Conformation therapy using a computer controlled telecobalt unit for advanced cervical carcinoma.

This retrospective analysis evaluates the results of conformation radiotherapy for patients with advanced cervical carcinoma. Between January 1980 and September 1987, 16 patients with high common iliac/para-aortic node metastases from advanced carcinoma of the uterine cervix were treated using conformation radiotherapy. A large area from L1/L2 to the pelvis, with an average length of 23 cm, was treated to a total tumour dose of 5000-5500 cGy, with a daily tumour dose of 180-200 cGy in 28-30 daily fractions, using a computer controlled tracking cobalt unit (CCTCU). Before external beam irradiation, 11 patients underwent laparotomy/hysterectomy, seven were given chemotherapy and eight received brachytherapy. The preliminary results are encouraging. The actuarial 1-year, 3-year and 5-year survival rates after treatment were 81%, 44% and 37%, respectively. The locoregional control rate was 62.5%. None of the patients relapsed in the para-aortic nodes. All patients tolerated the large area of tracking irradiation therapy very well. None had any severe acute or delayed radiation complications. Use of the conformation radiotherapy technique to include the pelvic and para-aortic nodes has been shown to be an effective form of radiotherapy with minimal morbidity.

Incidence of cataracts after single fraction total body irradiation: the role of steroids and graft versus host disease.

Eighty-eight patients who received single fraction total body irradiation (sfTBI) as part of their conditioning for allogeneic BMT have been evaluated for the risk of cataract formation. Thirty-eight (43%) have developed cataracts; 11 required surgery. With 9.5-13.6 years follow-up (median 10.7 years), all 12 recipients of unmanipulated marrow allografts have developed cataracts; the actuarial risk of needing surgery was 32 (+/- 18%, 95% confidence intervals (CI)). Ten of these 12 required high-dose steroids (prednisolone > 1 mg/kg/day) for the treatment of GVHD. Seventy-six patients received T cell-depleted allografts; 14 of 76 required post-transplant immunosuppression with high-dose steroids. With 1-9.4 years follow-up (median 5 years), the actuarial risk of cataract formation in T cell-depleted allograft recipients is 72% (+/- 52% CI), the actuarial risk for needing surgery is 20% (+/- 9% CI). Recipients of sfTBI and non-T cell-depleted allografts had a significantly greater risk of developing cataracts (p = 0.003, long rank test) and of needing surgery (p < 0.05, log rank test) than patients receiving T cell-depleted BM. Cataracts occurred more frequently in patients requiring post-transplant immunosuppression with steroids (relative risk 2.12, p < 0.01 log rank test).

Conformation therapy: a method of improving the tumour treatment volume ratio.

Restriction of the volume irradiated is a fundamental tenet of radiotherapy. Conventional two-dimensional treatment results in geometrically shaped high-dose regions, the sizes of which are defined by the greatest dimensions of a tumour mass. Conformation therapy permits a tumour to be considered for treatment as multiple short segments, and the radiation field to be tailored to fit each segment accurately. This paper demonstrates that this results in a reduction of the treatment volume of between 10% and 80%, depending on the shape of the tumour. Also, it is shown that a greater proportion of the high-dose region is occupied by tumour, thus reducing the volume of normal tissue treated to a high dose. Smaller treatment volumes allow the prescription of tumoricidal doses and improve the tolerance of radiation by patients.

Treatment of medulloblastoma using a computer-controlled tracking cobalt unit.

Radiation therapy of the length of the spinal column presents various clinical and physical problems. The completed plan may be complicated to set up, be time-consuming and require daily variation to achieve reasonable dose homogeneity. A case of medulloblastoma is used to illustrate the steps in producing a plan for dynamic treatment using a computer-controlled tracking cobalt unit. After definition by computed tomography, the target is considered in segments in order to develop a plan which keeps the spinal cord constantly positioned at the beam isocentre. The main computer is used to develop the patient treatment file and information is transferred to a second computer which controls and monitors the safe functioning of the cobalt unit. The cranial fields are treated separately in a conventional way. Good and consistent control of the dose distribution is achieved along the entire target volume. This technique is a marked improvement over all existing methods of treating the spinal axis.

Depletion of T lymphocytes in donor marrow prevents significant graft-versus-host disease in matched allogeneic leukaemic marrow transplant recipients.

For more than 15 years preclinical studies have suggested that acute graft-versus-host disease (aGvHD) might be prevented by the removal of immunocompetent T lymphocytes from the donor marrow inoculum. To test this observation in man 14 patients were given marrows virtually (greater than 99%) depleted of identifiable donor marrow T lymphocytes by the use of a "cocktail" of specific anti-T-cell monoclonal antibodies (MBG6 and RFT8) and rabbit complement. Patients were not given immunosuppressive prophylaxis after bone-marrow transplantation. Moderate to severe (grades II-IV) GvHD was totally prevented. 2 of 13 evaluable patients showed mild (grade I) skin GvHD only. Although peripheral blood recovery was slower than that obtained with other forms of GvHD prophylaxis, no fatal infections occurred. All patients survived the early post-transplant period.

Five years hospital experience with the Amersham caesium 137 manual afterloading system.

The Amersham caesium 137 manual afterloading system for treatment of cancer of the uterine cervix and endometrium has been in use at the Royal Free Hospital for more than five years. The system uses permanently loaded flexible source pencils in combination with standard packs of disposable plastic applicators. Both sources and applicators have proved trouble-free in use. The sources are transported in special containers designed and built at the Royal Free Hospital and are inserted and removed on the ward by nursing staff. A set of sources is used in theatre for rectal and bladder dose measurements when the applicators are inserted. Staff radiation doses are low. The system is mainly used to produce pear-shaped dose distributions similar to those of the Manchester system, but simple cylindrical distributions are possible using symmetrically loaded source pencils.

Conformation therapy at the Royal Free Hospital. A progress report on the tracking cobalt project.

A computer-controlled tracking cobalt unit (CCTCU) was commissioned for treating patients in January 1980. The system has proved to be reliable and acceptable in routine use for conventional and conformation therapy. The system comprises a modified TEM MS90 Mobaltron, a Hewlett-Packard System 1000 Model 30 mini-computer and user programmes. Tracking techniques are suitable for the treatment of tumours of the oesophagus, thyroid, bronchus, chains of lymph nodes or medulloblastoma. Tumours 85 cm long can be treated at the isocentre. The high dose volume may be considerably reduced when tracking techniques are used instead of conventional techniques. The major obstacle to the routine use of conformation therapy is treatment planning. Work in progress is designed to produce a computerized planning system linking a CT scanner and the CCTCU. It is expected that the system will produce both a plan optimized in 3-D and the necessary control data in machine readable form within an hour of a patient being scanned. The present planning system is based on a Rad-8 planning system and an Alderson phantom to verify the dose distribution in 3-D. An outline of the tracking technique is given. The computer control system is described briefly, with its methods of use for treating patients. Brief reverence is made to work at other centres using conformation therapy.