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In this study, we focus on the clinical and dosimetric aspects in the treatment of cancer of the cervix by brachytherapy, particularly through the dose distribution using the Manchester (prescription point A) and the method recommended by the ICRU-38 (International Commission on Radiation Units and measurements, Report No. 38) which advocates the dose prescription in terms of volumes to be processed. We used these methods for the choice of the reference isodose, also to estimate the dose at organs at risk. The results show differences between these dosimetrics methods. However, the method recommended by the ICRU-38 seems more realistic for the choice of the reference isodose [1-5]. By cons, to protect organs particularly monitored namely the bladder and rectum, the ICRU-38 recommendations’ and Manchester system shows that doses are significant but still below the tolerance dose [6].

Two diametric systems applied for twenty-three (23) patients with cervical cancer, treated with brachytherapy (60 Gy) in three (03) anticancer centers.

Method 1

Manchester System (Paterson-Parker 1948) specifies the dose at two points called: Manchester point A and B (Figure 1), it also evaluates the dose to organs at risk points precisely the bladder and rectum [6].

Figure 1: The Manchester a point.

Method 2

The ICRU-38 report, recommended for the description of the dose distribution according to the dimensions of the treated volume (in front dw and dh (Figure 2) and dt in profile (Figure 2), and the dose at points of critical organs (bladder, rectum, pelvic wall and lymphatic trapezoid Fletcher) [1-5].

Figure 2: a) Front treated volume dimensions b) Profile treated dimensions.

Choice of reference isodose

Our results (Figure 3) show that the reference isodose calculated on the basis of the recommendations of the ICRU 38 and the three centers are higher than those recommended by the application of the system in Manchester [7-10]. In other dosiemetric terms, we asserted that the best prescription is based on the ICRU-38 due to the inclusion of volumes, while the Manchester system based on the prescription point A shows a under dosing a large part of the tumor volume and this, notwithstanding the fact that at the clinical level, we do not have hindsight to detect a biological effect.

Figure 3: Comparaison of the two dosimetric methods for the three centers.

Dose to organs at risk

Our results (Figure 3) show for the organs carefully monitored namely the bladder and rectum, the doses are significant but still below the tolerance dose (70 Gray), except for the rectal dose in the center C due to lack of rectal probe.

Doses to specific points in the pelvic wall and lymphatic trapezoid fletcher

Our results (Figure 3) of doses to specific points of the right and left pelvic wall and lymphatic trapezoid Fletcher show that the values are around (10 Gray). Dosimetrical, this is consistent with the literature, but it is important to have such assessment which actually allows estimating the dose to add possibly by radiotherapy if the radiotherapist finds a balance shown by the review of pathology after .

Both methods have significant differences in the choice of the reference isodose three centers. However, the method that best approximates clinical reality for the choice of the reference isodose is that recommended by the ICRU-38.

Both methods show that received doses to organs at risk are within tolerance.Despite this, the role of the radiation therapist for this type of treatment is still important.

I express my sincere thanks and deep gratitude to all members of the three radiotherapy centers for has agreed to guide my work and have made me the pleasure of enjoying for their experience and their skills.

Centre A: Centre Pierre et Marie Curie (CPMC), Algers, Algeria.

Centre B: Centre Anti Cancer (CAC), Blida, Algeria.

Centre C: Hôpital Central de l’Armé (HCA), Ain Naadja, Algers, Algeria.

Cology, Accra, Ghana. (1998).