Dosimetric comparison among cyberknife, helical tomotherapy and VMAT for hypofractionated treatment in localized prostate cancer

Abstract

Hypofractionation for localized prostate cancer treatment is rapidly spreading in the medical community and it is supported by radiobiological evidences (lower α/β ratio compared with surrounding tissues). Stereotactic body radiation therapy (SBRT) is a technique to administer high doses with great precision, which is commonly performed with CyberKnife (CK) in prostate cancer treatment. Since the CyberKnife (CK) is not available at all radiotherapy center, alternative SBRT techniques are available such as Volumetric Modulated Arc Therapy (VMAT) and Helical Tomotherapy (HT). The aim of the present study was to compare the dosimetric differences between the CK, VMAT, and HT plans for localized prostate cancer treatment. Seventeenpatients have been recruited and replanned using VMAT and HT to this purpose: they received the treatment using the CK with a prescription of 36.25 Gy in 5 fractions; bladder, rectum and penis bulb were considered as organs at risk (OAR). In order to compare the techniques, we considered DVHs, PTV coverage, Conformity Index and new Conformity Index, Homogeneity Index, beam-on time and OARs received dose. The 3 treatments methods showed a comparable coverage of the lesion (PTV 95%: 99.8 ± 0.4% CK; 98.5 ± 0.8% VMAT; 99.4 ± 0.5% HT. P < .05) and good sparing of OARs. Nevertheless, the beam-on time showed a significant difference (37 ± 9 m CK; 7.1 ± 0.3 m VMAT; 17 ± 2 m HT. P < .05). Our results showed that, although CK is the best SBRT technique for prostate cancer treatment, in case this technology is not available, it can be replaced by a similar treatment delivered by VMAT technique. VMAT can be administrated only if it has an appropriate Image Guided Radiation Therapy (IGRT) tracking system.

Ultrahypofractionated Radiotherapy versus Conventional to Moderate Hypofractionated Radiotherapy for Clinically Localized Prostate Cancer

“…For the delivery of SBRT, there are several radiation techniques used to deliver a large-fraction dose to the prostate [ 27 , 28 , 29 , 30 ]. RT modality, as provided by the robot-assisted technique Cyber Knife ® (CK), which can deliver such radiation within a high-fraction dose, is currently witnessing increased usage in the treatment of prostate cancer with low to intermediate risk [ 27 , 28 , 29 , 30 ].…”

Hybrid Tomo‐Helical and Tomo‐Direct radiotherapy for localized prostate cancer

“… 11 High‐dose moderate hypofractionation RT is thought to reduce the effect of tumor cell repopulation 12 and improve treatment outcomes in the RT of LPC. 13 , 14 , 15 , 16 , 17 …”

“…11 High-dose moderate hypofractionation RT is thought to reduce the effect of tumor cell repopulation 12 and improve treatment outcomes in the RT of LPC. [13][14][15][16][17] Tomotherapy (Accuray Inc.) is an RT device with IGRT capability by taking daily Megavoltage Computed Tomography scan before treatment. 18 Tomotherapy has different version treatment devices and one of them is TomoHDA.…”

“…However, the hypofraction program recently has been accepted as an external beam RT strategy in prostate cancer 11 . High‐dose moderate hypofractionation RT is thought to reduce the effect of tumor cell repopulation 12 and improve treatment outcomes in the RT of LPC 13–17 …”

Constraint Analysis and Bladder Wall Low-Dose-Constraint Reduction in Five-Fraction Urethra-Sparing Prostate SBRT

“…As it is shown in [19] it is correlated with high doses to the rectum wall. Several strategies have been implemented to reduce rectum wall doses, mainly by means of planning strategies [20], by the utilization of an endorectal balloon [21] or by the insertion of prostate-rectal spacers [22] [23] [24]. Under-dosing the periurethral transition zone of the prostate may be employed to reduce the risk of urinary toxicity after radiation therapy [25] [26] [27].…”