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Biomedical subjects

C A Perez

Publications and source records attributed to C A Perez.

At least 19 recordsLinked to original sources
PubMed1992

Effect of tumor size on the prognosis of carcinoma of the uterine cervix treated with irradiation alone.

The authors conducted a retrospective analysis of 1178 patients with histologically proven invasive carcinoma of the uterine cervix treated with irradiation alone. The minimum follow-up time was 3 years. The 10-year actuarial pelvic failure rate in Stage IB was 6% for tumors less than 3 cm, 15% for tumors 3 to 5 cm, and 30% for tumors more than 5 cm (P = 0.0018). The 10-year actuarial pelvic failure rate in Stage IIA was 10% for tumors less than 3 cm, 28% for tumors 3 to 5 cm, and 20% for tumors more than 5 cm (P = 0.09). Stage IIB unilateral nonbulky tumors (less than 5 cm) had a 20% pelvic failure rate compared with 28% for bilateral lesions and 35% for unilateral bulky tumors (more than 5 cm) (P = 0.35). In Stage IIB, pelvic failures were greater when disease extended into the lateral parametrium (30%) compared with medial parametrial involvement only (17%) (P = 0.01). In Stage III unilateral nonbulky tumors, the pelvic failure rate was 28% compared with 45% to 50% for unilateral bulky lesions (P = 0.002). Bilateral parametrial disease in Stage IIB did not increase the pelvic failure rate (21% in both subgroups) (P = 0.83), whereas in Stage III, bilateral parametrial involvement was associated with a 48% pelvic failure rate versus 28% for unilateral extension (P less than or equal to 0.01). Five-year disease-free survival (DFS) rates for IB tumors less than or equal to 3 cm was 90% versus 67% for tumors more than 3 cm (P = 0.01). In Stage IIA tumors less than or equal to 3 cm, 5-year DFS was 70% versus 45% for tumors more than 3 cm. Patients with Stage IIB nonbulky tumors (less than or equal to 5 cm in diameter) had better 10-year DFS (65% to 70%) compared with those with bilateral bulky tumors (45% to 55%) (P = 0.10). Stage III patients with unilateral nonbulky tumors had a 55% 10-year DFS compared with 35% to 40% for bulky tumors or bilateral parametrial involvement (P = 0.002). The authors concluded that clinical stage and size of tumor are critical factors in the prognosis, therapy selection, and evaluation of results in carcinoma of the uterine cervix.

Age Factors↗
PubMed1992

Postoperative radiotherapy for malignant fibrous histiocytoma.

Between 1974 and 1989, 49 patients with histologically confirmed malignant fibrous histiocytoma received postoperative radiotherapy at the Mallinckrodt Institute of Radiology for primary (41) or recurrent (8) disease. Median age of the patients was 63 years, and the median follow-up period was 41 months. Patients were grouped according to the 1988 AJC staging classification: stage IA (one patient), stage IIA (4 patients), stage IIB (9 patients), stage IIIA (15 patients), stage IIIB (18 patients), and stage IVA (2 patients). Eight tumors (16%) were in the pelvis, 8 (16%) in the trunk, 4 (8%) in the head and neck, and 29 (60%) in the extremities. Primary surgical procedures included incisional biopsy (4 patients), excisional biopsy (19), narrow margin excision (14), wide local excision (9), and removal of the entire compartment (3). Based on pathology reports, the margins of resection were classified as positive in 23 (5 gross, 18 microscopic), 5 close, 11 negative, and 10 unknown. Patients were irradiated with shrinking field technique; the median radiation dose was 6000 cGy, with more than 95% of patients receiving at least 4500 cGy. In addition, seven patients received postoperative chemotherapy. The 5-year overall survival rate was 62%, disease-free survival 64%, local control 68%, and freedom-from-distant metastasis 85%. Thirteen patients had local recurrences, with greater than 75% recurring within 3 years. Sites of local recurrence were as follows: trunk (3), pelvis (3), lower extremities (4), and head and neck (3). There appears to be a correlation of local failure with positive surgical margin: of 23 patients with positive margins, 9 (39%) had local recurrences, whereas 1 of 11 patients (9%) with negative margins had local recurrence. Three of 13 patients with persistent or recurrent disease were salvaged by additional treatment, rendering ultimate local control in 80% (39/49). Thirty-four of 36 patients with local control obtained good to excellent function. Two patients were found to have grade 3 complications: 1 patient had edema of the extremity, and the other developed necrotic skin ulcer that was successfully treated with hyperbaric oxygen. Five patients developed distant metastases, with 80% occurring within 2 years. In summary, adequate but conservative surgery with postoperative radiotherapy for malignant fibrous histiocytoma can achieve local tumor control as well as preservation of functional limbs with acceptable morbidity in a large proportion of patients.

Adolescent↗
PubMed1992

Design and implementation of a microcomputer-based tutorial in radiation oncology.

The design and implementation of a computer-based training system for radiation oncology was undertaken. A frame-based system was chosen, with factual information from Principles and Practices of Radiation Oncology, by Perez and Brady, as the body of knowledge. Each unit of the system was based on a site (chapter) and consists of three sections: text, review questions, and patient management problems. The text section contains text, tables, and references and defines the information upon which the review questions and clinical cases are based. The review questions are multiple choice and true-false, and immediate feedback is given for both correct and incorrect responses. The patient management problems are interactive and provide alternative methods of presenting information and stimulating problem-oriented thought. The emphasis in all sections is on learning rather than testing. Advantages of a computer-based tutorial include the ability to present large volumes of information easily, the capacity for immediate feedback, and the flexibility of format in presentation of material. Potential applications are discussed.

Computer-Assisted Instruction↗
PubMed1992

Distant metastases after irradiation alone in carcinoma of the uterine cervix.

This is a retrospective analysis of 1211 patients with invasive carcinoma of the uterine cervix treated with irradiation alone from 1959 through 1986, of whom 322 developed distant metastases during the course of the disease. The 10-year actuarial incidence of distant metastases was 3% in Stage IA (34 patients), 16% in Stage IB (384 patients), 31% in Stage IIA (128 patients), 26% in Stage IIB (353 patients), 39% in Stage III (292 patients), and 75% in Stage IVA (20 patients). A multivariate analysis of factors influencing the incidence of distant metastases showed clinical stage, endometrial extension noted by dilatation and curettage (D&C) prior to therapy, and pelvic tumor control within each stage to be significant indicators of distant dissemination; histology, volume of disease, and age of patient were not significant. The frequency of metastases in all stages except IVA was greater when endometrial tumor extension was detected by D & C before to definitive irradiation (Stage IB, 28%; Stage IIA, 48%; Stage IIB, 42%; Stage III, 72%; and Stage IVA, 75%). In contrast, with normal D & C findings, the incidence of distant metastases was 15% in Stage IB, 29% in Stage IIA, 25% in Stage IIB, 45% in Stage III, and 84% in Stage IVA. The incidence of metastases in patients with pelvic tumor control was 11% in Stage IB, 22% in Stage IIA, 21% in Stage IIB, 34% in Stage III, and 50% in Stage IVA; in contrast, the corresponding incidence in patients failing in the pelvis was 76% in Stage IB, 88% in Stage IIA, 62% in Stage IIB, 87% in Stage III, and 74% in Stage IVA. The frequency of metastases per histology was comparable in squamous cell carcinoma and other histologic types. The incidence of metastases to other organs was 56%: Most frequent sites were lung, abdominal cavity, liver, and gastrointestinal tract. The incidence of clinically apparent lymph node involvement was 22%, predominantly to paraaortic, supraclavicular, and inguinal nodes. Bone metastases occurred in 16% of the patients, most commonly to the lumbar and thoracic spine. Despite aggressive local therapy with excellent local control, the incidence of distant metastases in patients with invasive carcinoma of the uterine cervix is high. The management of these patients and their response to salvage therapy are discussed. The need for effective adjuvant systemic therapy in the management of patients with invasive carcinoma of the cervix is also discussed.

Female↗
PubMed1992

Source configuration and dose rates for the Selectron afterloading equipment for gynecologic applicators.

This paper describes source train configurations of the Selectron LDR-6 that can be used to duplicate commonly used manually afterloadable source configurations for gynecological intracavitary brachytherapy. We demonstrate that the recommended source configuration using 2.5 mm 137Cs spheres is dosimetrically equivalent to its manually afterloaded counterparts using 3M 137Cs sources (20 mm overall length, 14 mm active length). Isodose distributions are in agreement to within 5% for the Fletcher-Suit-Delclos family of tandems, colpostats, and vaginal cylinders. Our data also demonstrate that the isotropic point source model used by most computerized treatment planning systems is a good approximation to source trains of filtered, spherical sources interspersed with solid steel spacers. We conclude that the use of 2.5 mm 137Cs sources in the Selectron remote afterloading system can accurately reproduce the isodose distribution achieved with linear 137Cs manually afterloaded sources.

Brachytherapy↗
PubMed1992

Carcinoma of the nasopharynx: factors affecting prognosis.

This is a retrospective analysis of 143 patients with histologically confirmed epidermoid carcinoma of the nasopharynx treated with definitive irradiation. Patients were treated with a combination of Cobalt-60, 4 to 6 MV X rays, and 18 to 25 MV X rays to the primary tumor and the upper necks, excluding the spinal cord at 4000 to 4500 cGy to total doses of 6000 to 7000 cGy. At 10 years the actuarial primary tumor failure rate was 15% in T1, 25% in T2, 33% in T3, and 60% in T4 lesions. The corresponding failure rate in the neck was 18% for N0, 14% for N1, and 33% for N2 and N3 lymphadenopathy. The incidence of distant metastasis was related to the stage of the cervical lymphadenopathy: 16% in patients with N0-N1 nodes compared with 40% in the N2-3 node group. The actuarial 10-year disease-free survival rate was 55% to 60% for T1-3N0-1 tumors, 45% for T1-3N2-3 tumors, 35% for T4N0-1, and 20% for T4N2-3 lesions. The overall 10-year survival rate was about 40% for patients with T1-2N0-1 tumors, 30% for those with T3 any N stage tumors, and only 10% for the patients with T4 lesions. Multivariate analysis showed that tumor stage and histological type, cranial nerve involvement, patient age, and doses of irradiation to the nasopharynx were significant prognostic factors for local/regional tumor control. Increasing doses of irradiation resulted in nasopharynx tumor control in 80% of the patients receiving 6600 to 7000 cGy and 100% of those receiving over 7000 cGy in the T1, T2, and T3 tumors. However, the tumor control rate did not rise above 55% even for doses over 7000 cGy in the T4 lesions. Local tumor control was higher in patients who had simulation (55/78 = 71%) compared with those on whom simulation was not performed (34/61 = 56%) (p = 0.10). Moreover, patients with more than 75% of the reviewed films judged as adequate had 69% primary tumor control (66/96) compared with 53% (23/43) for those with fewer than 75% adequate portal films (p = 0.07).

Carcinoma, Squamous Cell↗
PubMed1992

Survival following locoregional recurrence of breast cancer: univariate and multivariate analysis.

Although prognostic variables for locoregional recurrence of breast cancer have been evaluated by univariate analysis, multifactorial analysis has not been previously performed. In the present study, survival following chest wall and/or regional lymphatic recurrence was determined in 230 patients with locoregionally recurrent breast cancer without evidence of distant metastases treated at the Radiation Oncology Center, Mallinckrodt Institute of Radiology and affiliated hospitals. Multifactorial analysis demonstrated that the site of recurrences correlated most strongly with overall survival (p = 0.001). The 5-year actuarial overall survival was 44-49% for patients with isolated chest wall, axillary, and internal mammary lymph node recurrence. Patients with either supraclavicular, multiple lymphatic, or concomitant chest wall and lymphatic recurrence had an 21-24% 5-year overall survival. The 5-year disease-free survival was 28-37% for patients with chest wall, axillary, or internal mammary recurrences compared to 4-13% for those with supraclavicular, chest wall and lymphatic, or those with multiple sites of lymphatic recurrence. Disease-free interval from mastectomy to recurrence was also found to be a significant prognostic factor for overall survival (p = 0.005). Fifty percent of patients with a disease-free interval of at least 2 years survived 5 years following locoregional relapse, compared to 35% for those with disease-free interval of less than 2 years. In the subset of patients with small chest wall recurrences (excised or less than 3 cm) and a disease-free interval of at least 2 years, the 5-year overall and disease-free survivals were 67% and 54%, respectively. These results suggest that subsets of patients with locoregional recurrence of breast cancer can survive for long periods of time. The conventional wisdom that chest wall and/or regional nodal recurrence following mastectomy uniformly confers a dismal prognosis is not necessarily true.

Adult↗
PubMed1992

Comparison of pathologic and clinical evaluation of lymph nodes in prostate cancer: implications of RTOG data for patient management and trial design and stratification.

RTOG 77-06 and 75-06 were studies of nodal irradiation in prostate cancer, for which the status of nodes was determined by lymph node dissection (LND), lymphangiography (LAG), or computer assisted tomography (CT) based on investigator preference. Actuarial 5 year endpoints of survival, NED survival, local recurrence and distant metastasis have been determined by stage for 805 eligible patients with a comparison of pathologic vs clinical (imaging test) determined nodal status. Patients with pathologically negative lymph nodes show significantly improved 5 year survival (Stage T-2 (B) 84% vs 77%, Stage T-3,4 (C) 82% vs 65%) and NED survival (Stage T-2 (B) 72% vs 63%, Stage T-3,4 (C) 64% vs 44%) compared to patients clinically negative. Free of metastasis rates are increased in Stage T-3,4 (C) pathologic negative patients compared to imaging negative patients (75% vs 60%). A comparison of clinical positive versus clinical negative patients shows no difference in survival, NED survival or rate of metastasis, while a similar comparison of pathologic positive versus pathologic negative shows significant difference for all three endpoints (survival: Stage T-2 (B) 84% vs 61%, Stage T-3,4 (C) 82% vs 66%, NED survival: Stage T-2 (B) 72% vs 32%, Stage T-3,4 (C) 64% vs 32%; free of metastasis: Stage T-2 (B) 82% vs 64%, Stage T-3,4 (C) 75% vs 44%). The clinical determination of nodal status, therefore, has no prognostic value in contrast to pathologic determination and should not be used for stratifying patients in clinical trials. The CT scans often used to evaluate nodal status are more useful if delayed until they can be done as part of the treatment planning process where the CT has value. When imaging tests suggest positive lymph nodes in prostate cancer patients, the imaging finding is confirmed by biopsy.

Humans↗
PubMed1992

Clinical stage I endometrial cancer: prognostic factors for local control and distant metastasis and implications of the new FIGO surgical staging system.

A retrospective analysis is reported in 858 patients with clinical Stage I carcinoma of the endometrium treated definitively with combined irradiation and total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) from January 1960 through December 1986. Most patients received a preoperative intracavitary insertion (3500-4000 mgh to the uterus and a 6500 cGy surface dose to the upper vagina) followed by a TAH-BSO within 1-2 weeks. Some patients received postoperative external beam irradiation (2000 cGy whole pelvis and an additional 3000 cGy to the parametria, with a midline stepwedge) when factors such as deep myometrial invasion were present. Occasionally patients were treated with a preoperative intracavitary insertion and preoperative external beam irradiation (2000 cGy whole pelvis). The 5-year progression-free survivals by FIGO (1988) surgical stage were 93% for IA, 90% for IB, and 91% for Stage IC. An analysis of multiple variables was performed to ascertain their prognostic significance. Factors that significantly affected the 5-year progression-free survivals by univariate analysis were grade (grade 1 = 95%, grade 2 = 88%, grade 3 = 73%; p less than 0.0001), histology (adenoacanthoma = 96%, clear cell = 89%, adenocarcinoma = 89%, papillary = 81%, adenosquamous = 80%; p = 0.04), lower uterine segment involvement (uninvolved = 89%, involved = 73%; p = 0.006), depth of myometrial invasion (no residual tumor = 91%, limited to the endometrium = 96%, less than 1/3 myometrial penetration = 92%, 1/3 - 2/3 = 100%, greater than 2/3 = 50%; p = 0.02), peritoneal cytology (negative = 92%, positive = 56%, p less than 0.0001), uterine serosal involvement (uninvolved = 89%, involved = 55%; p less than 0.0001), vascular space invasion (absent = 89%, present = 75%; p = 0.001), and the presence of extrauterine disease (absent = 90%, present = 64%; p less than 0.0001). A multivariate analysis of these prognostic variables showed that histological grade (p = 0.001), peritoneal cytology (p = 0.004), and uterine serosal involvement were prognostic for local failure and that peritoneal cytology (p less than 0.001), grade (p = 0.001), age (p = 0.002), and extrauterine disease (p = 0.02) were prognostic for the development of distant metastasis.

Brachytherapy↗
PubMed1992

Dosimetry and dose specification for a new gynecological brachytherapy applicator.

A new afterloadable gynecological intracavitary applicator has been designed and is now in use for the treatment of a wide range of vaginal, cervical, and endometrial cancers in a single application, with a dose distribution that more closely matches the prescribed treatment than previous methods. The plexiglass applicator consists of a bulbous section that is inserted up to the vaginal apex and loaded with right and left ovoid sources. The distal portion is cylindrical with a central channel for tandem sources. A straight tandem is used when the target volume extends to the vaginal apex, but an intrauterine tandem can also be used. Extensive dosimetric and radiographic evaluations were performed to guide design refinements and to validate the surface dose predictions of the brachytherapy treatment planning system. The final applicator design delivers 110-120 cGy/hr to the vaginal apex surface and 95-100 cGy/hr to the distal vaginal surfaces when loaded with a 144.6 U (20 mgRaEq) cesium tube in each ovoid channel and 72.3, 72.3, and 144.6 U (10, 10, and 20 mgRaEq) cesium tubes in the vaginal cylinder channel. A system for treatment dose specification has been established that includes dose tables for manually calculating surface doses to reference points. A dose distribution comparison with a sequential colpostat-vaginal cylinder treatment demonstrates that dose delivery is more precise and uniform with this new applicator.

Brachytherapy↗
PubMed1992

Combined hyperthermia and irradiation in the treatment of superficial tumors: results of a prospective randomized trial of hyperthermia fractionation (1/wk vs 2/wk).

From December 1984 to December 1989, 240 superficially located recurrent/metastatic malignant lesions (173 patients) were enrolled in a prospective randomized study of one versus two hyperthermia fractions per week. In the majority of patients, the dose of radiation therapy was less than 4000 cGy over 4 to 5 weeks. Stratification was by tumor size, site, and histology. The goal of the hyperthermia sessions were 42.5 degrees C for 45-60 min minimum intra-tumor measured temperature. Hyperthermia was given after radiation within 30-60 min. External applicators, both microwave (over 90% of treatments) and ultrasound, were used. Overall, complete response rate in 222 evaluable lesions was 56.3% (125/222) with a minimum follow-up of 6 months and a maximum follow-up of 52 months. The complete response rate for once a week versus twice a week hyperthermia group was 54.7% and 57.8%, respectively. The severe complication rate was 18% (41/222). There was no difference between the two treatment arms. Cox regression analyses were performed to study the prognostic significance of patient characteristics, tumor characteristics, and treatment parameters. Detailed analysis and results are presented.

Adult↗
PubMed1992

Prognostic significance of pelvic recurrence and distant metastasis in prostate carcinoma following definitive radiotherapy.

This report is a retrospective analysis of 317 patients with recurrent prostate carcinoma, following definitive radiation therapy to 738 patients with histologically confirmed, clinical Stage T1b-T4(A2-D1) adenocarcinoma of the prostate. Seventy-four patients (10%) experienced pelvic recurrence only; 100 (13%) both pelvic recurrence and distant metastasis, while 143 (20%) developed distant metastasis only. The diagnosis of prostate recurrence was histologically confirmed in 92/174 (53%), while in the others diagnosis was based on clinical and radiographic evidence. Ninety percent of all recurrences occurred within 7 years of initial treatment. The median survival from time of recurrence for all patients was 27 months, with 5-, 8-, and 10-year survival rates of 24%, 12%, and 7%, respectively. In patients who experienced pelvic recurrence only, the 5-, 8-, and 10-year survival rates were 50%, 30%, and 22%, respectively (p < 0.0001). The 5-year survival rate from time of recurrence for patients who experienced pelvic recurrence with initial Stage T1b(A2) and T2(B) disease was 71% as opposed to 39% for patients with initial Stage T3(C) disease. The time of recurrence (i.e., the disease-free interval from initial treatment) significantly affected subsequent survival: the 5-year survival rates from time of recurrence for patients with pelvic recurrence were 20%, 49%, and 94% for those who recurred within 2 years, 2 to 5 years, and more than 5 years, respectively. Two-thirds of the patients with recurrence received hormonal therapy, including bilateral orchiectomy. Salvage therapy with hormones, including bilateral orchiectomy, has a favorable impact on patient survival: The 5-year survival rate from time of pelvic recurrence salvaged with hormones was 70% compared with 21% for patients not receiving hormonal therapy. In conclusion, the prognostic factors that affect subsequent patient survival after pelvic recurrence include initial stage, disease-free interval from initial treatment, and salvage therapy with hormones. Patients with distant metastasis with or without pelvic recurrence showed statistically worse survival and were apparently not influenced by initial tumor stage, or disease-free interval from initial treatment.

Adenocarcinoma↗
PubMed1992

The prognostic significance of race and survival from prostate cancer based on patients irradiated on Radiation Therapy Oncology Group protocols (1976-1985).

A number of studies have identified race as a prognostic factor for survival from prostate cancer. To evaluate the prognostic significance of race in a controlled setting, we evaluated 1294 patients treated on three prospective randomized trials conducted by the Radiation Therapy Oncology Group between 1976 to 1985. One-hundred and twenty (9%) of the patients were coded as black, while 1077 (83%) of the patients were coded as white. Protocol 7506 included 607 patients with clinical Stage T3-T4Nx or T1b-T2N1-2. Protocol 7706 included 484 patients with clinical Stage T1b or T2 who were node negative. Protocol 8307 included 203 Stage T2b-T4 patients with no lymph node involvement beyond the pelvis. Univariate and multivariate analyses were used to assess the possible independent significance of race and other prognostic factors, including Gleason score, serum acid phosphatase, nodal status, and hormonal status. Protocols 7706 and 8307 revealed that race was not of prognostic significance for disease-free or overall survival by either univariate or multivariate analysis. Univariate analysis of Protocol 7506 revealed that the median survival for blacks was somewhat shorter (5.4 years vs. 7.1 years, p = 0.02). This difference persisted after a multivariate analysis. A higher percentage of blacks treated on 7506 had an abnormally elevated serum acid phosphatase compared to whites (p = 0.006), and the time to distant failure tended to be shorter (p = 0.07). These findings suggest that blacks treated on 7506 may have had more extensive disease at presentation. Based on these prospective randomized trials, it is most likely that the lower survival noted for black Americans with prostate cancer reflects the tendency for blacks to present with more advanced disease. Differences in access to care, the quality of care received, and the impact of co-morbid conditions may explain the lower survival reported for black Americans elsewhere in the literature.

Black or African American↗
PubMed1992

Locoregional recurrence of breast cancer: a retrospective comparison of irradiation alone versus irradiation and systemic therapy.

The role of systemic therapy in addition to irradiation for locoregional recurrence of breast cancer is controversial. In the absence of prospective randomized trials, treatment decisions must be based on retrospective studies. We retrospectively analyzed 230 patients treated for locoregionally recurrent breast cancer between 1964 and 1986. Forty-seven were premenopausal, 173 were postmenopausal, and the menopausal status was unknown in 10 patients. Each patient treated with radiotherapy (RT) and chemotherapy or with RT and hormonal therapy was matched with a control patient treated with RT alone. The addition of hormonal therapy to radiation therapy significantly improved the 5-year overall survival (50 versus 28%), disease-free survival (37 versus 26%), and distant metastases-free survival (45 versus 29%). No improvement in locoregional control was observed. In contrast, chemotherapy did not confer such survival benefits, but there was a trend towards improvement in 5-year locoregional control (68 versus 50%), p = 0.08. Our data support the use of hormonal therapy along with RT at the time of locoregional recurrence of breast cancer. Although our data suggest that chemotherapy is not routinely indicated, controlled clinical trials are needed to define which subsets of patients, if any, benefit from systemic therapy.

Adult↗
PubMed1991

Reduction in radiation exposure to nursing personnel with the use of remote afterloading brachytherapy devices.

The radiation exposure to nursing personnel from patients with brachytherapy implants on a large brachytherapy service were reviewed. Exposure to nurses, as determined by TLD monitors, indicates a 7-fold reduction in exposure after the implementation of the use of remote afterloading devices. Quarterly TLD monitor data for six quarters prior to the use of remote afterloading devices demonstrate an average projected annual dose equivalent to the nurses of 152 and 154 mrem (1.5 mSv). After the implementation of the remote afterloading devices, the quarterly TLD monitor data indicate an average dose equivalent per nurse of 23 and 19 mrem (0.2 mSv). This is an 87% reduction in exposure to nurses with the use of these devices (p less than 0.01).

Brachytherapy↗