Michael S. Gossman

NRC restrictions on the packaging of radioactive material should be expressed more explicitly than simply in terms of “activity”

Suggestions for topics suitable for these Point/Counterpoint debates should be addressed to the Moderator: William R. Hendee, Medical College of Wisconsin, Milwaukee: whendee@mcw.edu. Persons participating in Point/Counterpoint discussions are selected for their knowledge and communicative skill. Their positions for or against a proposition may or may not reflect their personal opinions or the positions of their employers.

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

BACKGROUND With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. AIMS This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. MATERIALS & METHODS We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. RESULTS We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. DISCUSSION Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. CONCLUSION Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.

Intact performance of a cochlear implant following radiotherapy in a child with acute lymphoblastic leukemia

Cochlear implants, via direct electrical stimulation of the auditory nerve, allow the restoration of hearing and speech recognition in both adults and children having sensorineural deafness. These devices typically contain both external components (speech processor, microphone, transmitter) and internal components (including the cochlear stimulator and electrode array), which are surgically placed under the skin behind the ear and in the cochlea. According to the National Institute on Deafness and other Communications Disorders, by June 2010, over 188,000 individuals worldwide had received cochlear implants, including approximately 41,500 adults and 25,500 children in the US.1 Given the important role of radiotherapy (RT) in the multidisciplinary management of various malignancies, the tolerance of cochlear implants to therapeutic doses of radiation is an important consideration. In this work, we present a case of a pediatric patient with leukemia found to have sensorineural

Image‐Guided Radiation Therapy.

An overview of Intensity Modulated Radiation Therapy (IMRT), a true revolution in the field of radiation oncology in that it provides the unprecedented means of conforming to the shape of the target tissues in 3-dimensions, reducing the risk of complications thereby improving the quality of life of irradiated patients. Moreover, IMRT provides the means to deliver higher than conventional doses thus improving the chance of cure in these patients. Despite its established benefits, several barriers exist to the widespread clinical implementation of IMRT.

NRC restrictions on the packaging of radioactive material should be expressed more explicitly than simply in terms of “activity”: Point/Counterpoint

Suggestions for topics suitable for these Point/Counterpoint debates should be addressed to the Moderator: William R. Hendee, Medical College of Wisconsin, Milwaukee: whendee@mcw.edu. Persons participating in Point/Counterpoint discussions are selected for their knowledge and communicative skill. Their positions for or against a proposition may or may not reflect their personal opinions or the positions of their employers.