Intrafraction motion during CyberKnife® prostate SBRT: impact of imaging frequency and patient factors

Author:

Rose Clarecia1ORCID,Ebert Martin A.2,Mukwada Godfrey2,Skorska Malgorzata2,Gill Suki2

Affiliation:

1. University of Western Australia

2. Sir Charles Gairdner Hospital

Abstract

AbstractPurpose: To determine the relationship between imaging frequencies and prostate motion during CyberKnife stereotactic body radiotherapy (SBRT) for prostate cancer. Methods: Intrafraction displacement data for 331 patients who received treatment with CyberKnife for prostate cancer were retrospectively analysed. Prostate positions were tracked with a large variation in imaging frequencies. The percent of treatment time that patients remained inside various motion thresholds for both real and simulated imaging frequencies was calculated. Results: 84,920 image acquisitions over 1635 fractions were analysed. Fiducial distance travelled between consecutive images were less than 2, 3, 5, and 10 mm for 92.4%, 94.4%, 96.2%, and 97.7% of all consecutive imaging pairs respectively. The percent of treatment time that patients received adequate geometric coverage increased with more frequent imaging intervals. No significant correlations between age, weight, height, BMI, rectal, bladder or prostate volumes and intrafraction prostate motion were observed. Conclusions: There are several combinations of imaging intervals and movement thresholds that may be suitable for consideration during treatment planning with respect to imaging and CTV-to-PTV margin calculation, resulting in adequate geometric coverage for approximately 95% of treatment time. Rectal toxicities and treatment duration need to be considered when implementing combinations clinically.

Publisher

Research Square Platform LLC

Reference128 articles.

1. Presentations at Leading Radiation Oncology Meeting Highlight CyberKnife Prostate Outcomes from Patients at More Than 40 Centers: The CyberKnife System, with its Unique Ability to Track and Correct for Motion During Treatment, Demonstrates Strong Results in Prostate Cancer. Journal Article, Cancer therapies Hospitals Oncology Presentations Press conferences Prostate cancer Radiation therapy Studies, CyberKnife SBRT for patients with intermediate-risk prostate cancer was the focus of a study presented by Robert Meier, M.D., a radiation oncologist with the Swedish Cancer Institute in Seattle, and co-lead by Beth Israel Deaconess Medical Center in Boston., PR newswire, 2012

2. (2014) Findings from University of Zurich Provides New Data about Prostate Cancer [Long-term intra-fractional motion of the prostate using hydrogel spacer during Cyberknife treatment for prostate cancer - a case report] [Long-term intra-fractional ...]. Cancer Weekly : 52 Journal Article, Care and treatment Prostate cancer Radiotherapy Research, 1532-4567

3. T K, B. and K M, G. and A, P. and C A, M. (2020) Cyberknife, Helical Tomotherapy and Rapid Arc SIB-SBRT Treatment Plan Comparison for Carcinoma Prostate. Asian Pac J Cancer Prev 21(4): 1149-1154 https://doi.org/10.31557/APJCP.2020.21.4.1149, Journal Article, Adenocarcinoma Follow-Up Studies Humans Male Organs at Risk Prognosis Prostatic Neoplasms Radiosurgery Radiotherapy Dosage Radiotherapy Planning, Computer-Assisted Radiotherapy, Intensity-Modulated Retrospective Studies CyberKnife Helical tomotherapy Prostate Cancer RapidArc SIB-SBRT, This study was conducted to dosimetrically compare plan quality of Simultaneous Integrated Boost - Stereotactic Body Radiotherapy (SIB-SBRT) generated for different techniques such as Cyberknife (CK), Helical Tomotherapy (HT) and RapidArc (RA) for carcinoma prostate with same treatment margins.|SIB-SBRT plans were generated for CK, HT and RA for thirteen CT data sets. The dose prescription was 45Gy in 5 fractions to GTV45 and 37.5Gy in 5 fractions to PTV37.5. The plan quality evaluation of the three techniques was done by comparing the DVH parameters, conformity index (CI) and gradient index (GI). For OAR's mean, maximum dose and dose volumes were compared for bladder, rectum and bilateral femoral heads. The number of Monitor Units (MU) delivered and Beam-on time (BOT) were also compared.|D2%, D50% and DMean to GTV45 was significantly higher in the CK compared to HT and RA (CK vs HT: p values, <0.001, 0.002 and 0.003

4. CK vs RA: p values, 0.001, 0.004 and 0.004) respectively. RA gives a better gradient index compared to CK and HT. Conformity indices of the RA plans were better than the CK plans (P<0.001). Normal tissue and integral dose delivered to the patient in HT and CK were found to be significantly higher than RA. The average number of MU's and BOT were significantly higher in CK (p<0.001).|Using the same treatment margins and dose constraints, RA achieved better target dose distribution and sparing of critical structures compared to CK and HT. RA seemed to be the optimal planning technique for SIB-SBRT treatment of carcinoma prostate.
., https://www.ncbi.nlm.nih.gov/pubmed/32334484, T K, Bijina K M, Ganesh A, Pichandi C A, Muthuselvi 2020/4/27, 2476-762X

5. Badakhshi, H. and Wust, P. and Budach, V. and Graf, R. (2013) Image-guided radiotherapy with implanted markers and kilovoltage imaging and 6-dimensional position corrections for intrafractional motion of the prostate. Anticancer Res 33(9): 4117-21 Journal Article, Humans Male *Motion Prostatic Neoplasms/*radiotherapy Radiotherapy Dosage Radiotherapy, Image-Guided/*methods Prostate cancer image-guided intervention infrafractional motion, BACKGROUND/AIM: To assess intrafractional prostate and patient movement using intra-prostatic fiducials and stereoscopic kilovoltage (kV) X-ray imaging in a 6-dimensional (6D) position correction protocol. To evaluate potential gains of intra-treatment repositioning with respect to treatment margins. PATIENTS AND METHODS: In intensity-modulated radiotherapy of prostate cancer patients were positioned according to internal fiducials in six dimensions by the use of ExacTrac/Novalis Body ™ (ET/NB) System and a robotic couch. Intrafractional displacement of both, prostate and patient were analyzed in 427 treatment fractions of 13 patients. Systematic and random components were specified and used for intra-treatment margin calculation. The potential reduction of treatment margins, and intrafractional repositioning by use of the ET Snap Verification presumed, was simulated. RESULTS: The mean treatment duration was 14.2 ±2.6 min. Standard deviations (SDs) of the effective intrafractional target displacement in superior-inferior (SI) and anterior-posterior (AP) axes were 2.4 mm and 2.1 mm, respectively. Systematic errors for patient were 1.8 and 1.7 mm, and for prostate movement were 2.1 and 2.0 mm in SI and AP, respectively. The SDs of intrafractional rotation errors of the prostate around SI and left right (LR) were on average 2.2 and 3.6 degrees, respectively. Margins covering intrafractional motion were 4.5 and 4.3 mm in SI and AP without intrafractional correction and were estimated to 2.9 mm and 2.8 mm in SI and AP, respectively for simulated intra-treatment intervention. CONCLUSION: After positioning according to fiducials, intrafractional motion is significant for treatment margins. Despite correcting rotational deviations by couch angulation, the systematic error for the component of prostate motion was somewhat larger than that of patient displacement. Intrafractional correction could be useful in reducing treatment margins., 1791-7530 Badakhshi, Harun Wust, Peter Budach, Volker Graf, Reinhold Journal Article Greece Anticancer Res. 2013 Sep;33(9):4117-21., 0250-7005

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