Figure - available from: Journal of Applied Clinical Medical Physics
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Steps for the anterior DSB device, (a) the patient was placed in the supine position on a headrest (b) Shell molded over the entire face and bolus in place at the forehead (c) another shell molded at the forehead and chin area, (d) Picture of the final anterior DSB device.
Source publication
Malignancies with a superficial involvement of the scalp/skull present technical challenges for radiation‐treatment‐planning, such as achieving skin coverage with the prescribed dose and with the desirable conformity, homogeneity, and lower brain dose. We report a radiotherapy treatment technique for a patient diagnosed with diffuse basosquamous ce...
Citations
... But MCAT has been shown to be inferior to IMRT with respect to dose homogeneity and over-dosage. 11 Another techniques like a double archs VMAT plans have been investigeted in few reports with several arrangements, 12 showing an improved dosimetry. Indeed in a comparison with IMRT arrangements, target coverage, homogeneity and OAR protection, have been found slightly superior in VMAT plans, 13 showing similar quality with that of 9-field IMRT, but spending a reduced delivery time. ...
... Several studies have now used OSL as a reference when investigating new dosimetry techniques, (50)(51)(52)(53) for addressing clinical questions, (54)(55)(56)(57) for the determination of dose to patients due to radiation leakage from the linear accelerator head, (58,59) and for addressing radiation protection issues, such as the estimation of eye lens dose during fluoroscopy interventions. (60)(61)(62) Several examples of TLD and OSLD applications were already described in the AAPM Task Group 191 report. ...
... (4) Therefore, these results are not going to be repeated here. New publications since then focused mostly on actual use of the OSLDs to address clinical questions, as already mentioned, (54)(55)(56)(57) or on the characterization of the OSLDs for specific applications. ...
If the first decade of the new millennium saw the establishment of a more solid foundation for the use of the Optically Stimulated Luminescence (OSL) in medical dosimetry, the second decade saw the technique take root and become more widely used in clinical studies. Recent publications report not only characterization and feasibility studies of the OSL technique for various applications in radiotherapy and radiology, but also the practical use of OSL for postal audits, estimation of staff dose, in vivo dosimetry, dose verification and dose mapping studies. This review complements previous review papers and reports on the topic, providing a panorama of the new advances and applications in the last decade. Attention is also dedicated to potential future applications, such as LET dosimetry, 2D/3D dosimetry using OSL, dosimetry in magnetic resonance imaging-guided radiotherapy (MRIgRT) and dosimetry of extremely high dose rates (FLASH therapy).
... 41 To overcome the inhomogeneous dose distribution disadvantage of electron beams, several combined volumetric arc therapy approaches have recently been tested, to obtain superior target coverage and produce concave or convex dose distributions, in agreement with the scalp conformation. 42 Nevertheless, this modern treatment approach is chosen based on the available resources at institutions, thus electron beam 3D-CRT remains the most widely available treatment modality. The results of our experience using electron beam 3D-CRT for elderly frail patients with giant NMSCs of the head appear to be consistent with all previously published reports of managing NMSCs. ...
Adequate dose homogeneity and full prescription dose delivery to the scalp still remains a dosimetric problem during scalp irradiation due to the anatomical shape of the cranium. Confounding variables such as gravity, the irregular and convex shape of the cranium, air gaps between scalp surface and commercial bolus, and potential inconsistencies in a 3D printed bolus can negatively impact the dose delivered to the scalp surface during scalp irradiation. The purpose of this retrospective case study was to implement the use of a 3D milled rigid bolus technique combined with volumetric modulated arc therapy (VMAT) treatment planning and evaluate the dosimetric efficacy in delivering dose to the surface of the scalp.
The 8-patient retrospective case study consisted of patients with a scalp lesion treated using a 3D milled bolus, VMAT, 6 megavoltage (MV) photon beams, and aligned for treatment using daily conebeam computed tomography (CT) and 6° of freedom couch positioning. Dose volume histograms (DVHs) were used to evaluate maximum dose delivered to the planning target volumes (PTVs) while the dose homogeneity index (DHI) was calculated and compared to that of an ideal value of 1. The researchers evaluated the minimum dose delivered to the individual PTVs after plan normalization.
The researchers found that the 3D milled bolus coupled with volumetric modulated arc therapy increased surface dose homogeneity, while also increasing the percentage of planning target volumes receiving full prescription dose. With statistically significant results, patient specific 3D milled rigid bolus offers a viable bolus option for treatment of superficial scalp lesions when combined with volumetric modulated arc therapy treatment planning. However, a larger sample size used in a scientific research study across multiple institutions would be desirable to validate these case study findings.
Purpose
A bolus is usually required to ensure radiation dose coverage of extensive superficial tumors of the scalp or skull. Oftentimes, these boluses are challenging to make and nonreproducible, so an easier method was sought out.
Methods and Materials
Thermoplastic sheets are widely available in radiation oncology clinics and can serve as bolus. Two template cutouts were designed for anterior and posterior halves to encompass the cranium of children and adults.
Results
The created bolus was imaged using computed tomography (CT), which demonstrated good conformity and minimal air gaps.
Conclusion
While making a bolus for treating superficial tumors of the scalp or head and neck is challenging, the presented technique enables thermoplastic to be used as a bolus and is quick, easy, and reproducible.
