(OA35) Impact of Staging 68Ga-PSMA-11 Pet Scans on Radiation Treatment Plans in Patients With Prostate Cancer

Abstract Background The aim of this study was to evaluate and compare the performance of intensity modulated radiation therapy (IMRT) plans, planned for low-field strength magnetic resonance (MR) guided linear accelerator (linac) delivery (labelled IMRT MRL plans), and clinical conventional volumetric modulated arc therapy (VMAT) plans, for the treatment of prostate cancer (PCa). Both plans used the original planning target volume (PTV) margins. Additionally, the potential dosimetric benefits of MR-guidance were estimated, by creating IMRT MRL plans using smaller PTV margins. Materials and methods 20 PCa patients previously treated with conventional VMAT were considered. For each patient, two different IMRT MRL plans using the low-field MR-linac treatment planning system were created: one with original (orig.) PTV margins and the other with reduced (red.) PTV margins. Dose indices related to target coverage, as well as dose-volume histogram (DVH) parameters for the target and organs at risk (OAR) were compared. Additionally, the estimated treatment delivery times and the number of monitor units (MU) of each plan were evaluated. Results The dose distribution in the high dose region and the target volume DVH parameters (D98%, D50%, D2% and V95%) were similar for all three types of treatment plans, with deviations below 1% in most cases. Both IMRT MRL plans (orig. and red. PTV margins) showed similar homogeneity indices (HI), however worse values for the conformity index (CI) were also found when compared to VMAT. The IMRT MRL plans showed similar OAR sparing when the orig. PTV margins were used but a significantly better sparing was feasible when red. PTV margins were applied. Higher number of MU and longer predicted treatment delivery times were seen for both IMRT MRL plans. Conclusions A comparable plan quality between VMAT and IMRT MRL plans was achieved, when applying the same PTV margin. However, online MR-guided adaptive radiotherapy allows for a reduction of PTV margins. With a red. PTV margin, better sparing of the surrounding tissues can be achieved, while maintaining adequate target coverage. Nonetheless, longer treatment delivery times, characteristic for the IMRT technique, have to be expected.

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Clinical integration of machine learning for curative-intent radiation treatment of patients with prostate cancer

Nature Medicine ◽

10.1038/s41591-021-01359-w ◽

2021 ◽

Author(s):

Chris McIntosh ◽

Leigh Conroy ◽

Michael C. Tjong ◽

Tim Craig ◽

Andrew Bayley ◽

...

Keyword(s):

Prostate Cancer ◽

Machine Learning ◽

Radiation Treatment ◽

Clinical Integration ◽

Curative Intent

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[18F]fluoroethylcholine-PET/CT imaging for radiation treatment planning of recurrent and primary prostate cancer with dose escalation to PET/CT-positive lymph nodes

Radiation Oncology ◽

10.1186/1748-717x-6-44 ◽

2011 ◽

Vol 6 (1) ◽

Cited By ~ 77

Author(s):

Florian Würschmidt ◽

Cordula Petersen ◽

Andreas Wahl ◽

Jörg Dahle ◽

Matthias Kretschmer

Keyword(s):

Prostate Cancer ◽

Lymph Nodes ◽

Treatment Planning ◽

Dose Escalation ◽

Radiation Treatment ◽

Ct Imaging ◽

Radiation Treatment Planning ◽

Primary Prostate Cancer ◽

Pet Ct ◽

Positive Lymph Nodes

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Bony-based and prostate-based image guidance for lo-calized prostate cancer radiotherapy

Brazilian Journal of Radiation Sciences ◽

10.15392/bjrs.v8i1.1175 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Saulo Santos Fortes ◽

Luiz Antonio Ribeiro Da Rosa

Keyword(s):

Prostate Cancer ◽

Normal Tissue ◽

Bone Structure ◽

Absorbed Dose ◽

Target Volume ◽

Image Guided Radiotherapy ◽

Beam Modulation ◽

Significant Difference ◽

Treatment Volume ◽

Treatment Plans

An important modality for the treatment of prostate cancer is teletherapy. The use of image-guided radiotherapy (IGRT) is a valuable tool in this treatment. This study retrospectively compared how repositioning the patient based on bone structure (B-ISO) and the prostate itself (P-ISO) affected the volumetric dose in the rectum, bladder, and clinical treatment volume (CTV). Additionally, the probability of normal tissue complication (NTCP) for the rectum was computed. We evaluated 155 cone-beam computed tomography (CBCT) from 8 patients. The treatment plans used beam modulation techniques. The planning target volume (PTV) margin adopted in both scenarios was 1 cm. The organs of interest were outlined over each CBCT and then treatment plans were applied so that the absorbed dose could be computed. NTCP values were calculated for the rectum. Analyzing dose-volume metrics published by the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC), there was no significant difference between the two repositioning strategies for the rectum and bladder. There was a slight degradation in CTV coverage for the B-ISO strategy, but still with adequate coverage. Analysis of the uniform equivalent dose (EUD) and NTCP for the rectum showed little sensitivity to the strategy used. The present study showed that the use of CBCT in radiotherapy for prostate cancer treatment did not significantly improve volumetric doses for the rectum, bladder, and CTV, as well as NTCP for the rectum.

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