Comparative dosimetrical analysis of intensity-modulated arc therapy, CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer

Georgina Fröhlich; Péter Ágoston; Kliton Jorgo; Gábor Stelczer; Csaba Polgár; Tibor Major

doi:10.5603/RPOR.a2021.0028

Comparative dosimetrical analysis of intensity-modulated arc therapy, CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer

Rep Pract Oncol Radiother. 2021 Apr 14;26(2):196-202. doi: 10.5603/RPOR.a2021.0028. eCollection 2021.

Authors

Georgina Fröhlich^{1

2}, Péter Ágoston^{1

3}, Kliton Jorgo^{1

3}, Gábor Stelczer¹, Csaba Polgár^{1

3}, Tibor Major^{1

3}

Affiliations

¹ Centre of Radiotherapy, National Institute of Oncology, Budapest, Hungary.
² Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
³ Department of Oncology, Faculty of Medicine, Budapest, Hungary.

Abstract

Background: The objective of the study was to dosimetrically compare the intensity-modulated-arc-therapy (IMAT), Cyber-Knife therapy (CK), single fraction interstitial high-dose-rate (HDR) and low-dose-rate (LDR) brachytherapy (BT) in low-risk prostate cancer.

Materials and methods: Treatment plans of ten patients treated with CK were selected and additional plans using IMAT, HDR and LDR BT were created on the same CT images. The prescribed dose was 2.5/70 Gy in IMAT, 8/40 Gy in CK, 21 Gy in HDR and 145 Gy in LDR BT to the prostate gland. EQD2 dose-volume parameters were calculated for each technique and compared.

Results: EQD2 total dose of the prostate was significantly lower with IMAT and CK than with HDR and LDR BT, D90 was 79.5 Gy, 116.4 Gy, 169.2 Gy and 157.9 Gy (p < 0.001). However, teletherapy plans were more conformal than BT, COIN was 0.84, 0.82, 0.76 and 0.76 (p < 0.001), respectively. The D₂ to the rectum and bladder were lower with HDR BT than with IMAT, CK and LDR BT, it was 66.7 Gy, 68.1 Gy, 36.0 Gy and 68.0 Gy (p = 0.0427), and 68.4 Gy, 78.9 Gy, 51.4 Gy and 70.3 Gy (p = 0.0091) in IMAT, CK, HDR and LDR BT plans, while D_0.1 to the urethra was lower with both IMAT and CK than with BTs: 79.9 Gy, 88.0 Gy, 132.7 Gy and 170.6 Gy (p < 0.001). D₂ to the hips was higher with IMAT and CK, than with BTs: 13.4 Gy, 20.7 Gy, 0.4 Gy and 1.5 Gy (p < 0.001), while D₂ to the sigmoid, bowel bag, testicles and penile bulb was higher with CK than with the other techniques.

Conclusions: HDR monotherapy yields the most advantageous dosimetrical plans, except for the dose to the urethra, where IMAT seems to be the optimal modality in the radiotherapy of low-risk prostate cancer.

Keywords: Cyberknife therapy; intensity-modulated arc therapy; interstitial high-dose-rate brachytherapy; interstitial low-dose-rate brachytherapy; prostate cancer.