Medical Student Rotations
Vice Chair of Education
Neha Vapiwala, MD
Assistant Professor of Radiation Oncology
Associate Director of Medical Education
Abigail T. Berman, MD
Assistant Professor, Radiation Oncology
Education Officer for Trainees
Michael J. LaRiviere, MD
Visiting Medical Students
Thank you for your interest in enrolling as a visiting student in Radiation Oncology at the Perelman School of Medicine at the University of Pennsylvania. Please click on the links below to find out more information about the program and our application process. Note that this application is only for U.S. and Canadian Medical Students.
Goals and Expectations of the Radiation Oncology Elective Course
- To learn more about the general principles of oncology, including:
- Basic scientific principles of neoplasia
- Clinical presentation, diagnosis, workup and staging of various cancers
- Multidisciplinary treatment decisions and guidelines
- Principles of surgery, systemic therapy, and radiation therapy
- Supportive medical care and palliative care of cancer patients
- To understand the role of radiation therapy in the treatment of cancer.
- To attend all tumor boards, chart rounds, and educational conferences/sessions (see below).
- To observe specialized procedures of radiation therapy for cancer, including
- General simulation and treatment of common radiation therapy fields.
- Planning and administration of CT-planned external beam radiation therapy.
- Planning and administration of brachytherapy (optional).
- Intraoperative photodynamic therapy (optional).
- Give an oral presentation on a clinical topic related to your assigned rotation (see below).
Fundamentals of Radiation Oncology
Steps involved in Clinical Radiation Therapy
- Consultation, including decision to irradiate
- Pre-radiation workup, including staging, dental evaluation, nutritional assessment
- Simulation, including immobilization of the area to be irradiated
- Dosimetry (Calculation of radiation dose to tumor and normal structures)
- Setup or final quality assurance planning session
- Radiation Treatments, including on-treatment visits by the physician(s)
- Conedown(s) --- if applicable ---- : Repeat of steps 3 through 6
- Post-radiation follow-up visits
Examples of Indications for Radiation Therapy
- Definitive Radiotherapy alone for early larynx cancer.
- Preoperative Radiotherapy prior to resection of a low-lying rectal cancer.
- Postoperative Radiotherapy after mastectomy for locally advanced breast cancer.
- Palliative Radiotherapy for a massive incurable lung cancer causing pain/bleeding
- Benign (rarely used) Radiotherapy to prevent coronary artery restenosis after PTCA.
Different Radiation Therapy Dose Fractionation Schedules
(1 cGy = 1 rad = approximately the radiation dose absorbed in getting a typical CT scan)
- Conventional Radiotherapy 180-200 cGy/day, 5 days/wk to 6600-7200 cGy; no planned interruptions
- Accelerated Hypofractionated Radiotherapy 250-300 cGy/day, 5 days/wk to 5000-5400 cGy; no planned interruptions
- Non-accelerated Hypofractionated Radiotherapy 250-300 cGy/day, 3-4 days/wk to 5000-7000 cGy; no planned interruptions
- Split course Radiotherapy 200-300 cGy/day, 5 days wk to 6000-7200 cGy; 1-2 wk break in the middle of therapy
- Hyperfractionated Radiotherapy 110-125 cGy b.i.d., 5 days wk to 7000-8000 cGy; no planned interruptions
- Accelerated Hyperfractionated Radiotherapy 140-160 cGy b.i.d., 5 days wk to 6600-7200 cGy; usually requires 1-2 wk break in the middle of therapy
- Accelerated, Concomitant Boost Radiotherapy 180-200 cGy/day, 5 days wk to 3500-4500 cGy followed by 150-180 cGy b.i.d. "conedown" boost radiotherapy to 6600-7200 cGy; no planned interruptions
- Continuous Hyperfractionated Accelerated Radiotherapy 120-180 cGy b.i.d or t.i.d. 7 days wk to 5000-5400 cGy; no planned interruptions
The Four "R’s" of Radiation Biology
- Repair: Cells repair DNA damage from radiation in between radiation fractions (doses). Larger radiation doses, radiation sensitizers (e.g. concurrent chemotherapy) partly overcome repair.
- Redistribution: Cells "redistribute" from radioresistant phases (e.g. S phase) of the cell cycle to more radio-sensitive cell cycle phases (e.g. M phase) in between radiation fractions Hyperfractionated radiotherapy (increased number of XRT fractions increases the probability of cells being in M phase during a treatment).
- Reoxygenation: Cells may go from a hypoxic (and thus radioresistant) environment to a well-oxygenated state as a course of treatment proceeds Hyperfractionated radiotherapy; hypoxic cell sensitizers; carbogen or hyperbaric oxygen during XRT.
- Repopulation: Cells may respond to the death of adjacent cells by "accelerated repopulation" Accelerated radiotherapy kills off cells before they gain the opportunity to repopulate.
Glossary of Terms Related to Radiation Therapy
- Adjuvant: Generally refers to postoperative therapy. However, chemotherapy given after "definitive" radiotherapy would also be considered adjuvant.
- Blocks: Thick shields made of a lead-like alloy which can be shaped for each patient to "block" portions of their anatomy that would otherwise fall into the radiation field. In the treatment of head and neck cancer, for example, every attempt is made to block as much CNS tissue as possible.
- Brachytherapy: radiotherapy given in the form of radioactive sources placed directly into or around a patient’s tumor. This may be given interstitially (sources imbedded directly into tissue) or intracavitary (sources laid into a cavity such as the nasopharynx.
- cGy (centigray): A modern basic unit of radiotherapy dose; 1 cGy = 1 rad. One cGy = 100 ergs per gram of absorbed energy.
- Cobalt-60 therapy: A form of external beam radiotherapy in which the source of radiation is not x-rays, but gamma rays emitted from a machine containing radioactive Cobalt-60.
- Conedown: Shrinking the field size sometime during the course of radiotherapy, to take advantage of the decreasing size of tumor during treatment and to minimize the amount of toxicity of treatment. For example, a patient may begin radiotherapy with a 15 x 15 cm field and then have a conedown midway through treatment to a 10 x 10 cm field.
- Conformal Radiotherapy: The use of extremely sophisticated imaging studies and dosimetry to design radiation fields that "conform" precisely to the shape of a patient’s tumor. Conformal radiotherapy usually uses smaller "safety margins" around a patient’s tumor, a larger number of fields, and less prophylactic radiotherapy of clinically uninvolved lymph node areas.
- Consolidative: Refers to radiotherapy given after a maximal or complete response to chemotherapy, as is often done in the treatment of lymphomas.
- Course: A series or program of radiation treatments or fractions with a specific goal in mind for a patient, e.g. a seven-week course of daily radiotherapy to the lung for attempted cure.
- Definitive: Refers to radiotherapy given with the intention of cure without radical surgery. May be given with other non-surgical treatment such as chemotherapy.
- Dosimetry: The process of optimizing the radiotherapy fields and dose by calculating the radiation dose to be received by a tumor and/or normal tissues in a radiation field(s). Physicists and "dosimetrists" work with the radiation oncologist in comparing possible radiation treatment plans with the goal of maximizing the radiation dose to the tumor while minimizing dose to normal tissue, often requiring sophisticated computer programs. Dosimetry can be described as the radiotherapy version of pharmacokinetics.
- External beam radiotherapy (x-ray therapy): radiotherapy given from a machine (usually a linear accelerator) which produces a high-energy x-ray beam which is then aimed at a patient’s tumor and/or suspected tumor areas.
- Field: An area at which a radiotherapy beam is directed, usually described as a rectangular shape, in cm (e.g. 10 x 14 cm). "Blocks" are often used to further customize the shape of a field. A single fraction of radiotherapy may include multiple fields, typically two to four.
- Fraction: A single radiation therapy session, usually given over one to three minutes. A fraction may consist of one or multiple "fields," and any dose, as prescribed by the radiation oncologist. Most courses of radiotherapy involve one fraction per day, Monday through Friday, over one to seven weeks, although an infinite number of possible fractionation schedules are possible.
- Gy (Gray): The SI modern basic unit of radiotherapy dose; 1 Gy = 100 cGy = 100 rad. One Gy = 1 Joule per kilogram of absorbed energy.
- Hyperfractionation (see also fraction): The delivery of two or more radiation fractions per day, generally given with a four or more hour interval between fractions.
- Neoadjuvant: Generally refers to preoperative therapy. However, chemotherapy prior to "definitive" radiotherapy would also be considered neoadjuvant.
- Palliative: Refers to therapy given with the goal of relieving distressing symptoms, without any anticipated effect on survival.
- Prophylactic: Refers to radiotherapy given to a site at which there is no known tumor but which is considered to be at high risk for harboring occult "microscopic" disease, such as lymph node areas.
- Rad: Basic unit of radiotherapy dose; terminology has now changed to the S.I. units (cGy and Gy). 1 rad = 1 cGy (See Gray).
- Radiation Therapy Oncology Group (RTOG): A National Cancer Institute-sponsored multicenter clinical trials cooperative group which performs studies related to radiation therapy, including many lung cancer studies.
- Radiosensitizers: Drugs or other treatments which increase the cellular response to radiotherapy. Many chemotherapeutic drugs have radiosensitizing properties.
- RTOG: See Radiation Therapy Oncology Group.
- Safety Margin: A margin of "normal-appearing" tissue which is added onto the visible tumor area for the purposes of radiation planning. Typically 1.5-2 cm in all dimensions is added, to account for microscopic extension of tumor cells and the possibility of slight patient motion during treatment.
- Simulation: A detailed planning session for radiation therapy, which "simulates" but does not actually deliver a radiation treatment. Simulation consists of immobilization of the patient in an appropriate position for radiation therapy, marking the patient’s skin, localizing the area to be treated under fluoroscopy, taking radiographs of the area to be treated, and taking measurements of the patient’s contour for dosimetry purposes.
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