectal Toxicity ◽  
Rectal Balloon ◽  
Intensity Modulated ◽  
The Mean

153 Background: The volume of rectum receiving high-dose (i.e. > or = 60 Gy) is consistently associated with the risk of Grade > or = 2 rectal toxicity or rectal bleeding based on common terminology criteria for adverse events (CTCAE). Our goal was to compare intensity-modulated photon radiotherapy (IMRT) with proton radiotherapy in regard to the rectal dose using the normal tissue complication probability (NTCP). Methods: Between July 2014 and September 2015 the first 10 consecutive low or intermediate risk prostate cancer patients were treated with proton therapy at our institution. All 10 patients were planned with three-dimensional conformal proton therapy (3D-CPT) using two parallel opposed fields as well as comparison IMRT plans. A rectal balloon filled with water was used in all patients treated. Prescribed dose to the prostate was 79.2 Gy or cobalt Gy equivalent (CBE) for protons. Dose-volume histograms were compared. The Lyman-Kutcher-Burman model (n = 0.09, m = 0.13, and TD50 = 76.9 Gy) was used to generate NTCP estimates for both IMRT and proton plans. Results: At least 95% of the planning target volume received the prescription dose for both proton and IMRT plans. Dose constraints placed on the rectum included volume receiving 65 Gy (V65) less than 17% and V40 less than 35%. The mean dose to the rectum was 24.5 Gy (range, 19.5-30.1 Gy) and 31.7 Gy (range, 23.7-39.4 Gy) for the proton and IMRT plans, respectively. The V65 constraint was unachievable in 3 of the proton plans and 3 of the IMRT plans. The mean V70 and V75 for proton plans was 8.4% and 5.4% compared to 7.5% and 4.8% for the IMRT plans. The mean NTCP for proton treatment plans was 7.72% (range, 2.7-11.7%) and 7.92% (range, 1.7-15.3%) for IMRT (P = 0.45). After median follow-up of 6 months, no grade 2 or higher toxicity has been reported. Conclusions: Utilizing NTCP estimations, proton therapy and IMRT have similar predicted rates of rectal toxicity. Currently, a Phase III randomized clinical trial is underway comparing proton therapy and IMRT with regards to rectal toxicity and quality of life.

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