Arbind Dubey

Diagnosis and Management of Spinal Metastasis of Glioblastoma.

BACKGROUND When patients with cranial glioblastoma develop weakness, a rare differential diagnosis is spinal metastases. METHODS Chart and literature reviews were performed. RESULTS The reported patient had delayed onset spinal drop metastasis that was only detected by magnetic resonance imaging (MRI). A 48-year-old patient had supratentorial glioblastoma, treated with radiotherapy (RT) and concurrent temozolomide followed by six cycles of adjuvant temozolomide. Four years after completion of all treatments (62 months from initial presentation), he developed low backache and weakness in both legs. Positron emission tomography/computed tomography scans demonstrated intracranial recurrence only. Spinal drop metastases were detected only by MRI scan. Local spinal RT 40 Gy in 20 fractions with concurrent and maintenance temozolomide were given. Because of disease progression after nine cycles of temozolomide, systemic therapy was changed to bevacizumab, which greatly improved his symptoms for 4 months before deterioration of mental status. He is still alive with disease at 22 months after diagnosis of spinal metastases (84 months from initial glioblastoma diagnosis). CONCLUSIONS MRI is the diagnostic imaging of choice for spinal metastases. This illustrative case of delayed-onset spinal metastases shows unusual slow progression. Local RT, temozolomide, and targeted therapy may improve survival. This illustrative case is the first report of bevacizumab as a second-line therapy in drop metastasis of glioblastoma.

Emotional Turmoil in Oncology Patients

Emotional turmoil is a negative mental state involving feelings of panic, confusion and agitation. People experiencing emotional turmoil feel physically and mentally unwell which results in difficulty making decisions cancer diagnosis is hard to take and having cancer is not easy. As the patient face their own mortality and cope with the many demands of cancer, often patient and their families look at their religious beliefs, personal and family values.Literature has shown that at least 70-75% of the oncology patients will be exposed to some sort of psychological or emotional shut down mainly depression during their journey from diagnosis to follow up. The main reason is anxiety, fear of the unknown, pain, suffering and fear of death. In the literature it seems most oncological patients do not have clarity about their disease or what is squeal of their disease or treatment offered. Clinical practice guidelines established by the National Comprehensive Cancer Network (NCCN) recommend that all oncological patients should undergo routine screening for distress when they report first time and at important points in their disease or treatment process. Recommendations highlights that oncology team adopts approved distress assessment tools available today for screenings and scientifically proven clinical pathways upon assessment results.

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.

218: Using 3D Printer Technology to Manufacture Anatomic Models for Patient Education: A New Frontier

PURPOSE/OBJECTIVES The use of 3D printing technology to create precise anatomical models is well documented. These models are used by surgeons to better plan upcoming operations and to save valuable operating room time. They are also used to educate other members of the health care team, such as residents, medical students and nurses. However, the use of these anatomically accurate models to educate patients in the clinical setting has been underutilized. At our centre, we are using 3D printer technology to generate accurate clinical models of mandibles. Our objective is to use these models to better educate and prepare head and neck cancer patients for upcoming surgery where manibulectomy is part of the surgical procedure. This has been used to educate 3 consecutive patients.

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.

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 08: A Low-Cost Optical Scanner and Gantry for use with 3D Printing of Radiation Therapy Accessories

Purpose: Three-dimensional printing has been implemented at our institution to create customized treatment accessories including shielding and bolus. In order to effectively use 3D printing, the topography of the patient must first be acquired. To this end, we have evaluated a low-cost structured-light 3D scanner in order to assess the clinical viability of this technology. Methods: For ease of use, the scanner (3D Systems, Sense 3D Scanner) was mounted in a simple gantry that guided its motion and maintained an optimum distance between the scanner and the object. To characterise the spatial accuracy of the scanner, we used a geometric phantom and an anthropomorphic head phantom. The geometric phantom was machined from plastic and had overall dimensions of 24 cm by 15 cm and included a hemispherical and a tetrahedron protrusion roughly the dimensions of an average forehead and nose respectively. Meshes acquired by the optical scanner were compared to meshes generated from high-resolution CT images. Results: Scans were acquired in under one minute. Most of the optical scans contained noticeable artefacts although in most instances these were considered minor. Using an algorithm that calculated distances between the two meshes, we found most of the optical scanner measurements agreed with those from CT to within about 1 mm for the geometric phantom and to within about 2 mm for the head phantom. Conclusion: In summary, we deemed this scanner to be clinically acceptable and it has been used to design treatment accessories for several skin cancer patients.

Poster - 38: On the physical and dosimetric properties of 3D printed electron bolus fabricated using polylactic acid

Purpose: 3D printing technology could simplify and improve electron bolus fabrication. The purpose of this study was to characterize the density, dimensional accuracy, uniformity, and attenuation of PLA boluses fabricated with a low-cost 3D printer. Methods: Several solid square slabs were printed with specific requested dimensions and 100% infill using different fill patterns. These pieces were imaged using an x-ray flat panel imager in order to check for uniformity of the prints. Percentage depth doses (PDDs) were measured downstream of the slabs in solid water using a parallel plate chamber and compared to measurements in water in order to characterize attenuation. The dimensions of the PLA slabs were measured using digital calipers. The slabs were also weighed to find their density. Results: The fill pattern used to create boluses can affect the attenuation of the bolus. Fill patterns should be chosen carefully and quality assurance should be done for each printed piece. PLA causes the electron PDD to shift towards shallower depths, compared to water, by 1.7 mm for each centimeter of PLA. Agreement with design dimensions was within 1 mm in the plane of the printer bed, and within 1/3 of a millimeter (roughly the thickness of a single layer), perpendicular to the printer bed. Average density was in the range 1.20 – 1.22. Conclusions: 3D printing shows great promise for use in fabricating electron bolus. This work indicates that printed PLA can be a suitable material provided the increased attenuation is properly accounted for.

Luteinizing hormone-releasing hormone antagonists for urinary obstruction in prostate cancer

Luteinizing hormone-releasing hormone (LHRH) antagonists rapidly reduce testosterone and are preferred to LHRH agonists in situations when early response is important. The lack of flare reaction, as compared to LHRH agonists, is particularly desirable as it would not aggravate the problem. A 78-year-old man presented with symptoms of urinary tract obstruction. He had a prostate-specific antigen (PSA) of 91.3 ug/L and serum creatinine 146 umol/L. He had a large pelvic mass due to histologically confirmed prostate cancer, resulting in moderate left hydronephrosis and deteriorating renal function (serum creatinine of 163 umol/L). He was started on combined degarelix and bicalutamide on the day of consultation (day 0). The hydronephrosis resolved on the repeat computerized tomography scan performed on day 10. Serum creatinine normalized to under 130 umol/L on day 18. The PSA fell to 11 ug/L on day 18, 2.8 ug/L on day 28, and 0.5 ug/L on day 53. Therefore, LHRH antagonists are particularly useful in urgent situations. It is the preferred choice in these circumstances.