[Beep] [National Library of Medicine, HF 1492] [This transfer made: 06/12/06. Length: 00:25:17] [Screen goes dark] [Focus Picture] [Narrator:] This leader allows the projectionist to complete adjustments before presenting the film. This voice has the same intensity and tone quality as the sound on the film which follows. [Adjust Volume and Tone] [American Cancer Society Professional Educational Film] [Radiation Therapy in the management of Cancer. MCMLXX American Cancer Society, Inc.] [Consultant: Walter T. Murphy, M.D., Chief, Dept of Radiation, The Buffalo General Hospital, Buffalo, New York] [A radiologist places X-rays on a screen to be read.] [Narrator:] The management of cancer involves the services of several disciplines. Utilizing the judgment and skills of the surgeon. The pathologist. The internist. And the radiation therapist. At the very outset, it is important to determine which modality of treatment, or combination, will most likely benefit the patient. And whether treatment is to be given with intent to cure, or for palliation. Radiation doses and treatment schedules vary greatly depending upon therapeutic aims. And the radiation therapist, like the surgeon and chemotherapist, is guided by the classic dictum, "First do no harm". The objective: to deliver a cancerocidal dose to the tumor with the least possible damage to the surrounding tissues. In outlining a treatment plan, the therapist considers many factors. The general status of the patient. The type and location of the tumor. Its volume. Its expected response to radiation. These and other physical and biological factors will govern the selection of the appropriate type of radiation. Isodose charts showing the penetration of the beam for a given energy, will help verify the suitability of the radiation for the particular location of the tumor. Radiation therapy uses a variety of equipment, providing a wide spectrum of wavelengths and penetration characteristics. This low voltage, 100 kilovolt unit is suitable for treating superficial, thin lesions, such as this basal cell carcinoma. The 100 kilovolt unit produces soft x-rays of low penetration, which deposit most of their energy in the first few centimeters of tissue. Generators in the 250 to 300 kilovolt range produce x-rays of somewhat greater penetration, useful for treating superficial thick lesions; as for example, this tumor of the carotid gland. Megavolt -- million volt equipment -- produces still harder, more penetrating radiation. A two million volt machine, such as this resonant transformer, is suitable for treating deeper lesions. Here, used to irradiate paraaortic lymph node metastases, in a patient with a testicular carcinoma. Six million volt x-rays are produced by this linear accelerator. With a betatron, 35 or even 45 million electron volt x-rays can be obtained. The penetration achieved with these high energies permits treatment at depths beyond the effective reach of lower energy beams as seen in this comparison. As noted earlier, the energy from a low-voltage, 100 KEV unit is quickly absorbed. And does not penetrate much beyond the superficial tissues. With approximately eight percent of the maximum dose measurable at a depth of 10 cm. Approximately 35 percent of the maximum dose reaches this level with 250 KEV radiation. The two million volt generator delivers approximately 50 percent of its maximum dose at this depth. The six million volt linear accelerator delivers 70 percent, and the 35 MEV betatron delivers a full 85 to 90 percent of its dose maximum at 10 centimeters. Isodose charts used by the therapist in planning treatment show the dose distribution in percentages of the maximum dose for a given energy at various depths below the skin's surface. Each chart identifies the modality, the source skin distance, and the field size. The penetration of these high energy beams permits effective irradiation of deep-seated tumors. In addition, at higher energies, the edges of the beam are sharp because these highly energetic x-rays are not significantly scattered by the irradiated tissues either backward or laterally, as is the case with low-energy radiation where there is significant scatter outside the field. The more sharply defined edges of the high energy beam confine the radiation more precisely to the treated area. Another advantage of high-energy radiation is that the maximum dose is not reached at the skin's surface, but at varying depths beneath it . so that skin reactions are not a limiting factor. High energy ionizing radiation in the megavolt range can also be obtained with relatively simple equipment using radioactive isotopes such as Cobalt60. The Cobalt60 unit emits gamma radiations, which are similar in penetration to x-rays produced by a three million volt generator. The gamma radiation from isotopes is indistinguishable from electrically-produced x-rays of the same energy. Of all high energy installations in use today, more than 80 percent are Cobalt60 units. Here, used to treat the patient with Hodgkins Disease. The quantity of emitted radiation is expressed in roentgens, a unit of measure of ionization in air. However, the amount of energy absorbed in tissue is measured in rads, the unit of radiation absorbed dose. One rad equalling 100 ergs of energy absorbed per gram of tissue. Absorbed dose, however, varies with tissue composition and radiation energy. As illustrated in this x-ray film, at low energies -- 250 KEV or less -- there is a significant difference in absorption between soft tissue and bone. because of the greater absorption of energy by the denser, skeletal tissues. At higher energies, this absorption differential does not exist, and the amount of energy absorbed by bone and soft tissue is about equal. This allows treatment to cancerocidal doses in the vicinity of bone without producing bone damage because of increased absorption. This side-by-side comparison shows the difference in absorption at low and high energies. The effects of radiation are initiated by the interaction of the x-rays or gamma rays with the orbital electrons of the tissue atoms. The displaced electrons and scattered photons cause increasingly large numbers of ionizations as they penetrate the tissue. The released electrons act as chemically reactive reducing substances, forming free radicals and producing chemical damage, including damage to DNA. Damage to DNA may be reparable, or may result in cell death -- clinically observable as tumor shrinkage. The initial manifestation of cell death often occurs at the time of mitosis. This cell, which has previously been irradiated, is about to divide. At first it appears normal. However, as cell division proceeds, the chromosomes tend to clump together, and a chromosome bridge can be seen to connect the two potential daughter cells. This abortive division is one of a number of manifestations of lethal cell damage following irradiation. In general, the sensitivity of a cell to the effects of radiation seems largely related to its mitotic activity. Cells which are mitotically most active are usually the most radiosensitive, illustrated here by this poorly differentiated, squamous cell carcinoma of the nasal pharynx. Among the most radiosensitive tumors are the malignant lymphomas and leukemias. Undifferentiated, squamous cell carcinomas and germinal tumors such as seminomas and dysgerminomas. Moderately radiosensitive are the well-differentiated squamous cell carcinomas of the skin and mucus membranes. Adenocarcinomas and some sarcomas. Relatively radio-resistant tumors include osteogenic sarcomas, malignant melanomas, and some gliomas. Radiosensitivity of a tumor however, is not necessarily related to curability, since tumors with a high degree of radiosensitivity are often those which also show marked anaplasia, aggressive growth, and wide dissemination. In fact, the chances for cure of a cancer by irradiation depend mainly on its location, its size and accessibility, its biological behavior, and probably on immunological factors. The general condition of the patient is of considerable importance, and can significantly influence the patient's tolerance to irradiation. Cancer of the cervix is a classic example in which radiation therapy is given with the intent to cure. With irradiation as the principal treatment modality, recent five-year survival rates free of disease were reported by a major institution as follows. This patient was initially examined by her referring gynecologist, who biopsied a lesion on the cervix. Examination of the biopsy specimen showed a moderately differentiated, squamous cell carcinoma. And she was referred to the radiation therapist for consultation. The cystoscopic examination and intravenous urogram were within normal limits. Blood count and chemistries were also normal. Vaginal examination revealed a normal-sized, slightly anteflexed uterus with a tumor involving the external cervical os and extending into the left fornix. On rectal/vaginal examination, the lesion is felt to involve the medial aspect of the left parametrium without reaching the pelvic wall, classifying this as a stage 2B tumor. In order to plan the treatment, certain measurements are needed. The anterior/posterior diameter is measured and recorded on plotting paper. The contour of the pelvis is then obtained with lead tape, and is also traced... and superimposed on the appropriate isodose chart. Treatment will be given through two opposed fields. The dose contribution of the anterior field is plotted. And then that of the posterior. This will result in a relatively homogenous dose distribution in the volume to be treated, avoiding regions of overdosage or underdosage. Compounding of the doses contributed by each field results in these summation curves. The limits of the treatment field are outlined on the skin and entered in the patient's treatment chart. She will receive daily treatments of 200 rads through both the anterior and posterior fields, until a tumor dose of about 4,000 rads has been reached, well within the tolerance of the normal pelvic tissue. Fractionating the total dose into small increments over a protracted period results in greater dose tolerance and favors recovery of the noncancerous tissues. The field size is optically simulated, using a beam collimator, which is adjusted to conform with a treatment field. And the treatment is started. If there are no interruptions in the treatment schedule, the goal of 4,000 rads will be obtained in approximately four weeks. On the last day of cobalt therapy, the left parametrium has returned to almost normal consistency. And the lesion at the cervical os is now visible as a small, whitish area of neurotic tumor tissue. Treatment will be completed with intravaginal and intrauterine radium therapy. This permits delivery of a very high dose to the central, most resistant part of the lesion. And simultaneously increases the dose to the lateral, pelvic tissues. A tumor dose of the level attained by this method cannot be reached by external radiation alone. After cervical dilatation, a tandem is inserted into the uterine canal. Followed by colpostats placed into the lateral fornices. The position of the radium-containing applicators is verified radiographically. These films permit calculation of the exact dose delivered to the tumor and adjacent structures. Examination after completion of the full course of treatment shows the healed cervix. Radiation therapy with a goal of palliation is exemplified in this patient with a six- month history of difficulty in swallowing solid foods, and recent weight loss. The esophagram demonstrated a mid-thoracic, obstructive lesion, which on biopsy proved to be a squamous cell carcinoma. Treatment will be given by rotating beam technique. On a contour of the patient's chest, radii are drawn from the axis of rotation to the skins surface. The axis is located at the exact center of the tumor. The radii will be used in the computation of the summation curves. These indicate a maximum dose region surrounding the tumor, and a much lower dose to the adjacent organs. The chances for cure in carcinoma of the esophagus are statistically very small since metastases are frequently present when the cancer is diagnosed. Nevertheless, one can usually obtain significant palliation with radiation therapy. This split-screen comparison shows the grossly normal appearance of the esophagus, approximately one month after the end of treatment. In addition to its use as a primary modality of treatment, radiation therapy can be effective in combination with other types of therapy. For example, children with Wilms Tumor show a higher survival rate when radiation therapy is used, in addition to surgery and chemotherapy. In this post-operative patient, irradiation may limit metastatic spread by destroying any cancer cells which may have been left behind in the renal bed. In some cases of this disease, preoperative irradiation is given in an effort to destroy tumor cells which might be disseminated at nephrectomy. In recent years, the combination of surgery, radiation, and chemotherapy has resulted in a dramatic increase in survival rates in Wilm's Tumor. Radiation therapy also has a major role in the treatment of many other types of cancer. In a patient with carcinoma of the larynx, with a lesion limited to one or both chords and no fixation, radiation therapy can offer a cure and has the advantage of preserving the voice. This patient received a course of Cobalt 60 therapy over a period of 43 days. One month after completion of treatment, laryngoscopy showed no evidence of residual tumor. As with all patients treated by irradiation, this man is now seen regularly for follow-up examination. [Physician:] Mr. Benkowsky you feel well? [Mr. Benkowsky:] Yes sir. [Physician:] How long has it been now? About five years since [inaudible] -- [Mr. Benkowsky:] Five years -- five years, longer than that... [Physician:] Mm-hmm. And your voice stays strong? [Mr. Benkowsky:] Oh yes. Strong enough all the time. [Physician:] And how about the swallowing? [Mr. Benkowsky:] The swallowing is okay. [Physician:] You want to take your dentures out and put them into this? [Mr. Benkowsky:] Oh sure, I'll do that. I can do that. [Mr. Benkowsky:] Yes. [Physician:] Now open your mouth up wide. Now stick your tongue out and let me see it. All right. Now say "E". [Mr. Benkowsky:] "E". [Mr. Benkowsky:] "E". [Physician:] Say "E" again. [Mr. Benkowsky:] "E". [Mr. Benkowsky:] "E" . [Physician:] Very good. That's fine. [Narrator:] Whether used with the intent to cure, or with the intent to palliate... Alone, or in combination with other treatment modalities, radiation therapy has a major role in the management of cancer. In fact, at some time in the course of treatment, at least 50 percent of patients with cancer can benefit from radiation therapy. About half of these treated for cure, and half for palliation. [Radiation equipment is switched on and a regular ticking/knocking sound is heard.] [Images of different types of cancers pre- and post-treatment are shown.] [Images fade out; ticking stops.] [This film was made possible by a special grant from the New York State Division, American Cancer Society] [The American Cancer Society gratefully acknowledges the assistance and cooperation of] [Yehuda G. Laor, M.D. The Buffalo General Hospital, Buffalo, New York] [John Webster, M.D., Roswell Park Memorial Institute, Buffalo, New York] [Charles Botstein, M.D., George Schwartz, M.D. Montefiore Hospital and Medical Center, Bronx, New York] [John Boland, M.D., The Mount Sinai Hospital, New York, New York] [Produced by Campus Film Productions, New York, N.Y.] [Radiation Therapy in the Management of Cancer] [American Cancer Society Professional Educational Film] [Film ends]