Abstract
BackgroundImmobilization devices are crucial to minimize patient positioning uncertainties in radiotherapy (RT) treatments. Accurate inter and intra-fraction motions is particularly important for intracranial and stereotactic radiation treatment which require high precision in dose delivery. Recently, a new immobilization device has been developed specifically for the radiation treatment of intracranial malignancies. To date, no data are available on the use of this device in daily clinical practice. The aim of this study is to investigate the intra and inter-fraction variations, patient comfort and radiographer confidence of the immobilization system from two distinct institutions: HagaZiekenhuis, Den Haag, Netherlands and IRCCS Ospedale Sacro Cuore Don Calabria, Negrar, Italy.Material and methodSixteen patients (10 diagnosed with brain metastases and 6 with primary central nervous systemic tumor) from IRCCS Ospedale Sacro Cuore Don Calabria and 17 patients (all diagnosed with brain metastases tumor) from HagaZiekenhuis were included in this study. The median target volume was 436 cc (range 3.2–1628 cc) and 4.58 cc (range 0.4–27.19 cc) for IRCCS and Haga, respectively. For patients treated in IRCCS Sacro Cuore Don Calabria, the median dose prescription was 30 Gy (range 27–60 Gy) and median number of fractions 10 (range 3–30). In Haga the median dose prescription was 21 Gy (range 8–21 Gy) and the median number of fraction was 1 (range 1–3). The immobilization device was assembled during CT simulation. A short interview to the patient regarding the device’s comfort level was conducted at the end of the simulation procedure. Additionally, simulation setup time and radiographer (RTT) procedures (i.e. mask preparation) were evaluated. Prior to radiation treatment delivery, an automatic rigid match on the cranial bones between cone beam computed tomography (CBCT) and planning-CT was performed. A couch shift was performed subsequently. An extra post-treatment CBCT was acquire after the treatment delivery. This post-treatment CBCT was matched with pre-treatment CBCT to identify any possible intra-fraction motion. All online matches were validated by experienced radiation oncologist or RTT. A total of 126 CBCT’s were analyzed offline by radiation oncologist/medical physicist. The data of the pre-treatment CBCT match was used to quantify inter-fraction motion. The post-treatment CBCT was matched with pre-treatment CBCT to identify any possible intra-fraction motion.ResultsDuring the molding of the mask, all patients responded positive to the comfort. Median time required by the RTTs to assemble the immobilization system was 9 min (range 6–12 min). In terms of comfort, all patients reported a good-to high level of satisfaction. The RTTs also respond positively towards the use of the locking mechanism and clips. Results of positioning uncertainties were comparable between the two institutes. The mean inter-fraction motion for all translational and rotational directions were < 2 mm (SD < 4 mm) and < 0.5°(SD < 1.5°), respectively, while the mean intra-fraction motions were < 0.4 mm (SD < 0.6 mm) and 0.3° (SD < 0.5°).ConclusionsThis study demonstrates the efficacy and feasibility of the immobilization device in the intracranial radiation treatment. Both patient comfort and preparation time by RTTs are considered adequate. In combination with online daily imaging procedure, this device can achieve submillimeter accuracy required for intracranial and stereotactic treatments.
Highlights
Accuracy in radiation treatment is considered one of the most relevant issues in modern radiotherapy (RT) [1]
Median time required by the RTTs to assemble the immobilization system was 9 min
A new immobilization device dedicated to the treatment of intracranial disease, including in particular high precision in stereotactic radiotherapy treatment and patient comfort in conventional intracranial treatments
Summary
Accuracy in radiation treatment is considered one of the most relevant issues in modern radiotherapy (RT) [1] This concept included two distinct aspects, the delivery of high radiation doses to the tumor (e.g. stereotactic cranial and extracranial RT and hypofractionation) and the decrease in normal tissue irradiation. To achieve this balance, several aspects have to be considered: i) the precise definition and verification of the oncological target, supported by radiological and metabolic images (Image guided radiotherapy therapy – IGRT), ii) the use of modern radiotherapy delivery techniques (Intensity Modulated Radiotherapy – IMRT and volumetric modulated arc therapy – VMAT) and during radiation delivery, iii) limiting the inter- and intra-fraction motion with suitable immobilization devices (and, if available, real-time monitoring system such surface guided systems). The aim of this study is to investigate the intra and inter-fraction variations, patient comfort and radiographer confidence of the immobilization system from two distinct institutions: HagaZiekenhuis, Den Haag, Netherlands and IRCCS Ospedale Sacro Cuore Don Calabria, Negrar, Italy
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