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. 2020 Aug 10:15:66-71.
doi: 10.1016/j.phro.2020.07.005. eCollection 2020 Jul.

A study of the clinical, treatment planning and dosimetric feasibility of dose painting in external beam radiotherapy of prostate cancer

Steve W Blake  1 , Alison Stapleton  1 , Andrew Brown  1 , Sian Curtis  2   3 , Janice Ash-Miles  4 , Emma Dennis  5 , Susan Masson  5 , Dawn Bowers  5 , Serena Hilman  5
Affiliations

A study of the clinical, treatment planning and dosimetric feasibility of dose painting in external beam radiotherapy of prostate cancer

Steve W Blake et al. Phys Imaging Radiat Oncol. .

Abstract

Background and purpose: Radiotherapy dose painting is a promising technique which enables dose escalation to areas of higher tumour cell density within the prostate which are associated with radioresistance, known as dominant intraprostatic lesions (DILs). The aim of this study was to determine factors affecting the feasibility of radiotherapy dose painting in patients with high and intermediate risk prostate cancer.

Materials & methods: Twenty patients were recruited into the study for imaging using a 3 T magnetic resonance imaging (MRI) scanner. Identified DILs were outlined and the scan registered with the planning computed tomography (CT) dataset. Intensity-modulated plans were produced and evaluated to determine the effect of the organ-at-risk constraints on the dose that could be delivered to the DILs. Measurements were made to verify that the distribution could be safely delivered.

Results: MRI scans were obtained for nineteen patients. Fourteen patients had one to two DILs with ten overlapping the urethra and/or rectum. The target boost of 86 Gy was achieved in seven plans but was limited to 80 Gy for five patients whose boost volume overlapped or abutted the urethra. Dosimetric measurements gave a satisfactory gamma pass rate at 3%/3 mm.

Conclusions: It was feasible to produce dose-painted plans for a boost of 86 Gy for approximately half the patients with DILs. The main limiting factor was the proximity of the urethra to the boost volumes. For a small proportion of patients, rigid registration between CT and MRI images was not adequate for planning purposes.

Keywords: Computer-assisted/methods; Feasibility studies; Focal boost; Intensity-modulated/methods; Magnetic resonance imaging; Multi-parametric MRI; Prostate radiotherapy; Radiotherapy; Radiotherapy dosage; Radiotherapy planning; Urethra.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Patient images from the study showing (a) MRI scan with CTV and PTV marked (b) CT image of same patient with colourwash of dose levels during treatment planning.
See this image and copyright information in PMC

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