核医学与放射治疗

Radiation therapy (RT) is an important part of a multidisciplinary treatment for many pediatric tumors and has been integral to the improvement in disease control seen over the past few decades. However, long-term survivors experience late morbidity related to RT. Proton radiation therapy is an emerging type of radiotherapy that can mitigate the incidence of acute and late side effects by minimizing the dose of radiation to normal tissues with a significant reduction of integral dose compared with photons. Furthermore, true clinical advantages are now being measured and published in the medical literature, showing both excellent disease control rates and reduction of late effects. The purpose of this review is to summarize the early clinical outcomes after proton radiotherapy in childhood available in the literature.

Purpose: To evaluate the usefulness of a 6-degrees-of freedom (6D) correction using ExacTrac Robotics system in patients with head-and-neck (HN) cancer receiving radiation therapy. Methods: Local setup accuracy was analyzed for 12 patients undergoing intensity-modulated radiation therapy (IMRT). Patient position was imaged daily upon two different protocols, cone-beam computed tomography (CBCT) and ExacTrac (ET) images correction. Setup data from either approach were compared in terms of both residual errors after correction and punctual displacement of selected regions of interest (Mandible, C2 and C6 vertebral bodies). Results: On average, both protocols achieved reasonably low residual errors after initial correction. The observed differences in shift vectors between the two protocols showed that CBCT tends to weight more C2 and C6 at the expense of the mandible, while ET tends to average more differences among the different ROIs. Conclusions: CBCT, even without 6D correction capabilities, seems preferable to ET for better consistent alignment and the capability to see soft tissues. Therefore, in our experience, CBTC represents a benchmark for positioning head and neck cancer patients.

Introduction: Previously we have published data showing how clinician awareness surrounding radiation doses from common diagnostic modalities is poor. Evidence suggests that radiation exposure, from diagnostic and interventional procedures is placing patients at a small but significant increased risk of malignancy. As the usage of radiation in endourological surgery increases, urologists need to have an understanding of the variables affecting perioperative radiation exposure. Here we look at how the operating consultant, the patient triage status (elective vs. emergency admission) and the endourological procedure performed impacts upon perioperative radiation exposure.

Method: One hundred patients, who had undergone an endourological procedure in 2012 were randomly selected. The image intensifiers were interrogated for stored data of radiation dose and screening times. Computerised patient records provided the consultant’s identity (A-D), the patient’s triage status and the exact endourological procedure performed.

Results: There was no difference in radiation exposure when comparing elective and emergency patients. Endourological procedures requiring therapeutic intervention led to higher levels of radiation exposure when compared with diagnostic endourological procedures (p value<0.05). The operating consultant significantly varied the radiation exposure. Consultant B’s radiation dosages and screening times were significantly lower compared to consultants A, C and D (p values<0.05).

Conclusion: The operating consultant causes a significant variation in the perioperative radiation dosage. This could be due to a subjective judgment about the importance of minimising perioperative radiation exposure. Alternatively it could be due to the consultant’s operating technique, the communication methods used with the radiographer or the consultant’s own awareness about the risks of radiation exposure. With the usage of perioperative radiation increasing, further studies are warranted to better understand the variables that affect and increase its use. This will allow future surgeons to consciously reduce perioperative exposure and patient harm.

Objective: We investigated the effects of partial volume and respiratory motion using a National Electrical Manufacturers Association (NEMA) phantom and proposed a simple method for correction of maximum standardized uptake value (SUVmax) for respiratory motion in early lung cancer. Methods: The maximum recovery coefficient (RC) in static mode were measured using the NEMA phantom and a dynamic moving platform. The phantom on the platform was either at rest or moving sinusoidally along the longitudinal axis of the scanner to simulate respiratory motion. We also calculated estimated RC using our approximation. Results: RC of the sphere of 28mm in diameter decreased from 0.96 to 0.80 and 0.41 with 20 and 50 mm of motion amplitude, respectively. For the sphere of 10 mm in diameter, RC was decreased from 0.40 to 0.18 and 0.08 with 20 and 50 mm of motion amplitude, respectively. Our results showed that RC decreased with increase in motion amplitude. Average percentage differences between measurement and estimation in the sphere of 37, 28, 22, 17, 13 and 10 mm were -1.8 ± 3.7, -3.1 ± 11.3, -2.8 ± 10.5, -8.1 ± 6.6, -7.0 ± 12.3 and -1.8 ± 12.2 %, respectively. This result showed that our simple correction method could estimate SUVmax with moderate accuracy. Conclusions: Our results clearly demonstrated that RC decreases with increase in motion amplitude, as expected. Our simple correction with moderate accuracy method could not precisely estimate RC. However, the estimated values agreed with the measurements. Thus, our methods could be used in clinical practice to calculate the approximate SUVmax for lung cancer patients undergoing radiotherapy showing the malignancy grading for early lung cancer.

Cutaneous malignancies constitute some of the most commonly diagnosed cancers in the United States (USA), comprising more than half of all cancers diagnosed per year [1]. In this review article we aim to present our experience at a tertiary referral center using PET/CT in the staging and treatment planning in patients with Merkel cell carcinoma (MCC) and melanoma and review the current literature.