Osteoradionecrosis of the hyoid induced by combined modality therapy for laryngeal carcinoma.

Contemporary management of laryngeal carcinoma often incorporates multiple modalities of therapy. We report a case of osteoradionecrosis of the hyoid bone in a patient treated with surgery, chemotherapy, and radiation therapy for a supraglottic squamous cell carcinoma. A discussion regarding pathophysiology, radiation dosimetry and treatment options is also presented.

Adjuvant external beam therapy for pathologic stage I and occult stage II endometrial carcinoma.

Eighty-six patients with pathologic Stage I or occult Stage II carcinoma of the endometrium and myometrial invasion and/or Grade 2 or Grade 3 histologic condition received whole-pelvis external radiation therapy (RT) after extrafascial total abdominal hysterectomy and bilateral salpingo-oophorectomy. Twenty-one patients received 4250 cGy in 25 daily fractions for 5 weeks (Group 1), 28 received 4500 cGy in 25 daily fractions for 5 weeks (Group 2), and 37 received 5100 cGy in 30 daily fractions for 6 weeks (Group 3). Seventeen patients had intravaginal brachytherapy after whole-pelvis RT. Local recurrence developed in two patients (2.3%) (one in Group 1 and one in Group 2). Statistical analysis showed that the depth of myometrial invasion significantly influenced survival (P = 0.016). Tumor grade, pathologic stage, whole-pelvis radiation dose, and the use of brachytherapy did not influence survival. Complications occurred in 9.5% of patients in Group 1, 24.7% in Group 2, and 40.5% in Group 3. Three patients who received brachytherapy had rectal injuries. The authors conclude that 4250 cGy in 25 fractions for 5 weeks of whole-pelvis RT appears to induce fewer complications than higher doses, and may be sufficient to prevent local recurrence in most patients who require adjuvant RT. A clinical trial is needed to determine the optimum dose-time-fractionation regimen.

Sacral plexus injury after radiotherapy for carcinoma of cervix.

A 42-year-old woman developed lower extremity weakness and sensory loss 1 year after external and intracavitary radiotherapy for Stage IB carcinoma of cervix. She has been followed for 5 years posttreatment, and the neurologic abnormalities have persisted, but no evidence of recurrent carcinoma has been found. We believe this to be a rare case of sacral plexus radiculopathy developing as a late complication after radiotherapy. Suggestions are made for improving the radiotherapy technique to prevent this complication in future cases.

Bladder and rectal complications following radiotherapy for cervix cancer.

One-hundred and thirty-two patients with cervix carcinoma who were treated with whole pelvis irradiation and two intracavitary applications had bladder and rectal dosimetry during brachytherapy with contrast agents placed into the bladder and rectum prior to orthogonal simulator radiographs. Doses were computer calculated at points A and B, F (bladder), R1 (rectum), and R2 (rectosigmoid). Late occurring bladder and rectal complications were graded on a severity scale of 1 to 3, and 14% had grade 2 or 3 injuries (9% developed fistulas). Statistical evaluation of the data showed that severe bladder and rectal injuries occur more commonly in stage IIIA and IIIB disease and in those receiving high external beam doses (5000 rad +). Analysis of variance tests revealed a significant correlation of brachytherapy dose to points R1 and R2 with severe rectal injuries but there was not a correlation of dose to F with bladder injuries. Nor was there correlation of injuries with dose to point A or the milligram-hour dose. We conclude that our technique for rectal dosimetry is adequate but that an improved technique of bladder dosimetry is needed. Also, when combining whole pelvis irradiation with two intracavitary applications (4000 rad to point A), the whole pelvis dose should probably not exceed 4000-4500 rad.

The preservation of ovarian function in young women undergoing pelvic radiation therapy.

Because cervical carcinoma rarely metastasizes to the ovaries, it became logical to preserve ovarian function by the method of lateral ovarian transposition as part of the management of young women with this disease. This technique prevents castration should subsequent radiation therapy be planned or become necessary. Forty patients with carcinoma of the cervix or vagina underwent unilateral or bilateral ovarian transposition. Eighteen patients received radiation therapy. Of these, 16 had gonadotropin measurements and only 6 (37%) had levels elevated to the postmenopausal range. If patients whose ovaries were not shielded or who received paraaortic radiotherapy are excluded, then only two (17%) had elevated gonadotropin values. It is concluded that, if properly performed, lateral ovarian transposition and ovarian shielding will protect ovarian function in patients receiving pelvic radiotherapy.

Weight loss during pelvic irradiation: cobalt-60 vs. 10 MV.

The effect of radiotherapy treatment unit and technique on body weight loss during 5 to 6 weeks of pelvic irradiation was assessed in 129 patients with cervix or endometrial cancer. The patients treated with the 60Co APPA technique lost 2.91 +/- 2.28 percent, whereas the patients treated with the 10-MV APPA technique lost only 1.30 +/- 2.58 percent (P = 0.003). The patients treated with the 60Co "box" technique lost 4.36 +/- 3.85 percent and the patients treated with the 10-MV "box" technique lost 2.00 +/- 2.69 percent (P = 0.04). Patients treated with 60Co experienced more nausea during treatment than the 10-MV patients but the incidence of diarrhea was similar for the treatment units. Weight loss during radiotherapy was somewhat greater for cervix patients and for patients having advanced disease but was not adversely affected by previous pelvic surgery. We conclude technical factors such as treatment unit and technique can influence the amount of weight lost by patients during pelvic irradiation.

An inexpensive variable-frequency microwave system for hyperthermia.

A microwave hyperthermia system is described which uses surplus communications equipment. The most costly components of the microwave system, the signal generator and amplifier, were obtained through the Federal Surplus Supply System. The cost of the entire system, including 2450 MHz applicator and temperature monitoring system, is under $1200. Extensive testing has demonstrated the capability of heating several cm3 mouse tumors to a temperature of 42.5 degrees C. Depth of heating can be varied by adjusting the frequency of the oscillator or by adjusting the output attenuator.

Thin-walled parallel plate ionization chamber for use with photon and electron beam dosimetry.

The design and construction of a thin-walled parallel plate ionization chamber is described. The chamber makes use of a sputtered collecting electrode. The characteristics of this chamber include low leakage (less than 10(-13) A), no stem effect, and reproducibility within 1%. No polarization effects have been seen for electron beams over an energy range 7-25 MeV while for cobalt 60-25 MV photon beams, it is only 10%-15%.

Tumor sterilization following high-dose pre-operative irradiation for advanced cancer of the larynx or pyriform sinus.

Twenty-two patients with advanced laryngeal cancer and 5 with advanced pyriform sinus cancer were given 51 Gy (5,100 rad) followed by surgical resection. In 10 (45%) of patients with laryngeal cancer, no tumor was found at the primary site pathologically; 15 (68%) had negative neck specimens. All of those with pyriform sinus cancer had positive specimens. Eighteen patients with laryngeal cancer are free of disease. In contrast, only 1 with pyriform sinus cancer is free of disease; 1 has had a local recurrence and 3 have had metastases. The data suggest that 51 Gy (5,100 rad) are insufficient to sterilize pyriform sinus cancer; higher doses together with adjuvant chemotherapy are needed.

Stereo-photogrammetry for the determination of patient surface geometry.

A stereo-photographic system has been developed with which surface contours of a human subject may be obtained rapidly and objectively. Nonmetric cameras are used and the results are obtained from direct measurements of the photographs. Software has been developed for interpretation of the photographic data with the assistance of a small computer and desk-top digitizer such as those routinely used in radiotherapy treatment planning. With the system the coordinates of a point on the subject may be determined with an accuracy of +/- 1-2 mm.

A method of increasing the linear activity of 192Ir sources for interstitial implantation.

The authors suggest that low-intensity 129Ir wires be twisted together to increase linear activity and dose rate for interstitial implantation. This technique saves time and expense for the patient and reduces radiation to personnel.

"Measurements of surface dose using build-up curves" obtained with an extrapolation chamber.

Surface dose was measured in an extrapolation chamber and was found to be less than previously reported. The slope of the build-up curve was less steep with the Clinac 4 than with 60-Co and much steeper with the Clinac 35 at 25 MV than with the betatron at the same energy. The gradient of the depth-dose curve in the build-up region is probably the best indicator of skin damage.

Build-up region of megavoltage photon radiation sources.

Measurements of surface dose and build-up have been measured for photon radiation sources with maximum energy from 1.2 to 25 MeV. A variable volume ionization chamber was used and the results extrapolated to what would be obtained with a zero volume chamber. The results are found to depend systematically on the plate separation of a parallel plate ionization chamber and an empirical method was derived for correcting measurements made with a fixed volume chamber. The relationship of dose build-up curves with skin reactions in radiation therapy patients is discussed.