Ahmet Leylek

Low-cost optical scanner and 3-dimensional printing technology to create lead shielding for radiation therapy of facial skin cancer: First clinical case series

Purpose Three-dimensional printing has been implemented at our institution to create customized treatment accessories, including lead shields used during radiation therapy for facial skin cancer. To effectively use 3-dimensional printing, the topography of the patient must first be acquired. We evaluated a low-cost, structured-light, 3-dimensional, optical scanner to assess the clinical viability of this technology. Methods and materials For ease of use, the scanner was mounted to a simple gantry that guided its motion and maintained an optimum distance between the scanner and the object. To characterize the spatial accuracy of the scanner, we used a geometric phantom and an anthropomorphic head phantom. The geometric phantom was machined from plastic and included hemispherical and tetrahedral protrusions that were roughly the dimensions of an average forehead and nose, respectively. Polygon meshes acquired by the optical scanner were compared with meshes generated from high-resolution computed tomography images. Most optical scans contained minor artifacts. Using an algorithm that calculated the distances between the 2 meshes, we found that most of the optical scanner measurements agreed with those from the computed tomography scanner within approximately 1 mm for the geometric phantom and approximately 2 mm for the head phantom. We used this optical scanner along with 3-dimensional printer technology to create custom lead shields for 10 patients receiving orthovoltage treatments of nonmelanoma skin cancers of the face. Patient, tumor, and treatment data were documented. Results Lead shields created using this approach were accurate, fitting the contours of each patients face. This process added to patient convenience and addressed potential claustrophobia and medical inability to lie supine. Conclusions The scanner was found to be clinically acceptable, and we suggest that the use of an optical scanner and 3-dimensional printer technology become the new standard of care to generate lead shielding for orthovoltage radiation therapy of nonmelanoma facial skin cancer.

Analysis of First Case Series in the World of Skin Cancer Patients Where Lead Shielding for Radiation Therapy of Facial Skin Cancer was Designed Utilizing Optical Scanner and 3D Printer Technology

Purpose Radiation is one of the modalities used to treat non-melanoma skin cancers. For facial lesions; ortho-voltage radiotherapy (RT) can require the creation of lead shielding to protect vulnerable organs at risk (OAR). Creating a lead shield is often difficult due to the complex contours of the face. The traditional method involves creating a plaster mould of a patients face to use as a template for creating a shield. This requires another patient visit, and for patients who are claustrophobic or medically unable to lie flat, this strategy is not ideal. We address this by utilizing optical scanner and 3D printer technology to create lead shields and report the first case series in the English literature here.

86: Using Optical Scanner and 3D Printer Technology to Create Lead Shielding for Radiotherapy of Facial Skin Cancer with Low Energy Photons: An Exciting Innovation

Treatment of non-melanoma skin cancers of the face using ortho-voltage radiotherapy may require lead shielding to protect vulnerable organs at risk (OAR). As the human face has many complex and intricate contours, creating a lead shield can be difficult. The process can include creating a plaster mould of a patients face to create the shield. It can be difficult or impossible for a patient who is claustrophobic or medically unable to lie flat to have a shield made by this technique. Other methods have their own shortcomings. We aimed to address some of these issues using an optical scanner and 3D printer technology.

74: Innovative Approach for Generating Soft Silicone Bolus using 3D Printing for Electron Treatment of Skin Cancers in Areas with Irregular Contours

S29 _________________________________________________________________________________________________________ cardiac four-dimensional CT (4D-CT) synchronized to the electrocardiogram were obtained in treatment position, using a prospective sequential acquisition method including the extreme phases of systole and diastole. On a MimVista® image registration workstation, dose distributions were transferred to the cardiac 4D-CT. The left coronary artery, left ventricle and heart were contoured on both phases of the cardiac cycle. The maximum and minimum doses to the left coronary, left ventricle and heart were compared using a bilateral paired Student T test. Results: Preliminary data from the first eight patients enrolled are presented. Median age was 60 years (56-71) and median planned dose to the left breast was 42.56 Gy (42.56-50) in 16 fractions (16-20). For the left coronary artery, mean dose, V5 and V20 in systole versus diastole were 6.1 Gy versus 7.9 Gy (p = 0.02), 37% versus 48% (p = 0.02) and 10% versus 16% (p = 0.04), respectively. For the left ventricle, mean dose, V5 and V20 in systole versus diastole were 1.3 Gy versus 1.6 Gy (p = 0.005), 6% versus 9% (p = 0.03) and 1% versus 2% (p > 0.1), respectively. For the whole heart, mean dose, V5 and V20 in systole versus diastole were 0.9 Gy versus 1.3 Gy (p = 0.005), 21 cc versus 32 cc (p = 0.07) and 4 cc versus 5 cc (p > 0.1), respectively. Conclusions: Beyond DIBH, systolic irradiation would be associated with a further reduction in V5, V20 and mean dose to the left coronary artery, as well as a reduction in V5 and mean dose to the left ventricle and heart as a whole. The potential clinical impact of this reduction as well as the feasibility of cardiac gated irradiation are to be further investigated.

Sci‐Sat AM: Radiation Dosimetry and Practical Therapy Solutions ‐ 07: A mould room in a box – 3D scanning and printing technology in the radiotherapy clinic

Purpose: We describe the process by which our centre is currently implementing 3D printing and scanning technology for treatment accessory fabrication. This technology can increase efficiency and accuracy of accessory design, production and placement during daily use. Methods: A low-cost 3D printer and 3D optical scanner have been purchased and are being commissioned for clinical use. Commissioning includes assessing: the accuracy of the 3D scanner through comparison with high resolution CT images; the dosimetric characteristics of polylactic acid (PLA) for electron beams; the clinical utility of the technology, and; methods for quality assurance. Results: The agreement between meshes generated using the 3D scanner and CT data was within 2 millimeters for an anthropomorphic head phantom. In terms of electron beam attenuation, 1 centimetre of printed PLA was found equivalent to 1.17 cm of water. In proof-of-concept tests, several types of treatment accessories have been prototyped to date that will benefit from this technology. These include electron and photon bolus for areas with complex surface contours including the ear for electron treatments, the extremities for photon treatments and lead shielding for orthovoltage treatments. Imaging with CT and x-ray showed minimal defects, which will have no significant clinical impact. Geometric fidelity and fit to volunteers and patients was found to be excellent. Conclusions: 3D Printing and scanning can increase efficiency in the clinic for treatments requiring custom accessories. Customized boluses and shielding had excellent fit and reduced uncertainty in positioning.

Poster – 39: Using Optical Scanner and 3D Printer Technology to Create Lead Shielding for Radiotherapy of Facial Skin Cancer with Low Energy Photons

Purpose: Treatment of skin cancers of the face using orthovoltage radiotherapy often requires lead shielding. However, creating a lead shield can be difficult because the face has complex and intricate contours. The traditional process involved creating a plaster mould of the patients face can be difficult for patients. Our goal was to develop an improved process by using an optical scanner and 3D printer technology. Methods: The oncologist defined the treatment field by drawing on each patients skin. Three-dimensional images were acquired using a consumer-grade optical scanner. A 3D model of each patients face was processed with mesh editing software before being printed on a 3D printer. Using a hammer, a 3 mm thick layer of lead was formed to closely fit the contours of the model. A hole was then cut out to define the field. Results: The lead shields created were remarkably accurate and fit the contours of the patients. The hole defining the field exposed only a minimally sized site to be exposed to radiation, while the rest of the face was protected. It was easy to obtain perfect symmetry for the definition of parallel opposed beams. Conclusion: We are routinely using this technique to build lead shielding that wraps around the patient as an alternative to cut-outs. We also use it for treatment of the tip of the nose using a parallel opposed pair beams with a wax nose block. We found this technique allows more accurate delineation of the cut-out and a more reproducible set-up.