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Biomedical subjects

R R Dobelbower

Publications and source records attributed to R R Dobelbower.

At least 55 records · Page 3Linked to original sources
PubMed1986

125I interstitial implant, precision high-dose external beam therapy, and 5-FU for unresectable adenocarcinoma of pancreas and extrahepatic biliary tree.

Twelve patients with adenocarcinoma of the pancreas and two patients with carcinoma of the extrahepatic biliary tree received combined therapy with 125I implant, precision high-dose (PHD) photon external beam therapy, and systemic 5-fluorouracil (5-FU). The 125I implant delivered 120 to 210 Gy (median 140 Gy). PHD external beam therapy was given with high-energy photons (10, 15 or 45 meVp) and was initiated 4 to 6 weeks postimplant. A dose of 48.6 to 63 Gy was delivered over 5.5 to 7 weeks in 1.8 Gy increments. Six patients received 5-FU, 500 mg/m2 via weekly intravenous bolus injection. No patient was lost to follow-up (range, 3.5-57 months). Acute postoperative morbidity included pancreatic fistula in two patients and gastrointestinal tract bleeding, pulmonary embolism, and cholangitis in one patient each. No patient died of radiation complications. Median survival of the patients with pancrease cancer was 15 months. One patient is alive at 41 months with hepatic metastasis. Satisfactory palliation was observed in patients with pancreas cancer treated with 125I interstitial implant followed by PHD external beam photon therapy and 5-FU. Patient survival did not seem superior to that of patients treated with PHD external beam therapy +/- chemotherapy, a less morbid procedure. Two cases of bile duct cancer treated in similar fashion are presented.

Adenocarcinoma↗
PubMed1983

Predictions of blood flow from thermal clearance during regional hyperthermia.

In order to provide a method for estimation of regional blood flow during hyperthermia, a mathematical model has been developed which employs thermal clearance to measure this physiologic parameter. Limbs of mongrel dogs were heated with 2450 megaHertz microwaves to temperatures of 43 degrees C, 45 degrees C, or 47 degrees C and thermal washout was measured at five minute intervals throughout each treatment period. Calculated blood flow indicates that in response to heat challenge, normal tissue compensates by increasing regional blood flow within the treatment volume. This increase in blood flow continues to a maximum value after which the blood flow begins to decrease. Data indicate that the time for maximum increase in blood flow (induction time) decreases as treatment temperature increases. These induction times were 40 minutes, 25 minutes, and 15 minutes for treatment temperatures of 43 degrees, 45 degrees, and 47 degrees C, respectively. The data also show that the calculated value of peak blood flow is directly related to treatment temperature. Calculated peak blood flow values reached 37.8, 59.0, and 183.0 ml/minute/100 grams of tissue during 43 degrees, 45 degrees, and 47 degrees C, hyperthermia, respectively. It is suggested that a therapeutic advantage could be gained by treating tumors for a specific length of time during which the blood flow in adjacent normal tissues continues to increase. This would take maximum advantage of normal tissue's ability to compensate for increased temperature, and would exploit any decreased ability of tumor tissue to perform this same function.

Animals↗
PubMed1982

Pancreatic tumours in patients with previous malignancy.

One hundred and ten patients were seen in the Department of Radiation Therapy at Thomas Jefferson University Hospital for pancreatic tumours between January 1975 and June 1980. Twelve patients had previously been treated for a non-pancreatic malignancy. Pancreatic biopsies were performed in nine patients and were interpreted as pancreatic carcinoma. When the previous pathological material was compared to the pancreatic biopsy, the diagnosis was changed in five of the 12 patients to recurrent non-pancreatic malignancy. We emphasise the importance of the distinction between primary pancreatic malignancy and metastatic disease in the pancreas.

Adenocarcinoma↗
PubMed1982

Combined pre and postoperative radiation for carcinoma of the rectum.

Since 1976, a new approach to adjuvant radiation therapy in carcinoma of the rectum has been used at Thomas Jefferson University Hospital. Seventy-eight patients with biopsy-proven invasive carcinoma of the rectum have been treated with low dose preoperative radiation, 500 rad given either on the day of or the day before surgery. Following surgery, the lesions were pathologically staged according to Astler-Coller's Modification of Duke's staging. Patients with good prognostic features (Stage A or B1) were followed with no further treatment while patients with poor prognostic characteristics (Stage B2, C1 and C2) were treated with aggressive postoperative pelvic radiation, 4500 rad delivered in five weeks. All patients entered into this study received the preoperative dose of 500 rad. Fifty-six patients underwent an A-P resection, four patients underwent a low anterior resection and ten patients had a combined abdominal transsacral resection. Eight patients were found to have liver metastasis at laparotomy and underwent a colostomy followed by palliative therapy. Twenty-nine patients were found to have early disease, Stage A or B1, and were given no further therapy. Of 41 patients with Stage B2 or C, 25 patients received the full course of postoperative radiation. Sixteen patients did not receive postoperative radiation for a variety of reasons. Follow-up in these patients ranges from six months to a maximum of 48 months with a median follow-up of 18 months. Sixty-nine of the total group of 78 patients are currently alive. Two patients with early tumor (Stage A or B1) have died of metastasis. One other patient with Stage A carcinoma died of unrelated causes. Two of the 25 patients receiving postoperative radiation developed metastatic disease, but none of the patients developed local recurrence in the pelvis. Six of 16 patients who should have received postoperative radiation, but did not recurred. Four of these six recurrences have been in the pelvis. Both the incidence of failure and the pattern of recurrence between these two groups of patients who did not receive postoperative radiation is suggestive of a better effect in the PR unrelated group. Survival of patients treated with this approach appears to be improved.

Follow-Up Studies↗
PubMed1981

Current radiotherapeutic approaches to pancreatic cancer.

Adenocarcinoma of the pancreas is not a radioresistant neoplasm, as was once believed. The data now suggest that in some instances this cancer may be radiocurable. This fact seems to justify the risk of pancreatic biopsy even in the face of unresectable disease, for it is well known that many benign conditions imitate pancreatic cancer. Clinical benefit from radiation for pancreatic cancer treatment is dose related. Careful delineation of tumor margins, precision treatment planning, and precision dose delivery can minimize damage to adjacent normal tissues. Interstitial implantation and intraoperative electron beam therapy are being studied as methods of accurate dose delivery for pancreatic cancer. Fractionation studies and high LET studies are in embryonic stages. Combined modality regimens may have much to offer in terms of improved palliation and survival for patients with localized adenocarcinoma of the pancreas.

Adenocarcinoma↗
PubMed1978

Pancreatic carcinoma treated with high-dose, small-volume irradiation.

Eighteen patients with unresectable ductal adenocarcinoma of the pancreas received definitive, high-dose, small-volume radiation therapy. All patients had at least one laparotomy, at which time a biopsy was obtained, radio-opaque clips were placed to define the extent of the gross tumor, and usually some form of bypass procedure was performed. External-beam irradiation was delivered from a 45-MV betatron to an area encompassing the clipped tumor volume plus a 1 to 2 cm margin. A three-field technique, employing opposed lateral 45-MV photon beams and an anterior "mixed beam" (50% 45-MV photons and 50% 15- to 35-MeV electrons), was used to treat 13 of the patients. The choice of electron energy used for these patients was based on the depth of the posterior margin of the target volume. Five patients were treated by either four-field "box" or three-field, 45-MV photon techniques. Minimum tumor dose was 6300-6700 rads delivered in 180-rad fractions in 7-9 weeks. With the three-field technique, all fields were treated daily; with the four-field technique, two fields were treated daily. The projected survival rate 12 months post idagnosis is 59%, with the median length of survival, 11.8 months. Seven patients are alive 11.5 to 57 months after diagnosis, all clinically free of disease. Treatment has been generally well tolerated, and there have been no severe late radiation complications. This therapeutic modality appears capable of producing improved palliation, if not offering definitive radiotherapeutic management of localized unresectable carcinoma of the pancreas.

Adenocarcinoma↗
PubMed1978

Betatron therapy for unresectable pancreatic cancer. A preliminary report.

Nineteen-patients with unresectable but localized ductal adenocarcinoma of the pancreas were treated with definitive high dose, small volume, external beam radiotherapy with promising results. The tumors of all patients were histologically confirmed. A 45 MV betatron was used for radiation of the clipped tumor volume plus a 1 to 2 cm margin. Fourteen patients were treated by a three-field technic with the use of opposed lateral photon beams and an anterior mixed photon-electron beam. Five patients were treated with either a four-field "box" or a three-field photon technic. Tumor doses of 5,900 to 6,700 r were delivered over seven to nine weeks. The twelve month survival rate after diagnosis is 53%. This compares favorably with published reports of patients treated surgically for cure. Four patients are alive 18.5 to 64 months after diagnosis. Three are clinically free of disease. Treatment has been well tolerated and there have been no significant radiation complications.

Adenocarcinoma↗
PubMed1975

The effect of age on the long-term response of bone marrow to local fractionated irradiation.

The in-field long-term progressive response of bone marrow to localized fractionatedradiation to the thoracic spine was observed in weanling and adult rats. Total dose levels were 1800,3600 and 5400 rads given in daily fractions of 180 rads for 900 rads perweek, to simulate the clinical setting. Animals were sacrificed at 4 1/2, 6, 8, and 10months after irradiation, and bone marrow from within the treated area was ezamined. The juvenile marrow repopulated to higher levels of cellularity and after higher doses of radiation than the adult. The degree of marrow depletion, time of repopulation, and ultimate level of repopulation after cessation of irradiation were all dependent on the total dose. Some of the suggested clinical implications include re-evaluation of the lower doses given to children.

Age Factors↗