Ninjaflex vs Superflab: A comparison of dosimetric properties, conformity to the skin surface, Planning Target Volume coverage and positional reproducibility for external beam radiotherapy

IPEM topical report: guidance on 3D printing in radiotherapy

There has been an increase in the availability and utilization of commercially available 3D printers in radiotherapy, with applications in phantoms, brachytherapy applicators, bolus, compensators, and immobilization devices. Additive manufacturing in the form of 3D printing has the advantage of rapid production of personalized patient specific prints or customized phantoms within a short timeframe. One of the barriers to uptake has been the lack of guidance. The aim of this topical review is to present the radiotherapy applications and provide guidance on important areas for establishing a 3D printing service in a radiotherapy department including procurement, commissioning, material selection, establishment of relevant quality assurance, multidisciplinary team creation and training.

Dual application of Polyvinyl Alcohol Glutaraldehyde Methylthymol Blue Fricke hydrogel in clinical practice: Surface dosimeter and bolus

An essential issue is an accurate evaluation of surface dose distribution for such sensitive treatments. This work aimed to feasibility of the dual application of the Ferrous Polyvinyl Alcohol Glutaraldehyde Methylthymol Blue (PVA-GTA-MTB) gel as a bolus compensator and surface dosimeter in breast radiotherapy. The differences between the surface dose measured using PVA-GTA-MTB gel and film dosimetry in the medial and lateral parts of the breast were 3.74% and 4.18%, respectively. A qualitative comparison of the isodose curves showed that the PVA-GTA-MTB bolus creates a uniform dose distribution similar to the superflab bolus in the target volume.

Mechanical and medical imaging properties of 3D-printed materials as tissue equivalent materials

Three materials of polylactic acid (PLA), polyamide 12 (PA12), and light curing resin (LCR) were used to construct phantom using 3D printing technology. The mechanical and medical imaging properties of the three materials, such as elastic modulus, density, effective atomic number, X-ray attenuation coefficient, computed tomography (CT) number, and acoustic properties, were investigated. The results showed that the elastic modulus for PLA was 1.98 × 103  MPa, for PA12 was 848 MPa, for LCR was 1.18×103  MPa, and that of three materials was close to some bones. In the range of 40∼120 kV, the X-ray attenuation coefficient of three materials decreased with increasing tube voltage. The CT number for PLA, PA12, and LCR was 144, -88, and 312 Hounsfield units at 120 kV tube voltage, respectively. The density and the effective atomic number product (ρ*Zeff ) were computed from three materials and decreased in the order of LCR, PLA, and PA12. The acoustic properties of materials were also studied. The speeds of sound of three materials were similar with those of some soft tissues.

3D Printing Polymer-based Bolus Used for Radiotherapy

Bolus is a kind of auxiliary device used in radiotherapy for the treatment of superficial lesions such as skin cancer. It is commonly used to increase skin dose and overcome the skin-sparing effect. Despite the availability of various commercial boluses, there is currently no bolus that can form full contact with irregular surface of patients' skin, and incomplete contact would result in air gaps. The resulting air gaps can reduce the surface radiation dose, leading to a discrepancy between the delivered dose and planned dose. To avoid this limitation, the customized bolus processed by three-dimensional (3D) printing holds tremendous potential for making radiotherapy more efficient than ever before. This review mainly summarized the recent development of polymers used for processing bolus, 3D printing technologies suitable for polymers, and customization of 3D printing bolus. An ideal material for customizing bolus should not only have the feature of 3D printability for customization, but also possess radiotherapy adjuvant performance as well as other multiple compound properties, including tissue equivalence, biocompatibility, antibacterial activity, and antiphlogosis.